Western Anatolia is a complex assemblage of terranes, including the Sakarya Terrane and the Tauride-Anatolide Platform that collided during the late Cretaceous and Palaeogene (80-25 Ma) after the closure of the Izmir-Ankara Ocean. Determining the precise timing at which this ocean closed is particularly important to test kinematic reconstructions and geodynamic models of the Mediterranean region, and the chronology of suturing and its mechanisms remain controversial. Here, we document the Cretaceous-Eocene sedimentary history of the Central Sakarya Basin, along the northern margin of the Neotethys Ocean, via various approaches including biostratigraphy, geochronology, and sedimentology. Two high-resolution sections from the Central Sakarya Basin show that pelagic carbonate sedimentation shifted to rapid siliciclastic deposition in the early Campanian (~79.6 Ma), interpreted to be a result of the build-up of the accretionary prism at the southern margin of the Sakarya Terrane. Rapid onset of deltaic progradation and an increase in accumulation rates in the late Danian (~61 Ma), as well as a local angular unconformity are attributed to the onset of collision between the Sakarya Terrane and the Tauride-Anatolide Platform. Thus, our results indicate that though deformation of the subduction margin in Western Anatolia started as early as the Campanian, the closure of the İzmir-Ankara Ocean was only achieved by the early Palaeocene.

The Lopu Range, located ~600 km west of Lhasa, exposes a continental high‐pressure metamorphic complex beneath India‐Asia (Yarlung) suture zone assemblages. Geologic mapping, 14 detrital U‐Pb zircon (n = 1895 ages), 11 igneous U‐Pb zircon, and nine zircon (U‐Th)/He samples reveal the structure, age, provenance, and time‐temperature histories of Lopu Range rocks. A hornblende‐plagioclase‐epidote paragneiss block in ophiolitic mélange, deposited during Middle Jurassic time, records Late Jurassic or Early Cretaceous subduction initiation followed by Early Cretaceous fore‐arc extension. A depositional contact between fore‐arc strata (maximum depositional age 97 ± 1 Ma) and ophiolitic mélange indicates that the ophiolites were in a suprasubduction zone position prior to Late Cretaceous time. Five Gangdese arc granitoids that intrude subduction‐accretion mélange yield U‐Pb ages between 49 and 37 Ma, recording Eocene southward trench migration after collision initiation. The south dipping Great Counter Thrust system cuts older suture zone structures, placing fore‐arc strata on the Kailas Formation, and sedimentary‐matrix mélange on fore‐arc strata during early Miocene time. The north‐south, range‐bounding Lopukangri and Rujiao faults comprise a horst that cuts the Great Counter Thrust system, recording the early Miocene (~16 Ma) transition from north‐south contraction to orogen‐parallel (E‐W) extension. Five early Miocene (17–15 Ma) U‐Pb ages from leucogranite dikes and plutons record crustal melting during extension onset. Seven zircon (U‐Th)/He ages from the horst block record 12–6 Ma tectonic exhumation. Jurassic—Eocene Yarlung suture zone tectonics, characterized by alternating episodes of contraction and extension, can be explained by cycles of slab rollback, breakoff, and shallow underthrusting—suggesting that subduction dynamics controlled deformation.

Debate persists concerning the timing and geodynamics of intercontinental collision, style of syncollisional deformation, and development of topography and fold-and-thrust belts along the >1,700-km-long İzmir-Ankara-Erzincan suture zone (İAESZ) in Turkey. Resolving this debate is a necessary precursor to evaluating the integrity of convergent margin models and kinematic, topographic, and biogeographic reconstructions of the Mediterranean domain. Geodynamic models argue either for a synchronous or diachronous collision during either the Late Cretaceous and/or Eocene, followed by Eocene slab breakoff and postcollisional magmatism. We investigate the collision chronology in western Anatolia as recorded in the sedimentary archives of the 90-km-long Sarıcakaya Basin perched at shallow structural levels along the İAESZ. Based on new zircon U-Pb geochronology and depositional environment and sedimentary provenance results, we demonstrate that the Sarıcakaya Basin is an Eocene sedimentary basin with sediment sourced from both the İAESZ and Söğüt Thrust fault to the south and north, respectively, and formed primarily by flexural loading from north-south shortening along the syncollisional Söğüt Thrust. Our results refine the timing of collision between the Anatolides and Pontide terranes in western Anatolia to Maastrichtian-Middle Paleocene and Early Eocene crustal shortening and basin formation. Furthermore, we demonstrate contemporaneous collision, deformation, and magmatism across the İAESZ, supporting synchronous collision models. We show that regional postcollisional magmatism can be explained by renewed underthrusting instead of slab breakoff. This new İAESZ chronology provides additional constraints for kinematic, geodynamic, and biogeographic reconstructions of the Mediterranean domain.

Located along the İzmir-Ankara-Erzincan Suture (IAES), the Maastrichtian -Paleogene Orhaniye Basin has yielded a highly enigmatic -yet poorly dated-Paleogene mammal fauna, the endemic character of which has suggested high faunal provincialism associated with paleogeographic isolation of the Anatolian landmass during the early Cenozoic. Despite its biogeographic significance, the tectono-stratigraphic history of the Orhaniye Basin has been poorly documented. Here, we combine sedimentary, magnetostratigraphic, and geochronological data to infer the chronology and depositional history of the Orhaniye Basin. We then assess how our new data and interpretations for the Orhaniye Basin impact (1) the timing and mechanisms of seaway closure along the IAES and (2) the biogeographic evolution of Anatolia.Our results show that the Orhaniye Basin initially developed as a forearc basin during the Maastrichtian, before shifting to a retroarc foreland basin setting sometime between the early Paleocene and 44 Ma. This chronology supports a two-step scenario for the assemblage of the central Anatolian landmass, with incipient collision during the Paleocene -Early Eocene and final seaway retreat along the IAES during the earliest Late Eocene after the last marine incursion into the foreland basin. Our dating for the Orhaniye mammal fauna (44-43 Ma) indicates the persistence of faunal endemism in northern Anatolia until at least the late Lutetian despite the advanced stage of IAES closure. The tectonic evolution of dispersal corridors linking northern Anatolia with adjacent parts of Eurasia was not directly associated with IAES closure and consecutive uplifts, but rather with the build-up of continental bridges on the margins of Anatolia, in the Alpine and Tibetan-Himalayan orogens.

Detrital zircons from the Late Cretaceous Murdunu-Göynük forearc basin and the Paleogene Saricakaya foreland basin; part of the greater Central Sakarya Basin located along the Sakarya Zone of the Western Pontides were analyzed to better understand the closure history of the Tethyan oceans. In northwest Turkey, the Variscan Orogeny is characterized by abundant 350-300 Ma zircon U-Pb ages and minimally to highly evolved εHf values. In εHf vs. age space no distinct trends are apparent, consistent with a north dipping subduction zone that emplaced plutons into a southward growing, heterogeneous accretionary margin. From 300-250 Ma εHf values trend from highly to minimally evolved, interpreted as crust thinning, a result of slab rollback and rifting of the Intra-Pontide Ocean. The Cimmerian Orogeny is characterized by a decrease in magmatism from 250-230 Ma associated with minimally to moderately evolved εHf evolution, followed by a 230-200 Ma magmatic gap consistent with crustal thickening followed by flat-slab underthrusting of the Karakaya Complex. Zircons with 200-115 Ma U-Pb ages are all but absent, interpreted as a magmatic lull. The Alpine Orogeny in northwest Turkey is characterized by an increase in magmatism from 115-85 Ma, associated with minimally intermediate to moderately evolved εHf evolution of Late Cretaceous Murdunu-Göynük forearc zircons. At 100 Ma, Late Cretaceous zircons only found within Paleogene Saricakaya foreland basin sediments deviate from similar aged εHf evolution in forearc basin sediments and plot in both the juvenile and intermediate domains. Minor zircon U-Pb age peaks and contrasting interbasinal εHf evolution are interpreted to represent onset of Andean-style subduction along the southern margin of the Sakarya Zone at ~115 Ma followed by 100 Ma initiation of intra-oceanic subduction within the İzmir-Ankara Ocean. Epsilon Hf values from zircons with 85-75 Ma U-Pb ages sampled from forearc basin sediments trend from moderately evolved to moderately Table of Contents Introduction……………………………………………………………………………………...1 Regional Geology……………………………………………………………………………….4

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 Multi-phase intercontinental collision is identified in western Anatolia by sedimentary basin changes  Sedimentary provenance change indicate collision was at 76 Ma, but significant thickskinned deformation was delayed until 54 Ma  The 20 Myr duration of initial collision can be explained by three multi-stage mechanisms involving changes in plate coupling manuscript submitted to Geochemistry, Geophysics, Geosystems

Nitrogen is the dominant constituent of the atmosphere and a key component in the biosphere. High-density CO 2 -N 2 inclusions have been detected in high-grade metamorphic rocks from the upper mantle and lower crust (i.e., granulites and eclogites) 1-3 . In silicates, under conditions of elevated temperatures, low water activity, and high oxygen fugacity, N 2 is favorably released from minerals containing ammonium (e.g., feldspar and mica) 4,5 . Scheelite containing nitrogen is most commonly recognized to be traced from sedimentary rocks 6 . In sedimentary-type deposits, tungsten (W) is liberated as a result of exhalative processes, forming stratiform scheelite 6 , in which mineralizing fluids containing CH 4 and N 2 are generally attributed to in situ organic matter 6 . Several examples of scheelite deposits related to metamorphic hydrothermal fluids are reported to contain small amounts of N 2 7,8 . These types of scheelite deposits are of interest to the geologist, because they are related to Au deposits 9 . Furthermore, Gibert 8 found that the addition of only 5% N 2 would decrease the solubility of scheelite in micaschists from 40 ppm to less than 3 ppm W, indicating that N 2 may drive scheelite participation.Nearly pure N 2 (>88 mol%) was identified in fluid inclusions in W-mineralized quartz veins, which is absent of hydrocarbons. Previous studies have shown that NaCl-H 2 O and CO 2 fluid inclusions are common in ore-forming fluids; however, the presence of N 2 -rich fluids in ore deposits is rarely reported. This study aims to identify the origin of the W-mineralizing fluid and the formation of the N 2 -rich fluid inclusions by combining petrography, Raman microspectroscopy, H, O and N isotope geochemistry, and microthermometry on fluid inclusions. Results from this study will improve our understanding of how N 2 modulate scheelite mineralization. Geology of the Yangjingou scheelite depositThe Yangjingou scheelite is the largest identified scheelite deposit in the Yanbian belt, NE China. It is located between the Cuihongshan and Sanjiazi scheelite deposits in the Heilongjiang-Jilin metallogenic belt, 8 km south of the Xiaoxinancha Au deposit, approximately 25 km east of the Russian border (Fig. 1c). In this deposit, the main economic mineral is scheelite, accompanied by minor Au, Cu, Mo, Fe, and P mineralization. The area is dominated by low-grade metamorphic rocks of the Wudaogou Group, which formed during a regional episode of low-grade epidote to low-grade amphibolite metamorphism. Regional stratigraphic correlations, metamorphic studies, and U-Pb geochronology from metamorphic detrital zircons indicate that sedimentation and regional metamorphism dated 323 ± 23 Ma 10 and 266-249 Ma, respectively 11 . The Wudaogou Group is subdivided into