Lisard Torró
email: lisardtorró@hotmail.com

Andrea Julieta Millán-Nuñez

Diego Benites

José María González-Jiménez

Oscar Laurent

Lorenzo Tavazzani

Jean Vallance

Cyril Chelle-Michou

Joaquín A Proenza

Carlos Flores

José María González-Jiménez

Joan Carles Melgarejo

Silvia Rosas

Lluís Fontboté

E Compañía

Minera San

Ignacio De Morococha

S A A ( Simsa

Calle Manuel Gonzales

Germanium-and gallium-rich sphalerite in Mississippi Valley-type deposits: the San Vicente district and the Shalipayco deposit, Peru

Keywords: Critical raw materials, high-tech elements, by-product, Zn-Pb deposits, Andes, mineral color

come

Introduction

Germanium and gallium are considered critical raw materials by the European Commission (2020) due to their high economic importance and risk of supply. Germanium is mainly used in infrared optical devices, fiber-optic systems, photovoltaic cells, and as a catalyst in plastic production [START_REF] Höll | Metallogenesis of germanium -a review[END_REF][START_REF] Melcher | Germanium[END_REF]Cook et al. 2015a). Gallium is mainly employed to manufacture optoelectronic devices (i.e., directly converting electricity into laser light), integrated circuits, thin-film photovoltaic cells, and military technology (e.g., satellites, radars, night vision equipment), as well as in the pharmaceutical industry for cancer treatment [START_REF] Moskalyk | Gallium: the backbone of the electronic induestry[END_REF][START_REF] Foley | Gallium. In: Critical Mineral Resources of the United States, Economic and Environmental Geology and Prospects for Future Supply[END_REF]. Germanium and gallium are recovered as by-products of zinc mining in sulfide deposits (e.g., Mississippi Valley-type [MVT], sedimentary-exhalative [SEDEX], volcanogenic massive sulfides [VMS], or Kipushi-type deposits; [START_REF] Foley | Gallium. In: Critical Mineral Resources of the United States, Economic and Environmental Geology and Prospects for Future Supply[END_REF][START_REF] Shanks | Germanium and indium[END_REF]). In addition, Ge is recovered from fly ash residues from coal burning and Ga is a by-product in bauxite deposits [START_REF] Shanks | Germanium and indium[END_REF][START_REF] Ujaczki | Recovery of gallium from bauxite residue using combined oxalic acid leaching with adsorption onto zeolite HY[END_REF].

In sulfide deposits, Ge and Ga are mainly extracted from sphalerite, in which they are incorporated under certain crystallization conditions and mostly via coupled substitutions [START_REF] Möller | Germanium and gallium distribution in sphalerite: a key to the genesis of sediment-hosted sulphide mineralizations[END_REF][START_REF] Cook | Trace and minor elements in sphalerite: a LA-ICPMS study[END_REF][START_REF] Belissont | LA-ICP-MS analyses of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerites from the Noailhac -Saint-Salvy deposit (France): insights into incorporation mechanisms and ore deposition processes[END_REF]Cook et al. 2015a;[START_REF] Frenzel | Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type -A meta -analysis[END_REF][START_REF] Liu | Germanium speciation in experimental and natural sphalerite: implications for critical metal enrichment in hydrothermal Zn-Pb ores[END_REF][START_REF] Luo | Germanium enrichment in sphalerite with acicular and euhedral textures: an example from the Zhulingou carbonate-hosted Zn(-Ge) deposit, South China[END_REF]. Sphalerite from MVT deposits is of particular interest because it usually contains the highest Ge contents and, in general, is enriched in both Ge and Ga in comparison to deposits of magmatic-hydrothermal origin [START_REF] Bernstein | Germanium: geochemistry and mineralogy[END_REF][START_REF] Paradis | Indium, germanium and gallium in volcanic-and sediment-hosted base-metal sulphide deposits[END_REF][START_REF] Frenzel | Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type -A meta -analysis[END_REF][START_REF] Shanks | Germanium and indium[END_REF][START_REF] Bauer | Trace element geochemistry of sphalerite in contrasting hydrothermal fluid systems of the Freiberg district, Germany: insights from LA-ICP-MS analysis, near-infrared light microthermometry of sphalerite-hosted fluid inclusions, and sulfur isotope geochemistry[END_REF][START_REF] Wei | LA-ICP-MS analyses of trace elements in base metal sulfides from carbonate-hosted Zn-Pb deposits, South China: A case study of the Maoping deposit[END_REF][START_REF] Benites | Distribution of indium, germanium, gallium and other minor and trace elements in polymetallic ores from a porphyry system: the Morococha District, Peru[END_REF][START_REF] Benites | Geology, mineralogy, and cassiterite geochronology of the Ayawilca Zn-Pb-Ag-In-Sn-Cu deposit, Pasco, Peru[END_REF]. Background information on MVT deposits is available in [START_REF] Sangster | Mississippi Valley-type lead-zinc[END_REF], [START_REF] Bradley | Tectonic controls of Mississippi Valley-type lead-zinc mineralization in orogenic forelands[END_REF], [START_REF] Leach | Sediment-hosted lead-zinc deposits: a global perspective[END_REF][START_REF] Leach | A deposit model for Mississippi Valley-type lead-zinc ores. In: Chapter A of mineral deposit models for resource assessment[END_REF], [START_REF] Wilkinson | Sediment-hosted zinc-lead mineralization[END_REF], [START_REF] Ostendorf | Formation of Mississippi Valley-type deposits linked to hydrocarbon generation in extensional tectonic settings: Evidence from the Jabali Zn-Pb-(Ag) deposit (Yemen)[END_REF], and [START_REF] Saintilan | Petroleum as source and carrier of metals in epigenetic sediment-hosted mineralization[END_REF].

A MVT belt extends along the Eastern Cordillera and Sub-Andean Zone morphotectonic units of central and northern Peru (Fig. 1). It includes the San Vicente, Shalipayco, and Florida Canyon deposits, as well as dozens of inactive artisanal mines, prospects, and mineral showings [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF][START_REF] Carlotto | Dominios geotectónicos y metalogénesis del Perú[END_REF][START_REF] Fontboté | Ore deposits of the Central Andes[END_REF]Mondillo et al. 2018a;[START_REF] De Oliveira | The Zn-Pb mineralization of Florida Canyon, an evaporite-related Mississippi Valley-type deposit in the Bongará district, Northern Peru[END_REF][START_REF] De Oliveira | Structural control and timing of evaporite-related Mississippi Valley-type Zn-Pb deposits in Pucará Group, Northern Central Peru[END_REF][START_REF] Chirico | Genesis of the Florida Canyon Nonsulfide Zn Ores (Northern Peru): New Insights Into the Supergene Mineralizing Events of the Bongará District[END_REF]. The iconic San Vicente deposit is operated by Compañía Minera San Ignacio de Morococha S. A.A. -SIMSA. From 1970to 2019, it produced more than 27 Mt ore grading 9.21 % Zn and 0.74 % Pb and as of 2021, the ore reserves and indicated resources amount to 3.4 Mt grading 9.51 % Zn and 0.48 % Pb (SIMSA 2021). The Chilpes and Huacrash prospects in the San Vicente district (Fig. 2) were explored in the 1990s by SIMSA through underground adits and diamond drilling and have yielded several low-grade Zn-Pb, mostly manto, ore bodies. The Shalipayco Project, located 100 km NE of San Vicente (Fig. 1), is a joint venture between Nexa Peru and Pan American Silver Peru S.A.C. As of 2017, the Shalipayco deposit had total measured and indicated mineral resources of 6.29 Mt grading 5.61 % Zn, 0.43 % Pb, and 38.5 g/t Ag, containing approximately 353,000 t Zn, 27,000 t Pb, and 7.8 Moz Ag [START_REF] Robson | NI 43-101 Technical report on the preliminary economic assessment of the Shalipayco project, Junín Region[END_REF].

Further north (Fig. 1), and not studied in the present work, is the Bongará MVT district, which includes the Florida Canyon deposit. Florida Canyon is under exploration by Nexa Peru and has total measured and indicated resources of 2.4 Mt grading 10.6 % Zn, 1.3 % Pb, and 15 g/t Ag and inferred resources of 14.8 Mt grading 9.6 % Zn, 1.3 % Pb, and 11.2 g/t Ag [START_REF] Hulse | NI 43-101 Technical Report on Resources Florida Canyon Zinc Project[END_REF]. Samples of non-sulfide mineralization formed by supergene alteration of hypogene MVT sulfide ore bodies in the Bongará district yielded Ge bulk contents up to 496 ppm (avg 162 ppm; [START_REF] Chirico | Genesis of the Florida Canyon Nonsulfide Zn Ores (Northern Peru): New Insights Into the Supergene Mineralizing Events of the Bongará District[END_REF]). In the same district, Mondillo et al. (2018b) also reported relatively high Ge bulk values (up to 216 ppm) in samples of non-sulfide ore in the Cristal prospect, and Ga contents of up to 27 ppm. Trace element determinations on precursor MVT sphalerite from this deposit yielded average Ge contents of 142 ppm and average Ga contents of 1.3 ppm (Mondillo et al. 2018b).

This work provides novel data on the minor and trace element contents of sphalerite from the San Vicente district and the Shalipayco deposit in Peru acquired by means of LA-ICP-MS analysis, focusing on Ge and Ga. Single-spot analysis guided by petrographic determinations made it possible to recognize sphalerite types that are particularly enriched in Ge and Ga and their position in the respective paragenetic sequences. The microanalytical work was complemented by a combination of focused ion beam and high-resolution transmission electron microscopy (FIB/HRTEM) that allowed observation of atomic-scale ordering of the different sphalerite types, including those with Ge-rich domains. Additionally, the poorly understood possible correlation between trace element contents and crystal color is explored in order to develop practical tools for targeting Ge-rich sphalerite from early exploration stages in MVT deposits.

Geological setting

The MVT belt in Peru

The MVT belt stretches along the Eastern Cordillera and Sub-Andean Zone morphotectonic units of central and northern Peru. Mineralization is hosted by carbonate rocks of the NNW -SSE trending Pucará Basin (Fig. 1; Benavides-Cáceres 1999; [START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]). The Pucará Group, which in most studied places is more than 2,000 m thick, was deposited on top of Paleozoic units and Triassic syn-rift volcanic and continental sedimentary rocks of the Mitu Group in a wide carbonate platform during regional subsidence in Upper Triassic to Lower Jurassic times [START_REF] Noble | Comendite (peralkaline rhyolite) and basalt in the Mitu Group, Peru: evidence for Permian-Triassic lithospheric extension in the Central Andes[END_REF][START_REF] Kontak | The rift associated Permo-Triassic magmatism of the Eastern Cordillera: a precursor of the Andean orogeny[END_REF][START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF][START_REF] Spikings | Characterisation of Triassic rifting in Peru and implications for the early disassembly of western Pangaea[END_REF]).

The Pucará Group extends for ~1,000 km in a NW -SE direction from central to northern Peru and comprises, from base to top, the Chambará, Aramachay, and Condorsinga formations [START_REF] Szekely | Stratigraphy of the carbonate, black shale, and phosphate of the Pucará Group (Upper Triassic-Lower Jurassic), Central Andes, Peru[END_REF][START_REF] Mégard | Etude géologique des Andes du Pérou Central, contribution à l'étude géologique des Andes[END_REF][START_REF] Loughman | A facies analysis of the Pucará Group (Norian to Toarcian carbonates, organic-rich shale and phosphate) of Central and Northern Peru[END_REF][START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]). The Norian-Rhaetian Chambará Formation is predominantly dolomitic, composed of a thick sequence of dolostones interlayered with dolomitic, dark-gray, and fossiliferous limestones. In the lower part of the sequence, a higher content of detrital material is observed; nodules of chert are common [START_REF] Rosas | Evolución sedimentológica del Grupo Pucará (Triásico Superior -Jurásico Inferior) en un perfil SW-NE en el Centro del Perú[END_REF]. Shallow water carbonate deposits are abundant and in parts include carbonate pseudomorphs after Ca-sulfates [START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]). The upper Rhaetian-Sinemurian Aramachay Formation is mostly formed by black argillaceous bituminous limestones and black shales with high organic matter content [START_REF] Szekely | Stratigraphy of the carbonate, black shale, and phosphate of the Pucará Group (Upper Triassic-Lower Jurassic), Central Andes, Peru[END_REF][START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]). In the Western Cordillera of Central Peru, abundant material derived from siliceous sponges typical of shallow platforms has been identified pointing out that, locally, the Aramachay Formation does not record the typical transgression described by facies observed along the Altiplano and Eastern Cordillera [START_REF] Ritterbush | Andean sponges reveal longterm benthic ecosystem shifts following the end-Triassic mass extinction[END_REF][START_REF] Rosas | Profundización sedimentaria solo en la parte de la cuenca Pucará (Perú Central) durante el Hetangiano Sinemuriano[END_REF]. The upper Sinemurian-Toarcian Condorsinga Formation comprises packstone to grainstone limestone with chert, dolomitic limestone with macrofossils, bioturbated limestone and, at its upper portions, interbedded evaporite lenses [START_REF] Rosas | Evolución sedimentológica del Grupo Pucará (Triásico Superior -Jurásico Inferior) en un perfil SW-NE en el Centro del Perú[END_REF]. Compared to the Chambará Formation, the Condorsinga Formation shows lower degrees of dolomitization and less chert [START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]).

Massive anhydrite/gypsum occur at the base of the Chambará Formation in different places, including Morococha [START_REF] Stipetich | Role of massive anhydrite bodies in the Cordilleran-type polymetallic mineralization of Morococha district, Peru: 3D geological modeling and Sr-S-O isotope constraints[END_REF], Ayawilca, [START_REF] Benites | Geology, mineralogy, and cassiterite geochronology of the Ayawilca Zn-Pb-Ag-In-Sn-Cu deposit, Pasco, Peru[END_REF][START_REF] Ramírez | Isotopic compositions of sulfides (S) and anhydrite (S, O, Sr) from the Ayawilca polymetallic deposit[END_REF]), and at San Vicente, interbedded with red sandstone [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF][START_REF] Moritz | Sr, C and O isotope systematics in the Pucará basin, Central Peru[END_REF]. Evaporite beds occur also in other stratigraphic positions within the Pucará Group [START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]) and in time-equivalent units in the Amazonian foreland of Peru [START_REF] Carrillo | Sedimentary evolution of an Upper Triassic salt giant and a synchronous carbonate unit between the Peruvian Andean Cordillera and the Brazilian Amazonian foreland[END_REF]. Evidence of salt tectonics have been described by Berrospi-Rodriguez et al. (2018), [START_REF] Sempere | An overlooked giant salt basin in Peru[END_REF][START_REF] De Oliveira | The Zn-Pb mineralization of Florida Canyon, an evaporite-related Mississippi Valley-type deposit in the Bongará district, Northern Peru[END_REF], 2020), and [START_REF] Benites | Geology, mineralogy, and cassiterite geochronology of the Ayawilca Zn-Pb-Ag-In-Sn-Cu deposit, Pasco, Peru[END_REF]. Sporadic andesitic-basaltic flows and local tuffaceous layers occur at different stratigraphic positions in the Pucará column [START_REF] Muñoz | Vulcanismo asociado a los carbonatos del Grupo Pucará (Triásico Superior -Liásico) en el área de Shalipayco[END_REF][START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF][START_REF] Schaltegger | Precise U-Pb age constraints for end-Triassic mass extinction, its correlation to volcanism and Hettangian post-extinction recovery[END_REF].

Reactivation of pre-Andean, steeply dipping NW -SE and NE -SW striking fractures resulted in the formation of horsts and grabens that controlled the facies of the Pucará Group sediments and could also act as feeders during mineralization. MVT mineralization along the belt was most probably synchronous with first overthrusting in the Sub-Andean region [START_REF] Dávila | Exploración y geología del yacimiento San Vicente. In: Yacimientos minerales peruanos[END_REF][START_REF] Badoux | The Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru: an Andean syntectonic deposit[END_REF], which occurred as early as in Upper Cretaceous -Paleocene times according to [START_REF] Baby | The Peruvian Sub-Andean foreland basin system: structural overview, geochronologic constraints, and unexplored plays[END_REF], during the Peruvian episode of the Andean orogeny (see [START_REF] Benavides-Cáceres | Orogenic evolution of the Peruvian Andes: the Andean cycle. In: Skinner BJ (ed) Geology and Mineral Deposits of the Central Andes[END_REF]. This time constraint of the mineralization based on structural features in the San Vicente deposit accords well with Rb-Sr dates on sphalerite from the Florida Canyon MVT deposit at ca. 86-83 Ma (de Oliveira et al. 2020).

The San Vicente deposit and the Chilpes and Huacrash prospects

The San Vicente MVT district is located ~300 km east of Lima at an altitude between 1,200 and 2,500 m.a.s.l. in the Sub-Andean Zone, at the limit with the Eastern Cordillera. It includes the San Vicente deposit (11°14′S, 75°22′W) and several prospects such as Puntayacu Junior, Palmapata, Quebrada Seca, Chilpes, Huacrash, Sillapata, and Piñón, all of them hosted by dolomitic rocks of the Pucará Group (Figs. 1,2).

As in other parts of the Sub-Andean region, the San Vicente area was affected by Upper Cretaceous and Tertiary thin-skinned tectonics with numerous low-angle N -S to NNW -SSE striking faults with E-vergence (Fig. 2; [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF][START_REF] Dávila | Exploración y geología del yacimiento San Vicente. In: Yacimientos minerales peruanos[END_REF]. In addition, regional steep NW -SE and SW -NE striking faults cross-cut the rock sequence in the area. The oldest rocks occur in the western part of the study area as a major tectonic slice of the pre-Devonian [START_REF] Chew | Proto-Andean evolution of the Eastern Cordillera of Peru[END_REF]) Maraynioc metamorphic complex thrust on top of younger rocks (Fig. 2). The Maraynioc metamorphic complex is composed of deformed micaschist, amphibolite, and gneiss cut by Carboniferous intrusive rocks [START_REF] Chew | Proto-Andean evolution of the Eastern Cordillera of Peru[END_REF].

More to the east and in the footwall of this major overthrust occurs the Carboniferous Utcuyacu Granite (U-Pb zircon date of 307.05 ± 0.65 Ma on a sample collected 8 km NW of San Vicente, at the road between Tarma and San Ramón; [START_REF] Chew | U-Pb geochronologic evidence for the evolution of the Gondwanan margin of the northcentral Andes[END_REF]) that, in turn, was thrust on top of Pucará Group rocks. In the San Vicente mine, [START_REF] Gunnesch | Lead isotope variations across the Central Peruvian Andes[END_REF] dated the so-called "Tarma granite", which is also thrust on the Pucará sequence, at 240 ± 4 Ma. As explained by Fontboté and Gorwaski (1990), in the mine reports the terms Utcuyacu granodiorite and "Tarma Grey Granite" are used indistinctly although the quoted dates suggest that rocks of different ages are included under both terms.

Phyllites of the Excelsior Group, of probable Devonian age [START_REF] Mclaughlin | Geology and physiography of the Peruvian Cordillera, Departments of Junin and Lima[END_REF][START_REF] Jenks | Triassic to Tertiary stratigraphy near Cerro de Pasco, Peru[END_REF][START_REF] Saintilan | Osmium isotopic constraints on sulphide formation in the epithermal environment of magmatic-hydrothermal mineral deposits[END_REF], underlying the Mitu Group have been recognized 15 km southeast of the San Vicente mine (Fig. 2; [START_REF] Dávila | Exploración y geología del yacimiento San Vicente. In: Yacimientos minerales peruanos[END_REF]. Sedimentary rocks of the Pennsylvanian-Early Permian Tarma-Copacabana Group, including limestone and subordinate sandstone, black shale, and cherty limestone [START_REF] Wood | The paleogeographic and biostratigraphic significance of fusulinacean and smaller foraminifers, and palynomorphs from the Copacabana Formation (Pennsylvanian-Permian), Madre de Dios Basin, Peru. In: Hills LV, Henderson CM, Bamber EW (eds) Carboniferous and Permien of the World[END_REF], occur to the east and southeast of San Vicente (Fig. 2). The Lower Triassic San Ramon Granite, dated at 246 ± 10 Ma [START_REF] Capdevila | Le batholite de San Ramón, Cordillére Orientale du Pérou central[END_REF] recalculated by [START_REF] Lancelot | U/Pb radiochronology of two granitic plutons from the Eastern Cordillera (Peru) -extent of Permian magmatic activity and consequences[END_REF] and at 255 ± 1 Ma [START_REF] Gunnesch | Lead isotope variations across the Central Peruvian Andes[END_REF], occurs east of San Vicente (Fig. 2).

In the central part of the San Vicente deposit, the three formations constituting the Pucará Group have a total thickness of 1,400 m [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF]. The Chambará Formation is 1,200 m thick and includes two main ore-bearing dolomitic units known as the San Judas Dolomite (~280 m thick) and theby far economically more important -San Vicente Dolomite (~ 300 m thick; [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF][START_REF] Spangenberg | Carbon and oxygen isotope study of hydrothermal carbonates in the zinc-lead deposits of the San Vicente district, Central Peru: a quantitative modeling on mixing processes and CO2 degassing[END_REF][START_REF] Spangenberg | An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, Central Peru; implications for ore fluid composition, mixing processes, and sulfate reduction[END_REF]. Both units consist mainly of dolomitized barrier calc-arenite (oolitic packstone to grainstone) intercalated with very fine-to fine-grained dolomite deposited in lagoon and tidal flat environments with fairly abundant evaporite pseudomorphs [START_REF] Rosas | Tectonic evolution and paleogeography of the Mesozoic Pucará basin, Central Peru[END_REF]). Massive anhydrite layers occur at the bottom of the Chambará Formation intercalated with red sandstone. The Aramachay Formation is represented in San Vicente by the Uncush bituminous limestone (8 to 250 m thick), a hydrocarbon-source rock characterized by its high organic matter content and pyrite dissemination that acted as a main seal during the mineralization process atop the San Vicente unit [START_REF] Dávila | Exploración y geología del yacimiento San Vicente. In: Yacimientos minerales peruanos[END_REF][START_REF] Spangenberg | Carbon and oxygen isotope study of hydrothermal carbonates in the zinc-lead deposits of the San Vicente district, Central Peru: a quantitative modeling on mixing processes and CO2 degassing[END_REF][START_REF] Spangenberg | An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, Central Peru; implications for ore fluid composition, mixing processes, and sulfate reduction[END_REF]. Mapping of the strong thickness variations (8 to 250 m) of the Aramachay Formation indicates that at least part of the NNW -SSE steep faults were active during sedimentation. The overlying Condorsinga Formation (~120 m thick, top cut by overthrust faults) includes a third ore-bearing dolomitic unit, the Alfonso Dolomite, which has similar characteristics as the San Judas and San Vicente dolomitic units.

Orebodies of the San Vicente mine are mostly lens-shaped and tend to be parallel to the bedding and to the low-angle overthrust planes, mainly in the upper portion of the central and northern part of the deposit [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF]. In addition, the orebodies are limited by steep NWW -SEE striking fractures, particularly in the deeper and southern parts of the deposit [START_REF] Dávila | Exploración y geología del yacimiento San Vicente. In: Yacimientos minerales peruanos[END_REF][START_REF] Dávila | Estilo y geometría de mineralización MVT en la mina San Vicente[END_REF]. Both the low-angle thrust faults and the steep NWW -SEE trending fractures are interpreted to have acted as feeders of the metal-bearing fluids.

Ore minerals are essentially dark to light brown sphalerite and subordinate galena, with traces of pyrite, marcasite, chalcopyrite, and sulfosalts. The gangue is mainly constituted by hydrothermal dolomite, ranging from fine-to coarse-grained and including white sparry dolomite (WSD), and minor calcite. In addition to disseminated organic matter in dolomite, massive bitumen is present along faults and coating WSD. In the upper, northern part of the deposit, lenticular bodies of massive pyrite pseudomorphic after marcasite occur. A significant portion of the ore shows zebra (cf. [START_REF] Fontboté | Self-organization fabrics in carbonate-hosted ore deposits: the example of diagenetic crystallization rhythmites (DCRs)[END_REF][START_REF] Leach | Sediment-hosted lead-zinc deposits: a global perspective[END_REF][START_REF] Merino | Self-accelerating dolomite-for-calcite replacement: self-organized dynamics of burial dolomitization and associated mineralization[END_REF][START_REF] Kelka | Zebra rocks: compaction waves create ore deposits[END_REF], breccia, and vein textures and structures. Zebra, vein, and breccia fabrics occur also abundantly in barren parts of the ore-bearing units with similar textures [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF][START_REF] Fontboté | The Mississippi Valley-type zinc-lead mine of San Vicente, Eastern Pucará basin, Peru[END_REF][START_REF] Spangenberg | Geochemical (elemental and isotopic) constraints on the genesis of the Mississippi Valley-type zinc-lead deposit of San Vicente[END_REF][START_REF] Badoux | The Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru: an Andean syntectonic deposit[END_REF]. Volumetrically minor Fe-poor orange and yellow sphalerite is found in steep veins that cross-cut the main mineralization and belongs to a minor second mineralization step in the San Vicente deposit that, as explained below, has a particular geochemical signature.

Ore formation is interpreted to have resulted mostly from the ingression of metal-bearing basinal brines that encountered H2S formed by thermochemical sulfate reduction (TSR) in hydrocarbon traps located in dolomitized oolitic bars (Fontboté andGorzawski 1990, Fontboté et al. 1995;[START_REF] Spangenberg | Geochemical (elemental and isotopic) constraints on the genesis of the Mississippi Valley-type zinc-lead deposit of San Vicente[END_REF][START_REF] Spangenberg | Organic geochemistry of the San Vicente zinc-lead district, eastern Pucará Basin, Peru[END_REF][START_REF] Spangenberg | An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, Central Peru; implications for ore fluid composition, mixing processes, and sulfate reduction[END_REF].

Lead and strontium isotope compositions of ore and host rocks suggest that the brines scavenged metals from basement rocks. TSR as the main process for sulfur reduction is indicated by the sphalerite and galena sulfur isotope composition close to that of Triassic evaporites, the study of hydrocarbons occurring in ore and host rocks, and the very light carbon isotope signaturestypical of organic carbonmeasured in certain hydrothermal carbonate generations of San Vicente. Exploratory fluid inclusion microthermometry on sparry dolomite yielded homogenization temperatures in the range between 115 and 162°C and salinities between 9.5 wt% and 26 wt% NaCl equivalent [START_REF] Moritz | Sr, C and O isotope systematics in the Pucará basin, Central Peru[END_REF]. This temperature range is compatible with sulfur isotope sphalerite-galena geothermometry reported by [START_REF] Schutfort | The genesis of the San Vicente lead-zinc rhythmites deposit, Peru: a petrologic, geochemical, and sulfur isotope study[END_REF].

The Chilpes (11°15′S, 75°22′W) and Huacrash (11°16′S, 75°22′W) prospects are located approximately 7 km and 8 km to the SSE of the San Vicente deposit, respectively (Fig. 2). At both sites, low-grade Zn-Pb mineralization occurs in the Chambará Formation. Mineralization at Chilpes is hosted by the San Judas dolomite and comprises sphalerite and galena dissemination in coarsely crystalline dolomite with relictic oolitic grainstone texture; two massive pyrite bands a few centimeters in thickness within fault planes are described by [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF] as a distinctive feature at Chilpes. At Huacrash, an ~60 m-thick portion of the San Vicente dolomite contains irregular ore lenses with sphalerite, galena, and coarse-grained sparry dolomite. Centimetric patches of massive pyrite occur too and bitumen coats joints and voids.

A Pb isotope study on sulfide minerals (sphalerite, galena, pyrite, and marcasite) from the San Vicente deposit and the Chilpes and Huacrash prospects has been recently performed [START_REF] Bastian | Fluid and metal sources of Zn-Pb sulfides of San Vicente[END_REF]written communication of Lena Bastian, ETHZ). The results indicate that sulfides that crystallized during the volumetrically dominant first mineralization step in the San Vicente deposit are more radiogenic than sulfides in the Chilpes and Huacrash prospects, as well as sulfides crystallized during the volumetrically much restricted second mineralization step at the San Vicente deposit.

The Shalipayco deposit

The Shalipayco deposit (10°51′S, 75°58′W) is located ~170 km northeast of Lima in the central Eastern Cordillera of Peru at an altitude of 4,400 m.a.s.l. (Fig. 1). An unconformity separates the Chambará Formation from the underlying Mitu Group [START_REF] De Oliveira | The Zn-Pb mineralization of Florida Canyon, an evaporite-related Mississippi Valley-type deposit in the Bongará district, Northern Peru[END_REF]. The orehosting Pucará Group carbonate rocks in the Shalipayco area are moderately folded, occurring at the deposit site as a monocline dipping between 30° and 45° to the southwest [START_REF] Robson | NI 43-101 Technical report on the preliminary economic assessment of the Shalipayco project, Junín Region[END_REF]. The NW -SE oriented Ulcumayo-San Rafael thrust fault separates the Mitu Group from the underlying Pucará Group, and the Yanacocha-Quilcatacta thrust fault, also NW -SE striking, is within limestone of the Condorsinga Formation [START_REF] Robson | NI 43-101 Technical report on the preliminary economic assessment of the Shalipayco project, Junín Region[END_REF]. Steeply dipping N -S to NW -SW striking faults, including Eddy, San Teodoro, Virgencita, Pucará, and Santa Inés could have served as feeder channels for mineralization [START_REF] Robson | NI 43-101 Technical report on the preliminary economic assessment of the Shalipayco project, Junín Region[END_REF][START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. Geologic maps showing the geology of the Shalipayco deposit are available in De [START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF] divided the Chambará Formation, host of the mineralization in Shalipayco, into four members which, from base to top, are i) the ~320 m-thick Chambará I Member, which is mainly formed by dark-gray lime mudstone to wackestone with chert clasts and calcite as cavity-filling and veins; ii) the ~120 m-thick Chambará II Member, which essentially constitutes porous gray dolostone (wackestone) with local mudstone; iii) the ~80 mthick Chambará III Member, which is composed of beige dolomite boundstone with evaporitic rocks and calcite veins; and iv) the ~130 m-thick Chambará IV Member, which is composed of light gray mudstone with local dolomitization.

The strataboundat the outcrop scaleand mostly stratiform orebodies in Shalipayco, namely Intermedios and Resurgidora, are largely hosted by the Chambará II and III members, respectively [START_REF] Robson | NI 43-101 Technical report on the preliminary economic assessment of the Shalipayco project, Junín Region[END_REF][START_REF] De Oliveira | Structural control and timing of evaporite-related Mississippi Valley-type Zn-Pb deposits in Pucará Group, Northern Central Peru[END_REF][START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. The Intermedios level has an average thickness of 8 m (up to 25 m) and extends for at least 2 km along strike [START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. It is located above dark gray mudstone and wackestone and below dark gray sparry fetid dolomite rich in organic matter [START_REF] Oldham | Reporte annual de exploraciones[END_REF]. Approximately 45% of the Zn-Pb mineralization occurs along this horizon and is mainly hosted by porous coarse-grained dolostone. The Resurgidora level has an average thickness of 4 m (up to 11 m) and extends for at least 4 km along strike [START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. It is located between two horizons of coarse-grained, dark, fetid dolomite rich in organic matter [START_REF] Oldham | Reporte annual de exploraciones[END_REF]) and is mainly hosted by coarse-grained dolostone and evaporitic breccia [START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]). Vein mineralization is mainly represented by the Eddy vein (up to 8 m thick), currently considered as one of the potential feeders [START_REF] Robson | NI 43-101 Technical report on the preliminary economic assessment of the Shalipayco project, Junín Region[END_REF][START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. The main ore minerals are sphalerite and galena with lesser amounts of pyrite, marcasite, and Ag sulfosalts [START_REF] Moritz | Sr, C and O isotope systematics in the Pucará basin, Central Peru[END_REF][START_REF] Oldham | Reporte annual de exploraciones[END_REF]. The main gangue minerals are dolomite, calcite, quartz, and barite.

Strontium isotope signatures evolve from values typical of Norian seawater in least-altered limestone to increasingly more radiogenic values in diagenetic replacement dolomite and oreintergrown dolomite and calcite, thus suggesting enhanced interaction with hydrothermal fluids that circulated through basement rocks with radiogenic Sr [START_REF] Moritz | Sr, C and O isotope systematics in the Pucará basin, Central Peru[END_REF][START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. As in San Vicente, C and O isotope values of carbonates from Shalipayco also show a progression from signatures that match the  13 C and  18 O of Triassic marine limestones to isotopically lighter signatures along the aforementioned carbonate sequence [START_REF] Moritz | Sr, C and O isotope systematics in the Pucará basin, Central Peru[END_REF][START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF]. Light  34 S values in sulfides from Shalipayco led de [START_REF] De Oliveira | Geology and genesis of the Shalipayco evaporite-related Mississippi Valley-type Zn-Pb deposit, Central Peru: 3D geological modeling and C-O-S-Sr isotope constraints[END_REF] to propose that reduced sulfur mainly originated from bacteriogenic sulfate reduction and that, in addition, evaporitic sulfate subsequently underwent thermochemical reduction by bacteriogenic H2S.

Sampling and analytical methods

Sampling and petrography

Sampling was focused on sphalerite of different color and/or textural features, ideally enabling to establish a paragenetic sequence. A total of 36 sphalerite-rich ore samples were collected from the San Vicente deposit (n = 16) and the Chilpes (n =3) and Huacrash (n = 1) prospects in the San Vicente district, and from the Shalipayco deposit (n = 16). In the San Vicente deposit, sampling was conducted on drillholes (n =14) and mine adits (n = 2) in the central (Ayala Inferior manto) and the northernmost (Orcopunco) parts of the deposit. Samples from Chilpes and Huacrash were taken from prospection adits. In Shalipayco, all samples were picked from drillcore and come from the Resurgidora and Intermedio levels. Location including name/label of the sampled mine adits and drillholes, and the mineralogy and hand sample textures are given in Table S1 in the Electronic Supplementary Material. A total of 44 thick polished sections were prepared at the QEMSCAN laboratory of the Pontifical Catholic University of Peru (PUCP) for study under the optical microscope using reflected light. A selection of 5 samples was examined on a Tescan VEGA II XMU SEM with a BRUKER xFlash 6/30 EDS microanalysis system at BIZALab S.A.C., Lima. The operating conditions were 20 kV accelerating voltage and 105 µA in backscattered electron (BSE) imaging mode.

Electron microprobe analysis (EMPA)

Mineral chemical analyses of sphalerite from San Vicente were performed using a five-channel JEOL JXA-8230 electron microprobe at Centres Científics i Tecnològics of the University of Barcelona (CCiT-UB). The instrument was operated at 20 kV acceleration voltage, 20 nA beam current, and with a beam diameter of 5 µm. Analytical standards and emission lines used for analyses were as follows: sphalerite (Zn and S, K), chalcopyrite (Cu, K), FeS2 (Fe, K), PbS (Pb, M), CdS (Cd, L), GaAs (As, L; Ga, K), In2Se (In, L), Ag (Ag, L), Sb (Sb, L), Sn (Sn, L), and Ge (Ge, K). The detection limits (d.l.) for each element and representative analyses (values in wt% and atoms per formula unit -a.p.f.u.) are given in Table S2 in Supplementary Material. Sphalerite compositions were normalized to 1 S.

Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)

Analyses of sphalerite trace element content were carried out at ETH Zürich, Switzerland, by laser ablation-inductively coupled plasma-sector field-mass spectrometry (LA-ICP-SF-MS) using a RESOlution S-155 (ASI/Applied Spectra) 193 nm ArF excimer laser system attached to an Element XR (Thermo) sector-field ICP-MS. We used a laser repetition rate of 3 Hz, a spot diameter of 19 μm, and a laser energy density of ca. 2.5 J•cm -2 . The sample surface was cleaned before each analysis by three pre-ablation pulses. Ablation was performed in a dual-volume, fast-washout S-155 ablation cell (Laurin Technic) fluxed with carrier gas consisting of ca. 0.5 l•min -1 He and make-up gas consisting of ca. 1 l•min -1 Ar and 2 ml•min -1 N2. The ablated aerosol was homogenized via flushing through an in-house built squid device before being introduced in the plasma.

The ICP-MS instrument is equipped with a high capacity (80 m 3 •h -1 ) interface pump to achieve, in combination with jet sampler and normal H-skimmer cones, a detection efficiency (based on U in NIST-SRM612 glass) in the range of 2% [START_REF] Guillong | New analytical and data evaluation protocols to improve the reliability of U-Pb LA-ICP-MS carbonate dating[END_REF]. The instrument was optimized for maximum sensitivity on the entire mass range while keeping low the production of oxides ( 248 ThO + / 232 Th + ≤0.15%) and the U/Th ratio at ca. 1 (on NIST SRM612 glass). The list of analyzed isotopes and corresponding dwell times is provided in Table S3 in the Electronic Supplementary Material. A total of 68 mass scans (ca. 0.72 s sweep time each) were acquired over ca. 50 s measurement (25 s of background measurement followed by 25 s of sample ablation).

The resulting intensities were subsequently processed offline with the stand-alone version 1.3.2 of the SILLS program [START_REF] Guillong | SILLS: a matlab-based program for the reduction of Laser Ablation ICP-MS data of homogeneous materials and inclusions. In: Sylvester P (ed) Laser Ablation ICP-MS in the Earth Sciences: current practices and outstanding issues[END_REF]) and the version 4.5 of the Iolite v4.5 software [START_REF] Paton | Iolite: Freeware for the visualisation and processing of mass spectrometric data[END_REF]. The pressed pellet MASS-1 sulfide standard (former PS-1; [START_REF] Wilson | Development of sulfide calibration standards for the laser ablation inductively-coupled plasma mass spectrometry technique[END_REF] was used as the primary reference material for trace element quantification and instrumental drift correction using conventional standard-sample bracketing. The Zn contents obtained by EMPA for sphalerite from the San Vicente deposit were used as internal standard for relative sensitivity corrections. For sphalerite from Chilpes, Huacrash, and Shalipayco, which are Fe-poor, stoichiometric Zn was used as internal standard. The analyzed In intensities on masses 113 and 115, respectively, were corrected for polybaric interferences by subtracting the contribution of 113 Cd and 115 Sn, respectively, based on the measured 111 Cd and 118 Sn intensities and using natural isotope ratios for Cd and Sn recommended by IUPAC. Because of the very high 111 Cd signal (>10000 cps), the extent of the correction is much higher in the case of 115 In than in the case of 113 In, especially because the analyzed sphalerite crystals all show relatively low Sn contents (<100 ppm). Therefore, we considered only the contents based on the interferencecorrected 115 In intensities. The data are reported in Table S4 in the Electronic Supplementary Material; a summary of the obtained minor and trace element contents is reported in Table 1.

The analytical reproducibility was checked by repeated measurements of the GSD-1G [START_REF] Guillong | Preliminary characterisation of new glass reference materials (GSA-1G, GSC-1G, GSD-1G and GSE-1G) by laser ablation-inductively coupled plasma-mass spectrometry using 193 nm, 213 nm and 266 nm wavelengths[END_REF]) and NIST-SRM610 [START_REF] Jochum | Determination of reference values for NIST SRM 610-617 glasses following ISO guidelines[END_REF]) glass reference materials, and ranges from 10 to 30% relative (2σ) for most elements. The quoted uncertainties for each analysis correspond to the internal (2σ) statistical error and analytical reproducibility propagated by quadratic addition. Accuracy was controlled by repeated measurements of the pressed pellet UQAC-FeS-1 sulfide standard (unpublished data from D. Savard, UQAC, 2018; see also [START_REF] Baumgartner | Accumulation of transition metals and metalloids in sulfidized stromatolites of the 3.48 billion-year-old Dresser Formation, Pilbara Craton[END_REF]. The results (reported in Table S4 in the Electronic Supplementary Material) show that the measurements are accurate within the calculated uncertainties.

High-resolution transmission electron microscopy (HRTEM)

The HRTEM study was done on four thin foils of sphalerite from the San Vicente deposit. Two thin foils cover contacts between white (sl2w in the classification scheme explained in the "Mineralogy and textures" section below) and black (sl1bl) and between white (sl2w) and yellow (sl2y) sphalerite types, while the other two thin foils are from the inner portion of yellow (sl2y) and orange (sl2o) sphalerites types. The thin foils were prepared and extracted by using a focused ion beam-scanning electron microscope (FIB-SEM) in the Laboratorio de Microscopías Avanzadas (LMA) at the Instituto de Nanociencia de Aragón (INA) -University of Zaragoza, Spain. The TEM thin foil preparation was performed using a Dual Beam FEI Thermo-Fisher Scientific, model Helios 650. The selected regions of interest were first covered by a thin carbon strip (~300 nm) by focused electron beam induced deposition (FEBID) and subsequently with a second strip (~1 µm) of Pt. These strips act as protection during the milling, polishing, and extraction process of the thin foils. The bulk material was first removed on both sides of the lamella by rough Ga + ion milling with a 30 kV current at 2.5 nA and the subsequent polishing with a 30 kV current at 0.23 nA. The final polishing step was performed on the sample until electron transparency was achieved. This was completed by subsequently milling the thin foil with a 5 kV current at 68 pA. The electron transparency was monitored by an Everhart-Thornley SE detector using a 5 kV electron beam. After achieving the electron transparency, the thin foil was rapidly polished using a low energy 5 kV current at 10 pA to reduce amorphization until a final thin foil thickness of ~90 nm was attained. Subsequently, the thin foil was undercut with a 30 kV at 2.5 nA current, lifted out, and transferred from the sample to a TEM grid using an OmniProbe nano-manipulator with a tungsten tip. To weld the thin foil to the tungsten tip and the TEM grid, ion-beam assisted Pt deposition was performed.

A FEI Titan G2 transmission electron microscope (TEM) equipped with a field emission gun XFEG was used to analyze the thin foils at the Centro de Instrumentation Científica of the University of Granada, Spain. The FEI Titan G2 microscope is equipped with four energy dispersive X-ray (EDX) detectors (FEI microanalysis Super X) and a high-angle annular darkfield detector (HAADF). This FEI Titan G2 microscope also includes a spherical correction for the objective lens. Selected mineral areas of samples of interest within the thin foils were imaged by the FEI Titan G2 microscope using a combination of high-angle annular dark-field (HAADF) to obtain good Z-contrast images, and high-resolution transmission electron (HRTEM) images to characterize the texture of the grains and to properly define the ordering of the mineral aggregates. All these images were treated using the Digital Micrograph® software (version 1.71.38) while maps were processed with the VELOX® software package. The FEI Titan G2 run at 300 kV working conditions while HRTEM images were acquired using a Gatan CCD Camera. Single-spot and elemental maps were also processed using the VELOX® software.

Mineralogy and textures

San Vicente district

The studied samples from the San Vicente district are mainly composed of sphalerite with lesser proportions of galena, pyrite, marcasite, and gratonite [Pb9As4S15]. Hydrothermal dolomite is the main gangue mineral, whereas hydrothermal calcite and quartz are locally present.

The main textures include the following: a) zebra-type, with up to 1 cm-wide dark bands of fineto medium-grained dolomite and sphalerite overgrown by up to 2 cm-wide bands of sparry dolomite ± sphalerite and galena displaying a more or less rhythmical pattern (Fig. 3A); b) colloform banding of sphalerite and dolomite (Figs. 3B-E); c) breccias with clasts constituted mainly of fine-to medium-grained dolomite ± sphalerite cemented by white sparry dolomite (WSD; Fig. 3F); and d) replacement between different types of sphalerite and hydrothermal carbonates (Figs. 3G-I). Textures shown in Fig. 3C indicate significant dissolution between precipitation of sphalerite and white sparry dolomite 1 yielding a breccia-like appearance not caused by fracturing but by corrosion. Three generations of hydrothermal dolomite have been recognized in the studied samples: dark replacement dolomite (DRD), white sparry dolomite 1 (WSD1), and white sparry dolomite 2 (WSD2), the latter two formed mainly as open space-filling. Hydrothermal calcite appears as thin veins across and filling spaces within WSD and is generally younger than dolomite (see also textural descriptions in [START_REF] Spangenberg | An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, Central Peru; implications for ore fluid composition, mixing processes, and sulfate reduction[END_REF]. Dark replacement dolomite is very-fine to medium-grained, and in many places shows inclusions of fine-grained pyrite, organic matter, and quartz.

In general, sphalerite grains at San Vicente are between ~25 µm and <1 mm in size, and are mostly devoid of visible mineral inclusions, except for local dissemination of pyrite/marcasite (Figs. 4A-C). Up to seven types of sphalerite have been differentiated according to their color (including the color of internal reflections under the petrographic microscope) and textural relationships. These sphalerite types have been ascribed to the two aforementioned mineralizing episodes or "steps". Sphalerite formed during the first mineralization step (sl1) accounts for most of the San Vicente ore and includes the black (sl1bl), reddish-brown (sl1rb), yellowish-brown (sl1yb), and yellow (sl1y) types. Black sphalerite (sl1bl) occurs mostly in the central part of sphalerite zebra bands where it is followed from the inside outwards by reddishbrown (sl1rb) and yellowish-brown (sl1yb) sphalerite bands (Figs. 3A). Black sphalerite (sl1bl) is also found replacing DRD without zebra fabric, and is commonly overgrown by reddish-brown (sl1rb), yellowish-brown (sl1yb), and yellow (sl1y) sphalerite (Figs. 3B-C, 4B-C). Under the petrographic microscope, black sphalerite (sl1bl) forms micro-to millimeter-sized anhedral to subhedral crystals often intergrown with fine-grained DRD (Figs. 4A-C).

Sphalerite that crystallized during the second mineralization step is recognized by generally lighter colors and replacement and crosscutting (mostly in steep veins) relationships with sphalerite and other minerals (e.g., notably, WSD1; Figs. 3F-I , G-H) and, in places, partially replacing sphalerite of the first mineralization step and DRD (Figs. 3G-H, 4E-F). The sequence of the second mineralization step starts with orange sphalerite (sl2o), which is frequently epitaxially overgrown by yellow (sl2y) and white (sl2w) sphalerite (Figs. 4D,H). White sphalerite also occurs as veinlets that crosscut black sphalerite (sl1bl), WSD1, and WSD2 (Figs. 3I; 4A, F).

Different textural types of pyrite have been distinguished in the studied samples, all with sizes of <400 µm: i) fine disseminations in sl1 (Figs. 4A-C, I), ii) pseudomorphic pyrite according to disseminated marcasite in DRD (Fig. 4G), and iii) subhedral-euhedral crystals in fractures and cavities of sl1 (Fig. 4A). In the studied samples, galena occurs as i) subhedral crystals in WSD1 and WSD2 (Fig. 3B), often filling spaces (Fig. 4I), and ii) in fine veinlets that cut WSD1 and WSD2 (Fig. 3D). Locally, galena is intergrown with anhedral aggregates of gratonite.

From the above-described textural relationships, a general paragenetic sequence has been produced for the studied samples (Fig. 5), the deposition sequence being also broadly consistent with petrographic descriptions by [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF] and [START_REF] Spangenberg | An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, Central Peru; implications for ore fluid composition, mixing processes, and sulfate reduction[END_REF]. New is the recognition of the volumetrically minor mineralization formed during a second step with its conspicuous orange (sl2o) and yellow (sl2y) sphalerite.

In the Chilpes prospect, sulfide mineralization mostly occurs as sphalerite and galena with minor proportions of pyrite in coarse-grained white sparry dolomite (Figs. S1A-B, S2, Electronic Supplementary Material). In addition, two bands a few centimeters in thickness of massive, coarse-grained pyrite (up to 0.5 cm) are observed (Fig. S1C). Sphalerite color grades from reddish-brown (slrb) to yellowish-brown (slyb), orange (slo), and yellow (sly; Figs. S2A-F). In general, sphalerite has a "dirty" appearance (e.g., Fig. S2A,C,E), due to the presence of abundant tiny inclusions of dolomite and subordinately, pyrite, indicating that sphalerite is to a large extent of replacive nature similarly to a part of WSD that reveals ghosts of grainstone oolites (Fig. S2L). Sphalerite of reddish-brown (slrb) and yellowish-brown (slyb) colors appears mainly intergrown with coarse-graine WSD and also within massive pyrite and usually forms aggregates of grains that are up to 1 cm in size individually (Fig. S2A-F). Reddish-brown (slrb) sphalerite may grade towards yellowish-brown (slyb) color toward the border of individual grains (Fig. S2B). Orange (slo) and yellow (sly) sphalerite has been only found intergrown with coarsegrained WSD (Fig. S2G-L). Galena appears mostly as grains <1 cm in size, mainly as openspace filling within the coarse-grained WSD; it is also observed as thin veinlets that crosscut WSD and in the massive pyrite bands (Fig. S2G-J).

In the studied sample from the Huacrash prospect, sphalerite forms anhedral grains that are up to 1 cm in size and display brownish-orange (slbo) color cemented by WSD (Fig. S3A-F). As in Chilpes, sphalerite grains show abundant micro-inclusions and irregular, corroded boundaries and are veined by dolomite. Galena is scarce and appears as anhedral grains less than 100 µm in size (Fig. S3A-B).

Study by reflected light microscope coupled with a cold-stage cathodoluminescence (CL) system reveals oscillatory and sector zoning in orange and yellow sphalerite from Chilpes (sample FSV50) in contrast with weak or nil CL response in sphalerite formed during the first mineralization step (Fig. S4).

Shalipayco deposit

Sphalerite constitutes the main ore mineral, and appears along with traces of galena, pyrite, and marcasite. The main gangue mineral is dolomite; other gangue minerals in minor amounts include barite, calcite, and quartz. Two generations of dolomite were recognized in the studied samples: i) dolomite 1 (dol1), which occurs as replacement of the host limestone and contains interstitial early sphalerite, and ii) dolomite 2 (dol2) which is coarser-grained and intergrown with late sphalerite. These textural features are consistent with those described by de Oliveira et al.

(2021).

The sphalerite grains are between ~20 µm and 1 mm in size and are largely free of visible inclusions of other sulfides. According to de Oliveira et al. ( 2021), there was a single ore-forming episode at Shalipayco. Following the same criteria as for the discrimination of sphalerite types in San Vicente, five types of sphalerite were recognized: black (slbl), reddish-brown (slrb), yellowish-brown (slyb), yellow (sly), and white (slw; var. cleiophane). Black sphalerite (slbl) appears as micro-to millimeter-sized anhedral to subhedral crystals with rectilinear and subroundish grain boundaries (Figs. 6A-D). Black sphalerite (slbl) is commonly intergrown with pyrite aggregates and tiny (< 20 µm) prismatic crystals of marcasite (Figs. 6A,C). Reddishbrown sphalerite (slrb) forms anhedral to subhedral grains chiefly grown on black sphalerite (slbl) and overgrown by yellowish-brown sphalerite (slyb; Figs. 6E-H). In places, reddish-brown (slrb) and yellowish-brown (slyb) sphalerite appears interstitially between barite crystals (Figs. 6E-F) and as open space filling together with dol2 (Figs. 6G-J). Yellow sphalerite (sly) appears as anhedral grains that grew on yellowish-brown sphalerite (slyb; Figs. 6G-L) whereas white sphalerite (slw) forms small anhedral grains in contact with yellow sphalerite (sly; Figs. 6K-L).

Two different textural types of pyrite have been observed: i) subhedral to anhedral grains <200 µm in size as void and fracture-filling in dol1, commonly intergrown with black sphalerite (slbl; Figs. 6A-B) and ii) fine to medium-grained subhedral to euhedral cubic crystals <10 µm, as dissemination and within microfractures in dol1 and dol2, and at borders of yellowish-brown (slyb) and yellow (sly) sphalerite types (Figs. 6E-J). Traces of galena occur in voids and narrow veinlets that crosscut yellowish-brown (slyb) and yellow sphalerite (sly; Figs. 6I-J).

Taking into account the aforementioned petrographic observations as well as textural descriptions carried out by de Oliveira et al. ( 2021), a paragenetic sequence has been produced for the Shalipayco deposit (Fig. 7).

Sphalerite geochemistry

A summary of sphalerite compositions (LA-ICP-MS and EMPA data), including minimum, maximum, median, mean, and interquartile range (IQR) values is presented in Table 1. LA-ICP-MS results are presented in box-and-whisker plots (Fig. 8). At Shalipayco, only trace element analyses for reddish-brown (slrb), yellowish-brown (slyb), and yellow (sly) sphalerite types were Sphalerite from the San Vicente and Shalipayco deposits displays a relatively wide range of minor and trace element contents. Amongst these, Fe and Cd are the only elements that reached contents higher than 1 wt%. In sphalerite from the San Vicente deposit, Fe contents measured with LA-ICP-MS (IQR = 2.0-0.55 wt%, up to 4.3 wt%) are broadly comparable with those measured with EMPA (IQR = 2.4-0.64 wt%, up to 4.7 wt%; Table 1). In this deposit, Fe contents show a pronounced depletion in sphalerite from the first (sl1; mostly > 1 wt%) to the second (sl2; systematically < 125 ppm) mineralization steps. Within the first step, a gradual decrease from sl1bl to sl1y is recognized (Fig. 8A). In sphalerite grains from the Chilpes prospect, Fe contents are generally low (< 187 ppm), much lower in reddish-brown (slrb; IQR = 9.4-9.0 ppm) and yellowish-brown (slyb; IQR = 9.5-9-0 ppm) than in orange (slo; IQR = 102-87 ppm) and yellow (sly; IQR = 128-93 ppm) sphalerite. Sphalerite grains from the Huacrash prospect, of brownish-orange color (slbo), yielded highly variable Fe contents with an IQR of 0.26 wt%-8.0 ppm. In Shalipayco, the Fe content (IQR = 0.20-0.07 wt%, up to 3.7 wt%) decreases from reddish-brown (slrb) to yellow (sly) sphalerite types. Iron values in sphalerite from the Cristal deposit (EMPA data: IQR = 9.95-6.2 wt%) are higher compared to sphalerite from San Vicente and Shalipayco. Zinc shows a negative correlation with Fe (Fig. S5 in Electronic Supplementary Material), pointing to the commonly observed dominant Fe 2+ ↔ Zn 2+ simple substitution [START_REF] Johan | Indium and germanium in the structure of sphalerite: an example of coupled substitution with copper[END_REF][START_REF] Cook | Trace and minor elements in sphalerite: a LA-ICPMS study[END_REF]) when Fe > ~1 wt%.

Cadmium contents are broadly comparable in sphalerite of the second mineralization step (sl2) of the San Vicente deposit (IQR = 0.57-0.34 wt%), in sphalerite from the Chilpes (IQR = 1.0-0.50 wt%) and Huacrash (IQR = 0.79-0.74 wt%) prospects, and in sphalerite from the Shalipayco deposit (IQR = 0.45-0.27 wt%). These values are comparable to those reported by Mondillo et al. (2018b) in sphalerite from Cristal (IQR = 0.59-0.26 wt%), and higher than those of sphalerite from the first mineralization step (sl1) at San Vicente (IQR = 0.11-0.05 wt%; Fig.

8B).

As for the critical elements (i.e., Ge, Ga, and In), sphalerite from the San Vicente deposit shows significantly higher Ge contents in grains from the second mineralization step (sl2; IQR = 566-41 ppm), particularly in orange (sl2o; IQR = 1,207-375 ppm, up to 1,861 ppm) and yellow (sl2y; IQR = 269-130 ppm, up to 1,096 ppm) sphalerite types relative to sphalerite from the first mineralization step (sl1; IQR = 91-44 ppm); white sphalerite (sl2w) yielded, however, the lowest Ge values (IQR = 0.23-0.14 ppm, up to 2.1 ppm) among all analyzed sphalerite types (Fig. 8C).

Sphalerite from Chilpes yielded variable Ge contents, which were higher in reddish-brown (slrb; IQR = 445-22 ppm, up to 1,745 ppm), orange (slo; IQR = 172-96 ppm), and yellow (sly; IQR = 164-55 ppm) than in yellowish-brown (slyb; IQR = 11-5 ppm) types. Sphalerite from Huacrash yielded Ge contents with an IQR of 650-34 ppm (up to 855 ppm). In Shalipayco, the highest Ge values were registered in yellow sphalerite (sly; IQR = 375-267 ppm, up to 1,119 ppm). Despite the fact that the highest individual Ge values were found in sphalerite from the second step of mineralization at San Vicente, sphalerite from Shalipayco yielded, on average, higher Ge contents (Table 1; Fig. 8C). Sphalerite from the Cristal deposit also has significant Ge contents (IQR = 231-31 ppm, up to 386 ppm).

The highest Ga values were obtained for the reddish-brown sphalerite (slrb; IQR = 1,156-0.26 ppm, up to 3,943 ppm) from the Chilpes prospect, whereas the yellowish-brown (slyb; IQR = 10-0.9 ppm), orange (slo; IQR = 0.7-0.2 ppm), and yellow (sly; IQR = 1.4-0.1 ppm) sphalerite types at this site yielded lower Ga contents. In the San Vicente deposit, Ga reaches maximum values in sphalerite from the second mineralization step (sl2; IQR = 93-15 ppm), particularly in orange sphalerite (sl2o; IQR = 200-12 ppm, up to 997 ppm; Fig. 8D). Sphalerite from Huacrash yielded an IQR for Ge of 97-50 ppm. In sphalerite from Shalipayco and Cristal, Ga values were systematically <7 ppm and down to  0.1 ppm.

Indium contents in sphalerite from San Vicente, Shalipayco, and Cristal deposits are systematically low, mostly at the sub-ppm level (Fig. 8E). The highest In values were recorded in reddish-brown sphalerite from Chilpes (slrb; IQR = 26-0.021 ppm, up to 92 ppm), and in orange sphalerite from the San Vicente deposit (sl2o; IQR = 8.2-2.2 ppm, up to 18 ppm). Other elements that occur in trace amountscommonly between a few ppm to some hundreds of ppmare Mn (Fig. 8F), Cu (Fig. 8G), Ag (Fig. 8H), As (Fig. 8I), and Hg (Fig. 8J).

Nanostructure of sphalerite

The thin foil #1, prepared from sample 2019-SV-05, covers a portion of black sphalerite (sl1bl) and a larger area of white sphalerite (sl2w) in discontinuous contact (Fig. 9A). The HAADF-STEM images reveal general crystal homogeneity within the black sphalerite and the presence of a set of identically oriented nano-sized ( 250 nm) crystalline fringes within white sphalerite (Figs. 9A,10A,C). These images combined with the TEM-EDS area mapping also reveal chemical homogeneity in both the white and black sphalerite, regardless the occurrence of fringes, except for the presence of a pyrrhotite inclusion (Fig. 9A). The measured d-spacing from the SAED collected from the black sphalerite cluster at ~1.95 Å, very close to the ideal 1.9405 Å of plane (110) in the hexagonal 2H structure polytype in wurtzite (Fig. 10B). In contrast, the white sphalerite sampled in this thin foil exhibits larger d-spacings from 2.850 to 3.047 Å; the former has not been reported previously for sphalerite, whereas the latter is very close to the ideal 3.0483 Å of plane (104) in the hexagonal 10H wurtzite polytype (Fig. 10D).

Noteworthy, HRTEM images show no significant mismatch of plane orientation between fringes corresponding to stacking fault defects and matrix in white sphalerite but a remarkable polycrystalline nature.

The inner portion of the yellow (sl2y) sphalerite sampled by the thin foil #2 (prepared from sample 2019-SV-15A) also exhibits nano-sized crystalline fringes and chemical homogeneity (Fig. 9B).

The HRTEM imaging and the SAED show a wide range of d-spacings from 2.706 to 3.150 Å, also within a polycrystalline matrix, matching hkl common to the cubic 3C of and hexagonal 10H structures of sphalerite and wurtzite, respectively (Figs. 10E-H).

The HAADF-STEM imaging along with TEM-EDS mapping (Fig. 9C) of the thin foil #3 (from sample 2019-SV-15B) reveals crystal and compositional homogeneity within the orange sphalerite (sl2o), despite the polycrystalline nature of the matrix (Fig. 10I). The measured dspacing from the SAED of 3.01 Å (Fig. 10J) accords well with the (104) of the 10H structure of wurtzite. D-spacings measured from the HRTEM images are in the range between 2.513 and 3.308 Å (Figs. 10K-L), therefore being also very close to the ideal 2.5244 Å, 2.7933 Å, and 3.3117 Å of the planes ( 108), ( 106), and (111), respectively.

The cross-section of the thin foil #4 (from sample 2019-SV-15B) reveals discontinuity along the contact between white (sl2w) and yellow (sl2y) sphalerite as well as chemical homogeneity within each sphalerite type (Fig. 9D). These two types of sphalerite consist of a polycrystalline matrix made up of an aggregation of crystalline domains with a range of orientations. The d-spacing measured from SAED and HRTEM images for the white sphalerite range from 1.65 Å to 5.403 Å, which matches the ideal plane (311) and theoretical cell parameter of cubic 3C sphalerite, respectively, as well as the d-spacing 2.789 Å, 2.515 Å, and 3.12 Å documented for the 10H structure of wurtzite (Figs. 10M-N). The latter is also identified (1.65 Å to 3.03 Å) for yellow sphalerite (Figs. 10O-P).

Discussion

Enrichment of MVT sphalerite in Ge and Ga

In San Vicente, sphalerite deposited during the first mineralization step, which is the volumetrically most abundant in this deposit, yielded Ge contents (IQR = 91-44 ppm; Table 1) similar to sphalerite from other MVT deposits in Peru (Cristal: IQR = 231-31 ppm, up to 386 ppm Ge; Mondillo et al. 2018b) and worldwide (normal range between 10 and 300 ppm, Paradis 2015; about 400 ppm in MVT zinc ore concentrate, [START_REF] Shanks | Germanium and indium[END_REF]. The Ge content is remarkably higher in sphalerite of the volumetrically minor second mineralization step at the San Vicente deposit, particularly in orange sphalerite (sl2o, IQR = 1,207-375 ppm, up to 1,861 ppm; 1). Similar to Ge, Ga contents are also higher in sphalerite from the second mineralization step at the San Vicente deposit and in sphalerite from Chilpes (with some peaks of up to 3,943 ppm) and Huacrash relative to sphalerite of the first mineralization step at the San Vicente deposit. Sphalerite from the Shalipayco and Cristal deposits shows low Ga contents (Table 1). Finally, In content in sphalerite from the San Vicente district and the Shalipayco deposit, as expected in MVT deposits [START_REF] Cook | Trace and minor elements in sphalerite: a LA-ICPMS study[END_REF][START_REF] Ye | Trace and minor elements in sphalerite from base metal deposits in South China: A LA-ICPMS study[END_REF][START_REF] Ye | Trace elements in sulfide from the Tianbaoshan Pb-Zn deposit, Sichuan province, China: a LA-ICPMS study[END_REF][START_REF] Yuan | Element enrichment characteristics: insights from element geochemistry of sphalerite in Daliangzi Pb-Zn deposit, Sichuan, Southwest China[END_REF], is systematically low (mostly < 1 ppm).

Even if systematic trends in the Ge and Ga contents have been determined, there is a relatively large variation range within each sphalerite type/locality (Fig. 8C-D) and even within single crystals. This fact could be related to oscillatory and sector element zoning as mapped in Gerich sphalerite through CL imaging (e.g., in orange and yellow sphalerite from Chilpes; Fig. S4 in Electronic Supplementary Material). CL activator or and/or co-activator elements in the sphalerite structure include Cd, Mn, and Hg (Çiftçi 2009), which have higher values in sphalerite grains from the second mineralization step in the San Vicente deposit and from Chilpes and Huacrash (i.e., those that are also richer in Ge; Fig. 8).

The minor and trace element contents in sphalerite from the studied Peruvian MVT return variable crystallization temperatures calculated with the GGIMFis geothermometer of Frenzel et al. (2016) (Table 2). Despite the large error associated with the method, the obtained temperatures fall mostly within the 50 -200ºC bracket typical of mineralizing fluids in MVT systems [START_REF] Leach | Sediment-hosted lead-zinc deposits: a global perspective[END_REF]). Sphalerite from Cristal, which is unusually Fe-rich for a MVT deposit (Mondillo et al. 2018b), yielded higher crystallization temperatures (234 ± 77ºC, 2-sigma error; Fig. 12). In the San Vicente deposit, there is a sharp decrease of the calculated sphalerite crystallization temperature from the first mineralization step, at around 180ºC, to the second mineralization step, at around 50ºC. Sphalerite from the Chilpes and Huacrash prospects would have crystallized at similar temperatures as sphalerite from the second mineralization step in the San Vicente deposit. In the Shalipayco deposit, sphalerite records a progressive decrease in the crystallization temperature from around 130ºC to 60ºC from reddish-brown to yellow sphalerite.

For the San Vicente district, the two mineralization steps correlate with the aforementioned sphalerite compositional groups, defined in terms of Ge and Ga contents and crystallization temperatures, and those determined by [START_REF] Bastian | Fluid and metal sources of Zn-Pb sulfides of San Vicente[END_REF] based on Pb isotope ratios. Thus, sphalerite from the second mineralization step at the San Vicente deposit and from the Chilpes and Huacrash prospects (i.e., Ge-and Ga-rich) is characterized by less radiogenic Pb isotope signatures than sphalerite from the first mineralization step at the San Vicente deposit (i.e., Geand Ga-depleted; Fig. 8C-D). The less radiogenic signature of the former can be due to dominant metal sourcing from Mitu Group rocks as already suggested for similar low-radiogenic Pb isotope signatures of Shalipayco galena (Fontboté et al. 1990). More radiogenic signatures could be related to additional metal sourcing from older basement rocks [START_REF] Fontboté | Genesis of the Mississippi Valley-type Zn-Pb deposit of San Vicente, Central Peru; geologic and isotopic (Sr, O, C, S, Pb) evidence[END_REF][START_REF] Chiaradia | Separate lead isotope analyses of leachate and residue rock fractions: implications for metal source tracing in ore deposit studies[END_REF] and/or hydrocarbon-related fluids [START_REF] Bastian | Fluid and metal sources of Zn-Pb sulfides of San Vicente[END_REF]. Although [START_REF] Luo | Germanium enrichment in sphalerite with acicular and euhedral textures: an example from the Zhulingou carbonate-hosted Zn(-Ge) deposit, South China[END_REF] have recently linked higher Ge contents in sphalerite from carbonate-hosted Zn deposits in China with mineralizing fluids scavenging Ge from Ge-rich basement rocks, the available Pb isotope data of the MVT belt in the Pucará Group do not permit to assign Ge and Ga sphalerite enrichment to specific source rocks.

Incorporation mechanisms of Ge and Ga into sphalerite

The mineralogical expression of Ge, Ga and other elements found in minor and trace amounts is assessed from a nano-mineralogical and compositional point of view in the following. TEM-EDS mapping on samples from San Vicente shows chemical homogeneity within all analyzed sphalerite types and lack of mineral inclusions, except for the anecdotic presence of pyrrhotite nano-inclusions in black sphalerite (Fig. 9A). Therefore, high contents of such trace elements detected by LA-ICP-MS in the analyzed sphalerite cannot be attributed to the presence of nanoto-micron sized inclusions. It is worth to note that black sphalerite from San Vicente (sl1b) yielded d-spacings of ~1.95 Å, which are significatively lower than those of neighboring white sphalerite (sl2w; 3.0483 Å) despite both sphalerite types exhibiting an identical wurtzite-type 2H structure.

In contrast, the wider range of variation of d-spacing observed in yellow sphalerite (sl2y; 1.65 to 3.15 Å) is related to the coexistence of conversion of the cubic 3C to hexagonal wurtzite-type 10H structure, which was apparently complete in the orange sphalerite (sl2o) from this locality, displaying higher d-spacings between 2.513 and 3.308 Å, which have been exclusively reported in the wurtzite-type 10H structure. Coexistence of cubic and hexagonal polytype structures between (non)-paragenetic sphalerite grains and within single sphalerite grains have already been noted by other authors in several hydrothermal deposits and demonstrated to be promoted by screw dislocations and twin mechanisms [START_REF] Pósfai | Stacking disorder in the ZnS from Gyöngyösoroszi, Hungary[END_REF][START_REF] Bente | Thin films of semiconducting ZnS-CuInS2 alloys, their characterization and use for solar cells[END_REF][START_REF] Šrot | Stacking faults and twin boundaries in sphalerite crystals from the Trepča mines in Kosovo[END_REF][START_REF] Ciobanu | Focussed ion beamtransmission electron microscopy applications in ore mineralogy: Bridging micro-and nanoscale observations[END_REF]Cook et al. 2015b;[START_REF] Xu | Phase relationships in the system ZnS-CuInS2: Insights from a nanoscale study of indium-bearing sphalerite[END_REF]. There is an infinite number of different stacking sequences (polytypes) that are possible between the ideal cubic and hexagonal structures [START_REF] Ciobanu | Focussed ion beamtransmission electron microscopy applications in ore mineralogy: Bridging micro-and nanoscale observations[END_REF]. Various polytypes and polytypic sequences, both ordered and disordered, have been documented from both synthetic and natural sphalerite and conversion between structures has been debated in terms of incorporation of exotic elements accommodated by structural modification (e.g., [START_REF] Scott | Sphalerite-wurtzite equilibria and stoichiometry[END_REF][START_REF] Sokol | Ultrahigh-temperature sphalerite from Zn-Cd-Se-Rich combustion metamorphic marbles, Daba Complex, Central Jordan: Paragenesis, chemistry, and structure[END_REF][START_REF] Xu | Phase relationships in the system ZnS-CuInS2: Insights from a nanoscale study of indium-bearing sphalerite[END_REF]).

In the sphalerite grains from the four studied deposits and prospects, binary positive elemental correlations seem to be consistent with lattice bound incorporation of elements indeed related with substitution mechanism not readily detectable under HRTEM observations. Thus, positive correlations between Ge and Cu as those observed for some second-step yellow (sl2y) and orange (sl2o) sphalerite types in the San Vicente deposit and in sphalerite from the Chilpes prospect (Fig. 11A) lead us to suggest a 2Cu + + Ge 4+  3Zn 2+ coupled substitution, also documented in other deposits (Belissont 2016;Belissont et al. 2016;[START_REF] Bonnet | Trace element distribution (Cu, Ga, Ge, Cd, and Fe) in sphalerite from the Tennessee MVT deposits, USA, by combined EMPA, LA-ICP-MS, Raman spectroscopy, and crystallography[END_REF]Wei et The most common names used to refer to sphalerite varieties according to crystal color include i) cleiophane [START_REF] Palache | The system of mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892[END_REF], characterized by high transparency and by white color or being colorless, ii) ruby blende [START_REF] Dana | System of mineralogy[END_REF], with red shades, and iii) marmatite [START_REF] Boussingault | Analyse de la blende noire de Marmato, province de Popayán[END_REF][START_REF] Palache | The system of mineralogy of James Dwight Dana and Edward Salisbury Dana Yale University 1837-1892[END_REF], highlighted by its black color and opacity. Other less commonly used variety names for sphalerite include iv) golden sphalerite, with yellow to orange shades, and v) green sphalerite, among others. The use of these varietal names does not follow any criteria of specific element content ranges, crystal-chemical or structural parameters. The only proposal to define a particular sphalerite variety based on its chemical composition was made by [START_REF] Ramdohr | The ore minerals and their intergrowths[END_REF], who suggested that Fe should be equal to, or greater than, 10 wt% in marmatite. In the following we explore possible correlations between color and composition.

Iron is considered the most ubiquitous impurity element in sphalerite [START_REF] Benedetto | Compositional zoning in sphalerite crystals[END_REF] and for many years there has been a consensus that sphalerite color is directly and essentially dependent on Fe content [START_REF] Awadh | Iron content variations in sphalerite and their effects on reflectance and internal reflections under reflected light[END_REF][START_REF] Cook | Trace and minor elements in sphalerite: a LA-ICPMS study[END_REF][START_REF] Li | Orbitally forced sphalerite growth in the Upper Mississippi Valley district[END_REF][START_REF] Knorsch | Trace elements and textures of hydrothermal sphalerite and pyrite in Upper Permian (Zechstein) carbonates of the North German Basin[END_REF]). However, this principle is not always fulfilled, particularly in Fe-poor sphalerite (< 2-3 wt% Fe; see [START_REF] Roedder | Sphalerite color banding. Lack of correlation with iron content, Pine Point, Northwest Territories, Canada[END_REF]), as it is the case of most analyzed sphalerite samples (Table 1). In sphalerite from the San Vicente deposit, there is a general decrease in the Fe content from earlier (darker) to later (lighter) types; such Fe depletion is, however, not continuous and shows an abrupt depletion from first-step (including black [sl1bl], reddish-brown Black sphalerite is often related to higher Fe content [START_REF] Craig | Ore Microscopy and Ore Petrography[END_REF][START_REF] Katsev | Mechanism and duration of banding in Mississippi Valley-type sphalerite[END_REF]). However, Fe contents do not necessarily have to be high to produce such color, as observed in black sphalerite from San Vicente (sl1bl, IQR = 2.6-1.7 wt% Fe) and other MVT deposits elsewhere [START_REF] Bradbury | Mineralogy and the question of zoning, Northwestern Illinois zinc-lead district[END_REF][START_REF] Jolly | Mineral paragenesis and zoning in the Central Kentucky Mineral district[END_REF][START_REF] Roedder | Sphalerite color banding. Lack of correlation with iron content, Pine Point, Northwest Territories, Canada[END_REF], with contents even lower than those recorded in this study. In general, black sphalerite in San Vicente replaces the host rock, is fine-grained and contains impurities of other minerals (dolomite, pyrite) and, as identified in the present work by FIB-TEM, nano-inclusions of pyrrhotite, which could explain its dark color.

Reddish-brown sphalerite in the San Vicente (sl1rb) and Shalipayco (slrb) deposits also has low Fe contents (IQR = 2.1-1.1 wt%), and extremely low Fe contents are found in reddish-brown sphalerite from Chilpes (slrb; mostly <d.l.). Reddish-brown sphalerite from the three localities may show significant enrichment in Cd (particularly in Chilpes and Shalipayco; Fig. 8B), Cu (Chilpes and Shalipayco; Fig. 8G), Mn (Chilpes; Fig. 8F), Hg (Shalipayco; Fig. 8J), Ge (Chilpes and Shalipayco; Fig. 8C), and Ag (Shalipayco; Fig. 8H), thus suggesting that some of these elements could have an impact on crystal color. [START_REF] Sapalski | Estudio de la esfalerita de la mina de Ávila, Santander[END_REF] determined that red sphalerite from the Áliva MVT mine in Santander, Spain, coincides with high Ge and Hg contents, whereas [START_REF] Sanabria | Les sphalérites d'Aliva, Picos de Europa (Espagne)[END_REF] correlated this color with high Cd, Cu, and Hg contents. Yellowish-brown sphalerite has been identified in San Vicente (sl1yb), Chilpes (slyb), and Shalipayco (slyb). Again, Fe content alonewith variations of more than three orders of magnitude between yellowish-brown sphalerite from the three localities (Fig. 8A)cannot explain this color. Yellowish-brown may be considered an intermediate color tone between reddish-brown and yellow. [START_REF] Kelley | Textural, compositional, and sulfur isotope variations of sulfide minerals in the Red Dog Zn-Pb-Ag deposits, Brooks Range, Alaska: implications for ore formation[END_REF] suggested correlation of yellow sphalerite with relatively high As and Hg contents. The highest As values in our study were not found in sphalerite of yellow color but in sphalerite of reddish-brown color at Chilpes (slrb, IQR = 480-60 ppm, up to 1,857 ppm; Fig. 8I). Yellow sphalerite from the first mineralization step at San Vicente (sl1y) yielded the highest As content (IQR = 145-7.5 ppm) among analyzed yellow sphalerite, whereas yellow sphalerite from Shalipayco (sly; IQR = 5.1-3.4 ppm), Chilpes (< 11 ppm), and the second mineralization step at San Vicente (sl2y; IQR = 5.1-3.4 ppm) yielded much lower As. Therefore, we do not observe a systematic correlation between the yellow color and high As contents in the studied samples. On the other hand, Hg contents are not high in the analyzed yellow sphalerite from the three localities compared to the other sphalerite types (Fig. 8J).

Yellow cyclic growth bands of sphalerite have been correlated with higher Ge, Cu, and Pb contents in the North German Basin [START_REF] Knorsch | Trace elements and textures of hydrothermal sphalerite and pyrite in Upper Permian (Zechstein) carbonates of the North German Basin[END_REF]. Germanium is relatively high in yellow sphalerite in the studied samples compared to other sphalerite types from the respective localities and could therefore explain, in part, this color. [START_REF] Slack | Optical absorption of tetrahedral Fe 2+ (3d 6 ) in cubic ZnS, CdTe, and MgAl2O4[END_REF][START_REF] Slack | Far-infrared optical absorption of Fe 2+ in ZnS[END_REF] suggested that the absorption band of Fe 2+ and Zn 2+ (blue), added with the absorption of small amounts of Co 2+ (red), compound the yellow color. This does not seem to be the case for the studied sphalerite samples as all of them yielded very low Co contents, mostly below the detection limit.

Orange sphalerite from San Vicente (sl2o) displays relatively high contents of Cu, Ge, Ag, and Cd (Fig. 8). Orange sphalerite from Chilpes (slo) and brownish-orange sphalerite from Huacrash (slbo) are also relatively enriched in Ge and Cd, and to some extent also in Ag, but not in Cu.

High Cd is also reported in orange sphalerite from Áliva [START_REF] Gómez-Fernández | Metallogenesis of Zn-Pb carbonate-hosted mineralization in the southeastern region of the Picos de Europa (Central Northern Spain) Province: geologic, fluid inclusion, and stable isotope studies[END_REF].

Finally, white sphalerite is mainly correlated with very low Fe contents [START_REF] Ramdohr | The ore minerals and their intergrowths[END_REF]. Iron in white sphalerite from the San Vicente deposit (sl2w) is indeed not detectable. White sphalerite (sl2w) is also depleted in most of the other analyzed minor and trace elements with the remarkable exceptions of Cd, Ga, Mn, and Hg, which are relatively high compared to other sphalerite types from the same locality (Fig. 8). Therefore, we conclude that the role of some long-considered chromophore elements in sphalerite (i.e., Cd, Mn, Hg) per se should be reconsidered. Occasional pale green internal reflections in white sphalerite could be linked to trace contents of Co [START_REF] Hofmann | Green sphalerite from Zaire[END_REF][START_REF] Rager | Colour, crystal chemistry, and mineral association of a green sphalerite from Steinperf, Dill syncline, FRG[END_REF].

The above observations suggest possible relationship between sphalerite color and abundance of certain trace elements. Regarding Ge, high contents of this metalloid seem to be correlated with orange, and to lesser extent, yellow, colors in sphalerite. However, it is challenging to affirm which element or combination of elements and under which oxidation states could directly influence crystal colors since not enough evidence has been found yet. Unfortunately, we are not far from the conclusions reached by [START_REF] Roedder | Sphalerite color banding. Lack of correlation with iron content, Pine Point, Northwest Territories, Canada[END_REF], who stated that "the true coloring mechanism is not known" in sphalerite.

Conclusions

LA-ICP-MS analyses on sphalerite have been performed after a thorough petrographic study of ore samples from the MVT San Vicente district (including the San Vicente deposit and the Chilpes and Huacrash prospects) and the Shalipayco deposit in Peru. The results make it possible to correlate trace element contents with sphalerite types and fluid evolution.

In the analyzed samples, all types of sphalerite show substantial Ge contents (IQR = 118-44 ppm), as is typical in MVT mineralization. The highest Ge values (> 1,000 ppm) from the studied deposits were found in Fe-poor sphalerite that crystallized relatively late in the paragenetic sequences and probably from fluids of lower temperature relative to Ge-poorer sphalerite.

Gallium contents are, in general, lower than those of Ge. However, very high Ga values (> 3,000 ppm) are found in Fe-poor sphalerite from Chilpes. A correlation between Ga enrichment and mineralization sequence could not be determined. According to the obtained values, certain sphalerite types from the studied Peruvian MVT deposits are among the most enriched in Ge and Ga globally.

HRTEM observations revealed that trace elements detected in high amounts in the analyzed sphalerite types are lattice-bound. Correlations between molar contents suggest incorporation of Ge into the sphalerite crystal lattice coupled with monovalent cations through substitution schemes such as Ge 4+ + 2Cu +  3Zn 2+ , Ge 4+ + 2Ag +  3Zn 2+ , and Ge 4+ + 2(Cu + Ag + Tl) +  3Zn 2+ . Gallium contents do not correlate with Ge contents, thus suggesting incorporation via other independent substitution mechanisms such as Cu + + (Ga, In) 3+ + Sn 4+  4Zn 2+ coupled substitutions.

Targeting of ore rich in light-colored sphalerite, principally of orange and yellow colors, typically formed in low-temperature stages of the mineralization process, may preliminarily constitute a guideline in exploration for Ge in MVT deposits. Geochronology of igneous rocks from by [START_REF] Capdevila | Le batholite de San Ramón, Cordillére Orientale du Pérou central[END_REF], [START_REF] Lancelot | U/Pb radiochronology of two granitic plutons from the Eastern Cordillera (Peru) -extent of Permian magmatic activity and consequences[END_REF], [START_REF] Gunnesch | Lead isotope variations across the Central Peruvian Andes[END_REF][START_REF] Chew | U-Pb geochronologic evidence for the evolution of the Gondwanan margin of the northcentral Andes[END_REF][START_REF] Rosas | Profundización sedimentaria solo en la parte de la cuenca Pucará (Perú Central) durante el Hetangiano Sinemuriano[END_REF]; see text for details. WSD: white sparry dolomite Fig. 3 Hand-sample photographs showing different textures in ore samples from the San Vicente deposit. A) Rock with zebra-type texture consisting of bands of dark replacement dolomite + black sphalerite overgrown by reddish-brown and yellowish-brown sphalerite bands and white sparry dolomite 1. White sparry dolomite 1 cuts also the former bands (sample 2019-SV-02). B) Dark replacement dolomite + black sphalerite overgrown by reddish-brown and yellowish-brown sphalerite, followed by white sparry dolomite 1. Galena and white sparry dolomite 1 fill the remaining space (sample 2019-SV-11). C) Relictic dark replacement dolomite intergrown with black sphalerite, and reddish-brown and yellowish-brown sphalerite overgrowths replaced and cemented by white sparry dolomite 1 (sample 2019-SV-12). D) Colloform reddish-brown sphalerite and galena overgrown by yellowishbrown and yellow sphalerite and white sparry dolomite 1. Note also veinlets of galena crosscuting the white sparry dolomite 1 cement (sample 2019-SV-01). E) Reddish-brown and yellowish-brown sphalerite colloform bands overgrown by first-step yellow sphalerite; clasts have been rotated and cemented by white sparry dolomite 1 (sample 2019-SV-03). F) Detail of a breccia in a steep crosscutting vein with partially dissolved and rotated dark replacement Table S1 List of samples and their location.

Figure captions

Table S2 Representative EMPA analyses of sphalerite. Structural formulas of sphalerite are normalized to S = 1.

Table S3 LA-ICP-MS trace element analyses on sphalerite-Metadata.

Figures 1

 1 Figures 1 and 2 in de Oliveira et al. (2021).

  ) of the first mineralization step. Sphalerite formed during the second mineralization step (sl2) is volumetrically restricted. It occurs as micro-to millimeter-sized anhedral to subhedral crystals in microfractures and open spaces, mostly intergrown with WSD2 (Figs. 4D

  obtained. In addition, EMPA and LA-ICP-MS analyses of sphalerite from the MVT Cristal deposit obtained by Mondillo et al. (2018b) are shown for comparison. A significant effort was made to report only the content of elements whose variations respond to solid solutions and not to mixed mineral analyses (e.g., presence of mineral micro-inclusions) by selecting only flat, stable signal intervals from the LA-ICP-MS spectra. Of the analyzed elements, Sb, As, Tl, and Pb gave occasionally spiky LA-ICP-MS transient signals, possibly indicative of micro-scale solid inclusions (e.g., galena).

  Fig. 8C); to a lesser extent, also in sphalerite from the Chilpes (IQR = 193-20 ppm, up to 1,741 ppm) and Huacrash (IQR = 650-34 ppm, up to 855 ppm) prospects in the San Vicente district. In Shalipayco, yellow sphalerite (sly) is the one showing the highest Ge contents (IQR = 375-267 ppm, up to 1,119 ppm) in this deposit. The aforementioned maximum Ge values for sphalerite in Peruvian MVT deposits are comparable with those obtained in Ge-rich sphalerite from the Tres Marías deposit in Mexico (average = 960 ppm, up to 3200 ppm; Saini-Eidukat et al. 2009), which for some authors is a MVT deposit and for others is of magmatic affiliation (see discussion in Ostendorf et al. 2017), as well as with sphalerite deposited during the lowtemperature stage (140-80 ºC) of the Saint Salvy vein-type deposit (up to 2,600 ppm of Ge; Belissont et al. 2014). Noteworthy, in the porphyry-related Cordilleran polymetallic deposits of the Morococha District (central Peru), only local, late, low-temperature, colloform sphalerite shows relatively high Ge values (IQR = 129-74 ppm, up to 215 ppm; Benites et al. 2021). At generally lower contents, Ga also shows contrasting values amongst the analyzed sphalerite types and localities (Fig. 8D; Table

[

  sl1rb], yellowish-brown [sl1yb], and yellow [sl1y] types) to second-step (including orange [sl2o], yellow [sl2y], and white [sl2w] types; Fig. 8A) sphalerite.

Fig. 1 Fig. 2

 12 Fig. 1 Morphostructural units of Peru (modified from Benavides-Cáceres 1999), including the

Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 9

 45679 Fig. 4 Photomicrographs of polished sections taken with reflected light without analyzer (PPL)

Fig. 10

 10 Fig. 10 Nanostructure of selected areas of the analyzed thin foils on sphalerite from the San

Fig. S4

 S4 Fig. S4 Whole mount optical-CL photograph of a sphalerite-bearing sample from the Chilpes

Fig. S5

 S5 Fig. S5 Binary Fe vs Zn correlation plot for analyzed sphalerite from the San Vicente deposit

  Figure 1

  Figure 4

  Figure 6

  Figure 10

Table captions Table 1

 captions1 Summary of element contents in sphalerite from the San Vicente, Shalipayco, and

	Cristal deposits

Table 2

 2 Formation temperature (ºC) of sphalerite according to the GGIMFis geothermometer of[START_REF] Frenzel | Gallium, germanium, indium, and other trace and minor elements in sphalerite as a function of deposit type -A meta -analysis[END_REF]

Table S4

 S4 LA-ICP-MS trace element analyses on sphalerite and reference materials.

		Zn	Fe	Fe	Mn	Cd	In	Ge	Ga	Cu	Ag	Hg	Tl	As
		(wt%)	(wt%)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)	(ppm)
	MIN.	-	-	B.D.L.	B.D.L.	185	B.D.L.	B.D.L.	B.D.L.	B.D.L.	1.1	1.3	B.D.L.	B.D.L.
	MAX.	-	-	43,271	1,161	16,422	92	1,861	3,943	4,840	3,029	37	30	1,857
	Median	-	-	98	69	4,805	0.04	73	1.6	27	18	3.6	0.49	9
	Mean	-	-	5,792	185	5,286	3.5	191	160	383	88	5.5	1.8	95
	IQR	-	-	10,585-10	296-15	7,824-1,103	0.47-0.01	164-36	27-0.22	114-4.53	68-6	4.9-2.6	1.3-0.14	68-2
	MIN.	61.7	B.D.L.	B.D.L.	3.0	185	B.D.L.	B.D.L.	0.038	B.D.L.	1.8	1.9	B.D.L.	3
	MAX.	67.9	4.7	43,271	1,161	9,924	18	1,861	997	2,084	3,029	9.1	25	439
	Median	65.4	2.0	12,463	45	861	0.02	68	2.2	4	8.8	3.6	0.9	10
	Mean	65.3	1.6	13,061	122	1,778	0.8	148	27	92	117	4.0	2.1	34
	IQR	66.4-64.3	2.4-0.6	19,577-5,479	97-23	1,974-535	0.14-0.008	118-44	13-0.25	7-4	44,699	4.4-3.2	2.5-0.49	21-5
	MIN.	61.7	0.25	3,000	3.0	185	B.D.L.	13	0.038	B.D.L.	2	1.9	0.036	3
	MAX.	67.5	4.7	43,271	172	3,784	0.65	180	80	10	38	8.6	7.0	439
	Median	64.8	2.0	16,674	32	714	0.01	61	1.0	4	6	3.4	0.9	12
	Mean	65.0	2.0	17,038	39	840	0.039	71	4.4	4	9	3.5	1.4	41
	IQR	66.4-64.3	2.4-0.7	20,663-10,680	52-21	1,080-489	0.04-0.01	91-44	4.4-0.18	44,656	11-4	3.9-3.1	1.6-0.52	27-6
	MIN.	61.7	0.3	9,774	7.4	311	B.D.L.	19	0.064	B.D.L.	2	2.4	0.26	3
	MAX.	67.5	4.7	43,271	172	3,784	0.65	180	80	8	29	8.6	3.2	167
	Median	64.5	2.0	20,525	43	591	0.018	72	3.0	4	6.0	3.4	0.9	12
	Mean	64.6	2.2	22,066	47	762	0.067	79	7.0	5	9	3.7	1.1	21
	IQR	65.9-63.8	2.4-1.5	25,831-16,671	63-25	899-495	0.06-0.01	105-54	7.1-0.23	44,657	2-4	4.0-2.9	1.2-0.66	22-6
	MIN.	62.2	0.6	8,342	8.9	185	B.D.L.	31	0.038	B.D.L.	2	1.9	0.23	3
	MAX.	67.1	4.2	32,945	77	1,430	0.21	168	48	8	21	5.4	3.1	183
	Median	64.4	2.4	19,687	35	746	0.010	54	0.136	4	5	3.2	0.6	14
	Mean	64.6	2.3	19,531	39	727	0.028	71	3.4	4	6	3.2	0.91	26
	IQR	65.4-63.9	2.7-1.5	22,035-15,116	54-23	897-503	0.02-0.007	90-43	2.8-0.07	5-4	6-3	3.5-2.4	1.3-0.41	23-9
	MIN.	63.1	0.4	3,000	3.0	247	B.D.L.	13	0.044	B.D.L.	2	2.0	0.036	3
	MAX.	67.3	3.6	38,867	97	2,458	0.23	167	26	10	38	5.7	7.0	439
	Median	65.1	1.9	12,906	37	786	0.012	55	1.2	3.8	7	3.5	0.9	8.8
	Mean	65.0	1.8	13,278	38	912	0.030	63	3.4	4.1	9	3.5	1.6	54
	IQR	65.5-64.3	2.4-1.2	16,839-9,473	47-18	1,447-456	0.04-0.008	83-42	3.2-0.47	4-3.5	10-5	3.9-3.2	2.5-0.43	38-5
	MIN.	63.8	1.2	6,309	6.3	531	B.D.L.	37	0.049	B.D.L.	3	2.1	0.34	3
	MAX.	65.9	2.4	16,235	68	1,598	0.067	144	17	5	22	5.7	4.3	237
	Median	65.2	1.8	11,562	17	958	0.008	60	0.23	4	15	3.6	2.2	58
	Mean	65.1	1.8	11,281	20	1,039	0.016	78	2.5	4	14	3.7	2.1	79
	IQR	65.4-64.9	2.0-1.5	13,656-8,621	23-11	1,383-731	0.01-0.006	104-46	1.3-0.16	5-3	20-7	4.3-3.1	2.9-1.3	145-8
	MIN.	65.6	B.D.L.	B.D.L.	139	1,363	B.D.L.	B.D.L.	0.21	B.D.L.	6	3.5	B.D.L.	3.0
	MAX.	67.9	B.D.L.	122	1,161	9,924	18	1,861	997	2,084	3,029	9.1	25	173
	Median	66.6	-	14	338	4,356	1.2	177	47	104	33	5.2	3.7	4
	Mean	66.5	-	28	391	4,772	3.3	392	100	381	463	5.6	4.3	15
	IQR	66.3-64.3	-	30-11	471-261	5,704-3,440	4.5-0.39	566-41	93-14.9	461-17	627-15	6.2-4.5	7.4-0.25	9-4
	MIN.	66.2	B.D.L.	B.D.L.	139	3,489	0.0084	0.18	0.21	55	15	4.0	0.0093	4
	MAX.	67.6	B.D.L.	17	683	8,253	18	1,861	997	2,084	3,029	9.1	9.6	173
	Median	66.7	-	11	340	5,126	3.7	621	64	633	627	5.3	3.6	8
	Mean	66.8	-	11	379	5,577	5.9	747	172	890	990	5.5	3.6	27
	IQR	67.0-66.6	-	12-10	524-266	7,180-4,281	8.2-2.2	1,207-375	200-11.6	1,446-392 1,335-414	5.8-4.5	5.4-0.22	18-6
	MIN.	65.8	B.D.L.	B.D.L.	146	1,363	B.D.L.	6.7	0.76	B.D.L.	5.8	3.5	0.020	3
	MAX.	67.9	B.D.L.	122	1,161	9,924	8.6	1,096	306	1,149	1,959	7.3	25	82
	Median	66.1	-	29	314	3,440	0.5	176	25	18	20	4.8	5.1	4
	Mean	66.3	-	43	392	4,308	1.1	252	43	125	217	4.9	5.9	9
	IQR	66.7-65.8	-	62-15	375-244	5,307-3,120	0.93-0.18	269-130	49-15	80-4	69-13	5.2-4.4	8.1-1.9	5.1-3.4
	MIN.	67.4	B.D.L.	B.D.L.	273	3,817	3.8	B.D.L.	92	96	14	8.3	B.D.L.	4
	MAX.	67.4	B.D.L.	13	593	4,805	5.8	2.1	195	206	46	8.9	0.15	5

Table 1

 1

	Ore-body/vein	Sphalerite type		Zn (wt%)	Fe (wt%)	Fe (ppm)	Mn (ppm)	Cd (ppm)	In (ppm)	Ge (ppm)	Ga (ppm)	Cu (ppm)	Ag (ppm)	Hg (ppm)	Tl (ppm)	As (ppm)
			Median	67.4	-	11	382	4,497	4.5	0.16	99	112	27	8.5	0.01	4
			Mean	67.4	-	12	423	4,441	4.6	0.54	130	137	28	8.5	0.04	4
			IQR	-	-	12-11	486-381	4,727-4,356	5.0-3.9	0.23-0.14	171-93	172-96	30-22	8.5-8.4	0-0.01	4.0-3.8
			MIN.	n.a.	n.a.	B.D.L.	B.D.L.	4,024	B.D.L.	B.D.L.	B.D.L.	B.D.L.	1	1.3	B.D.L.	0.06
		All analyses (n = 175)	MAX. Median Mean	n.a. n.a. n.a.	n.a. n.a. n.a.	187 10 54	803 138 211	16,422 7,545 8,070	92 0.04 6.3	1,745 92 208	3,943 0.8 292	4,840 88 694	347 42 59	37 2.9 7.0	11 0.20 0.51	1,857 5 133
			IQR	n.a.	n.a.	98-9	433-1.6	10,103-4,965	0.33-0.011	193-20	22-0.2	392-38	85-11	7.7-2.1	0.4-0.07	100-0.8
			MIN.	n.a.	n.a.	B.D.L.	129	4,139	B.D.L.	B.D.L.	B.D.L.	5	2	1.5	0.020	0.17
			MAX.	n.a.	n.a.	13	716	10,310	92	1,745	3,943	4,840	347	37	2.4	1,857
		sl rb (n = 66)	Median	n.a.	n.a.	9	502	6,130	0.41	131	33	1,318	48	10	0.26	135
			Mean	n.a.	n.a.	9.3	452	6,496	16	383	759	1,686	63	13	0.40	329
			IQR	n.a.	n.a.	9.4-9.0	623-254	7,823-4,857	26-0.021	445-22	1,156-0.3	2,866-159	95-11	21-4.5	0.5-0.07	480-60
			MIN.	n.a.	n.a.	B.D.L.	122	4,024	B.D.L.	B.D.L.	0.040	B.D.L.	1	1.4	B.D.L.	0.10
			MAX.	n.a.	n.a.	10	438	7,071	3.0	736	139	1,495	52	25	0.21	386
			Median	n.a.	n.a.	9	144	4,422	0.03	7.3	1.4	44	4	2.0	0.05	24
			Mean	n.a.	n.a.	9	183	4,633	0.27	58	16	151	7	3.7	0.061	53
			IQR	n.a.	n.a.	9.5-9.0	195-139	4,682-4,290	0.18-0.011	11-5	11-0.9	82-27	6-2	3.5-1.7	0.1-0.04	54-6.4
			MIN.	n.a.	n.a.	74	B.D.L.	5,115	0.006	18	0.068	17	12	1.3	0.031	0.09
			MAX.	n.a.	n.a.	127	247	14,033	0.48	283	27	279	257	8.2	11	54
			Median	n.a.	n.a.	94	5.8	8,276	0.02	129	0.4	122	80	2.5	0.4	0.8
			Mean	n.a.	n.a.	97	26	8,972	0.095	134	2.9	126	95	3.0	2.2	10
			IQR	n.a.	n.a.	102-87	13-1.6	11,266-6,621	0.09-0.012	172-96	0.7-0.2	162-86	121-58	3.3-2.1	1.6-0.19	7-0.59
			MIN.	n.a.	n.a.	B.D.L.	B.D.L.	4,530	B.D.L.	0.31	B.D.L.	5	2	1.9	0.01	0.06
			MAX.	n.a.	n.a.	187	803	16,422	0.57	293	129	251	317	13	2.4	11
			Median	n.a.	n.a.	104	1.4	11,028	0.025	101	0.2	51	45	2.5	0.3	0.82
			Mean	n.a.	n.a.	108	26	10,833	0.066	112	6.6	63	68	3.1	0.38	0.74
			IQR	n.a.	n.a.	128-93	2.3-1.4	13,335-8,977	0.06-0.009	164-55	1.4-0.1	83-27	90-31	3.3-2.2	0.5-0.11	0.9-0.13
			MIN.	n.a.	n.a.	B.D.L.	114	3,491	0.37	10	4.1	10	14	3.9	0.56	1.0
			MAX.	n.a.	n.a.	6,934	722	8,200	3.6	855	107	37	330	5.0	30	1,126
			Median	n.a.	n.a.	21	307	7,713	1.5	205	61	17	84	4.2	10	35
			Mean	n.a.	n.a.	1,514	369	7,381	1.8	327	65	22	110	4.3	8.7	184
			IQR	n.a.	n.a.	2,597-8	505-279	7,970-7,403	2.6-1.0	650-34	97-50	31-15	188-27	4.4-4.0	15-0.85	291-3
			MIN.	n.a.	n.a.	181	B.D.L.	1,501	B.D.L.	2.7	B.D.L.	B.D.L.	6	3.0	0.011	4
			MAX.	n.a.	n.a.	37,888	14	7,687	2.6	1,119	32	5,090	1,600	780	6.7	93
			Median	n.a.	n.a.	1,017	1.4	3,808	0.01	299	0.4	5	270	115	1.1	13
			Mean	n.a.	n.a.	4,893	3.2	3,898	0.11	316	4.4	239	362	203	1.6	20
			IQR	n.a.	n.a.	2,793-666	3.4-1.1	4,487-2,741	0.01-0.007	425-101	2.8-0.08	131-4	508-56	313-58	1.9-0.44	22-8
			MIN.	n.a.	n.a.	384	B.D.L.	1,501	B.D.L.	4.5	0.032	B.D.L.	12	8.7	0.037	4
			MAX.	n.a.	n.a.	37,888	14	7,687	1.1	731	1.3	5,090	512	780	6.7	62
			Median	n.a.	n.a.	3,116	1.4	4,032	0.01	249	0.2	4	163	408	1.5	10
			Mean	n.a.	n.a.	11,193	5.2	3,943	0.10	254	0.5	429	192	315	2.0	18
			IQR	n.a.	n.a.	18,937-820	7.8-1.1	4,936-2,295	0.01-0.006	384-52	1-0.1	4.0-3.9	320-26	451-50	2.2-0.98	20-7
			MIN.	n.a.	n.a.	181	B.D.L.	2,425	B.D.L.	2.7	B.D.L.	B.D.L.	6	3.0	0.011	5
			MAX.	n.a.	n.a.	22,783	7.9	7,048	2.6	966	32	1,347	1,600	772	5.5	93
			Median	n.a.	n.a.	1,040	1.5	3,871	0.01	307	0.5	11	295	119	0.8	15
			Mean	n.a.	n.a.	3,151	2.7	4,094	0.11	321	4.5	183	389	180	1.4	23
			IQR	n.a.	n.a.	1760-786	3.2-1.2	4,639-3,396	0.01-0.007	468-71	3-0.1	183-4.5	511-63	272-75	1.6-0.25	26-8
			MIN.	n.a.	n.a.	424	B.D.L.	2,134	B.D.L.	156	0.073	B.D.L.	176	45	0.34	7
			MAX.	n.a.	n.a.	882	3.2	4,058	0.57	1,119	31	549	1,469	301	3.8	14
			Median	n.a.	n.a.	666	1.1	3,010	0.01	304	3.1	31	540	57	0.6	8
			Mean	n.a.	n.a.	659	1.47	2,977	0.12	409	11	128	562	95	1.4	9

sl yb (n = 27) sl y (n =16) sl y (n = 66) Chilpes prospect sl bo (n = 27) Huacrash prospect Shalipayco deposit All analyses (n = 50) sl rb (n = 13) sl yb (n = 30) sl y (n =7) sl 2w (n = 5)

  EMPA data in wt.%. LA-ICP-MS data in ppm. n refers to the number of LA-ICP-MS analyses B.D.L.: below detection limit; n.a.: not analyzed For values B.D.L., individual detection limits as shown in ESM TableS4have been taken into account for the calculation of median, average, and IQR values.

	Ore-body/vein	Sphalerite sl y (n =7) type Ore-body/vein IQR	Zn (wt%) n.a.	Fe (wt%) n.a. Sphalerite type Fe (ppm) 746-573	n	Mn (ppm) 1.4-1.1 Median 3,474-2,343 Cd (ppm) Mean	In (ppm) 0.13-0.01 2 sigma	Ge (ppm) 375-267	Ga (ppm) 21-0.2	Cu (ppm) 152-5	Ag (ppm) 574-300	Hg (ppm) 81-50	Tl (ppm) 1.9-0.52	As (ppm) 10-8
		MIN.	54.4	5.3	sl 1bl	n.a.	33	7.6	181	1,939 183	B.D.L. 41	0.25	B.D.L.	40	1	n.a.	n.a.	n.a.
	MAX. Median Mean IQR San Vicente deposit Cristal (n = 20; Mondillo et al. 2018b)	61.9 59.1 58.2 59.9-56.3	12.9 8.0 sl 1rb 8.2 10.0-6.2 sl 1yb sl 1y	n.a. n.a. n.a. n.a.	27 45 12	40 17 19 26-9 200 174 168	8,429 4,923 195 4,600 5,867-2,562 174 171	37 0.13 43 3.2 0.51-0.010 46 54	386 131 142 231-31	6.6 0.1 1.3 1.8-0.05	229 80 112 182-53	134 12 38 77-3	n.a. n.a. n.a. n.a.	n.a. n.a. n.a. n.a.	n.a. n.a. n.a. n.a.
					sl 2o		12		29	28	60
					sl 2y		18		56	51	31
					sl rb		66		35	39	100
		Chilpes prospect			sl yb sl o		27 16		70 65	71 67	68 53
					sl y		66		63	61	49
		Huacrash prospect			sl bo		27		59	82	105
					sl rb		12		142	136	101
		Shalipayco deposit			sl yb		30		83	98	113
					sl y		7		54	58	37
		Cristal (Mondillo et al. 2018b)		15		218	234	77

Table 2 ECUADOR

 2

	81º	77º	73º	69º
				2º
				6º
	10º			10º
	14º
	81º	77º	73º	69º

Acknowledgements

This study was economically supported by the Peruvian CONCYTEC-FONDECYT-World Bank project 107-2018-FONDECYT-BM-IADT-AV managed through the PROCIENCIA agency. We want to thank the staff of SIMSA -Unidad Minera San Vicente for the help and hospitality during sampling tasks and the Minera Nexa Resources for providing samples from the Shalipayco deposit. We appreciate the technical support by Xavier Llovet (CCiT-UB) during the acquisition of EMPA data and by Pete Tollan (ETH) during the acquisition of LA-ICP-MS data. Finally, we also would like to thank Alejandro Vargas (BIZALAB.SAC) for the SEM analyses. We are grateful to Frank Melcher, Associate Editor Hartwig Frimmel, and Editor-in-Chief Bernd Lehmann for their constructive comments which significantly improved the manuscript.

 al. 2019;[START_REF] Cave | The effect of co-crystallising sulphides and precipitation mechanisms on sphalerite. Geochemistry: a case study from the Hilton Zn-Pb (Ag) deposit[END_REF][START_REF] Liu | Germanium speciation in experimental and natural sphalerite: implications for critical metal enrichment in hydrothermal Zn-Pb ores[END_REF]. A positive correlation is also recognized between Ge and Ag, partially lying along the 1:2 ratio line (Fig. 11B). This correlation is mainly noticed for second-step orange (sl2o) sphalerite from San Vicente, most sphalerite types from Chilpes and Huacrash, and yellowish-brown (slyb) and yellow (sly) sphalerite from Shalipayco, suggesting a Ge 4+ + 2Ag +  3Zn 2+ coupled substitution as previously proposed by [START_REF] Cook | Trace and minor elements in sphalerite: a LA-ICPMS study[END_REF] and [START_REF] Belissont | LA-ICP-MS analyses of minor and trace elements and bulk Ge isotopes in zoned Ge-rich sphalerites from the Noailhac -Saint-Salvy deposit (France): insights into incorporation mechanisms and ore deposition processes[END_REF]. A fairly positive correlation between the molar contents of Ge and Tl in San Vicente and Shalipayco (Fig. 11C) is observed. The aforementioned correlations indicate that incorporation of Ge in the studied sphalerite was coupled with the incorporation of monovalent Cu, Ag, and Tl (Fig. 11D), and that combinations of these coupled substitution schemes (i.e., Ge 4+ + 2(Cu + Ag + Tl) +  3Zn 2+ ) are plausible.

As for Ga and In contents, they show no correlation with Ge (Figs. 11E-F), suggesting incorporation via other independent substitution mechanisms. Rough correlations between Ga and In (Fig. 11G) and of Ga and Sn (Fig. 11H) suggest coupled substitutions of these elements in sphalerite. Occasional positive correlation between Cu and Ga + In + Sn at 1:1 (Fig. 11I), especially in second-step white (sl2w) and some yellow (sl2y) sphalerite from the San Vicente deposit ad sphalerite from Chilpes, seems to suggest Cu + + (Ga, In) 3+ + Sn 4+  4Zn 2+ coupled substitutions. However, there is a set of data, which includes the rest of the analyzed sphalerite grains from San Vicente, Chilpes, Shalipayco, and Cristal that lies far above the Cu: Ga + In + Sn = 1:1 correlation line (Fig 11I ), pointing to higher Cu at a given Ga + In + Sn content, probably due to the fact that Cu is also involved in coupled substitutions for the incorporation of Ge, which is normally more abundant than Ga and In in the analyzed sphalerite.

Color of sphalerite vs. chemical composition

Conflict of interest

The authors declare no competing interest.

Electronic Supplementary Material (ESM)