Ali Mohammadi

Jonas B Ruh

Marcel Guillong

Oscar Laurent

Lotfollah Aghajari

From gondwana rifting to alpine orogeny

Keywords: Gondwana, Kopet Dagh Basin, Paleo-Tethys, Neo-Tethys, Rifting, Collision, Detrital zircon, Hf isotopes, Provenance anlysis

INTRODUCTION

The long-standing tectonic history between Gondwana and Eurasia includes several phases of rifting and collision, recorded by magmatic and metamorphic episodes in various domains of related orogenic belts; from the Alps in the west to the Himalayas in the east (for example Şengör, 1990a;1990b;Stampfli, 2000;[START_REF] Stampfli | A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons[END_REF]. The timing of main tectonic episodes including rifting, subduction initiation, and collision are crucial for the reconstruction of plate tectonics (for example [START_REF] Stampfli | A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons[END_REF]. Geochronology and geochemistry of magmatic and metamorphic rocks are widely applied in geodynamic studies to constrain the timing and other characteristics of tectonic events (for example [START_REF] Barbarin | A review of the relationships between granitoid types, their origins and their geodynamic environments[END_REF][START_REF] Brown | The contribution of metamorphic petrology to understanding lithosphere evolution and geodynamics[END_REF].

However, the occurrence and surface exposure of such igneous and metamorphic terranes may be limited in some tectono-sedimentary domains because of complete erosion or coverage by younger sediments. In addition, the application of different dating methods on igneous and metamorphic rocks provides a wide range of ages, which makes the exact timing of tectonic events difficult. In fact, timing constraints for tectonic events based only on magmatic or metamorphic rocks may be misleading. A more accurate detection of large-scale tectonic events can be found in clastic sedimentary successions, where the detritus source rapidly responds to any plate tectonic reorganization (Cawood and others, 2012;Fedo and others, 2003). Therefore, provenance analysis, zircon geochronology, and zircon isotopic composition on detrital sandstones may help to improve the precision when constraining the timing of tectonic events (for example Cawood and others, 2012;[START_REF] Weltje | Quantitative provenance analysis of sediments: review and outlook[END_REF].

Several episodes of continental rifting and collision took place between Gondwana and Eurasia since the Palaeozoic until the Cenozoic that ultimately climaxed in the Alpine-Himalayan orogeny (for example Şengör and others, 1984;Stampfli, 2000;[START_REF] Stampfli | A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons[END_REF][START_REF] Stöcklin | Possible ancient continental margins in Iran, The geology of continental margins[END_REF]. Separation of several continental slivers and microcontinental blocks from Gondwana occurred in two phases, coeval with the opening of two ocean basins, the Paleo-Tethys and Neo-Tethys oceans (for example [START_REF] Alavi | Tectonostratigraphic synthesis and structural style of the Alborz mountain system in northern Iran[END_REF]Stampfli, 2000;Şengör and others, 1984;[START_REF] Stöcklin | Possible ancient continental margins in Iran, The geology of continental margins[END_REF]. The opening of the Iranian segment of the Paleo-Tethys between the Iranian continent (Gondwana) and the Turan platform (Eurasia) was suggested to have occurred in the Early Palaeozoic (Ordovician-Silurian) based on ages of oceanic basalts [START_REF] Boulin | Hercynian and Eocimmerian events in Afghanistan and adjoining regions[END_REF]Stampfli, 2000). The subsequent northwards subduction of the Paleo-Tethys beneath Eurasia initiated during the Late Devonian and continued until the Late Triassic as shown from dating of the Darrehanjir-Mashhad ophiolites (for example Moghadam and others, 2015a;Stampfli, 2000;Wilmsen and others, 2009). The opening of a new ocean (Neo-Tethys Ocean) between the Arabian plate and the Central Iran block at the end of the Permian went hand in hand with the northward movement of the Central Iran block, resulting in the closure of the Paleo-Tethys Ocean in the Late Triassic, and the consequent collision of the Iranian plate with the Turan block; the Cimmerian orogeny (for example [START_REF] Berberian | Towards a paleogeography and tectonic evolution of Iran[END_REF]Muttoni and others, 2009;[START_REF] Şengör | Mid-Mesozoic closure of Permo-Triassic Tethys and its implications[END_REF]Zanchetta and others, 2013). This Cimmerian orogeny prevented further shortening along the northern segment of the Tethys and triggered the onset of subduction of the southern Neo-Tethys Ocean (for example Zanchetta and others, 2013).

The northward subduction of the Neo-Tethys Ocean beneath the Central Iran block was accompanied by the opening of the Greater Caucasus-South Caspian-Kopet Dagh basins during the Middle Mesozoic, potentially in form of a larger back-arc basin [START_REF] Alavi | The Triassic and associated rocks of the Nakhlak and Aghdarband areas in central and northeastern Iran as remnants of the southern Turanian active continental margin[END_REF][START_REF] Brunet | Integrated peri-Tethyan basins studies (peri-Tethys programme)[END_REF]Zanchi and others, 2006). The Neo-Tethys Ocean finally closed during the collision of the Arabian plate and Central Iran block in late Oligocene, which resulted in the Alpine orogeny (Pirouz and others, 2017). This collision related to the closure of the Neo-Tethys resulted in tectonic inversion of previously extensional domains (Greater Caucasus, South Caspian, and Kopet Dagh basins) along the Paleo-Tethys suture (for example Robert and others, 2014;[START_REF] Ruh | Effects of reactivated extensional basement faults on structural evolution of fold-and-thrust belts: Insights from numerical modelling applied to the Kopet Dagh Mountains[END_REF][START_REF] Ruh | Effects of fault-weakening processes on oblique intracontinental rifting and subsequent tectonic inversion[END_REF].

The Kopet Dagh Basin contains a stratigraphic record covering the last ~175 Myr (Middle Jurassic to Neogene sedimentary succession; Afshar Harb, 1982a;[START_REF] Moussavi-Harami | Lower Cretaceous (Neocomian) fluvial deposits in eastern Kopet-Dagh basin, northeastern Iran[END_REF]. Detailed provenance analysis of this shallowing-upward (deep marine-marinedeltaic-continental) sequence allows i) to reconstruct the Mesozoic-Tertiary sedimentary evolution of the Kopet Dagh Basin, ii) to clarify the general tectonic setting associated with the Turan and Iran plates, and finally iii) to precisely constrain the timing of rifting and collision events related to the opening and closure of the Paleo-Tethys and Neo-Tethys oceans.

In this study, we present combined results from sandstone modal framework, heavy mineral assemblage analysis, detrital zircon U-Pb age, and in-situ Hf isotope composition of Triassic (pre-rift basement), and Middle Jurassic to Paleocene detrital sediments from the Kopet Dagh.

Results are interpreted to identify and characterize the respective source rocks in terms of ages and genesis. Based on these data, we determine the provenance of sedimentary detritus and reconstruct the variety of rift-related, continental arc, and post-collisional tectonic settings from Gondwana-related rifting (opening of Paleo-Tethys) to Alpine orogeny (closure of Neo-Tethys).

GOLOGY OF THE KOPET DAGH

Tectonic Setting

The Kopet Dagh mountains in NE Iran strike over 700 km along the Iran-Turkmenistan border and form the northern limit of the Alpine-Himalayan orogeny (Golonka, 2004: Robert andothers, 2014;fig. 1). The Main Kopet Dagh Fault (MKF) and the East Alborz and Binalud mountains mark the northern and the southern boundary of the Kopet Dagh Basin, respectively (fig. 1). Tectonically, the Kopet Dagh Basin formed as an extensional back-arc to the Neo-Tethys subduction system farther to the south [START_REF] Mangino | The crustal structure of the southern Caspian region[END_REF]. The onset of extension is marked by a major nonconformity at the base, and rapid sediment facies and thickness variations in the Middle Jurassic (165 Ma to 170 Ma) deep-marine turbiditic sediments (Kavoosi and others, 2009;Robert and others, 2014;Thomas and others, 1999). In contrast to the Caspian Sea Basin in the west, there is no evidence for the formation of oceanic crust beneath the Kopet Dagh Basin (Brunet and others, 2003). After this rifting event, the basin experienced a phase of tectonic quiescence for at least 130 Myr until Oligocene-Miocene, when the extensional basins along the Paleo-Tethys suture experienced tectonic inversion as a consequence of the collision of Arabian and Eurasian plates to form the Zagros mountain range, and due to newly arranged relative plate motions (Hollingsworth and others, 2010;[START_REF] Lyberis | Oblique to orthogonal convergence across the Turan block in the post-Miocene[END_REF]. This tectonic inversion is synchronous with the onset of deposition of continental sedimentary facies in the Kopet Dagh Basin (Robertand others, 2014) and tectonic uplift of the Alborz mountains (Razaeian and others, 2012). Uplift of the Kopet Dagh mountains resulted in widespread folding and faulting of the Jurassic to Tertiary stratigraphy and an estimated N-S shortening of ~75 km (Allen and others, 2003;[START_REF] Lyberis | Oblique to orthogonal convergence across the Turan block in the post-Miocene[END_REF]. The compressional phase continued for about 15 Myr, with an increased component of dextral strike-slip movement since ~10 Ma (Hollingsworth and others, 2006).

Stratigraphy

The study area is located in the eastern part of the Kopet Dagh Basin covered by the Darreh Gaz, Mashhad, Sarakhs, Torbat-e-Heydarieh, and Torbat-e-Jam 1:250,000 geological maps published by the Geological Survey of Iran (figs. 1, 2;Afshar 1982aAfshar , 1982b;;Afshar and others, 1986;Behrouzi and others, 1993;Vaezi Pour and others, 1992). An up to seven-kilometersthick terrigenous and carbonate s edimentary succession was deposited into the Kopet Dagh Basin between Middle Jurassic to Neogene (figs. 2, 3;[START_REF] Moussavi-Harami | Lower Cretaceous (Neocomian) fluvial deposits in eastern Kopet-Dagh basin, northeastern Iran[END_REF].

The Middle Jurassic (late Bajocian to Bathonian) intervals of deep marine turbiditic conglomerate, thin-and thick-bedded sandstones, siltstone, and mudstone (Kashafrud Formation) are the oldest sediments deposited into the Kopet Dagh Basin (for example [START_REF] Poursoltani | Composition, porosity, and reservoir potential of the Middle Jurassic Kashafrud Formation, northeast Iran[END_REF]Poursoltani, and others, 2007). The Middle Jurassic sediments rest unconformably on Triassic basic intrusions and volcanogenic sedimentary rocks and exhibit variations in thickness across major extensional basement faults, indicating a syn-rifting depositional environment (Robert and others, 2014;Thomas and others, 1999). Thickness of the turbiditic sediments vary between 280 m to over 2000 m in the East Kopet Dagh Basin (fig. 3). The Middle Jurassic turbiditic succession is unconformably overlain by Upper Jurassic (Callovian-Kimmeridgian) thick (>1200 m) marine carbonates and shallow marine, coastal plain silisiclastic sediments (Mozduran Formation; Kavoosi and others, 2009;[START_REF] Lasemi | Platform carbonates of the Upper Jurassic Mozduran formation in the Kopet Dagh Basin, NE Iran-facies, palaeoenvironments and sequences[END_REF]fig. 3). Thick fluvial siliciclastic sediments of the Early Cretaceous (Surijeh Formation) record epicontinental sea retogradation in the eastern part of the Kopet Dagh Basin (fig. 3;[START_REF] Moussavi-Harami | Lower Cretaceous (Neocomian) fluvial deposits in eastern Kopet-Dagh basin, northeastern Iran[END_REF]. Contemporaneous deposition of marine carbonate indicates the presence of a marine environment in the western Kopet Dagh Basin. Further transgression established a marine depositional environment throughout the entire Kopet Dagh Basin until Late Cretaceous (Turonian). This transgressions system is characterized by intervals of oolitic limestone (Tirgan Formation), marl and shale (Sarcheshmeh Formation), shale (Sanganeh Formation), and glauconitic-carbonatic sandstone and shale (Aitamir Formation; fig. 3). This wide range of lithologies indicates sea level fluctuation and depositional environments represented by tidal flats, lagoons, carbonate ramps, continetal shelfs, and shallow marineshorefaces. A short-lived sea retogradation during the Late Cretaceous (Turonian) is responsible for an unconformity between the shallow marine glauconitic shale (Aitamir Formation) and shallow marine marl and limestones (Abderaz Formation; fig. 3). Between the Turonian until the Paleocene, the East Kopet Dagh Basin experienced other transgressional episodes characterized by marine environments including the deposition of shallow marine marl and limestones (Abderaz Formation), shelf and open marine marl and shale (Abtalkh Formation), shallow marine and shoreface glauconitic sandstone (Neyzar Formation), and shallow carbonate platform sandy limestones (Kalat Formation; fig. 3). Basin-scale sea retrogradation and surface exposure of strata is recorded by erosional surfaces within the uppermost part of Late Cretaceous sandy limestones (Kalat Formation; Mahboubi and others, 2006). In early Paleocene, reddish fluvial and lacustrine mudstones and sandstones (Pestehleigh Formation) were unconformably deposited onto uppermost Cretaceous marine sediments. During the late Paleocene, the Kopet Dagh Basin gradualy changed from a shallow continental sedimentary environment to a shallow carbonate paltform with marl and limestone sediments (Chehel Kaman Formation). The basin subsidence continued until Eocene-early Oligocene, when marine shale and sandstones (Khangiran Formation) conformably overlayed late Paleocene sediments. Repeated minor phases of transgressions and regressions followed into the Miocene, until the basin was tectonically inverted duing Alpine orogeny, accompanied by deposition of continental conglomerates, sandstones, and shale (Neogene red beds; fig. 3).

METHODS

Nineteen sandstone samples including one sandstone sample of a lens within Triassic polymictic conglomerate, and eighteen well-cemented medium-grained Jurassic to Paleocene turbiditic, fluvial-deltaic, and continental sandstone samples were investigated (with prefix KD-01-20 in the ETH collection). Studied sandstones represent five different litho-stratigraphic formations (Qara-Gheitan, Kashafrud, Shurijeh, Aitamir, and Pestehleigh formations) of the Kopet Dagh Basin (figs 1, 2, 3 and table S1). We combined sandstone framework composition and heavy mineral analysis, detrital zircon U-Pb geochronology, and in-situ Hf-isotopic composition to reconstruct the lithological composition of the source-rocks and the tectonic evolution of the source area.

Sandstone thin section

Sandstones modal framework analysis was performed in thin sections stained for carbonates and feldspars with the Gazzi-Dickinson method [START_REF] Dickson | Carbonate identification and genesis as revealed by staining[END_REF][START_REF] Norman | Improved techniques for selective staining of feldspar and other minerals using amaranth[END_REF]. For statistical reliability, at least 300 lithic fragments were counted in each thin section [START_REF] Folk | Petrology of Sedimentary Rocks[END_REF]. The Zuffa method was applied to count detrital grains [START_REF] Zuffa | Optical analyses of arenites: Influence of methodology on compositional results[END_REF]. Sand size lithic fragments (>63 µm) within rock fragments were counted as monomineralic grains. Results were converted to percentages for compositional comparison [START_REF] Weltje | Quantitative provenance analysis of sediments: review and outlook[END_REF]; table S2). Five standard complementary triangular diagrams were used to display the data (QFL, QmFLt, LvhLsLm, QmPK, and QpLvLsm;[START_REF] Folk | Petrology of Sedimentary Rocks[END_REF][START_REF] Dickinson | Interpreting provenance relations from detrital modes of sandstones[END_REF].

Heavy mineral separation

Approximately 2-3 kg of fresh rock were collected at each sample site for heavy mineral analysis. To obtain transparent heavy mineral fractions, sandstones were crushed with the SelFrag apparatus batch equipment using high voltage (130-150 kV) pulse power technology, which liberates morphologically intact minerals. From the <2 mm sieved fraction, carbonate was dissolved in warm (60-70°C), 10%-acetic acid. Heavy minerals were pulled out in separation funnels [START_REF] Mange | Heavy Minerals in Colour[END_REF] from 63 µm to 400 µm sieve fractions using bromoform (density 2.88 g/cm 3 ). The bulk heavy mineral fractions were mounted in piperine [START_REF] Martens | Piperine as an immersion medium in sedimentary petrography[END_REF] between a glass slab and a cover. Identification and quantification were carried out under a petrographic microscope by applying the mid-point ribbon and fleet counting methods. At least 200 grains were counted per sample [START_REF] Mange | Heavy Minerals in Colour[END_REF]; table SI3).

Zircon geochronology

Zircons were extracted from additional 2-3 kg of fresh sandstones crushed with the SelFrag apparatus. Standard Holman-Wilfley shaking tables and magnetic separation methods (Frantz magnetic separator) delivered mineral fractions enriched in zircons. Zircons of grain fraction 60-250 μm (non-magnetic) were handpicked under a binocular microscope. Selected grains were mounted in U-and Pb-free resin, polished to expose the internal parts of the minerals, and coated with carbon. Suitable zircon domains and inclusions were identified by cathodoluminescence (CL) and backscattered-electron (BSE) images obtained by split screen on a CamScan CS44 Scandunk Viermalning electron microscope (SEM; Tescan a.s., Brno) at ETH Zurich, and analyzed with laser ablation inductively coupled mass spectrometry (LA-ICP-MS) at ETH Zurich with an excimer laser (ArF 193 nm). Zircon characteristics were interpreted following the approach by Corfu and others (2003).

The laser ablation ICP-MS analyses were performed with a RESOlution (Australian Scientific Instruments/Applied Spectra) laser ablation system at ETH Zurich equipped with a dual-volume S-155 ablation cell (Laurin Technic, Australia), coupled to an Element XR (Thermo Scientific, Germany) sector-field ICP-MS. A laser repetition rate of 5 Hz, energy density of ca. 2.5 J/cm 2 , and spot diameter of 30 μm were applied. The carrier gas consisted of high-purity He (ca. 0.7 L/min) and make-up Ar (ca. 1 L/min) from the ICP-MS. Data acquisition time per spot was about 1 minute (30 s gas blank + 30 s ablation). The data were processed with the Igor Pro Iolite v2.5 software (Hellstrom and others, 2008), using the VizualAge data reduction scheme [START_REF] Petrus | VizualAge: A novel approach to laser ablation ICP-MS U-Pb geochronology data reduction[END_REF]. Laser-induced element fractionation (after Paton and others, 2010), instrumental mass discrimination, and drift through the analytical session were corrected by standard bracketing against zircon reference material "GJ-1" (using isotope ratios recommended by Horstwood and others, 2016). The quoted uncertainties for each individual analysis correspond to the internal error and propagated uncertainty based on the scatter of the primary reference material (see Paton and others, 2010). The accuracy and reproducibility within each run of analysis were monitored by periodic measurements of zircon reference materials "Plešovice" (337 Ma; Sláma and others 2008) and "91500" (1065 Ma; Wiedenbeck and others 1995). More details about the analytical conditions, the data from unknowns and reference materials are provided in table S5. Concordia diagrams were obtained using ISOPLOT v.3.0 (Ludwig, 2003). A concordant age is given by the overlap of the error ellipse with the Concordia age curve. In this study, ages with discordance >5% are not included for further interpretation (table S4). The frequency U-Pb age distribution diagram or probability density plot described by Ludwig (2003) includes a histogram representing the number of individual zircon grains within a short age range, and the probability curve depicts the mean age peaks of the contained age populations in one sample.

Zircon Lu-Hf isotopic analyses

Lu-Hf analyses were obtained by laser ablation multi-collection inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) at ETH Zurich, using a RESOlution (ASI/Applied Spectra) excimer (ArF) 193 nm laser ablation system attached to Nu Plasma II (Nu Instruments) multi-collector ICP-MS. A laser repetition rate of 5 Hz, a spot diameter of 50 μm, and a laser energy density of ca. 4 J/cm 2 was applied. Ablation was performed in a dual-volume, fastwashout S-155 ablation cell (Laurin Technic) fluxed with carrier gas consisting of ca. 0.37 L/min He and make-up gas consisting of ca. 0.92 L/min Ar. A typical run consisted of 40 s of background measurement followed by 40 s of sample ablation with an integration time of 0.5 s. The ICP-MS instrument was optimized for maximum sensitivity on 180 Hf, and optimal peak shape and coincidence for Yb, Lu, and Hf isotopes. The list of acquired masses and corresponding Faraday cups are provided in table S7.

The resulting intensities were processed offline with the Igor Pro Iolite v2.5 software, using an in-house data reduction scheme (Hellstrom and others, 2008). Background-subtracted intensities were used to calculate isotope ratios, which were corrected for instrumental mass bias by normalization to the natural abundance ratios 173 Yb/ 171 Yb (for both Yb and Lu isotope ratios) and 179 Hf/ 177 Hf (for Hf isotope ratios) of Chu and others (2002). The isobaric interferences of 176 Yb and 176 Lu on 176 Hf were subsequently corrected using the natural abundance ratios of 176 Yb/ 173 Yb = 0.79502 and 176 Lu/ 175 Lu = 0.02656. Accuracy and external reproducibility of the method were controlled by repeated analyses of reference zircon standards "GJ" (Morel and others, 2008), "Plešovice" (Sláma and others, 2008), "Mud Tank" and "Temora" [START_REF] Woodhead | A preliminary appraisal of seven natural zircon reference materials for in situ Hf isotope determination[END_REF], and "QGNG" (Woodhead and others, 2004). The 176 Hf/ 177 Hf ratios obtained on all reference materials are within uncertainties identical to the recommended values. Calculations of initial 176 Hf/ 177 Hf ratios and ε-Hf were performed applying the 176 Lu decay constant of Scherer and others (2001) and 176 Hf/ 177 Hf and 176 Lu/ 177 Hf values for the chondritic uniform reservoir (CHUR) recommended by Bouvier and others (2008). The quoted uncertainties on initial Hf isotopic composition correspond to the analytical uncertainty and the average 2 S.D (table S6). Reproducibility of the initial Hf isotopic compositions of all measured zircon reference materials (table S7), were propagated by quadratic addition. More details about the analytical conditions, the data from unknowns, and reference materials are provided in table S7.

RESULTS

Sandstone frame work

The studied Triassic and Jurassic sandstones are mainly classified as feldspathic litharenite and lithic arkose (fig. 4A). Cretaceous sandstones are classified as subarkose and sublitharenite.

The Paleocene sandstone sample is a litharenite. Quartz grains of all samples are mostly monocrystalline (~50% in Triassic, 50-75% in Middle Jurassic, and >80% in Cretaceous and Paleocene sandstones; figs. 4A, 4B, 4C and table S2). K-feldspars are dominant in feldspar grains (~73% in the Jurassic, and ~80% in the Cretaceous and Paleocene sandstones; fig. 4B and table S2). From Jurassic to Cretaceous and Paleocene sandstones, the percentage of monocrystalline quartz and K-feldspar grains increases, while the percentage of polycrystalline quartz and plagioclase grains decreases (figs. 4C and4d). The Triassic sandstone is rich in volcanics (~55%), with less sedimentary and metamorphic lithics (~45%). Jurassic sandstones are composed of sedimentary (~60%), volcanic (~30%), and metamorphic (~10%) rock fragments. In Cretaceous and Paleocene sandstones, sedimentary and metamorphic rock fragments (together >95%) are dominant, while volcanic lithics are less common (<5%). In both Jurassic and Cretaceous sandstones, sedimentary lithic grains mainly comprise siltstone, limestone, and dolomite, whereas metamorphic lithic grains generally consist of low-grade to medium-grade slate, phyllites, and schists. Volcanic lithic grains mainly represent andesite and volcanic glass (figs. 4C, 4D and table S2). Dominantly volcanic lithics (figs.

Heavy mineral study

Heavy mineral assemblages of sandstones from the Kopet Dagh are characterized as follows:

(1) A group of ultra-stable heavy minerals including zircon, tourmaline, and rutile (ZTR), sphene, monazite, and less stable apatite that are typically derived from acidic to intermediate magmatic rocks and recycled siliciclastic sandstones. The amount of ZTR ranges from 22% of total grain count in the Triassic sandstone and reaches up to 53% of total grain count in Jurassic and up to 74.5% in Cretaceous sandstones (Fig. 5). The percentage of apatite grains ranges between 9% in Triassic and 17.5% in Jurassic sandstones (fig. 5 and table S3). ( 2) A group of meta-stable heavy minerals including pyroxene and amphibole attributed to mafic magmatic source rocks. The amount of pyroxene in Triassic sandstones reaches up to 64% of the total heavy mineral grains, whereas Jurassic and Cretaceous sandstones contain 24% and 1.5% pyroxene, respectively (fig. 5 and table S3). (3) A third group describes meta-stable minerals, including the epidote group, garnet, chloritoid, andalusite, and staurolite, that are common heavy minerals related to medium-to high-grade metamorphic rocks. The percentage of these minerals varies from 1% of total counted grains in Triassic sandstones to 17% of total counted grains in Paleocene sandstones (fig. 5 and table S3). ( 4) Fourth, Cr-spinel (up to 4% of total grain count; fig. 5 andtable S3) indicates mafic-ultramafic rocks as source of detritus.

Detrital zircon U-Pb ages

Hf isotopic composition

Hafnium isotopic composition analysis was conducted on 151 concordantly dated zircon grains with internal growth structures that were large and thick enough to be examined with laser beams. The overall Hf isotopic compositions (epsilon hafnium values: ɛ-Hf(t)) of Triassic to Paleocene sandstones range from -23 to +15 (fig. 11). Late Paleoproterozoic zircon grains demonstrate evolved ɛ-Hf(t) values from -13 to +1. Early Silurian zircons show a mixed positive and negative pattern of ε-Hf(t) from -2 to +7 (fig. 11). Early Carboniferous zircons show positive ε-Hf(t) values of -1 to +12 with four grains between -17 and -4 (fig. 11). Similar to early Silurian zircons, the Late Triassic zircons show mixed positive and negative ɛ-Hf(t) values from -3 to +7 with one outlier of -15. The only analysed Early Cretaceous zircon shows a ε-Hf(t) value of +7.6 (fig. 11).

DISCUSSION

The presented multi-proxy study of Triassic to Palaeocene sandstones from the Kopet Dagh mountains refine our understanding of the corresponding sediment sources and allows for an improved reconstruction of the tectono-sedimentary evolution of the tectonically inverted Kopet Dagh Basin.

Evidence from sandstone frame work

The sandstone modal framework analysis of the sandstone lens within a Triassic

Evidence from heavy minerals assemblage

The heavy mineral assemblage of the Triassic sandstone with dominant pyroxene minerals (fig.

5 and table 3) indicates a source from mafic magmatic rocks (probably a magmatic arc), which is in concordance with sandstone modal framework results (figs. 4E and 4F). In addition, the internal textures (CL images) and Th/U ratios of detrital zircons from pebbles of the Triassic conglomerate suggest a magmatic origin for these zircons (Zanchetta and others, 2013). An increase in ultra-stable minerals (ZTR) along with a decreasing percentage of pyroxene minerals in the heavy mineral fraction of Jurassic sandstones (fig. 5 andtable 3) imply firstcycle sandstones that were transported over a long distance, or second-cycle sandstone formed by erosion and deposition of pyroclastic-volcanoclastic rocks in a deep-marine basin (Poursoltani and others, 2007). A significant increase of clastic sedimentary lithics compared to the Triassic sandstone and first appearance of garnets in Jurassic sandstones (fig. 5 andtable 3) point toward metamorphic rocks as a minor additional source of detritus. [START_REF] Poursoltani | Composition, porosity, and reservoir potential of the Middle Jurassic Kashafrud Formation, northeast Iran[END_REF] reported ultra-stable heavy minerals (ZTR), along with apatite and garnet as the main heavy mineral spectrum in the Jurassic sandstones, coinciding with our findings. Early

Cretaceous sandstones indicate a high percentage of ultra-stable minerals (ZTR) and a reduced quantity of pyroxene minerals in the heavy mineral assemblages with a much significant intensity. Vice versa, the amount of pyroxene (20%) in Jurassic sandstones decreases to 1.5% in Cretaceous sandstones (fig. 5 andtable 3). This indicates that the heavy mineral content was partly controlled by cannibalism and recycling of older sandstones. An increase of monocrystalline quartz content along with a decrease of less stable volcanic lithics in Early Cretaceous sandstones compared to older lithologies provides further evidence for recycling of Jurassic sandstones (table 3). In addition, based on geochemical analysis of Early Cretaceous sandstones, Mortazavi and others, (2013) suggested moderate to high weathering of the sediments during transportation before deposition, which is in agreement with recycling of older sediments. However, the effect of diagenetic processes on the decrease of metastable heavy minerals (mostly pyroxene group) and volcanic lithics, and partial alteration of feldspars to clay minerals should not be ignored (Mortazavi and others, 2014;[START_REF] Moussavi-Harami | Diagenesis of non-marine petroleum reservoirs: The Neocomian (Lower Cretaceous) Shurijeh Formation, Kopet-Dagh Basin, NE Iran[END_REF].

Paleocene sandstones indicate a heavy mineral spectrum similar to the one of Early Cretaceous sandstones. However, the amount of garnet increases from 3.5% in Early Cretaceous sandstones to 15.5% in Paleocene sandstones. This implies that erosion of garnet-bearing metamorphic rocks, along with recycling of the older sandstones, were the main sources of detritus in the Palaeocene. The most probable source of garnet and metamorphic lithic grains are Carbo-Permian metamorphic rocks to the southeast of the Kopet Dagh Basin (figs. 2 and 3).

Evidence from Detrital Zircon U-Pb Ages and Hf Isotopes

The S6). Possibly, these are inherited magmatic zircons or fragments of older reworked zircons from crystalline rocks of a craton. Because of the probability of repetitive reworking of detrital zircons through several tectonic cycles since the Archean, the possible metamorphic/igneous source area remains undefined. However, similar age spectra (with a major peak at 2.5 Ga and a minor peak at 1.8 Ga) were reported in Neoproterozoic to Cambrian, lower Permian and Middle Jurassic, and Devonian sandstones of the Alborz mountains (Horton and others, 2008;Moghadam and others, 2017). Also, Mesoarchean to Paleoproterozoic zircons were reported in Cretaceous to Eocene sandstones of Azerbaijan Basin (Mohammadi and others, 2020a), Eocene to Oligocene sandstones from the Sistan Basin (Mohammadi and others, 2016a), and Cretaceous to Miocene sandstones of the Makran Basin in Iran (Mohammadi and others, 2016b;2017). In addition, similar age spectra were reported in Paleozoic to Triassic sandstones of the Taurides mountains in Turkey (Abbo and others, 2015). There are no reported occurrences of Archean to Paleoproterozoic zircons in the Iranian or Anatolian continental crust (for example [START_REF] Ramezani | The Saghand region, central Iran: U-Pb geochronology, petrogenesis and implications for Gondwana tectonics[END_REF]Moghadam, and others, 2017;[START_REF] Moghadam | Repeated magmatic buildup and deep "hot zones" in continental evolution: The Cadomian crust of Iran[END_REF]. However, Archean to Paleoproterozoic zircons with main peaks at 2.5 Ga and 1.8 Ga were identified from metamorphic basement of the Afghan block (Faryad and others, 2016), the Tibetan terranes including Songpan Ganzi (Weislogel and others, 2006) and Nan Shan-Qilian Shan-Altun Shan (Gehrels and others, 2011), and the Tarim craton (Gehrels and others, 2011). The lack of a 1.8

Ga and presence of a 1.9 Ga zircon age peak in the Archean to Paleoproterozoic age spectrum of Iberia and African Neoproterozoic to Cambrian sandstones (Abdelsalam and others, 2002) excludes the Saharan meta-craton as a potential source area. In fact, the source of Archean to Paleoproterozoic zircons in the Kopet Dagh strata remains enigmatic. Restricting conjecture to the closest cratons points to the nearby Afghan Block with Archean to Paleoproterozoic metamorphic and igneous rocks (Faryad and others, 2016) as an original source area, which supplied detritus to the Kopet Dagh Basin through repetitive recycling of sedimentary successions (fig. 10).

Neoproterozoic Zircons

The second age population includes Neoproterozoic detrital zircons (1000-542 Ma) with a main peak at 643 Ma (fig. 9). This population represents ~18% of the total dated zircons.

Neoproterozoic zircons are mostly rounded or anhedral grains with sporadic magmatic or metamorphic growth zoning or lack zoning (fig. 6). Similar to Archean to Paleoproterozoic zircons, Neoproterozoic zircons show Th/U ratios with a wide range between 0.01 and 2.92 S6). Neoproterozoic (Pan-African) detrital zircons were reported from several Gondwana-related tectonostratigraphic domains such as Iran (for example Hassanzadeh and others, 2008;Hosseini and others, 2015;Nutman and others, 2014;[START_REF] Ramezani | The Saghand region, central Iran: U-Pb geochronology, petrogenesis and implications for Gondwana tectonics[END_REF], the Taurides (Abbo and others, 2015), Libya (Meinhold and others, 2013), the Arabian-Nubian Shield (Morag and others, 2012), and north Africa (Abati and others, 2010;Avigad and others, 2012).

(
Neoproterozoic detrital zircons with a main peak at 559-537 Ma (Cadomian age) were furthermore reported from Alborz and Zagros Neoproterozoic to Paleozoic strata (Horton and others, 2008;Moghadam and others, 2017). In addition, the Neoproterozoic detrital zircons without internal zoning with a main peak at 640-610 Ma were reported from Central Iranian

Ordovician to Silurian Zircons

The third age group denotes Ordovician to Silurian zircons (465-422 Ma) with a peak at 437

Ma with subhedral to euhedral shapes, dominantly magmatic zoning, and Th/U ratios above 0.5 (fig. 6 and table S4), demonstrating an abundant magmatic source. This population contains ~9.3% of the total dated zircons (table S4). ε-Hf(t) values (-1.9 to +6.7, only one grain with -8.9; fig. 11 and table S6) suggest rift-related magmatic rocks as detritus source (for example [START_REF] Vervoort | Evolution of the depleted mantle: Hf isotope evidence from juvenile rocks through time[END_REF]. Presented zircon ages correspond to major rifting episodes that occurred from late Ordovician to Silurian along the northern Gondwana margins [START_REF] Moghadam | Repeated magmatic buildup and deep "hot zones" in continental evolution: The Cadomian crust of Iran[END_REF][START_REF] Ruban | Late paleozoic transgressions in the Greater Caucasus (Hun Superterrane, Northern Palaeotethys): Global Eustatic Control[END_REF]Stampfli, 2000), which correspond to the separation of the Hun terranes from Gondwana along with the opening of Paleo-Tethys Ocean [START_REF] Moghadam | Repeated magmatic buildup and deep "hot zones" in continental evolution: The Cadomian crust of Iran[END_REF]. Late Ordovician to middle Silurian rift-related magmatism was furthermore reported from northern Central Iran (for example Nowrouzi and others, 2014), eastern Alborz [START_REF] Derakhshi | Soltan Maidan Complex (SMC) in the eastern Alborz structural zone, northern Iran: magmatic evidence for Paleotethys development[END_REF][START_REF] Moghadam | Repeated magmatic buildup and deep "hot zones" in continental evolution: The Cadomian crust of Iran[END_REF], and Anatolia (for example Topuz and others, 2020;Topuz and others, 2021). In the eastern Alborz, basaltic and basaltic-andesitic magmatism during the Silurian were reported (local name: Soltan Maidan Complex; [START_REF] Derakhshi | Soltan Maidan Complex (SMC) in the eastern Alborz structural zone, northern Iran: magmatic evidence for Paleotethys development[END_REF]Ghavidel-Syooki and others, 2011). Geochemistry of this volcanic units shows alkaline affinity with an intra-plate and continental-rift setting [START_REF] Derakhshi | Soltan Maidan Complex (SMC) in the eastern Alborz structural zone, northern Iran: magmatic evidence for Paleotethys development[END_REF]. The zircon U-Pb ages of rounded granitic pebbles from conglomerate layers at the base and in middle of the afore-mentioned volcanic unit indicate an early Silurian genesis (434 ± 6.4 Ma; Ghavidel-Syooki and others, 2011). Furthermore, zircon U-Pb ages of A-type granitic pebbles from Devonian sandstones (Padeha Formation) in the eastern Alborz indicate early Silurian ages (441 ± 3.1 Ma) with εHf(t) values ranging from +8.2 to +2.5 (Moghadam and others, 2017). The zircon U-Pb age of granitic pebbles from both Silurian and Devonian successions fit well with the main peak (437 Ma) of the late Ordovician to Silurian detrital zircon population of the Kopet Dagh sandstones (fig. 9). Furthermore, Ordovician to Silurian detrital zircons with a main peak at 435 Ma and εHf(t) values of -3.6 to +6.3 from late Ordovician (Qelli Formation) sandstones from eastern Alborz were reported by Moghadam and others (2017). Taking into consideration all above-mentioned criteria as well as a short transport distance between eastern Alborz and Kopet Dagh, Ordovician to Silurian detritus of the Kopet Dagh Basin was most probably supplied through recycling of Ordovician to Devonian sandstones from the eastern Alborz.

Devonian to Carboniferous Zircons

The forth age population (385-305 Ma) with a main peak at 340 Ma (fig. 9) exhibits dominantly euhedral zircon grains (~75%) with magmatic internal texture and high Th/U ratios (> 0.5; fig.

6 and table S4). This age spectrum comprises ~17% of the total analysed detrital zircons (table S4). Devonian to Carboniferous zircons display general ε-Hf(t) values between -1.4 and +15.3 and three grains between -12.1 and -17.7 (fig. 11 and table S6). Dominant positive ε-Hf(t) values suggest magmatic zircons with a depleted mantle signature as observed in mafic-ultramafic oceanic crustal and ophiolitic rocks [START_REF] Patchett | Hafnium isotope results from mid-ocean ridges and Kerguelen: Lithos[END_REF][START_REF] Blichert-Toft | The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system[END_REF].

Carboniferous detrital zircons with a main peak at 344-347 Ma from Cretaceous turbiditic sandstones of Azerbaijan (NW Iran) were reported by Mohammadi and others (2020a).

However, a further potential source area includes the northeast of Iran, where Devonian to Carboniferous magmatic rocks were reported from the Aghdarband (Darrehanjir) ophiolite complex (Moghadam and others, 2015a;Zanchetta and others, 2013). The Aghdarband window in the southeast of the Kopet Dagh Basin contains Permo-Triassic undifferentiated sedimentary, low-grade metamorphic, and igneous rocks. Igneous rocks include diabase, gabbro, ultramafic, and volcanoclastic sediments (figs. 2 and 3;Afshar-Harb 1982a;Behrouzi and others, 1993).

In the southern part of the Aghdarband complex, an upper Permian to Lower Triassic polymictic conglomerate (Qara-Gheitan Formation; Behrouzi and others, 1993) overthrusts the Triassic unit. The composition and age of the Aghdarband basement is generally poorly constrained.

However, the exposed Devonian to Carboniferous meta-sediments in the north of the Aghdarband complex (Behrouzi and others, 1993;Zanchetta and others, 2013) indirectly indicates the basement age of this complex. Besides this, zircon U-Pb ages of plagio-granitic dikes and ferro-diorites (382-380 Ma) from the Darrehanjir ophiolites also indicate a Late Devonian age for this basement complex (Moghadam and others, 2015a). Furthermore, the zircon U-Pb ages of granitoid cobbles in the Qara-Gheitan conglomerate indicate a late Carboniferous (314 Ma) age (Zanchetta and others, 2013). The wide range of Devonian to Carboniferous rocks in the Aghdarband complex is in concordance with detrital zircon ages in the Kopet Dagh sandstones (fig. 9). Supportively, positive zircon εHf(t) values (+13.8 and +14.9) of dated plagio-granites and ferro-diorites suggest a depleted mantel signature (Moghadam and others, 2015a). Devonian and Carboniferous granites and granitioids were reported from the Karakum-Mangyshlak and Karabogaz micro-blocks in Central Asia (for example [START_REF] Natalin | Late Palaeozoic to Triassic evolution of the Turan and Scythian platforms: the pre-history of the Palaeo-Tethyan closure[END_REF]. Widespread late Paleozoic to early Mesozoic volcanism in the Turan Block reported by [START_REF] Natalin | Late Palaeozoic to Triassic evolution of the Turan and Scythian platforms: the pre-history of the Palaeo-Tethyan closure[END_REF] could represent another possible source for early Carboniferous detrital zircons from the Kopet Dagh. However, the calc-alkaline affinity of these rocks indicates a magmatic arc setting, which is not in agreement with the Hf isotopic composition of detrital zircons. In addition, the reported general SE-NW paleocurrent direction in the Kopet Dagh sandstones (Poursoltani and others, 2007) strengthen the case that the Devonian to Carboniferous detritus was supplied from the Aghdarband Complex rather than from the Turan Block.

Permian to Triassic Zircons

The fifth zircon age spectrum in the Kopet Dagh sandstones (300-200 Ma) with a peak at 233 Ma (fig. 9) covers ~25.4% of the total dated zircons (table S4). Zircon grains of this population exhibit euhedral shapes (>80%) with magmatic zoning (fig. 6). Furthermore, over 90% of zircons in this spectrum indicate a high Th/U ratio (>0.55; table S4), which denotes magmatic origin. ε-Hf(t) values of Permo-Triassic zircons range between -5.9 and +10.3 (>80%) with two grains with values of -15 and -15. 2 (fig. 11 and table S6). Similar to Devonian to Carboniferous zircons, dominant positive ε-Hf(t) values of the Permo-Triassic zircons propose a depleted mantle signature related to mafic-ultramafic rocks from oceanic crust and ophiolite complexes [START_REF] Patchett | Hafnium isotope results from mid-ocean ridges and Kerguelen: Lithos[END_REF][START_REF] Blichert-Toft | The Lu-Hf isotope geochemistry of chondrites and the evolution of the mantle-crust system[END_REF]. Both Permian and Triassic ages were reported from the Fariman and Mashhad complexes in the south of the Kopet Dagh Basin (for example Chiu and others, 2017;Ghazi and others, 2001;Karimpour and others, 2010;[START_REF] Kozur | Pelagic Permian conodonts from an oceanic sequence at Sang-e-Sefid (Fariman, NE-Iran)[END_REF]Mirnejad and others, 2013;Moghadam and others, 2015a;Topuz and others, 2018;Zanchetta and others, 2013).

The Fariman complex consists of two units: i) The lower metamorphosed unit composed of green schists, metabasites, mafic-ultramafic rocks, and serpentinites, and ii) the upper volcanicsedimentary unit. Conodonts and radiolarian fossils reveal a late early Permian to middle Permian age for the Fariman complex (Zanchetta and others, 2013). In addition, 40 Ar-39 Ar dating of magmatic hornblende from olivine cumulates yielded early Permian (276 ±4 Ma) ages for the Fariman complex (Topuz and others, 2018). Furthermore, andesitic dykes dated at 211

Ma indicate Late Triassic magmatic activity in the Fariman complex (Zanchetta and others, 2013). The Fariman complex has been interpreted as a continental magmatic arc with an intraarc basin (Zanchetta and others, 2013), a subduction-and plume-related Paleo-Tethyan ophiolite (Moghadam and others, 2015a), as well as a fragment of an oceanic plateau (Topuz and others, 2018).

The Mashhad Complex in the south of the Kopet Dagh Basin represents a remnant of the Paleo-Tethys oceanic crust and includes three members: i) The lower member with ultramafics, gabbro-diorites, pillow lavas, marbles, and meta-sediments (Moghadam and others, 2015a). An early Permian age was suggest for the Mashhad ophiolite based on the study of pelagic conodonts [START_REF] Kozur | Pelagic Permian conodonts from an oceanic sequence at Sang-e-Sefid (Fariman, NE-Iran)[END_REF] and 40 Ar-39 Ar ages of hornblende from gabbros (287.6 Ma and 281.7; Ghazi and others, 2001). ii) The middle member consists of Permo-Triassic deep-water clastic turbidites and metamorphosed sedimentary rocks (accretionary prism). iii) The upper member exhibits arc-related acidic to intermediate pyroclastic rocks (Moghadam and others, 2015a). Post-collisional intrusive bodies crosscut the Mashhad complex that contain several granitoid and monzogranite suites with zircon U-Pb ages between 200 to 217 Ma (Karimpour and others, 2010;Mirnejad and others, 2013). In addition, the Mashhad granodiorite and Mashhad diorite were dated and others, 2009;Zanchi and others, 2016 ).

Early Cretaceous Zircons

The -Harb 1982a-Harb , 1982b;;Afshar-Harb and others, 1986;Behrouzi and others, 1993;Mortazavi and others, 2014;[START_REF] Moussavi-Harami | Diagenesis of non-marine petroleum reservoirs: The Neocomian (Lower Cretaceous) Shurijeh Formation, Kopet-Dagh Basin, NE Iran[END_REF]. The potential source area of Early Cretaceous zircons could be the Cheste Stratigraphic ages correspond to the 1:250,000 geological maps of Sarakhs (Afshar-Harb, 1982a), Darreh Gaz (Afshar-Harb, 1982b), Mashhad (Afshar-Harb and others, 1986), and

Torbat-e-Jam (Behrouzi and others, 1993). Torbat-e-Jam (Behrouzi and others, 1993). Black stars: sampled sedimentary sequences. , 1985); (E) QFL [START_REF] Dickinson | Interpreting provenance relations from detrital modes of sandstones[END_REF]; and (F) QmFLt [START_REF] Dickinson | Interpreting provenance relations from detrital modes of sandstones[END_REF]. Literature data of Middle Jurassic and Lower Cretaceous sandstones from [START_REF] Poursoltani | Composition, porosity, and reservoir potential of the Middle Jurassic Kashafrud Formation, northeast Iran[END_REF] and Mortazavi and others, (2013).

  4C and 4D) and pyroxene minerals (fig. 5) point toward a transitional arc as the source terrane of the Triassic sandstone, whereas Jurassic samples point to a dissected arc and mixed nature of the source terranes (figs. 4E and 4F). Cretaceous and Paleocene sandstones show a recycled orogenic source based on their rock fragment distributions, indicating mineralogical maturity (figs. 4E and 4F).

  Laser ablation ICP-MS U-Pb dating on 2478 detrital zircon grains was conducted on one Lower Triassic low-grade meta-sandstone (Qara-Gheitan Formation), five Jurassic turbiditic sandstones (Kashafrud Formation), three Lower Cretaceous fluvial-deltaic sandstones (Shurijeh Formation), and one Paleocene continental sandstone(Pestehleigh Formation; figs. 2, 3, 6, 7 ,8, 9, and tables S1 and S4). Late Triassic (217 Ma) and early Paleoproterozoic (2374 Ma) zircons are the youngest and oldest zircons of 232 analysed detrital zircons from the Lower Triassic sandstone (fig. 7; sample KD-08). This sandstone reveals a single probability peak at 337 Ma (early Carboniferous). Five Jurassic sandstones show zircon age distributions between 154 Ma (Late Jurassic) and 2966 Ma (Meso-Archean) based on a total of 1191 dated grains (Fig. 7; samples KD-01, KD-03, KD-06, KD-10, KD-15). Detrital zircons of the Jurassic sandstones are peaking at 232 Ma (Early Triassic), 343 Ma (early Carboniferous), 434 Ma (early Silurian), 643 Ma (middle Neoproterozoic), and 1833 Ma (late Paleoproterozoic; Fig. 7). A total of 865 zircons from three Lower Cretaceous sandstones revealed ages between Early Cretaceous (116 Ma) to Mesoarchean (2861 Ma) (fig. 8; samples KD-02, KD-09, KD-18). The Lower Cretaceous sandstones show a similar zircon age distribution as the Jurassic sandstones, but with an additional zircon probability peak at 132 Ma (Early Cretaceous; fig. 8). The Paleocene sandstone shows ages ranging between 119 Ma (Early Cretaceous) and 2781 Ma (Neoarchean) from 190 dated zircon grains (fig. 8; sample KD-14). The probability peaks of Paleocene sandstone zircon ages are similar to the ones of Cretaceous sandstones (fig. 8). The combined zircon ages call attention to late Paleoproterozoic, middle Neoproterozoic, early Silurian, early Carboniferous, Late Triassic, and Early Cretaceous protoliths in the potential source areas (figs. 9 and 10).

  (figs. 4E and 4F). However, petrographic analyses on the Qara-Gheitan sandstones by[START_REF] Ghaemi | Tectonic setting of sedimentary facies in the Kopet-Dagh Basement: Sedimentary Facies[END_REF] specify provenance from a dissected magmatic arc. Additionally, geochemical analysis of large granodiorites and tonalities pebbles of the Qara-Gheitan conglomerate byZanchetta and others, (2013) suggests an active margin setting with prevailing of I-type plutonic and high-K volcanic rocks. The discrepancy between our results and previously published data can be explained by sampling of different sandstone lenses within the inhomogeneous alluvial Qara-Gheitan Formation.The mineralogical composition of Middle Jurassic sandstones of the Kashafrud Formation composed of sedimentary and volcanic lithic fragments with subordinate metamorphic lithics (figs. 4C and 4D) suggest a provenance from a dissected magmatic arc and mixed-recycled orogeny (figs.4E and 4F). Modal framework and paleocurrent analysis along with stratigraphic studies of Middle Jurassic sandstones byPoursoltani and others, (2007) and[START_REF] Poursoltani | Composition, porosity, and reservoir potential of the Middle Jurassic Kashafrud Formation, northeast Iran[END_REF] are in agreement with our results. In addition, they suggested that the detritus was supplied from an active margin in the southeast to the extensional Kopet Dagh Basin in the northwest through channel systems to slope and basin-floor fans forming fluvial (basal conglomerate), deltaic (sandstone), and proximal to distal turbiditic (sandstone and mudstone) facies. Lower Cretaceous sandstones (Shurijeh Formation) show higher mineralogical and textural maturity compared to Middle Jurassic sandstones (figs. 4A, 4B, 4C and 4D) and indicate a recycled orogenic provenance (figs. 4E and 4F). In addition, modal framework analysis by Mortazavi and others (2013) on Lower Cretaceous sandstones supports a provenance characterized by recycled orogenic belts and craton interior signature. Paleocurrent directions of Lower Cretaceous sandstones suggest that sediments were supplied from the south and southwest into the Kopet Dagh Basin (Moussavi-Harami and Brenner, 1990). Therefore, Jurassic sandstones represent a potential source for second-cycle Lower Cretaceous sandstones. Paleocene continental sandstones (Pestehleigh Formation) show relativly higher mineralogical maturity compared to Triassic-Jurassic sandstones (figs. 4A, 4B, 4C and 4D), indicating a recycled orogenic provenance (figs. 4E and 4F). This interpretation agrees with findings of Moussavi-Harami (1993), who suggested that northward and northwestward thinning of coarse-grained Paleocene sandstone layers indicates that the detritus was supplied from the recycling of older sediments in the south and southeast.

  Neoproterozoic to Cambrian sandstones(Honarmand and others, 2016).Nutman and others (2014) reported 637 Ma U-Pb ages of magmatic zircons from the Central Iran crystalline basement (Chadegan orthogneiss). Therefore, repetitive recycling of the Cryogenian to Ediacaran crystalline basement of Central Iran is a plausible source of the Neoproterozoic detrital zircons of Kopet Dagh strata (fig.10).

  to 203 Ma and 219 Ma, respectively, with ε-Hf(t) values between -3 to +3(Chiu and others, 2017). The complex is unconformably is covered by Jurassic terrigenous sediments of the Kashafrud Formation. The southeastward continuation of the Mashhad Complex, which is known as the Torbat-e-Jam Complex, was also intruded by post-collisional I-type granitites (217 Ma;Zanchetta and others, 2013) and gabbro-quartz diorite (215 Ma; Ghavi and others, 2018) of similar ages.According toZanchetta and others (2013), the age range of post-collisional intrusions indicates that the obduction of the Mashhad ophiolites occurred before the Late Triassic (Norian-Rhaetian). The age spectrum and dominant positive ε-Hf(t) values of Permian to Triassic zircons, together with the presence of chromium spinel in the heavy mineral assemblage, indicates an exposure of mafic-ultramafic rocks in the source area. This interpretation is in agreement with unroofing and consequent deposition of the Mashhad and Fariman Complexes, and a remnant of Triassic continental arc in the Kopet Dagh Basin. Northward directed paleocurrents and the presence of Norian granodiorite pebbles (211 Ma) in the conglomerate underlying Jurassic sandstones indicate erosion and unroofing of post-collisional intrusive bodies and ophiolitic host rocks in Middle Jurassic time (for example Zanchetta and others, 2013; Zanchi

  Fig. 1. Simplified tectonic setting of Iran including Urumieh Dokhtar Magmatic Arc (white)

Fig. 2 .

 2 Fig. 2. Simplified geologic map of the East Kopet Dagh Basin and samples location.

Fig. 3 .

 3 Fig. 3. Composite stratigraphic section of the East Kopet Dagh Basin with local formation

Fig. 4 .

 4 Fig. 4. Detrital composition of Kopet Dagh sandstones in ternary classification schemes and

Fig. 5 .

 5 Fig. 5. Heavy mineral assemblages of the Kopet Dagh sandstones arranged by stratigraphic ages

Fig. 6 .

 6 Fig. 6. Representative cathodoluminescence images of dated detrital zircons of the Kopet Dagh

Fig. 7 .

 7 Fig. 7. Detrital zircon 206 Pb/ 238 U age probability density diagrams with corresponding

Fig. 8 .

 8 Fig. 8. Detrital zircon 206 Pb/ 238 U age population probability density diagrams with

Fig. 9 .

 9 Fig. 9. Combined zircon U-Pb age distribution pattern of Kopet Dagh sandstone samples.

Fig. 10 .

 10 Fig. 10. Detrital zircon U-Pb mean age populations versus stratigraphic age of the Kopet Dagh

Fig. 11 .

 11 Fig. 11. Time-corrected ɛ-Hf(t) values versus 206 U/ 238 Pb ages of Kopet Dagh detrital zircons.

Fig. 12 .

 12 Fig. 12. Tectonic reconstruction along N-S profiles of the Kopet Dagh Basin through time.

  table S4), which indicate both magmatic and metamorphic sources. Due to different grain shapes and internal growth structures, Neoproterozoic zircons are probably remnants of older recycled grains or inherited cores from continental crystalline rocks. The ε-Hf(t) values of Neoproterozoic zircons range between -19.3 and +11.3 (fig. 11 and table

  sixth and youngest age population (146-119 Ma) with a main peak at 132 Ma (fig.9) contains only 1.5% of the total dated zircon grains (tableS4). Zircons grains of this population

	are euhedral in shape, exhibit magmatic zoning, and show Th/U ratios >0.3 (fig. 6 and table
	S4). ε-Hf(t) values (+7.6) of this population indicate non-depleted mantle signatures (fig. 11 and
	table S6). Occurrence of Early Cretaceous zircons in Lower Cretaceous sandstones (samples
	KD-09 and KD-18) and the Paleocene sandstone (sample KD-14; figs. 8 and 10) indicate syn-
	sedimentary magmatic activity in the source area. Furthermore, the presence of detrital zircons
	with early Aptian ages (~124 Ma; average of 8 youngest ages) in Lower Cretaceous sandstones
	of the Shurijeh Formation indicate maximum depositional ages younger than the previously
	reported Neocomian stratigraphic age (for example Afshar

ACKNOWLEDGMENTS

The work supported by the Swiss National Science Foundation (grant no. 200021-153124/1).

We thank the National Iranian Oil Company for logistic support during field trips.

Kopet Dagh Basin and deposited in a submarine fan-delta complex. Early Cretaceous detritus was supplied from similar protoliths and furthermore from recycled Jurassic turbiditic sandstones. These sediments were deposited in a fluvial-deltaic complex. The Paleocene continental sediments were mainly supplied from recycling of exposed Jurassic to Early Cretaceous sediments.

Supplementary Table Captions

Table S1: Geographical location (degree, minute, second), lithology, local formation name, sedimentary environment, age and characteristics of the analyzed samples of eastern Kopet Dagh sandstones.

Analysis key: MFA: modal framework analysis, HM: heavy minerals, DZA: detrital zircon age and Hafnium isotopes.

Table S2: Sandstone framework data and calculated percentages for eastern Kopet Dagh sandstones.

Table S3: Heavy mineral data, calculated percentages and heavy mineral indexes of eastern Kopet Dagh sandstones.

Table S4: Zircon U-Pb isotopic data and calculated ages for eastern Kopet Dagh sandstones. C= Coarse grain (>200µ) and M= Medium grain (100-200µ).

Table S5: Zircon U-Pb dating details including sample preparation, analytical conditions, laser ablation system, ICP-MS instrument, data from unknowns and reference materials, and data processing.

Table S6: Lu-Hf isotopic data and calculated ratios for eastern Kopet Dagh sandstones.

Table S7: Zircon Lu-Hf isotopic analyses details including sample preparation, analytical conditions, laser ablation system, ICP-MS instrument, data from unknowns and reference materials, and data processing.