Vincent Combes
email: vincent.combes@univ-lorraine.fr

Aurélien Eglinger

Anne-Sylvie André-Mayer

Yoram Teitler

Mark Jessell

Armin Zeh

Laurie Reisberg

Arnauld Heuret

Pierre Gibert

Anne-Sylvie Andre-Mayer

Integrated geological-geophysical investigation of gold-hosting Rhyacian intrusions (Yaou, French Guiana), from deposit-to district-scale

Keywords: Mineral system, intrusion-hosted gold, Re-Os geochronology, Structural patterns, geophysics, Guiana Shield

à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Ore deposits are generated from a variety of natural processes, from lithospheric to nanoscale, that concentrate elements into a small volume that can be economically mined (Jenkin et al. 2015). Mineral deposits are by definition geographically small in extent compared to surface area and thickness of the crust, even if they result from geological and geodynamic processes that occur, and can be mapped, at a variety of larger scales [START_REF] Mccuaig | Translating the mineral systems approach into an effective exploration targeting system[END_REF][START_REF] Hronsky | A unified model for gold mineralisation in accretionary orogens and implications for regional-scale exploration targeting methods[END_REF]. Ore mobilization, transfer and deposition are linked to geological processes leading to the concept of mineral systems, which encompasses "all geological factors that control the generation and preservation of mineral deposits" [START_REF] Wyborn | Australian Proterozoic Mineral Systems: Essential Ingredients and Mappable Criteria[END_REF]McCuaig and Hronsky, 2014 and references therein). Although there are a variety of interpretations of what a mineral system is (e.g., [START_REF] Wyborn | Australian Proterozoic Mineral Systems: Essential Ingredients and Mappable Criteria[END_REF][START_REF] Mccuaig | Translating the mineral systems approach into an effective exploration targeting system[END_REF][START_REF] Huston | Australia through time: a summary of its tectonic and metallogenic evolution[END_REF], most include factors such as the geological setting, the timing and duration of deposition, the source(s) and nature of mineralising fluids (including melts), the pathways used by the respective fluids and fluid flow drivers, the depositional site, mechanisms of metal transport and deposition, and post-depositional modifications. Unravelling the structural and lithological settings of a gold deposit at various scale, from ore shoot to metallogenic province, is thus a key to understand the mineral system and enhancing exploration targeting.

For regional exploration, an understanding of mineral systems is important when zooming in from [START_REF] Shirey | Carius tube digestion for low-blank rhenium-osmium analysis[END_REF] province-scale (connection between lithospheric processes and metal endowment by studying plumbing structures as discussed by [START_REF] Bierlein | Lithospheric controls on the formation of provinces hosting giant orogenic gold deposits[END_REF][START_REF] Bierlein | Metallogeny of accretionary orogens-the connection between lithospheric processes and endowment[END_REF], [START_REF] Begg | Lithospheric, cratonic, and geodynamic setting of Ni-Cu-PGE sulfide deposits[END_REF], [START_REF] Hronsky | A unified model for gold mineralisation in accretionary orogens and implications for regional-scale exploration targeting methods[END_REF], and [START_REF] Motta | Archean crust and metallogenic zones in the Amazonian Craton sensed by satellite gravity data[END_REF]); to (2) district-scale architecture of structural networks [START_REF] Siddorn | Integrated Geologic-Geophysical Interpretation of District-Scale Structural Frameworks: Systematic Approaches for Targeting Mineralizing Systems[END_REF]. This scalability in mineral exploration requires the integration of a large set of geophysical, geological and geochemical data [START_REF] Niiranen | Scalability of the mineral prospectivity modelling -An orogenic gold case study from northern Finland[END_REF]Nykänen et al., 2017). Working both on the structural and lithological framework combining geological (structural geology, geochemistry, and geochronology) and geophysical (magnetometry, gamma-ray spectrometry, remote sensing, and gravimetry) techniques, in accordance with 3D models of Au deposits at the camp-scale, will deliver insights on the deposit to district-scale of such mineral system. Integration of regional geological and geophysical datasets is particularly useful in tropical regions where orebodies are commonly covered by dense vegetation and/or thick lateritic profiles such as on the Guiana Shield in South America or on the West African Craton. For such regions, integrated studies can provide deep insights into both [START_REF] Shirey | Carius tube digestion for low-blank rhenium-osmium analysis[END_REF] the lithospheric architecture and (2) the structural-metamorphic-magmatic evolution and related (gold) mineralization events. Such an intergraded approach has been carried out recently on the West African Craton, by deciphering litho-structural patterns such as shear zone geometries and kinematics [START_REF] Metelka | A geophysically constrained lithostructural analysis of the Eburnean greenstone belts and associated granitoid domains, Burkina Faso, West Africa[END_REF][START_REF] Jessell | The geophysical signatures of the West African Craton[END_REF][START_REF] Chardon | Eburnean deformation pattern of Burkina Faso and the tectonic significance of shear zones in the West African craton[END_REF], and their link to the distribution of gold deposits [START_REF] Perrouty | Revised Eburnean geodynamic evolution of the gold-rich southern Ashanti Belt, Ghana, with new field and geophysical evidence of pre-Tarkwaian deformations[END_REF][START_REF] Baratoux | Tectonic evolution of the Gaoua region: Implications for mineralization[END_REF]. On the Amazon Craton, it has been applied to unravel the lithosphere geometry of copper and gold mineralization systems using satellite gravimetry, airborne potential field data (gravimetry and geomagnetics), combined with information from passive seismic (wave speeds to constrain crustal and lithospheric thickness), geochronological, and isotope-geochemical data (Nd model ages, mineral crystallisation ages, Nd isotope ratios) - [START_REF] Motta | Archean crust and metallogenic zones in the Amazonian Craton sensed by satellite gravity data[END_REF]. This study will develop a similar approach in the Guiana Shield, focusing on the Yaou district located in French Guiana (Fig. 1). The Yaou gold deposit displays a polyphase gold mineralization where the main orebodies are defined as intrusion-hosted along the Central Yaou Shear Zone (CYSZ), [START_REF] Milesi | Gold deposits (gold-bearing tourmalinites, gold-bearing conglomerates, and mesothermal lodes), markers of the geological evolution of French Guiana: geology, metallogeny, and stable isotope constraints[END_REF], Eglinger et al., 2020;Combes et al., 2021a). While a first gold system related to the shearing of a pyrite-rich metasedimentary unit is observed (Combes et al., 2021a), most of the high-grade mineralization is associated with one set of hydrothermal quartz-calcite veins formed during the brittle D4YA deformation phase. A strong rheological controlled is demonstrated for the ore shoots, localized mostly within the intrusions.

Yaou is a typical undercover deposit with its dense Amazonian Forest and thick lateritic profiles [START_REF] Théveniaut | Timing of lateritization on the Guiana Shield: Synthesis of paleomagnetic results from French Guiana and Suriname[END_REF], representing a suitable ground for the application of such an integrated geological and geophysical approach New geological data (geochemistry, Lu-Hf isotopy and zircon U-Pb) for the Yaou quartz monzodiorite hosting the main economic gold vein system (dated here using the Re-Os geochronometer on pyrite) will allow time correlation within the Trans-Amazonian orogenic evolution. New district-, camp-and deposit-scale structural and lithological maps based on airborne geophysical data including airborne magnetometry and radiometry (Th, U and K), will help to define the relation between shearing, magmatism, and gold mineralization. All geological and geophysical data are integrated in a 4D model and discussed together, with the aim to target new gold deposits in the otherwise poorly exposed region. The results will help to improve mineral exploration strategies in French Guiana and in the whole Guiana Shield.

Geological background

Regional geology

The Guiana Shield, with at the south the Guapore Shield, and at the east its counterpart, the Leo Man craton in West Africa (Fig. 1), is spatially and temporally associated with the Trans-Amazonian orogenic cycle (ca. 2600(ca. -1950 Ma) Ma), (Delor et al., 2003a, b;[START_REF] Enjolvy | Processus d'accrétion crustale et régimes thermiques dans le bouclier des Guyanes: signatures géochimiques et thermochronologiques au transamazonien (2250-1950Ma)[END_REF][START_REF] Kroonenberg | Paleoproterozoic evolution of the Guiana Shield in Suriname: a revised model[END_REF] which is characterized by a period of crustal growth followed by a crustal reworking phase [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF].

Regarding main formations identified within the Guiana Shield, Archean terranes referred to as the Imataca Complex in Venezuela and the Amapá Block in Brazil [START_REF] Gibbs | The Geology of the Guiana Shield[END_REF] are present along with Rhyacian volcano-sedimentary formations (greenstone belts), TTG-like complexes, late high-K calc-alkaline intrusions, and late Rhyacian high grade belt (see Fig. 1 and synthesis by Kroonenberg et al., 2016 and references therein).

While moving from an oceanic-arc environment to an intracratonic basin environment, the tectonic framework established by [START_REF] Ledru | Le Proterozoique inferieur nord guyanais: revision de la lithologie, tectonique transcurrente et dynamique des bassins sedimentaires[END_REF], [START_REF] Gibbs | The Geology of the Guiana Shield[END_REF] and updated by [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF], Delor et al. (2003a, b), [START_REF] Enjolvy | Processus d'accrétion crustale et régimes thermiques dans le bouclier des Guyanes: signatures géochimiques et thermochronologiques au transamazonien (2250-1950Ma)[END_REF], and [START_REF] Kroonenberg | Paleoproterozoic evolution of the Guiana Shield in Suriname: a revised model[END_REF] defines an early D1 phase, associated with a compressional regime in a convergent context. [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF] proposed a subduction model favored by (i) the calcalkaline geochemical signature of the plutonic-volcanic intrusions; (ii) deformation recorded by the turbidites which is comparable to the deformation recorded in modern accretionary prisms and (iii) the HP-LT (high pressure-low temperature) metamorphism recorded by the sediments of the Upper Detrital Unit. This D1 phase, dated at ca. 2180-2130 Ma, produced TTG-type intrusions and volcanosedimentary formations within an oceanic volcanic arc or back-arc environment [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF]Delor et al., 2003b). A N-S convergence is proposed for this early phase. The following D2a phase (ca. 2110-2080 Ma) in a collisional context and ending of subduction is marked by trans-tension and sinistral sliding together with folding of the volcano-sedimentary formation [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF]Delor et al., 2003a, b). The North Guiana Trough (NGT) shear zone (Fig. 1 and 2) (Egal et al., 1991) is formed during this deformation phase [START_REF] Ledru | Le Proterozoique inferieur nord guyanais: revision de la lithologie, tectonique transcurrente et dynamique des bassins sedimentaires[END_REF][START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF]. The D2b deformation phase dated at ca. 2070-2060 Ma (Delor et al., 2003a, b) is responsable for dextral strike slip shearing [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF]Delor et al., 2003b) together with a crustal stretching. Regarding kinematic directions, a northeast-southwest convergence for D2a is proposed by Delor et al. (2003a, b). Delor et al. (2003b) define a late D2c phase associated with granulite facies metamorphism which is currently not present in French Guiana and dated at ca. 2110-1990Ma (DeRoever et al., 2003;[START_REF] Klaver | Charnockites and UHT metamorphism in the Bakhuis Granulite Belt, western Suriname: evidence for two separate UHT events[END_REF].

From the GIS-based lithological map of the BRGM, a simplified geological map of French Guiana is produced for this study (Fig. 2) where all dating information is from Delor et al. (2003a, b and references therein). first generation of TTG-like (dated at ca. 2183-2155 Ma) was emplaced both in the northern part and in the south of French Guiana (Fig. 2). The Central TTG-like complex, situated in the central part of French Guiana between the two east-west greenstone belts is composed of a granodioritic gneiss unit (dated at ca. 2152-2144 Ma) and undifferentiated TTG dated at ca. 2140-2120 Ma which are also encountered in the northern part of French Guiana. Minor mafic to ultramafic complexes are identified and dated at ca. 2149-2135 and ca. 2093-2090 Ma. A granitic suite dated at ca. 2105-2090 Ma is mostly displayed at the south and central east parts of the region (Fig. 2) followed by late Rhyacian units defined as peraluminous leucogranites (ca. 2092(ca. -2078 Ma) Ma) and late metaluminous plutonism (ca. 2069(ca. -2060 Ma) Ma). Apart from plutonism, the main units include the Lower volcanic and sedimentary unit (Paramaca greenstone belt) with its two east-west belts (Fig. 2) where all gold occurences are currently known [START_REF] Milesi | Gold deposits (gold-bearing tourmalinites, gold-bearing conglomerates, and mesothermal lodes), markers of the geological evolution of French Guiana: geology, metallogeny, and stable isotope constraints[END_REF] and the D2a-related Upper Detrital Unit associated with pull-apart basins composed of pelites, sandstones and conglomerates. Post-Trans-Amazonian units include mafic dikes (dolerites dated at ca. 1900-1800 Ma, ca. 808 Ma andca. 198-189 Ma) and Quaternary sediments, mostly mapped in the northern part of French Guiana, along the Atlantic coast (Fig. 2).

Geological features at the district-scale

In the Yaou district, several gold occurrences are known from a 50-60 km wide radius around the Yaou camp (Fig. 3), such as Dorlin, Bois Blanc, Chaina, and Tomantoni (among others).

Each gold occurrence is hosted either within metasedimentary or metavolcanic rock units of the southern PGB (Paramaca Greenstone Belt). According to the latest geological map of Delor et al. (2003b), which is based on historical BRGM surveys and airborne geophysical interpretations (Fig. 3), the Yaou district consists mainly of metavolcanic rocks locally intercalated by metasedimentary rocks, in particular in its eastern and western parts. This volcano-sedimentray succession was intruded by granodiorite at ca. 2152-2144 Ma, and subsequently by tonalite-trondhjemite-granodiorite (TTG) at ca. 2140-2120 Ma, and finally by a Neoproterozoic dolerite dike at ca. 808 Ma (Delor et al., 2003b). The dolerite dike strikes N165° and crosscuts the western part of the Yaou deposit. The CYSZ is located within the PGB, at the border with the eastern TTG-like complex. Regional structures, drawn mostly from aeromagnetic interpretations, strike northwest-southeast, east-west and north northeast-south southwest (Fig. 3).

Intrusion and deformation features at the camp-and deposit-scale

At the deposit-to the camp-scale, a multiphase deformation model has been established (Combes et al., 2021a). Considering all mineralized bodies within the central part of the Yaou deposit, a model is presented in Figure 4 where quartz monzodiorite bodies are aligned along the sinistral CYSZ. The linear array of intrusions, parallel to the CYSZ, can be traced for more than 4.5 km along strike (Combes et al., 2021a). The intrusions show a great range of wide, from a few meters up to 80 m in the central part of the deposit. The ductile D1/2YA phase is responsible for the main penetrative foliation (S2 striking N90°-N120° with a subvertical dip) while the D3YA phase is related to shearing (sinistral CYSZ; N60°, 70°NW; Fig. 4). An intrusive quartz monzodiorite event is identified as being pre-to syn-D3YA. The following phase D4YA represents a brittle quartz-carbonate veining set hosted preferentially within intrusive bodies and along the shear zone. A strong rheological control is interpreted for this main auriferous event (see Combes et al., 2021a). The D5YA brecciation event locally affects the D4YA vein system. These deformation phases are not precisely correlated to the petro-structural framework established by Delor et al. (2003b) for the whole region before the present study. The dominant host lithology at Yaou consists of a fine-grained, strongly schistosed and locally folded unit, characterized by a dark greenish chloritic alteration referred to as metavolcanite. Locally, a fine-grained, greyish to brownish, laminated and strongly schistosed metasediment is also observed, displaying a primary bedding and millimetric stretched lithic clasts of quartz and plagioclase. Both units belong to the Lower volcanic and sedimentary formation of the Paramaca Greenstone Belt [START_REF] Milesi | Gold deposits (gold-bearing tourmalinites, gold-bearing conglomerates, and mesothermal lodes), markers of the geological evolution of French Guiana: geology, metallogeny, and stable isotope constraints[END_REF].

With over 36 000 m drilled at Yaou (auger, RC and diamond drilling; AMG exploration database) a precise modeling of the central part of the deposit has been drawn at the camp-scale.

A Leapfrog Geo view (north northwest -south southeast) of the model is presented on Figure 5 using assay data, where the D3YA sinistral shear zone correlates with the N60° striking AuD0/D3/D4YA orebodies whereas the bulk of the AuD4YA orebodies are located within the quartz monzodiorite bodies giving two subparallel ore trends striking N60°.

When zooming out from the camp-scale to the district-scale, no detailed interpretation has been made prior to this study, as no outcrop was found for this work, so no lineation was measured, and no far-field stress established. The only data available are the geophysical survey and their interpretation as historical gold in soil surveys (AMG) do not help at the district-scale.

Methodology and data use

Whole-rock analyses of trace and major elements

Whole-rock analyses of trace and major elements (Table 1) were conducted on 20 cm-long halfdrillcore samples at the SARM (Service d'Analyses des Roches et des Minéraux) laboratory (CRPG, Centre de Recherches Pétrographiques et Géochimiques) in Nancy, France, following [START_REF] Carignan | Routine Analyses of Trace Elements in Geological Samples using Flow Injection and Low Pressure On-Line Liquid Chromatography Coupled to ICP-MS: A Study of Geochemical Reference Materials BR, DR-N, UB-N, AN-G and GH[END_REF]. Veins and unfresh pieces were removed prior to crushing and pulverization at the GeoRessources laboratory (Nancy, France). Trace elements were analysed by inductively coupled plasma mass spectrometry (ICP-MS) and oxides were analysed by inductively coupled plasma optical emission spectrometry (ICP-OES). Results are presented here for the five least altered samples out of twelve sampled cores after careful petrographic studies of hydrothermal alteration mineralogy.

U-Pb dating and Lu-Hf isotope analyses of zircon

Zircon grains were separated from ca. 30 kg of quartz monzodiorite saprock powdered with a jaw crusher and a roller mill at the CRPG in Nancy (France) and concentrated using a Gemini shacker table, followed by heavy liquids (diiodomethane: density = 3.31 g/cm 3 ) and a Frantz isodynamic magnetic separator. Individual grains were then handpicked, mounted in epoxy blocks, and polished to expose their cores. Prior to in-situ isotope analyses the internal textures of the zircon grains were characterised by means of cathodoluminescence (CL) and back scattered electron (BSE) imaging performed with a TESCAN VEGA 3 LM, with Gatan ChromaCL2UV at the SCMEM (GeoRessources, Nancy, France). In situ U-Pb and Lu-Hf isotope analyses of zircon grains/domains were carried out by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS), at Goethe Universtity Frankfurt am Main (Germany). Laser spots for Lu-Hf isotope analyses (40 µm in diameter) were placed on top of the U-Pb laser spots (33 µm in diameter) used for dating. The results of U-Pb dating and Lu-Hf isotope analyses are shown in Tables 2 and3 respectively. The values of zircon standards are provided as supplementary material.

Re-Os dating of pyrite

From selected drillcore intervals, centimetre-large pyrite grains (Py4 proximal to auriferous D4YA veins) were separated using a saw and then crushed (GeoRessources, Nancy, France). Re-Os analyses were performed on two aliquots of the crushed pyrite powder at the Centre de Recherches Pétrographiques et Géologiques (CRPG) in Nancy, France. Chemical separation techniques applied in this study are based on those described by [START_REF] Shirey | Carius tube digestion for low-blank rhenium-osmium analysis[END_REF] for sample digestion, using an Anton Paar HPA-S high pressure asher instead of Carius tubes, and [START_REF] Birck | Re-Os isotopic measurements at the femtomole level in natural samples[END_REF] for osmium extraction. For each sample, ~ 200 mg of pyrite powder were spiked with precisely weighed quantities of a mixed 185 Re-190 Os tracer solution and digested in a mixture of hydrochloric acid (2 mL), nitric acid (5 mL) and hydrogen peroxide (0.1 mL) at 260 °C for 16 h, under a pressure of 100 bars. After sample digestion, Os was separated by liquid-liquid extraction into liquid bromine. The Br2 was then evaporated, and the osmium fraction was purified by microdistillation [START_REF] Birck | Re-Os isotopic measurements at the femtomole level in natural samples[END_REF]. The Re was extracted from the residual acidic solution by anion exchange using chromatographic columns (AG1 X8 resin). Re isotopic compositions for isotope dilution calculations were measured using a Thermo Neptune MC-ICPMS. Instrumental mass fractionation during measurements was regularly monitored and corrected for using an 0.5 ppb Re standard with an assumed 187 Re/ 185 Re ratio of 1.6738.

The Os samples were loaded on platinum filaments for analysis by negative thermal ionization mass spectrometry (N-TIMS; [START_REF] Creaser | Negative thermal ion mass spectrometry of osmium, rhenium and iridium[END_REF][START_REF] Völkening | Osmium isotope determinations by negative thermal ionization mass spectrometry[END_REF], using a Finnigan MAT 262 instrument. About 0.2 μL of a saturated solution of Ba(OH)2 in 0.1 N NaOH [START_REF] Birck | Re-Os isotopic measurements at the femtomole level in natural samples[END_REF]) was added to the samples to maximise OsO3 -emission in the instrument. Analyses were made by peak jumping and ion counting using an ETP electron multiplier. Instrumental mass fractionation was corrected iteratively off-line by assuming that the true 192 Os/ 188 Os ratio of the sample loaded on the filament lay on a mixing line between the spike (5.00736) and natural (3.08271) values. The oxygen isotope composition determined by Nier ( 17 O/ 16 O = 0.0003708 and 18 O/ 16 O = 0.002045) was used to correct for isobaric interferences from heavy oxides. Common Os, including both the natural component and any contribution from the analytical blank, was monitored using mass 188 Os, and a correction to 187 Os was applied assuming a common 187 Os/ 188 Os value of 0.6 ± 0.5. The magnitude of this correction was about 0.02% for both aliquots. The Re blank associated with these samples was 24 ±7 pg while the total Os blank was 0.75 pg with a 187 Os/ 188 Os ratio of 6.1. The results of the Re-Os dating are shown in Table 4. All uncertainties are 2σ, and include all identified sources of uncertainty, including measurement uncertainties, blank variability, and the variation in the assumed initial 187 Os/ 188 Os ratio of the pyrite.

Airborne geophysical data processing and interpretation

Airborne geophysical data from (1) magnetic and (2) radiometric survey of Auplata Mining Group are used for this study. The covered area, of 360 km 2 represents 2201 km of northwestsoutheast striking lines, using a line spacing of 200 m with perpendicular tie lines flown every 1000 m. The height above ground of the sensor is 100 m. Data include (1) airborne radiometric data (K, Th, U) and (2) airborne magnetic data.

Airborne magnetic surveys help constraining structures and lithologies and are therefore excellent tools for constructing lithostructural maps (Aitken & Betts, 2009a, b;[START_REF] Baratoux | Tectonic evolution of the Gaoua region: Implications for mineralization[END_REF] especially in undercover domains [START_REF] Metelka | A geophysically constrained lithostructural analysis of the Eburnean greenstone belts and associated granitoid domains, Burkina Faso, West Africa[END_REF]. Raw data have been processed using a variety of filters to enhance short and long wavelength features. The total magnetic field data were reduced to the pole prior to further processing. Filters used include (1) the First Vertical Derivative (1VD), (2) the Tilt Derivative (TD) and (3) the Horizontal Derivative [START_REF] Blakely | Approximating edges of source bodies from magnetic or gravity anomalies[END_REF][START_REF] Miller | Potential field tilt-a new concept for location of potential field sources[END_REF][START_REF] Milligan | Enhancement and presentation of airborne geophysical data[END_REF][START_REF] Pilkington | The utility of potential field enhancements for remote predictive mapping[END_REF][START_REF] Verduzco | New insights into magnetic derivatives for structural mapping[END_REF]. Regarding the radiometric data, the original bands K, eTh, and eU and the ternary RGB (Red, Green, Blue) color composite are used. The gammaray signal gives information regarding the content and distribution of the radioactive elements in rocks. It can highlight anomalies due to geochemical alterations such as mineralization, hydrothermal alterations, and weathering [START_REF] Metelka | A geophysically constrained lithostructural analysis of the Eburnean greenstone belts and associated granitoid domains, Burkina Faso, West Africa[END_REF]. Finally, a SRTM digital elevation model shaded from northwest is utilized as a background image.

Geological results

Petrography of quartz monzodiorite

All magmatic rocks observed in drillcores are hydrothermally altered, and host abundant auriferous veins formed during brittle deformation D4YA (Combes et al., 2021a). Even the least altered quartz monzodiorite samples provide evidence for albitization (Fig. 6A). Albite is hydrothermal and associated with the syn-D4YA brittle veining system. The rock is phaneritic, fine to medium grained with no internal fabric. The observed mineral assemblage is albite, quartz, sericite and chlorite, with minor amounts of ankerite, magnetite, calcite and apatite, even though there are variation among the samples. Some samples show higher amounts of chlorite and ankerite (Fig. 6B) and/or of hematite (Fig. 6C). Under the microscope, the predominant minerals are quartz and albite, which commonly shows a polysynthetic twinning and evidence for sericitization, and sericite (Fig. 7A andD). Minor K-feldspar was rarely observed in a few samples (Fig. 7C). Some samples were affected by moderate to strong chloritisation (Fig. 7B).

Hydrothermal formation of ankerite (Fig. 7C andE) and/or hematite in interstitial domains between albite grains is common (Fig. 7F), causing the typical reddish color of the rocks.

Geochemistry of quartz monzodiorite

Whole-rock geochemical data for the five least altered samples are provided in Table 1. SiO2 contents range from 61.76 to 68.48 wt. % while Na2O concentrations vary from 5.61 to 7.42 wt. %, and Fe2O3 contents range from 2.35 to 4.66 wt. %. As previously mentioned in Combes et al. (2021a), these samples plot in the quartz monzodiorite field in the Q-A-P normative classification diagram (Fig. 8A) and in the trondhjemite field (Fig. 8C), though this designation must be taken with caution due to the great amount of hydrothermal albite. All five representative samples plot in the same field in the relatively immobile elements Th vs Co diagram (Fig. 8B), arguing for a single protolith for all the least altered samples. This protolith belongs to the calc-alkaline series based on the AFM diagram of [START_REF] Irvine | A Guide to the Chemical Classification of the Common Volcanic Rocks[END_REF].

Regarding trace elements, the Y content is below 11 ppm for all samples. Chondrite-normalised REE patterns [START_REF] Sun | Chemical and isotopic systematics ofoceanic basalts: Implications for mantle composition and processes[END_REF] A geochemical database of plutonic rocks sampled within French Guiana has been built for this study (over 40 key analysed and dated samples). To constrain the geodynamical significance of the quartz monzodiorite observed at Yaou and to integrate it into the context of known regional plutonic events, the chondrite normalized REE [START_REF] Sun | Chemical and isotopic systematics ofoceanic basalts: Implications for mantle composition and processes[END_REF] pattern of this rock is compared with patterns of the most representative samples of each main plutonic complex in the region as illustrated in figure 9. Representative samples are from the "Ile de Cayenne" Complex (Fig. 9A), the 1 st generation of TTG-like patterns (Fig. 9B), the 2 nd generation of TTG-like (Fig. 9C), the late 2 nd generation of TTG-like (Fig. 9D), the Granitic suite (Fig. 9E) and the peraluminous leucogranite unit (Fig. 9F). Comparisons are discussed in the Discussion section.

U-Pb dating and Hf isotope analyses

Zircon grains from the quartz monzodiorite were dated in-situ by LA-ICP-MS (Table 2) and analysed for Hf isotopes (Table 3). The dated zircon grains are euhedral to subhedral and vary in length from 100 to 400 µm (Fig. 10A). BSE images reveal oscillatory or banded magmatic zoning, even though many grains are more or less intensely altered and fractured (Fig. 10A).

All analyses, except one, show Th/U ratios >0.1 (Table 2) typical for magmatic zircon. Most analyses yielded discordant U-Pb ages, which define a Discordia line with upper and lower intercept ages at 2128.9 ± 5.1 Ma and 768 ± 210 Ma, respectively (Fig. 10B). The upper intercept age is identical, within error, with a Concordia age of 2130.6 ± 5.8 Ma (MSWD = 0.15, Probability of concordance = 0.7) obtained by fifteen spot analyses (Figure 10C). The Concordia age is interpreted to define the timing of magma crystallization, whereas the lower intercept age points to Pb loss during a Neoproterozoic event. The analysed zircon grains show a limite range in initial 176 Hf/ 177 Hf values between 0.281463 and 0.281588, corresponding to suprachondritic εHft values between +1.3 and +4.2, and hafnium (two stage) model ages between ca. 2.4 and 2.6 Ga (Fig. 10D, Table 3).

Re-Os dating of pyrite

The quartz monzodiorite is a preferential host for the main gold-bearing vein set with a strong rheological control (Combes et al. 2021a). These quartz-carbonate veins characterized by a strong proximal pyritization postdate the intrusive event and are interpreted as being synchronous to the D4YA deformation phase. The Py4 pyrite grains are coarse, homogeneous in composition, and can contain gold micro-inclusions and gold infilling fractures. Two aliquots of Py4 from the same sample powder yield Re-Os ages of 2110±30 Ma and 2101±17 Ma (Table 4). The average age of 2105±25 Ma is considered, and is interpreted to date the timing of pyrite precipitation cogenetic with Au mineralization during phase D4YA.

Geophysical interpretations

Lithological distribution

At the deposit-scale, the lithological distribution of the main units is relatively well identified (Combes et al., 2021a) from drillcore data and historical subsurface extraction and mapping.

When zooming out from the central part of Yaou, no outcrop data are available at the districtscale where no recent exploration work has been carried out within this dense Amazon Forest area. Magnetic and radiometric anomalies are used here to zoom out and to produce a lithological map up to the district-scale (i. e. beyond the Yaou tenement, see limits on Figure 3) with respect to the initial camp-scale map. All interpretations and corroborations between geophysical data and available field/core observation are made first at the well-studied campscale. The potassium anomaly map presented in Figure 11A defines in great details the spatial distribution of the metasedimentary unit belonging to the Paramaca greenstone belt. Itcorroborates the regional-scale map proposed by Delor et al. (2003b) based mainly on the BRGM radiometric survey for the whole country (Fig. 2 and3). At the camp-scale, this correlation (positive K anomalies and metasediment distribution) is demonstrated where drilled areas with logged metasediments show positive K anomalies. The U anomaly map delimits the northeastern U-rich plutonic body (Fig. 11B) while a clear delimitation of both TTG-like complexes (according to Delor et al., 2003b) is visible in the ternary map displaying the relative abundances of U, K and Th (Fig. 11C). The Eastern body is defined by a clear blue-green signature, in the gamma-ray spectrometry ternary image, associated with Fe-rich regolith covers, this preferential deep weathering (residual or depositional regolith cover) allows to precisely define this pluton.

The observations from the radiometric maps are supported by the 1VD grid (First Vertical Derivative, Fig. 11D) emphasing shallow features, with (1) the northeastern pluton delimited by its smooth texture, (2) the eastern pluton highlighted by its smooth texture (but to a lesser degree than the northeastern pluton), (3) the remanently magnetized dolerite dike striking N165°, (4) the metasediments without stipple textures observed in the N as opposed to (5) the main area with stipple textures typical of metavolcanite formations. Finally (6) some minor mafic intrusive plugs are identified in the northern part of the surveyed area together with a small circular late pluton (Fig. 11D). The whole interpreted lithological map is presented in Figure 11E on a shaded-relief image. A strong uncertainty in lithology discrimination remains, indeed the metasedimentary unit may be hidden by regolith as illustrated in Figure 11E with identified areas of possible occurrences of residual or depositional regolith cover.

Overall, based on the internal geophysical data set of the Auplata Mining Group, the present study proposes a more detailed lithological map compared to the one established by Delor et al. (2003b) for the whole country using the BRGM regional data set. The occurrence of the metasedimentary unit is extended toward the south and the TTG-like complexes are better delimited at their western borders. Unfortunately, the quartz monzodiorite bodies, which are well defined at the camp-scale could not be targeted with the resolution of the present data set.

Identified structures

No robust structural data are available for the area. Three filters are therefore used in an attempt to identify possible structures within the Yaou district, namely the 1VD (Fig. 12C), RTP-TD (Fig. 12A), and RTP-TD-HDR (Fig. 12 B) filters (see methods section). This work focuses here on the supra-crustal-scale only. As for the lithologic distribution, the study focuses first on the deposit to camp-scale and then zooms out. From core studies and internal reports, the identified structures at the camp-scale are as follow: a main subvertical foliation striking east-west and a shear corridor striking N60° (corresponding to the CYSZ, Combes et al., 2021a). While it is not possible with the used magnetic data set to define at this scale the main foliation, the CYSZ may correspond to a low magnetic N60°-striking lineament. Considering all filters, at the campscale, structures observed are low and high magnetic response northeast-southwest-striking linear structures. Locally, they may be offset by a N140° structure. When zooming out and considering the whole surveyed area (Fig. 3 and 12), possible interpreted structures can be defined as follow:

(1) The main lineaments strike roughly northeast-southwest (Fig. 12A,B), the RTP-TD (Tild Derivative) filter enhancing these magnetic lineaments that may correspond to a series of sub-parallel vertical features that could reflect a dipping stratigraphy or deformation fabric. These main structures are truncated by the dolerite and in the E, are parallel to contacts between the metavolcanites and the TTG-like complexes and seem wrapped around these complexes in the magnetic data. They locally display some folding together with some minor sinistral strike-slip faulting offsetting the main lineaments (northeast of the area, Fig. 12D);

(2) Some minor fabrics within the metasedimentary unit, in the northwest part of the area, show a weak magnetic intensity signal (Fig. 12C). In this area the main northeasttrending lineaments are not observed;

(3) Within the TTG-like complexes in the E, some internal northeast-southwest features are highlighted by the RTP-TD-HDR filter (Fig. 12B), suggesting that the TTG-like complexes have been affected by the deformation phase giving the main north northeastsouth southwest lineaments and were emplaced before the main deformation phase.

Margins of these plutons show a negative magnetic anomaly (Fig. 12C);

(4) The same minor N140° faults observed at the camp-scale are encountered elsewhere in the surveyed area (in red in Figure 12D) affecting the main northeast-southwest structures. Most gold occurrences (established by the BRGM, Guyanor and Auplata Mining Group-internal reports) are located in the vicinity of interconnections between these minor faults and the main lineaments (see Fig. 12D for some examples, other occurrences are not included here for confidentiality issues);

(5) Two parallel features, striking around 10 degrees east of north are truncating the northeast-southwest main lineaments (Fig. 12 C). Their extension toward the south could not be traced with the used geophysical data set.

The scale of the geophysical maps is not sufficiently detailed to delimitate the CYSZ which may also be hidden by high and low magnetic lineaments. The N60° low magnetic lineaments are continuous along strike and replicated toward the northwest (Fig. 12-A, B, C andD) and may correspond to potential shear zones.

Discussion

The Yaou intrusive event at the deposit-scale

Geochemical signature

Plots of trace elements normalized to primitive mantle abundances [START_REF] Sun | Chemical and isotopic systematics ofoceanic basalts: Implications for mantle composition and processes[END_REF], Fig. 8E), show patterns enriched in highly incompatible trace elements (LREE), depleted in HREE and enriched in large-ion lithophile elements (LILE) such as Rb, Ba, U and Pb. We observe a depletion in Cs, an enrichment in Sb and negative anomalies in Nb-Ta-Ti (Fig. 8E).

The Nb/Ta ratios are subchondritic (Nb/Ta ≤ 12.57 ppm).

These REE data from the Yaou quartz monzodiorite are compared to REE results from other plutonic rocks sampled within French Guiana in Fig. 9. The « Ile de Cayenne » complex samples show a flat pattern with no variation between LREE and HREE together with an Eu negative anomaly (Fig. 9A) that differs strikingly from the quartz monzodiorite's pattern. The Yaou samples share some similarities with the 1 st generation of TTG-like but those TTG display more depleted HREE and a marked positive Eu anomaly (Fig. 9B). The Yaou quartz monzodiorite pattern clearly ressembles those of the 2 nd generation of TTG-like (Fig. 9C), with an enrichment in LREE and a depletion of HREE. It is even better correlated with the pattern of the late samples of the same TTG-like generation, as visible in Figure 9D. Therefore, geochemically, the Yaou quartz monzodiorite can be interpreted as belonging to the 2 nd TTGlike generation, also referred to as the Central TTG-like Complex (Delor et al., 2003a, b) and dated between ca. 2140-2120 Ma for the main magmatic phase and ca. 2113-2101 Ma [START_REF] Enjolvy | Processus d'accrétion crustale et régimes thermiques dans le bouclier des Guyanes: signatures géochimiques et thermochronologiques au transamazonien (2250-1950Ma)[END_REF]Fig. 9) for the late phase interpreted as a continuum of the same 2 nd generation TTG-like magmatic event. Samples of the granitic suite follow a similar pattern to those of Yaou (Fig. 9E) but with much stronger REE absolute abundances and no relative Ho enrichment. Finally, peraluminous leucogranite samples show higher absolute LREE abundances, strong negative Ce and Eu anomalies, and a slightly sloping HREE segment, with absolute HREE abundances greatly exceeding those of the Yaou samples.

The interpretation of a TTG-type intrusion at Yaou is reinforced by the similarities between the Yaou samples and the typical TTG geochemical signatures [START_REF] Martin | An overview of adakite, tonalite-trondhjemite-granodiorite (TTG) and sanukitoid: relationships and some implications for crustal evolution[END_REF][START_REF] Moyen | Forty years of TTG research[END_REF]. Indeed, [START_REF] Moyen | Forty years of TTG research[END_REF] indicates that TTGs (1) do not present Eu anomalies, as for the Yaou samples, (2) show Yb content below 1.5 ppm (below 0.8 ppm for our samples), ( 3) an (La/Yb)N > 15 where the normalized ratios at Yaou are above 20.65 ; (4) a depletion in HREE and Y (same depletion for Yaou and a Y content below 11 ppm) and ( 5) Nb-Ta negative anomalies, also observed for this study with Nb/Ta < 13 ppm. TTG magmas result from melting and/or crystallization of hydrous low-potassium basalts [START_REF] Moyen | Forty years of TTG research[END_REF]. The geodynamic setting in which they are formed is still debated [START_REF] Laurent | Earth's earliest granitoids are crystal-rich magma reservoirs tapped by silicic eruptions[END_REF].

The low content of HREE implies the presence of garnet in the petrogenesis of the magma, either as residual or fractionating phase. Considering its stability field, it is therefore at highpressure conditions (>1.2 GPa, i.e. at >40 km depth). The Yaou quartz monzodiorite could have formed in an active margin context (i) by partial melting of a subducted oceanic crust, (ii) by melting of over-thickened arc roots or (iii) by fractionation of hydrous arc basalts [START_REF] Laurent | Earth's earliest granitoids are crystal-rich magma reservoirs tapped by silicic eruptions[END_REF] and references therein).

Timing of magmatism and gold mineralization

The Yaou gold deposit, mainly hosted by the quartz monzodiorite dated at ca. 2130 Ma, is located in the vicinity of the Central TTG-like Complex with two complexes in the east (Fig. 2) belonging to the 2 nd generation of TTG-like described by Delor et al. (2003a, b) and dated between ca. 2140-2120 Ma. Therefore, the quartz monzodiorite intrusions identified at the camp-scale could be associated (genetically and spatially) with these TTG-like complexes; yet outcrops of these two eastern intrusions are currently unkown for further geochemical studies.

An interpreted integration of the deposit/camp-scale litho-structural framework in the regionalscale scheme of Delor et al. (2003a, b) is presented in Figure 13 based on the robust timing of emplacement of the pre-to syn-shearing intrusion together with the geochemical comparison (REE patterns) of all types of magmatic rocks from French Guiana. Regarding the Re-Os pyrite age, the duplicate analyses are in excellent agreement and yield an average value of 2105 ±25 Ma. It suggests that the D4YA phase was concomitant with the regional D2a episode of Delor et al. (2003a, b) and most likely postdated the intrusive event dated at 2130.6±5.8 Ma. This is in agreement with the relative timing of Combes et al. (2021a) based on core observations. It is the first dating of a gold-bearing mineral in the region, allowing to bracket an absolute age of a major gold event. Considering the obtained U-Pb and Re-Os ages for the intrusive event and the D4YA phase respectively, the following interpretation can be proposed: (1) the D1YA/D2YA deformation phase would refer to the regional D1 deformation phase (subduction, oceanic island arcs/back arc basins dated between ca. 2180-2130 Ma with an N-S compression); (2) the D3/4YA would be related to the D2a phase (collision, compression to transpression dated between ca. 2110-2080 Ma). The major gold event is interpreted here to occur between ca. 2130-2125 Ma (lastest age of the intrusion; the Au-bearing pyritization being post-crystallization) and ca. 2084 Ma (youngest age obtained on Py4 permitted within uncertainties). The present work shows an age of intrusion emplacement at the transition between the regional D1 and D2a, therefore at the end of the magmatic arc activity (ca. 2180-2130 Ma) and at the beginning of the collision between magmatic arcs and crustal blocks (ca. 2110-2080 Ma). We propose that the D1/2YA deformation phase ends earlier than initially proposed by Delor et al. (2003bs) for the D1 phase (ca. 2180-2130 Ma) as the Yaou intrusion (ca. 2130 Ma) is interpreted as post-D2YA (Combes et al., 2021a). Also, the D2a deformation phase (dated at ca. 2110-2080 Ma), which is interpreted to correspond to the D3YA phase at Yaou, could start earlier. The D2a has only been dated in the northern belt of the PGB and not in the southern belt where the Yaou deposit is located (see Fig. 13). Regarding the late Granitic suite (ca. 2110-2070 Ma, Pb/Pb and U-Pb on zircon dating, see Fig. 13), both their geochemical signature (Fig. 9) and the relative timing of deformation phases (Fig. 13) distinguish these rocks from the intrusive rocks of Yaou.

Regarding the isotopic data, zircon Hf isotope compositions are supra-chondritic suggesting that the quartz monzodiorite derives from the reworking of Neoarchean-Siderian juvenile components as old as ca. 2.6-2.4 Ga. The juvenile character of the Yaou intrusion reinforces the interpretation of a TTG-like signature of the quartz monzodiorite. These Hf-isotopes signatures are similar to those calculated on the intrusive rocks studied by Parra-Avila et al. (2018,2019) in the Baoulé-Mossi domain of the southern West African Craton with 176 Hf/ 177 Hf(t) values, ranging from 0.2814 to 0.2815 [START_REF] Parra-Avila | Zircon Hf and O-isotope constraints on the evolution of the Paleoproterozoic Baoule-Mossi domain of the southern West African Craton[END_REF][START_REF] Hronsky | Deposit-scale structural controls on orogenic gold deposits: an integrated, physical process-based hypothesis and practical targeting implications[END_REF], witnessing that their magma source area is quite similar.

Zooming out from the camp-scale, a pre-to syn-shearing intrusive event

2D considerations

The spatial distribution of the intrusive bodies (aligned along a N60° trend) and their 3D geometry has been defined in great details at the deposit to camp-scale (Fig. 4 and5). The use of geophysics where no ground exploration has been carried out is therefore essential although the resulting interpretation may be weak. The CYSZ precisely delimited at the camp-scale and striking N60° corresponds to a low magnetic lineament (Fig. 14A,B). A lateral repetition of N60° structures toward the northwest (Fig. 14A) with alternating first order high and low magnetic structures are interpreted. The high magnetic response may correspond either to (1) a dipping stratigraphy possibly wrapped around the regional-scale plutons, or (2) fold hinges with horizontal axial traces [START_REF] Metelka | A geophysically constrained lithostructural analysis of the Eburnean greenstone belts and associated granitoid domains, Burkina Faso, West Africa[END_REF][START_REF] Baratoux | Tectonic evolution of the Gaoua region: Implications for mineralization[END_REF].

An interpretation is here proposed (Fig. 14 B) with the possible occurrence of a series of parallel shear zones located in low magnetic response areas (see the inferred D3YA shear zones in Fig. 14B). These parallel shear zones may (1) be related to a regional tectonic stress field (poorly constraint in the southern PGB; Delor et al., 2003b) or (2) be due to localization around a pair of large plutons (the plutons being emplaced prior to at least some of the deformation).

Regarding the quartz monzodiorite intrusion, the resolution of the geophysical maps does not allow to precisely delineate the intrusive bodies but possible occurrences using a correlation (as observed within Yaou Central) between demagnetized lineaments and altered intrusions is proposed (Fig. 14C). This association could be explained by the fact that quartz monzodiorite bodies display a high frequency of D4YA veins (Combes et al., 2021a) which produce magnetitedepleted (and pyrite-rich) zones due to the progressive replacement of magnetite by pyrite towards the veins by sulfidation reactions.

Importantly, brittle faults (west northwest-east southeast) are interpreted as being D4YA-related since these faults affect the interpreted D3YA structures. Furthermore, these faults are all located within known auriferous zones (near placers and/or gold showings such as Chaina, Tomantoni and the Yaou Central area, Fig. 3) and share similar strikes with the regional N120-140° structures. However, the largest offset identified is associated with an east-west fault (Fig. 12 B, C, D) and does not correspond to any known gold showing.

3D considerations

From these 2D interpretations, a 3D model can be discussed that integrates time as a component.

We interpret the relative timing of the shearing event and intrusive event at the camp-scale as follow. First, the Pre-D3YA phase D2YA (Combes et al. 2021a), is characterized by an east-west penetrative foliation (Fig. 15A) with both the metasediments and the metavolcanites being transposed in the S2. The following syn-D3YA shearing phase with the intrusive body is illustrated in Figure 15B. A 3D representation of the interpreted shearing-induced intrusive event is presented in Figure 15C with opening from shearing, associated magma injection emplacement and lateral repetition of syn-kinematic intrusions and shear zones. Two hypotheses are presented (Fig. 15C) that may explain the space opening in order to allow the intrusions between the parallel shear zones. Robust structural data would be needed to test these models. The first model implies the formation of tension gashes, which will rotate and deflect while the shearing is active. The second model implies a syn-shearing back-rotation of fabrics between the two shear zones, with an antithetic rotation. In this case the extension allowing magma injection is unsure. A structural overview at the plan view of the spatial relationship between the C/S3 fabrics (associated with the D3YA deformation phase) and the S2 fabrics (associated with the D2YA deformation phase) is proposed in Figure 15D. This relationship may reflect a protracted process during which intrusion emplacement and shearing are synchroneous.

Shear zone kinematic evidence (transtensional versus transpressional regime) is rare due to the lack of bedrock outcrops. Thus, it is contentious to ascertain the role of shearing. Since the CYSZ is parallel to the TTG-like complexes in the E, one simple interpretation could be that the shearing expressed at Yaou would be related to emplacement of these TTG-like complexes.

Alternatively, the plutons may have already been emplaced and deformation has been localized at their margins.

Yet, a more detailed structural study is needed to confirm the genetic link between shearing and magmatism at smaller scale. Based on the geometry of the deposit at the camp-scale and the geophysical interpretation at a smaller scale, we propose that the shearing could open spaces (extensional pull-apart-like structures; [START_REF] Bhattacharya | Alkaline intrusion in a granulite ensemble in the eastern ghats belt, India: Shear zone pathway and a pull-apart structure[END_REF] enabling the magma to rise and allowing the emplacement of various intrusive bodies along the shear structure [START_REF] D'lemos | Granite magma generation, ascent and emplacement within a transpressional orogen[END_REF][START_REF] Weinberg | Close spatial relationship between plutons and shear zones[END_REF]. [START_REF] Weinberg | Close spatial relationship between plutons and shear zones[END_REF] suggest « that magma ascent in shear zones is intermittent and characterized by magma entrapment, ballooning, renewed escape, and deflation as the system develops into a number of dilational sites in shear-zone shoulders interconnected by magma sheets within the shear zones ». The process of magma injection into a transtensional shear zone is exampled within the Variscan belt, southwest Iberia by [START_REF] Pereira | The multistage crystallization of zircon in calc-alkaline granitoids: U-Pb age constraints on the timing of Variscan tectonic activity in SW Iberia[END_REF]. Similar settings are described by [START_REF] Hutton | A tectonic model for the emplacement of the Main Donegal Granite, NW Ireland[END_REF], [START_REF] Guineberteau | The Mortagne granite pluton (France) emplaced by pull-apart along shear zone: structural and gravimetric arguments and regional implication[END_REF]; Joly et al. (2007) and [START_REF] Gébelin | Transpressional tectonics and Carboniferous magmatism in the Limousin, Massif Central, France: structural and 40Ar/39Ar investigations[END_REF] but have been debated by [START_REF] Paterson | Re-examining pluton emplacement processes[END_REF], [START_REF] Paterson | Is there a close spatial relationship between faults and plutons?[END_REF] and [START_REF] Paterson | Close spatial relationship between plutons and shear zones: comment and reply[END_REF] regarding the role/need of shear zones to provide a setting for the intrusions. An alternative model proposed by [START_REF] Neves | Shear-zone controlled magma emplacement or magma-assited nucleation of shear zone? Insights from northeast Brazil[END_REF] is a pluton-assisted shear zone nucleation (referred as pluton-induced shear zone).

Here shear zones are related to magma emplacement as mentionned for the Borborema Province of northeast Brazil with examples of intrusive bodies inducing strain localization and favoring shear zone nucleation [START_REF] Neves | Shear-zone controlled magma emplacement or magma-assited nucleation of shear zone? Insights from northeast Brazil[END_REF][START_REF] Neves | Emplacement and deformation of the Cachoeirinha pluton (Borborema province, NE Brazil) inferred through petrostructural studies: constraints on regional strain fields[END_REF]. More recently, Dering et al.

(2019) defined intrusion-related deformation as lateral/vertical propagation and inflation of dikes that generates both seismicity and deformation (Dering et al., 2019 and references therein).

Regarding the type of lithosphere involved in such compressive regime, two models are currently considered, namely (1) the horizontal tectonic model, followed by [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF] and Delor et al. (2003b) in the region, implying a modern-type tectonic where the lithosphere is defined as resistant and cold; and (2) the vertical tectonic model as defined by [START_REF] Gapais | Tectonics-mineralisation relationships within weak continental lithospheres: A new structural framework for Precambrian cratons[END_REF] following the work of Cagnard et al. (2006a), [START_REF] Chardon | Flow of ultra-hot orogens: a view from the Precambrian, clues for the Phanerozoic[END_REF] among other, with a weak and hot/buoyant lithosphere. The proposed model at the Yaou camp-scale does not allow us to decipher between a cold vs. hot orogenic setting without more structural data and absolute dating of the related fabric.

From the camp-to the district-scale, a new litho-structural model for gold targeting

A new litho-structural map is constructed at the district-scale (Fig. 16A) based on deposit-scale geological data (Combes et al., 2021a), 3D orebodies modelling, geochemical characterization of intrusions and airborne geophysical interpretations. When compared to the cross-section of Delor et al. (2003b) for the Yaou district as presented in Figure 16B the proposed lithologic distribution is similar although the present study better defines the structural grain, the brittle faults (D4YA-related) and internal fabrics within the pre-deformation intrusive complexes.

Importantly, the two plutons now appear separated by a metavolcanite unit of the Paramaca Greenstone Bet (Fig. 16 C). This integrated approach, and in particular the interpretation of airborne geophysical data, led to important findings and targeting keys previously unrecognized in the southern PGB. Indeed, best targets include (1) intersections of the main northeast-southwest lineaments with late N140° faults (many known occurrences follow this scheme); (2) near contacts of TTG-type intrusions and (3) areas in the northwest where occurrences in metasediments are inferred. As suggested by Combes et al. (2021a), the metasedimentary unit could be a primary source of gold (Au-bearing Py0).

Obtaining and interpreting geochronological, geochemical and geophysical datasets while downscaling progressively from the ore shoot-scale to the metallogenic province is critical in the mineral system approach. Within the southern PGB (where the Yaou deposit is located), the following keys parameters have to be considered to target new deposits, namely a favorable architecture (whole-lithosphere plumbing system), a geochemical fertility (sources of ore metals) and a favorable geodynamic framework (key geological settings with transient events); (McCuaig and Hronsky, 2014;[START_REF] Wyman | Orogenic gold and the mineral systemsapproach: resolving fact, fiction and fantasy[END_REF][START_REF] Hronsky | Deposit-scale structural controls on orogenic gold deposits: an integrated, physical process-based hypothesis and practical targeting implications[END_REF][START_REF] Niiranen | Scalability of the mineral prospectivity modelling -An orogenic gold case study from northern Finland[END_REF]Groves et al., 2020 and references therein). In that sense, the three following aspects must be examined:

(1) At all stages of exploration, a detailed petro-structural framework, at the deposit-scale, needs to be built (e.g., [START_REF] Thébaud | Protracted and polyphased gold mineralisation in the Agnew District (Yilgarn Craton, Western Australia)[END_REF]Tedeschi et al., 2018a, b;[START_REF] Perret | Subvertical, linear and progressive deformation related to gold mineralization at the Galat Sufar South deposit, Nubian Shield, NE Sudan[END_REF]Combes et al., 2021a) with relative and absolute constraints of deformation phases, veining system and lithologies (depending on available rocks and suitable minerals for dating). The dating of the possible shearing and/or intrusive events are required to understand the gold system of intrusion-hosted gold deposits spatially associated with shear zones. A time window for gold deposition is evidenced in this study (ca. 2130-2080 Ma; Fig. 13) which would be post-intrusive event (ca. 2130 Ma), and syn-to postshearing. This work confirms the conclusions of [START_REF] Milesi | Gold deposits (gold-bearing tourmalinites, gold-bearing conglomerates, and mesothermal lodes), markers of the geological evolution of French Guiana: geology, metallogeny, and stable isotope constraints[END_REF] considering that the main gold event is located between the late crustal growth phase (late regional D1) and the crustal reworking phase (regional D2a). Geochronology can then be used as an exploration tool in the southern PGB.

(2) Concerning the potential hosting units, this study highlights the importance of 2 m to 80 m wide quartz monzodiorite bodies (TTG-like) in building a gold deposit where orebodies volumes are depending on intrusions 3D geometries. The precise delimitation of lithological units/facies with similar rheological and geochemical characteristics representing traps for ore shoots is essential in the southern PGB with detailed geochemical characterization and comparison/correlation of geochemical signatures at various scales. Along this, the metasedimentary unit (of the PGB), that hosts goldbearing diagenetic pyrite grains (Combes et al., 2021a) can be mapped using K anomalies radiometric datasets (Fig. 11A). The north western part of the Yaou district is highly promising in that sense with the presence of large metasedimentary domains, locally covered by a deep weathering profile (Fig. 11E and16A). Overall, as stated by [START_REF] Cassard | Gold predictivity mapping in French Guiana using an expert-guided data-driven approach based on a regional-scale GIS[END_REF], the gold trends (observed or inferred) are localized preferentially in the metavolcanites and metasediments of the PGB or at contacts between these sequences and the TTG-like complexes [START_REF] Milesi | Gold deposits (gold-bearing tourmalinites, gold-bearing conglomerates, and mesothermal lodes), markers of the geological evolution of French Guiana: geology, metallogeny, and stable isotope constraints[END_REF]Delor et al., 2003b). These rocks (metavolcanites and metasediments) thus present potential sources for orogenic gold [START_REF] Phillips | The nature of Archaean gold-bearing fluids as deduced from gold deposits of Western Australia[END_REF][START_REF] Groves | Orogenic gold deposits-a proposed classification in the context of their crustal distribution and relationship to other gold deposit types[END_REF][START_REF] Pitcairn | Sources of metals and fluids in orogenic gold deposits: insights from the Otago and Alpine schists, New Zealand[END_REF][START_REF] Large | Gold and trace element zonation in pyrite using a laser imaging technique: Implications for the timing of gold in orogenic and Carlin-style sediment hosted deposits[END_REF][START_REF] Phillips | Formation of gold deposits: a metamorphic devolatization model[END_REF].

(3) Regarding the favorable architecture, the ore shoot distribution, at the deposit-scale, depends notably on micro deformation, with gold (re-) mobilization, liberation and reprecipitation (Fougerouse et al., 2016 and references therein). This control has been discussed at Yaou (Combes et al., 2021a) with a polyphase deformation and hydrothermal activity. Having no field-based structural data when zooming-out at the district to the camp-scale, transcurrent shear corridors interpreted from the airborne magnetic surveys must be defined and tested. Related to the eburnean-transamazonian orogenic system (Delor et al., 2003b;[START_REF] Chardon | Eburnean deformation pattern of Burkina Faso and the tectonic significance of shear zones in the West African craton[END_REF], these structures are of primary importance. The gold mineralization at Yaou being hosted by intrusive bodies and the N60°-striking shear corridor, these two gold-bearing features need to be recognized by both geological and airborne/ground geophysical surveys but also by drilling (oriented drill core) with precise 3D modelling of the geometry of the deposit (as previously proposed by [START_REF] Allibone | Contrasting Structural Styles of Orogenic Gold Deposits, Reefton Goldfield, New Zealand[END_REF]Cowan et al., 2019;[START_REF] Kreuzer | An integrated approach to the search for gold in a mature, data-rich brownfields environment: A case study from Sigma-Lamaque, Quebec[END_REF] for example) Within the southern PGB, large-scale structures as paleo-convergent margins need to be targeted and outlined by airborne geophysical methods. It is worth noticing that Yaou is located near the lithospheric-scale shear zones inherited from the transamazonian orogeny referred as the CGSZ, (Central Guiana Shear Zone; [START_REF] Lasserre | Le Protérozoïque de Guyane. Révision lithostructurale. Implications pour la formation détritique Orapu et la gîtologie de l'or[END_REF] which is a highly promising lineament that may ensure the circulation of gold-bearing fluids through the crust (McCuaig andHronsky, 2014, Groves et al., 2020b). The prospecting potential of the area is high, with possible features associated with mineralization, such as faults and intrusions, that can be mapped at the district-scale (recognized by both geological and airborne/ground geophysical data), (e.g., [START_REF] Stewart | Multi-scale analysis of Proterozoic shear zones: An integrated structural and geophysical study[END_REF][START_REF] Metelka | A geophysically constrained lithostructural analysis of the Eburnean greenstone belts and associated granitoid domains, Burkina Faso, West Africa[END_REF][START_REF] Baratoux | Tectonic evolution of the Gaoua region: Implications for mineralization[END_REF]. There, a particular focus has to be made on lineaments parallel to lithological contact between the TTG-like complexes and the volcanosedimentary packages (similar to the CYSZ).

At the cratonic-scale, gold deposits spatially associated with intrusions bodies within theGuiana Shield include the Omai gold deposit (Guyana, [START_REF] Voicu | Structural, Mineralogical, and Geochemical Studies of the Paleoproterozoic Omai Gold Deposit[END_REF]2001), which diplays intrusive rocks dated at ca. 2107-2081 Ma (U-Pb on zircon; [START_REF] Norcross | U/Pb and Pb/Pb age constraints on Paleoproterozoic magmatism, deformation and gold mineralization in the Omai area Guiana Shield[END_REF]. The so-called Omai Stock (quartz monzodiorite) of [START_REF] Voicu | Structural, Mineralogical, and Geochemical Studies of the Paleoproterozoic Omai Gold Deposit[END_REF] displays a REE chondrite-normalized pattern similar to that of the Yaou intrusion but with a slight enrichment in HREE. Like the Yaou quartz monzodiorite, the Omai intrusion postdates the regional foliation and is affected by a late phase of brittle deformation responsible for the network of Au-bearing veins [START_REF] Voicu | Structural, Mineralogical, and Geochemical Studies of the Paleoproterozoic Omai Gold Deposit[END_REF]2001). The targeting of quartz monzodiorite intrusive bodies with TTG-like signatures, in the vicinity of shear zones, should be considered in the whole region. The intrusion-hosted Yaoutype deposit may not be unique, similar structural settings may be considered as exploration targets in the Yaou and Dorlin districts.

Conclusions

The Yaou intrusion hosting the bulk of the gold mineralization, is dated at 2130.6±5.8 Ma (U-Pb on zircon) and show supra-chondritic εHft indicating that this quartz monzodiorite is derived from the reworking of Neoarchean-Siderian juvenile components. Using geochemical comparison (REE patterns) of all types of plutonic rocks from French Guiana, the quartz monzodiorite is associated to the 2 nd stage TTG-like rocks, which have the same age range. An integration of the deposit-scale framework is proposed where the quartz monzodiorite emplacement is defined between the regional D1 and D2a phases, therefore at the end of the crustal growth phase and at the beginning of the crustal reworking period. The main gold event hosted by this intrusion is dated by Re-Os on Au-bearing pyrite at 2105±25 Ma. In an outcropdepleted region with no robust structural data, the multi-scale approach using airborne magnetic and radiometric data, helps to better understand the spatial distribution of the intrusions and associated shear zones. Both are interpreted as being repeated along a N60° trends and laterally toward the northwest. The coupled geological and geophysical studies used in French Guiana are promising to localise/predict which structures and lithologies could be associated with gold at the district-scale. The Yaou-type intrusion-hosted mineralization may be targeted along the N60° structures and where possible occurrences of intrusive bodies are defined. Moreover, minor faults offsetting the D3YA N60° structures are high priority targets, knowing that the main gold event at Yaou is associated with the D4YA deformation phase. This integrated approach, and in particular interpretation of airborne geophysical data, opens some targeting possibilities, previously unrecognized within the southern Paramaca Greenstone Belt (PGB) at the provincescale.

Acknowledgment

Figure 1 Geology of the Guiana Shield (modified from [START_REF] Kroonenberg | Paleoproterozoic evolution of the Guiana Shield in Suriname: a revised model[END_REF]. Gold deposits presented have total resources > 10 Moz. MKSZ: Makapa-Kuribrong Shear Zone, NGT: Northern Guiana Trough, CGSZ: Central Guiana Shear Zone. Geographic coordinates are reported as WGS 84. [START_REF] Barker | Trondhjemite: Definition, environment, and hypotheses of origin[END_REF]. D. REE abundances normalized to chondritic values from [START_REF] Sun | Chemical and isotopic systematics ofoceanic basalts: Implications for mantle composition and processes[END_REF]. E. Spider plot normalized to primitive mantle values from [START_REF] Sun | Chemical and isotopic systematics ofoceanic basalts: Implications for mantle composition and processes[END_REF]. Figure 13 Geochronological synthesis of the Trans-Amazonian orogeny with deformation phases (Delor et al., 2003 a, b), compilation of published geochronological data of main plutonic events (zircon Pb/Pb and U-Pb; [START_REF] Vanderhaeghe | Contrasting mechanism of crustal growth: Geodynamic evolution of the Paleoproterozoic granite-greenstone belts of French Guiana[END_REF]Delor et al., 2003b;[START_REF] Enjolvy | Processus d'accrétion crustale et régimes thermiques dans le bouclier des Guyanes: signatures géochimiques et thermochronologiques au transamazonien (2250-1950Ma)[END_REF]) and interpreted integration of the Yaou camp-scale deformation phases from Re-Os dating on pyrite (Py4) and U-Pb dating on zircon (quartz monzodiorite i.e. intrusive event) in the regional framework. Figure 16 A. Litho-structural map produced from geological and geophysical data at the districtscale. B. Cross section of Delor et al.(2003b) through the Yaou district vs the updated crosssection from this study with two separated plutons. Table 1. Whole rock major (wt.%) and trace element (ppm) composition of sampled intrusive rocks (dl, detection limit)

Tables

  Fig. 8D) are highly reproducible and show a high degree of fractionation, characterized by a relatively steep slope form the LREE toward the HREE. The data reveal: (1) LREE (La, Ce, Pr, Nd) enrichment with the LaN content ranging from 90.81 to 109.23; (2) no marked Eu anomalies, and (3) [La/Yb]N ratios ranging from 20.7 to 38.6. The HREE patterns are shallowly dipping toward the right with low contents of HREE (Er, Yb, Lu); the YbN contents range from 2.46 to 4.39.

Figure 2

 2 Figure 2 Geological map of French Guiana with location of the main Au deposits including the Yaou deposit. Modified from Delor et al. (2003b). All geochronology data are from Delor et al. (2003b) and references therein.

Figure 3

 3 Figure 3 Regional geological map with location of the main Au occurences. Modified from Delor et al. (2003b), mainly based on geophysical interpretation of the regional BRGM survey. See Figure 2 for location.

Figure 4

 4 Figure 4 Schematic 3D block diagram of the deposit at the camp-scale after all deformation/ intrusion events occured, highlighting the geometry of the CYSZ associated with the D3YA deformation phase and the pre to syn-D3YA intrusive bodies

Figure 6

 6 Figure 6 Photographs of half-drillcore intervals presenting the least altered samples of the quartz monzodiorite intrusive bodies.

Figure 7

 7 Figure 7 Representative micrographs of the least altered quartz monzodiorite (XPL except F. in PPL) A. B. D Typical albitization and seritization, C. E. Strong ankeritization. F. Hematization

Figure 8 A

 8 Figure 8 A. QAP Streckeisen ternary diagram where all samples plot in the Qz monzodiorite field. B. Least altered samples plotted in a Th vs Co diagram. C. Ternary An-Ab-Or diagram

Figure 9

 9 Figure 9 Yaou Quartz monzodiorite REE Normalized to Chondrite (Sun and McDonough, 1989) patterns compared to the main intrusive units defined in French Guiana. A. The "Ile de Cayenne" Complex patterns. B. The 1 st generation of TTG-like patterns. C. The 2 nd generation of TTG-like patterns. D. The late samples of the 2 nd generation of TTG-like patterns. E. The Ganitic suite patterns. F. The peraluminous leucogranite patterns. Compared geochemical data are from Vanderhaeghe et al. (1998), Delor et al. (2003a, b) and Enjolvy (2008).

Figure 10 A

 10 Figure 10 A. BSE images of representative analysed zircon grains from the quartz monzodiorite intrusion. The circles indicate Lu-Hf and U-Pb laser spots. The numbers are respectively the sample ID, the 207 Pb/ 206 Pb age and the Hf model age of the corresponding spot. B. 207 Pb/ 235 U versus 206 Pb/ 238 U diagrams for the quartz monzodiorite (intercept). C. 207 Pb/ 235 U versus 206 Pb/ 238 U diagrams for the quartz monzodiorite (concordance). D. εHft as a function of intrusion age (Ma). Crustal evolution trends (between dotted lines) are calculated with a value of 176 Lu/ 177 Hf = 0.0113, value for average present-day continental crust. Stars at the intersection of depleted mantle and crustal evolution trends represent Hafnium model ages. CHUR = chondritic uniform reservoir; DM = depleted mantle.

Figure 11

 11 Figure 11 Lithological interpretations based on airborne geophysics. A. K anomaly grid used to map the metasedimentary unit. B. U anomaly map highlighting the U-rich TTG-like complex. C. Ternary radio-element map (relative abundance) of K, Th and U. D. 1VD image emphasizing shallow features. E. Overview of the interpreted distribution of lithologies at the district-scale

Figure 14

 14 Figure 14 Structural interpretation of the distribution of faults, shear zones and intrusive bodies A. High to low magnetic response in greyscale (RTP TD filter). B. Geophysical-based structural and lithogical interpretations displaying the proposed intrusive body trends, a serie of N60°striking shear zones (in low magnetic responses areas) and late D4YA-related faults interpreted using the TD-HDR filter. High magnetic response may correspond to a dipping stratigraphy or folded stratigraphy with horizontal fold axes.

Figure 15

 15 Figure 15 Sketches illustrating the structural settings at the camp-scale. A. The Pre-D3YA phase. B. The syn-D3YA shearing contemporaneous with the intrusive body. C. 3D representation of the interpreted shearing induced intrusive event with two hypotheses of formation, tension gashes or backfolding of fabric. D. Structural overview of the C/S3 fabrics (associated with the D3YA deformation phase) and the spatial relationship S2 fabrics (associated with the D2YA deformation phase).

Fig 8

 8 Fig 2 Color, 2-column fitting image.

Fig 9

 9 Fig 9 Color, 2-column fitting image.

  Fig 10 Color, 2-column fitting image.

  Fig 12 Color, 2-column fitting image.

Table 2

 2 Results of U-Pb-dating. size = 33µm.206 Pb/ 238 U error is the quadratic additions of the within run precision (2 SE) and the external reproducibility (2 SD) of the reference zircon.207 Pb/ 206 Pb error propagation ( 207 Pb signal dependent) following[START_REF] Gerdes | Zircon formation versus zircon alteration -New insights from combined U-Pb and Lu-Hf in-situ La-ICP-MS analyses of Archean zircons from the Limpopo Belt[END_REF].207 Pb/ 235 U error is the quadratic addition of the 207 Pb/ 206 Pb and 206 Pb/ 238 U uncertainty. a Within run background-corrected mean 207 Pb signal in cps (counts per second). b U and Pb content and Th/U ratio were calculated relative to GJ-1 reference zircon. c percentage of the common Pb on the 206 Pb. B.d. = below dectection limit. d corrected for background, within-run Pb/U fractionation (in case of 206 Pb/ 238 U) and common Pb usingStacy and Kramers (1975) model Pb composition and subsequently normalized to GJ-1 (ID-TIMS value/measured value); 207 Pb/ 235 U calculated using 207 Pb/ 206 Pb/( 238 U/ 206 Pb*1/137.88) e rho is the 206Pb/238U/207Pb/235U error correlation coefficient. f degree of concordance = 206 Pb/ 238 U age / 207 Pb/ 206 Pb age x 100 Hf) = ln( 179 Hf/ 177 Hf true / 179 Hf/ 177 Hfmeasured )/ ln (M179(Hf)/M177(Hf) ), M=mass of respective isotope. The 176 Lu/ 177 Hf were calculated in a similar way by using the 175 Lu/ 177 Hf and b(Yb). Quoted uncertainties (absolute) relate to the last quoted figure. The effect of the inter-element fractionation on the Lu/Hf was estimated to be about 6 % or less based on analyses of the GJ-1 and Plesoviče zircons. (b) Mean Hf signal in volt. (c) Uncertainties are quadratic additions of the within-run precision and the daily reproducibility of the zircon GJ-1. Uncertainties for GJ-1 is 2SD (2 standard deviation). (d) Initial 176 Hf/ 177 Hf and eHf calculated using the age (Ma), and the CHUR parameters: 176 Lu/ 177 Hf = 0.0336, and 176 Hf/ 177 Hf = 0.282785[START_REF] Bouvier | The Lu-Hf and Sm-Nd isotopic composition of CHUR: Constraints from unequilibrated chondrites and implications for the bulk composition of terrestrial planets[END_REF]. (e) two stage model age in billion years using the measured 176 Lu/ 177 Lu, the estimated age (Ma), a value of 0.01113 for the average coninental crust (second stage), and a depleted mantle 176 Lu/ 177 Hf

	Spot

Table 4 .

 4 The Re-Os data obtained on Py4 pyrite

	Name	Sample wt. (g)	[Re] ppb	total uncertainty	187 Re M/g	total uncertainty	188 Os M/g	% 188 Os from blank
	Yaou (1)	0.20292	26.57	0.3789	8.93E-11	1.27E-12 5.49E-15	22.9
	Yaou (2)	0.20165	26.16	0.2037	8.80E-11	6.74E-13 5.69E-15	22.4
	Name	187 Os ppb blank corr	187 rad if 187 / 188 (initial) =0.6	Total uncertainty	187 Os/ 188 Re	187 Os/ 187 Re uncertainty	Age (Ga)	Uncertainty
	Yaou (1)	0.595	3.18E-12	6.50E-15	3.58E-02	5.15E-04	2.11	0.03
	Yaou (2)	0.584	3.12E-12	6.00E-15	3.56E-02	2.83E-04	2.101	0.017
	All data are blank corrected.
	Radiogenic Os is estimated assuming an initial 187 Os/ 188 Os=
	0.6 ±0.5
	Total uncertainties (2 sigma) include measurement uncertainties, uncertainty on the blank reproducibility, and
	assumed variation in initial 187 Os/ 188 Os ratio.

This study is part of Vincent Combes's Ph.D. research at the Université de Lorraine within the GeoRessources laboratory, in Nancy, France. We are grateful to E. Davy of the CRPG in Nancy, France for helping us with zircon separation, to J. Perret for zircon handpicking and to D.

Chardon, A. Chauvet and T. Torvela for the scientific discussions on this study. The airborne geophysical data were reprocessed and interpreted during the SAXI workshop held in 2019 at Paramaribo, Suriname. Two anonymous reviewers are acknowledged for their careful reviews which have improved this manuscript substantially. V. Oliveros is thanked for the editorial work.

Funding

This research was funded by Auplata Mining Group (AMG) and benefited from the framework of the CREGU.