Megan A Mueller
email: megan.mueller@uconn.edu

Alexis Licht

Clay Campbell

Faruk Ocakoğlu

Gui G Akşit

Grégoire Métais

Pauline M C Coster

K Christopher

Christopher Beard

Michael H Taylor

Pauline M C Coster

K Christopher Beard

Sedimentary provenance from the evolving forearc-to-foreland Central Sakarya Basin, western Anatolia reveals multi-phase intercontinental collision

Keywords: Anatolia, Neotethys, Intercontinental Collision, Detrital Zircon Geochronology

ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Introduction

Continental collisions across the Tethyan realm are striking by their protracted and polygenetic history, often resulting in significant discrepancies among proxies of collision age: ~40 Myr for India-Asia (65-25 Ma; [START_REF] Ding | Paleocene-Eocene record of ophiolite obduction and initial India-Asia collision, south central Tibet[END_REF][START_REF] Hu | The timing of India-Asia collision onset -Facts, theories, controversies[END_REF][START_REF] Kapp | Mesozoic-Cenozoic geological evolution of the Himalayan-Tibetan orogen and working tectonic hypotheses[END_REF][START_REF] Najman | Timing of India-Asia collision: Geological, biostratigraphic, and palaeomagnetic constraints[END_REF] and ~20 Myr for Arabia-Eurasia [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF][START_REF] Cowgill | Relict basin closure and crustal shortening budgets during continental collision: An example from Caucasus sediment provenance[END_REF][START_REF] Darin | Rapid Late Eocene Exhumation of the Sivas Basin (Central Anatolia) Driven by Initial Arabia-Eurasia Collision[END_REF][START_REF] Mcquarrie | Cenozoic evolution of Neotethys and implications for the causes of plate motions[END_REF]Okay et al., 2010). Their unusual duration and complexity have even called into question the nature of the forces driving continental convergence [START_REF] Alvarez | Protracted continental collisions argue for continental plates driven by basal traction[END_REF][START_REF] Becker | Mantle conveyor beneath the Tethyan collisional belt[END_REF]. This has led to multi-stage collision scenarios involving varying plate coupling at the subduction interface [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF][START_REF] Beaumont | Mechanical model for subductioncollision tectonics of Alpine-type compressional orogens[END_REF][START_REF] Tye | Sedimentary response to a collision orogeny recorded in detrital zircon provenance of Greater Caucasus foreland basin sediments[END_REF] or the role of forearc, backarc, and other remnant basins as early buffers of deformation [START_REF] Cowgill | Relict basin closure and crustal shortening budgets during continental collision: An example from Caucasus sediment provenance[END_REF].

Collision age discrepancies are found in western and central Anatolia where continental collision between the Pontides and the Anatolide-affinity Tavşanlı Zone (TVZ) and Kırşehir Block along the İzmir-Ankara-Erzincan suture (İAES) closed the Neotethys Ocean (Figure 1; [START_REF] Okay | Tethyan sutures of northern Turkey[END_REF][START_REF] Şengör | Tethyan evolution of turkey: a plate tectonic approach[END_REF]. Collision estimates along the İAES span 20 Myr from the Late Cretaceous to early Eocene based on ophiolite obduction and Barrovian metamorphism [START_REF] Göncüoğlu | A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution[END_REF][START_REF] Seaton | Recrystallization of high-pressure marble (Sivrihisar, Turkey)[END_REF][START_REF] Whitney | Metamorphic and tectonic evolution of a structurally continuous blueschist-to-Barrovian terrane, Sivrihisar Massif, Turkey[END_REF], structural deformation [START_REF] Lefebvre | Reconstructing the geometry of central Anatolia during the late Cretaceous: Large-scale Cenozoic rotations and deformation between the Pontides and Taurides[END_REF][START_REF] Meijers | Late Cretaceous to Paleocene oroclinal bending in the central Pontides (Turkey)[END_REF][START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF], magmatism [START_REF] Dilek | Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt[END_REF]Ersoy, Akal, et al., 2017;[START_REF] Kasapoğlu | The petrology of Paleogene volcanism in the Central Sakarya, Nallıhan Region: Implications for the initiation and evolution of post-collisional, slab break-off-related magmatic activity[END_REF], and sedimentary basin analysis [START_REF] Kaymakci | Tectono-stratigraphy of the Çankırı Basin: Late Cretaceous to early Miocene evolution of the Neotethyan Suture Zone in Turkey[END_REF][START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF][START_REF] Okay | TAVSANLI ZONE: THE NORTHERN SUBDUCTED MARGIN OF THE ANATOLIDE-TAURIDE BLOCK[END_REF].

However, a model that encompasses the insights from all proxies is still missing.

To address this, we leverage the power of a ~50 Myr continuous depositional record from the Central Sakarya Basin system, a forearc-to-foreland basin directly north of the İAES.

Integrating new sedimentary provenance data with previously published stratigraphic and provenance data reveals a multi-phase collisional evolution. We evaluate the timing of this manuscript submitted to Geochemistry, Geophysics, Geosystems protracted collision in light of previously proposed multi-phase collision models for the Tethyan realm, including slab breakoff, relict basin closure, and passive margin underthrusting.

Background

The tectonic units in northwest Anatolia include, from north to south, the İstanbul Zone and Sakarya Zone (SKZ) of the Eurasian-affinity Pontides, the İzmir-Ankara-Erzincan suture zone (İAES), and the Tavşanlı Zone (TVZ) of the Gondwanan-affinity Anatolides (Figure 1; [START_REF] Okay | Tethyan sutures of northern Turkey[END_REF][START_REF] Şengör | Tethyan evolution of turkey: a plate tectonic approach[END_REF]. The Pontides rifted from the Eurasian margin between 94 and 75 Ma by backarc spreading of the Black Sea [START_REF] Akdoğan | Provenance of a large Lower Cretaceous turbidite submarine fan complex on the active Laurasian margin: Central Pontides, northern Turkey[END_REF][START_REF] Akdoğan | Striking Variation in the Provenance of the Lower and Upper Cretaceous Turbidites in the Central Pontides (Northern Turkey) Related to the Opening of the Black Sea[END_REF][START_REF] Okay | Early Cretaceous sedimentation and orogeny on the active margin of Eurasia: Southern Central Pontides, Turkey[END_REF][START_REF] Okay | Tectonic evolution of the southern margin of Laurasia in the Black Sea region[END_REF], and formed an isolated microcontinent where faunal endemism prevailed until the late Paleogene [START_REF] Métais | Eocene metatherians from Anatolia illuminate the assembly of an island fauna during Deep Time[END_REF]. The SKZ, bound to the north by the Intra-Pontide suture zone, presently occupied by the North Anatolian Fault, comprises Sakarya Zone basement units and the forearc-to-foreland Central Sakarya Basin system (Figure 2). The Sakarya Zone continental basement is subdivided into two units: (1) the Central Sakarya Basement (also called Söğüt metamorphics) comprising Paleozoic paragneiss, schist, and amphibolite rocks intruded by Carboniferous granitoids called the Söğüt magmatics, Central Sakarya granite, or Sarıcakaya granitoid [START_REF] Göncüoğlu | A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution[END_REF][START_REF] Ustaömer | Ion Probe U-Pb Dating of the Central Sakarya Basement: A peri-Gondwana Terrane Intruded by Late Lower Carboniferous Subduction/Collision-related Granitic Rocks[END_REF], and (2) the Permian-Triassic Karakaya Complex, partly metamorphosed clastic and volcanic rocks from either a rift or subduction-accretion complex setting (see [START_REF] Okay | The Karakaya Complex: A Review of Data and Concepts[END_REF]. Remnants of the Late Cretaceous volcanic arc associated with northward subduction along the Pontide margin are exposed along the present-day Black Sea southern coast, north of the CSB and Intra-Pontide Suture (Figure 3; [START_REF] Keskin | Stratigraphy, petrogenesis and geodynamic setting of Late Cretaceous volcanism on the SW margin of the Black Sea, Turkey[END_REF]. However, pyroclastic flows, volcanogenic sandstones, and tuffs within the southern margin of the CSB are associated with Late Cretaceous submarine volcanism (Duru & Aksay, 2002;Gedik & Aksay, 2002;[START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF][START_REF] Yilmaz | Cenomanian -Turonian Oceanic Anoxic Event (OAE2) in the Sakarya Zone, northwestern Turkey: Sedimentological, cyclostratigraphic, and geochemical records[END_REF]. Additionally, the 83-70 Ma Beypazarı Granite is <20 km south of the CSB (Figure 2; [START_REF] Helvacı | U-Pb zircon and K-Ar geochronology reveal the emplacement and cooling history of the Late Cretaceous Beypazarı granitoid, central Anatolia, Turkey[END_REF]Okay et al., 2019[START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF][START_REF] Speciale | Zircon ages from the Beypazarı granitoid pluton (north central Turkey): tectonic implications[END_REF]. The SKZ, İstanbul Zone, and TVZ contain Eocene (58-41 Ma) syn-collisional igneous rocks disputedly attributed to TVZ slab breakoff, lithospheric delamination, or anatexis of the lower crust [START_REF] Altunkaynak | Collision-Driven Slab Breakoff Magmatism in Northwestern Anatolia, Turkey[END_REF][START_REF] Altunkaynak | Eocene Granitic Magmatism in NW Anatolia (Turkey) revisited: New implications from comparative zircon SHRIMP U-Pb and 40Ar-39Ar geochronology and isotope geochemistry on magma genesis and emplacement[END_REF][START_REF] Dilek | Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt[END_REF]Ersoy, Akal, et al., 2017;Ersoy, Palmer, et al., 2017;[START_REF] Graham | Graphical representation of particle shape using triangular diagrams: an Excel spreadsheet method[END_REF][START_REF] Van Hinsbergen | Reconciling the geological history of western Turkey with plate circuits and mantle tomography[END_REF][START_REF] Kasapoğlu | The petrology of Paleogene volcanism in the Central Sakarya, Nallıhan Region: Implications for the initiation and evolution of post-collisional, slab break-off-related magmatic activity[END_REF][START_REF] Okay | Geochronology of Eocene plutonism and metamorphism in northwest[END_REF][START_REF] Ustaömer | Lutetian arc-type magmatism along the southern Eurasian margin: New U-Pb LA-ICPMS and whole-rock geochemical data from Marmara Island, NW Turkey[END_REF][START_REF] Yildiz | Petrogenesis of the post-collisional Eocene volcanic rocks from the Central Sakarya Zone (Northwestern Anatolia, Turkey): Implications for source characteristics, magma evolution, and tectonic setting[END_REF]. The Central Sakarya Basin system is manuscript submitted to Geochemistry, Geophysics, Geosystems divided into the Jurassic-Eocene forearc-to-foreland Central Sakarya Basin (CSB; also called the Mudurnu-Göynük Basin) to the north and the Eocene broken foreland Sarıcakaya Basin (SB) to the south (e.g., [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF][START_REF] Ocakoğlu | Orta Sakarya Bölgesi Geç Kretase-Paleojen Çökellerinin Sekans Stratigrafisi[END_REF][START_REF] Okay | Obduction, subduction and collision as reflected in the Upper Cretaceous-Lower Eocene sedimentary record of western Turkey[END_REF]. The south-vergent basement-involved Tuzaklı-Gümele Thrust (also termed the Söğüt Thrust or Nallıhan Thrust) structurally partitioned the CSB by the early Eocene and formed the SB by flexural loading.

Sakarya Zone basement units are exposed in the hanging wall (Duru & Aksay, 2002;Gedik & Aksay, 2002). The SB contains Ypresian-Lutetian terrestrial deposits that laterally transition to marine deposits in the east [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF][START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF], and hosts one of the Eocene volcanic belts [START_REF] Kasapoğlu | The petrology of Paleogene volcanism in the Central Sakarya, Nallıhan Region: Implications for the initiation and evolution of post-collisional, slab break-off-related magmatic activity[END_REF][START_REF] Yildiz | Petrogenesis of the post-collisional Eocene volcanic rocks from the Central Sakarya Zone (Northwestern Anatolia, Turkey): Implications for source characteristics, magma evolution, and tectonic setting[END_REF]. The fold-thrust belt is located within the CSB-SB system; W-E and SW-NE striking oblique thrust faults and folds deform Jurassic through Eocene units [START_REF] Aksay | Geologic map of Turkey (Zonguldak, Scale[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF]. Thin-skinned thrust faults in the CSB are likely positively inverted faults from a phase of Santonian-Campanian extension [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF].

The SKZ is bound to the south by the İAES, a highly deformed accretionary complex containing obducted ophiolite slabs, ophiolitic mélange, and their metamorphic equivalents (e.g., [START_REF] Göncüoğlu | A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution[END_REF][START_REF] Göncüoğlu | Oceanization of the northern Neotethys: Geochemical evidence from ophiolitic melange basalts within the İzmir-Ankara suture belt, NW Turkey[END_REF]. To the south, the TVZ is the passive margin of the northernmost Gondwana-derived Anatolide-Tauride Block (e.g., [START_REF] Okay | TAVSANLI ZONE: THE NORTHERN SUBDUCTED MARGIN OF THE ANATOLIDE-TAURIDE BLOCK[END_REF][START_REF] Okay | Paleo-and Neo-Tethyan events in northwestern Turkey: Geologic and geochronologic constraints[END_REF]. Platform carbonates and passive margin clastics were subducted and metamorphosed to blueschist facies between 92 and 83 Ma (e.g., [START_REF] Okay | Exhumation of blueschists along a Tethyan suture in northwest Turkey[END_REF][START_REF] Plunder | Accretion, underplating and exhumation along a subduction interface: From subduction initiation to continental subduction (Tavşanlı zone, W. Turkey)[END_REF][START_REF] Sherlock | 40Ar-39Ar and Rb-Sr geochronology of high-pressure metamorphism and exhumation history of the Tavsanli Zone, NW Turkey[END_REF][START_REF] Whitney | Metamorphic and tectonic evolution of a structurally continuous blueschist-to-Barrovian terrane, Sivrihisar Massif, Turkey[END_REF], exhumed sometime 85 to 60 Ma [START_REF] Seaton | Recrystallization of high-pressure marble (Sivrihisar, Turkey)[END_REF][START_REF] Sherlock | 40Ar-39Ar and Rb-Sr geochronology of high-pressure metamorphism and exhumation history of the Tavsanli Zone, NW Turkey[END_REF][START_REF] Whitney | Why is lawsonite eclogite so rare? Metamorphism and preservation of lawsonite eclogite, Sivrihisar, Turkey[END_REF], then underwent Barrovian-type metamorphism from 63 to 57 Ma [START_REF] Seaton | Recrystallization of high-pressure marble (Sivrihisar, Turkey)[END_REF][START_REF] Whitney | Metamorphic and tectonic evolution of a structurally continuous blueschist-to-Barrovian terrane, Sivrihisar Massif, Turkey[END_REF]. The blueschist unit is tectonically overlain by suture zone units, including metamorphosed accretionary complexes [START_REF] Plunder | Tectono-metamorphic evolution of the Tavşanli zone, Western Anatolia: implications for mechanical coupling during subduction/obduction processes[END_REF], ophiolitic mélange, and ophiolite slabs [START_REF] Göncüoğlu | Oceanization of the northern Neotethys: Geochemical evidence from ophiolitic melange basalts within the İzmir-Ankara suture belt, NW Turkey[END_REF][START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF]. The western Anatolian ophiolites have metamorphic sole ages between 101 and 88 Ma [START_REF] Dilek | Structure and petrology of Tauride ophiolites and mafic dike intrusions (Turkey): Implications for the Neotethyan ocean[END_REF][START_REF] Graham | Graphical representation of particle shape using triangular diagrams: an Excel spreadsheet method[END_REF][START_REF] Pourteau | Thermal evolution of an ancient subduction interface revealed by Lu-Hf garnet geochronology, Halilbağı Complex (Anatolia)[END_REF] and are cut by 92 to 90 Ma mafic dikes [START_REF] Dilek | Structure and petrology of Tauride ophiolites and mafic dike intrusions (Turkey): Implications for the Neotethyan ocean[END_REF], and, therefore, were obducted sometime after ~90 Ma during pre-collisional TVZ subduction [START_REF] Okay | Blueschists, Eclogites, Ophiolites and Suture Zones in Northwest Turkey: A Review and a Field Excursion Guide[END_REF][START_REF] Robertson | Melange genesis and ophiolite emplacement related to subduction of the northern margin of the Tauride-Anatolide continent, central and western Turkey[END_REF]. The blueschists and ophiolites are intruded by Eocene granodiorites [START_REF] Graham | Graphical representation of particle shape using triangular diagrams: an Excel spreadsheet method[END_REF] and unconformably overlain by lower Eocene shallow marine limestones and siliciclastic rocks [START_REF] Baş | Tertiary geology of the Domaniç-Tavsanli-Kütahya-Gediz Region[END_REF][START_REF] Özgen-Erdem | Biostratigraphic interpretation and systematics of Alveolina assemblages from the Ilerdian-Cuisian limestones of Southern Eskişehir, Central Turkey[END_REF] and lower-to-middle(?) Eocene continental deposits [START_REF] Turhan | Geologic map of Turkey (Ankara, Scale[END_REF]. Herein we refer to TVZ subduction as the phase manuscript submitted to Geochemistry, Geophysics, Geosystems when TVZ continental lithosphere was subducted beneath overlying oceanic lithosphere, whereas underthrusting refers to the phase when TVZ continental lithosphere was thrust beneath the upper plate Pontide continental lithosphere.

Central Sakarya Basin System Stratigraphy

Jurassic through Eocene sedimentation is preserved in the Central Sakarya Basin system (e.g., [START_REF] Aksay | Geologic map of Turkey (Zonguldak, Scale[END_REF]. Figure 4 displays stratigraphic columns with published stratigraphic ages for the Upper Cretaceous through Eocene units along two transects across the CSB (after [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF].

Unconformably overlying Sakarya Zone basement units are the Jurassic through Lower Cretaceous series of shallow water platform carbonates (Bilecik Fm.), pelagic micrites and calciturbidites (Soğukçam Fm.), and interbedded volcanics (Mudurnu Fm.;[START_REF] Altiner | Jurrasic-Lower Cretaceous stratigraphy and paleogeographic evolution of the southern part of North-Western Anatolia (Turkey)[END_REF][START_REF] Genç | Tectonic setting of the Jurassic bimodal magmatism in the Sakarya Zone (Central and Western Pontides), Northern Turkey: A geochemical and isotopic approach[END_REF]. The CSB formed as a rift basin, as indicated by overall basin deepening trend and bimodal Jurassic volcanism [START_REF] Altiner | Jurrasic-Lower Cretaceous stratigraphy and paleogeographic evolution of the southern part of North-Western Anatolia (Turkey)[END_REF][START_REF] Genç | Tectonic setting of the Jurassic bimodal magmatism in the Sakarya Zone (Central and Western Pontides), Northern Turkey: A geochemical and isotopic approach[END_REF][START_REF] Göncüoğlu | A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution[END_REF], bounded by two branches of the Neotethys Ocean: the Intra-Pontide Ocean to the north and the İzmir-Ankara Ocean to the south. There is uninterrupted Jurassic through Paleocene sedimentation in the eastern CSB (e.g., Nallıhan transect in Figure 4), whereas much of the Albian through Lower Campanian section is missing in the western CSB (e.g., [START_REF] Okay | Obduction, subduction and collision as reflected in the Upper Cretaceous-Lower Eocene sedimentary record of western Turkey[END_REF]. The Albian-Lower Campanian sequence includes the Yenipazar and Seben Fms. siliciclastic turbidites and pelagic mudstones that are interfingered with the Üzümlü Mbr. volcaniclastics and submarine lava flows, Değirmenözü Fm. pelagic carbonates, and Eymür Mbr. shallow marine clastic wedge and submarine canyon fill [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. Asymmetrical ripples, gravel and flute casts in Campanian-Maastrichtian deposits indicate paleocurrent directions to the NNW, N, NE, and rarely W [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. The shallow marine to deltaic Paleocene Taraklı Fm. conformably overlies the Yenipazar Fm. Cross beds and groove casts indicate paleocurrent directions to the NW and NE [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. The shelf edge was likely located near the Nallıhan section, where deltaic progradation began in early Paleocene times, then deltaic sands and muds reached the northern Taraklı section in the late Paleocene where sedimentation rates were briefly extremely rapid [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. manuscript submitted to Geochemistry, Geophysics, Geosystems

In the western Yenipazar section, the Kızılçay Fm. unconformably overlies the Yenipazar Fm., whereas in the eastern Nallıhan section, the Kızılçay Fm. conformably overlies the Taraklı Fm. The shoaling sequence is overlain by coal beds, cross bedded sandstones, and caliches of the Kızılçay Fm. [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. Ostracod fauna indicate a Ypresian age [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. In the proximal Nallıhan and Yenipazar sections, fluvial conglomerates contain clasts of reworked Upper Cretaceous strata and marine microfauna, and clast imbrications, cross beds, and channel geometries indicate paleocurrent directions to the NW and NE. The Kızılçay Fm.

grades northward into the Yenipazar Fm. where prograding delta front sandstones are present in the distal Akdoğan section [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. The coarse marine clastics, alternating sands and muds, and turbidite deposits of the conformable Kabalar Mbr., Güvenç Fm., Çataltepe Fm., and Halidiye Fm. sequence records a Ypresian through early Bartonian marine transgression [START_REF] Ocakoğlu | Evidence of orbital forcing in lake-level fluctuations in the Middle Eocene oil shale-bearing lacustrine successions in the Mudurnu-Göynük Basin, NW Anatolia (Turkey)[END_REF][START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF][START_REF] Şafak | Ostracoda assemblage and the environmental characteristics of the Eocene Succession of the Central Sakarya Region[END_REF]. Groove and flute casts and asymmetrical ripples in the Halidiye Fm. indicate paleocurrent directions to the NW, NE, and rarely W and E [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. The late Lutetian maximum flooding surface is recorded in sedimentary basins across the Black Sea region, including Anatolia, Crimea and the Caucasus (e.g., [START_REF] Licht | Tectonostratigraphy of the Orhaniye Basin, Turkey: Implications for collision chronology and Paleogene biogeography of central Anatolia[END_REF][START_REF] Lygina | Nummulitic facies of the Crimean-Caucasian Region[END_REF][START_REF] Mta | Geological map of Turkey[END_REF][START_REF] Özcan | The Ypresian to Lutetian marine record in NW Turkey: a revised biostratigraphy and chronostratigraphy and implications for Eocene paleogeography[END_REF][START_REF] Racey | A review of Eocene nummulite accumulations: Structure, formation and reservoir potential[END_REF]. The Gemiciköy Fm. comprises mudstone and cross-bedded sandstones that coarsen upward to fluvial conglomerates with clasts of reworked Cretaceous-Paleocene units [START_REF] Ocakoğlu | Orta Sakarya Bölgesi Geç Kretase-Paleojen Çökellerinin Sekans Stratigrafisi[END_REF]; it only crops out north of Yenipazar where it conformably overlies the Güvenç Fm. (Gedik & Aksay, 2002;[START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF].

The Sarıcakaya Basin fill begins with Ypresian alluvial fan deposits that unconformably overlie Permian-Triassic Karakaya Complex rocks in the west and Jurassic-Cretaceous sedimentary units in the east [START_REF] Campbell | Tectonic Evolution of the Izmir-Ankara Suture Zone in Northwest Turkey using Zircon U-Pb Geochronology and Zircon Lu-Hf Isotopic Tracers (M.S.)[END_REF][START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF]. The lower to middle Eocene strata include alternating overbank, conglomeratic fluvial channel, and lacustrine deposits interpreted to reflect changing accommodating due to flexural loading from the Tuzaklı-Gümele Thrust [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF]. Detrital zircon ages and clast compositions indicate that the SB received sediment from the İAES mélange, Karakaya Complex, and exposed Sakarya Zone crystalline basement in Ypresian-Lutetian times [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF]. Therefore, the basement-involved Tuzaklı-Gümele Thrust partitioned the CSB and formed the Sarıcakaya Basin by ca. 54 Ma. The eastern SB contains Ypresian marine shales and Lutetian shoreface and shallow marine deposits with nummulites sp. [START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF]. manuscript submitted to Geochemistry, Geophysics, Geosystems

Methods

We collected 37 sandstone samples from Cretaceous through Eocene strata in the CSB and 2 gneiss samples from the Central Sakarya Basement (Table 1). The sandstone samples were collected along five published measured sections from two proximal (south) to distal (north) transects through the CSB (Figure 4; [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. The provenance of sandstone samples was evaluated using detrital zircon (DZ) U-Pb geochronology and sandstone petrography.

For the new CSB samples, heavy mineral separation, analysis, and data reduction followed the University of Washington TraceLab protocol [START_REF] Licht | Paleogene evolution of the Burmese forearc basin and implications for the history of India-Asia convergence[END_REF][START_REF] Shekut | Late Middle Miocene Emergence of the Olympic Peninsula Shown by Sedimentary Provenance[END_REF]. Zircons were separated following standard heavy mineral separation procedures. A minimum of 140 grains per sample were mounted with reference materials, imaged in a backscattered electron detector with a scanning electron microscope, and analyzed using a quadrupole laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS). The data were reduced in Iolite using the Geochron Data Reduction Scheme [START_REF] Paton | Iolite: Freeware for the visualisation and processing of mass spectrometric data[END_REF].

Individual zircons with abnormal patterns in raw signal intensity, >20% discordance, or >5% reverse discordance are reported in the supporting information but are excluded from interpretations (following [START_REF] Gehrels | Detrital Zircon U-Pb Geochronology: Current Methods and New Opportunities[END_REF][START_REF] Gehrels | Detrital Zircon U-Pb Geochronology Applied to Tectonics[END_REF]. All zircon U-Pb ages are presented uncorrected for common lead [START_REF] Shekut | Late Middle Miocene Emergence of the Olympic Peninsula Shown by Sedimentary Provenance[END_REF], and the data are presented as probability density functions and kernel density estimates with an optimized fixed bandwidth, all plotted using detritalPy [START_REF] Sharman | detritalPy: A Python-based toolset for visualizing and analysing detrital geo-thermochronologic data[END_REF].

The ages of the sedimentary samples were constrained by published biostratigraphic and volcanic zircon U-Pb ages along the measured sections [START_REF] Campbell | Tectonic Evolution of the Izmir-Ankara Suture Zone in Northwest Turkey using Zircon U-Pb Geochronology and Zircon Lu-Hf Isotopic Tracers (M.S.)[END_REF][START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF].

Maximum depositional ages, calculated using the youngest cluster of 2 or more ages with overlapping 2s uncertainties [START_REF] Sharman | detritalPy: A Python-based toolset for visualizing and analysing detrital geo-thermochronologic data[END_REF], are included in Dataset S1 but do not provide any new age constraints.

We characterize the zircon age signature of potential sediment sources using new Central Sakarya Basement bedrock samples and published Central Sakarya Basement, Karakaya Complex, and İAES bedrock and modern river samples (Table 1). We also include crystallization ages of Cretaceous-Eocene plutons in central and eastern Anatolia compiled in [START_REF] Schleiffarth | Dynamics of episodic Late Cretaceous-Cenozoic magmatism across Central to Eastern Anatolia: New insights from an extensive geochronology compilation[END_REF]. The two new basement samples and one CSB sample (15YP15) were manuscript submitted to Geochemistry, Geophysics, Geosystems analyzed at the University of Kansas Isotope Geochemistry Laboratory following the analytical protocol outlined in [START_REF] Campbell | Tectonic Evolution of the Izmir-Ankara Suture Zone in Northwest Turkey using Zircon U-Pb Geochronology and Zircon Lu-Hf Isotopic Tracers (M.S.)[END_REF]. Zircons were separated following standard methods, mounted with international standards, and analyzed in a high resolution sector-field LA-ICP-MS.

Data were reduced in Iolite [START_REF] Paton | Iolite: Freeware for the visualisation and processing of mass spectrometric data[END_REF]ET_Redux (McLean et al., 2016) and are presented uncorrected for common lead.

We further characterize sedimentary provenance using petrographic analysis of sandstone samples (N=31). Thin sections were made by National Petrographic Service, Inc. and at least 400 framework grains per sample were point counted according to the Gazzi-Dickinson method [START_REF] Dickinson | Interpreting provenance relations from detrital modes of sandstones[END_REF]. The new CSB sandstone modal composition data are presented as ternary diagrams (Triplot; [START_REF] Graham | Graphical representation of particle shape using triangular diagrams: an Excel spreadsheet method[END_REF] and interpreted following standard source fields [START_REF] Dickinson | Interpreting provenance relations from detrital modes of sandstones[END_REF][START_REF] Dickinson | Plate Tectonics and Sandstone Compositions[END_REF].

Provenance Results

New DZ data (N=19; n=3188) are presented with published DZ data (N=13, n=1457).

Detrital zircon distributions of potential sediment source samples and basin samples are given in New (n=169) and published (n=1763) bedrock, detrital, and modern river zircon U-Pb ages characterize the zircon signature of basement units and volcanic arcs (Figure 5; Table 1). ages, yet for many SB samples, the pre-Cretaceous populations are more abundant than in the CSB.

The central and eastern

Three Phase Evolution of the Central Sakarya Basin System

We subdivide the samples into three age groups based on major changes in sedimentary provenance and basin evolution (Figure 8). The sample ages, and therefore sample groups, are constrained by published biostratigraphy, primarily planktonic foraminifera, one volcaniclastic U-Pb age, and one maximum depositional detrital zircon U-Pb age [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. The ages of the SB samples are constrained by volcaniclastic U-Pb ages [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF].

Maximum depositional ages of the new detrital zircon samples do not provide new chronologic constraints (Dataset S1).

All CSB and SB DZ ages from 150 to 30 Ma are combined and plotted alongside simplified composite stratigraphic columns (Figure 9). We interpret the combined DZ ages from 150 to 30 Ma as the magmatic arc tempo of the Anatolian arc [START_REF] Paterson | Arc Magmatic Tempos: Gathering the Evidence[END_REF]. The apparent magmatic lulls at 67-58 Ma and starting at 41 Ma are consistent with the 72-58 Ma and 40-20 Ma magmatic lulls in central and eastern Anatolia [START_REF] Schleiffarth | Dynamics of episodic Late Cretaceous-Cenozoic magmatism across Central to Eastern Anatolia: New insights from an extensive geochronology compilation[END_REF]. 6.1. Phase 1: Forearc Basin manuscript submitted to Geochemistry, Geophysics, Geosystems Phase 1 includes Turonian through lower Campanian (94-76 Ma) DZ samples from the eastern CSB. This phase is characterized by a major 76-110 Ma peak; few zircons are older than 110 Ma (n=22/660;Figure 8). Samples plot in the volcanic arc and recycled orogen fields (Figure 7). Given the volcanic arc sediment compositions, the prevalence of Late Cretaceous zircon ages, and the proximity to plutons and submarine volcanism in the southern Sakarya Zone, Phase 1 strata are presumably composed of first-cycle detritus derived from the nearby Late Cretaceous volcanic centers. The brief magmatic lull at 88 Ma (Figure 9) could be the signal of pre-collisional TVZ subduction. This 34 Myr phase is not associated with any significant changes in depositional environment, accumulation rate [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF] or sedimentary provenance. In Phase 1, the CSB was a forearc basin fed by the Late Cretaceous volcanic belt.

Phase 2: Initial Intercontinental Collision

Phase 2 includes the middle Campanian through lower Eocene samples (76-54 Ma).

Phase 2 is defined by a major change in provenance: the appearance of Paleozoic-Precambrian zircons (Figure 8). The start of Phase 2 at 76 Ma is determined by the oldest samples with pre-Mesozoic DZs. In the Nallıhan section, the oldest samples in this phase are between 77 Ma and 76 Ma based on planktonic foraminifera, and in the Göynük section the oldest Phase 2 sample has a published maximum depositional age of 76.4 ± 1.7 Ma based on the youngest 19 zircons [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF].

The Phase 2 sandstone compositions plot in the recycled orogen and volcanic arc fields and evolve toward increasing quartz and sedimentary and metamorphic lithic compositions (Figure 7). DZ samples are generally characterized by 67-90 Ma, 300-450 Ma and 550-700 Ma peaks (Figure 8). The presence of Carboniferous zircons alone or in tandem with Devonian to Proterozoic zircons are either first-cycle or poly-cyclic zircons from the Central Sakarya Basement, which is presently exposed in the hanging wall of the Tuzaklı-Gümele Thrust (Figure 2). The Triassic and Carboniferous age doublet is distinctively Karakaya Complex in origin (Figure 5) and, given the absence of Triassic igneous rocks across Anatolia (Figure 3 Exhumation and underthrusting continued through Phase 2 when the CSB records northward prograding deltas at 61 Ma, a major unconformity in the proximal (southern) basin, a lowstand systems tract, the transition from flysch to molasse, and an order of magnitude increase in accumulation rates [START_REF] Açıkalın | Stable isotopes and geochemistry of a Campanian-Maastrichtian pelagic succession, Mudurnu-Göynük Basin, NW Turkey: Implications for palaeoceanography, palaeoclimate and sealevel fluctuations[END_REF][START_REF] Ocakoğlu | Orta Sakarya Bölgesi Geç Kretase-Paleojen Çökellerinin Sekans Stratigrafisi[END_REF][START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. These CSB changes coincide with a 67-58 Ma magmatic lull (Figure 8), and 63-57 Ma Barrovian metamorphism of the TVZ to greenschist and amphibolite facies (e.g., [START_REF] Whitney | Metamorphic and tectonic evolution of a structurally continuous blueschist-to-Barrovian terrane, Sivrihisar Massif, Turkey[END_REF] and subsequent TVZ exhumation at 60 Ma as indicated by white mica 40 Ar/ 39 Ar cooling ages [START_REF] Seaton | Recrystallization of high-pressure marble (Sivrihisar, Turkey)[END_REF].

Phase 3: Thick-Skinned Deformation and Foreland Basin Partitioning

The start of Phase 3 is defined by the onset of deposition in the SB, which is dated to 52.4 ± 0.6 Ma by a volcaniclastic bed at the base of the Paleogene series in the SB [START_REF] Campbell | Tectonic Evolution of the Izmir-Ankara Suture Zone in Northwest Turkey using Zircon U-Pb Geochronology and Zircon Lu-Hf Isotopic Tracers (M.S.)[END_REF] manuscript submitted to Geochemistry, Geophysics, Geosystems [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF]. Thus, the start of Phase 3 is associated with the onset of basin partitioning and the first clear evidence for advanced thick-skinned deformation. The onset of basementinvolved deformation likely preceded the beginning of basin partitioning and SB deposition by several million years, but at this point the oldest SB deposits are the best minimum age estimate for the onset of thick-skinned deformation. Eocene SB DZ samples are generally characterized by a 46-58 Ma peak along with 200-250 Ma, 325 Ma, 375-400 Ma, 600 Ma, 1000 Ma, 2000 Ma and 2600 Ma peaks. Paleozoic to Proterozoic detrital zircon ages and clasts of quartz, mica and gneiss in the SB indicate that the Central Sakarya Basement, which was exposed in the hanging wall of the thrust, was a sediment source [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF]. In addition, the 46-58 Ma peak and 200-250 and 325 Ma doublet indicate that the SB received sediment from the Eocene volcanic belt within the SB and the Karakaya Complex, respectively [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF].

In the CSB, the increase in sedimentary lithics (Figure 7) along with negligible changes in DZ age spectra from Phase 2 to Phase 3-except for the appearance of 58-41 Ma zircons (Figure 8)-are consistent with continued sediment recycling and no major change in CSB provenance through the middle Eocene. The absence of the Karakaya Complex Triassic and Carboniferous age doublet and the scarcity of Silurian-Precambrian zircons in middle to upper Eocene CSB samples could point to disconnected CSB and SB depocenters. CSB-SB partitioning is roughly coeval with the resumption of deposition in the southwestern CSB and the 58-54 Ma transition from marine to continental facies and prograding clastic wedges [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. Sediment recycling and general northward-directed drainages [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF] suggest that Phase 1 and 2 deposits were unroofed along the Tuzaklı-Gümele Thrust hanging wall and recycled into the CSB during Phase 3. Therefore, during Phase 3, deformation and exhumation propagated north of the İAES; basement-involved shortening (Şahin et al., 2019) structurally partitioned the SB and CSB foreland along the Tuzaklı-Gümele Thrust (Figure 2; [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF]. Seaways persisted into Phase 3 as indicated by Ypresian-Lutetian marine deposition in the eastern SB [START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF] and Lutetian-Priabonian marine deposition in the distal (northern) CSB (e.g., [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF], which suggests there was not significant regional surface uplift or crustal thickening during . manuscript submitted to Geochemistry, Geophysics, Geosystems

Implications for Geodynamic Mechanisms Controlling Collisional Deformation

This section explores the possible geodynamic mechanisms that could explain a ~20 Myr multi-phase collision along the İAES. Multi-phased, "soft-hard" collisions have been proposed numerous times in the Tethyan domain (e.g., [START_REF] Ballato | Multiple Exhumation Phases in the Central Pontides (N Turkey): New Temporal Constraints on Major Geodynamic Changes Associated With the Closure of the Neo-Tethys Ocean[END_REF][START_REF] Beaumont | Mechanical model for subductioncollision tectonics of Alpine-type compressional orogens[END_REF]Darin et al., 2018;[START_REF] Jagoutz | Low-latitude arc-continent collision as a driver for global cooling[END_REF][START_REF] Kaymakci | Tectono-stratigraphy of the Çankırı Basin: Late Cretaceous to early Miocene evolution of the Neotethyan Suture Zone in Turkey[END_REF][START_REF] Pourteau | Neotethyan closure history of western Anatolia: a geodynamic discussion[END_REF][START_REF] Tye | Sedimentary response to a collision orogeny recorded in detrital zircon provenance of Greater Caucasus foreland basin sediments[END_REF] and worldwide. These scenarios are based on a variety of mechanisms: subduction of a highly extended lower plate oceanic and continental lithosphere [START_REF] Van Hinsbergen | Restoration of Cenozoic deformation in Asia and the size of Greater India[END_REF][START_REF] Van Hinsbergen | Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia[END_REF], arc-continent collision [START_REF] Jagoutz | Low-latitude arc-continent collision as a driver for global cooling[END_REF][START_REF] Martin | Paleocene latitude of the Kohistan-Ladakh arc indicates multistage India-Eurasia collision[END_REF]), slab breakoff (DeCelles et al., 2011;[START_REF] Sinclair | Flysch to molasse transition in peripheral foreland basins: The role of the passive margin versus slab breakoff[END_REF], relict basin closure [START_REF] Cowgill | Relict basin closure and crustal shortening budgets during continental collision: An example from Caucasus sediment provenance[END_REF], and increased lower plate lithospheric thickness [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF][START_REF] Soret | How Himalayan collision stems from subduction[END_REF]. One or a combination of these scenarios could explain the protracted nature of intercontinental collision in western Anatolia, including the thick-skinned deformation and basin partitioning at 54 Ma.

Several mechanisms for protracted Tethyan collisions are not applicable in western Anatolia. Discrepancies between shortening and convergence led to several geodynamic mechanisms for protracted and multi-stage India-Asia collision (e.g., [START_REF] Hu | The timing of India-Asia collision onset -Facts, theories, controversies[END_REF]Kapp & DeCelles, 2019 and references therein), such as a wide lower plate lithosphere (i.e., Greater India; [START_REF] Van Hinsbergen | Restoration of Cenozoic deformation in Asia and the size of Greater India[END_REF][START_REF] Van Hinsbergen | Greater India Basin hypothesis and a two-stage Cenozoic collision between India and Asia[END_REF] and initial collision of an intra-oceanic arc [START_REF] Jagoutz | Anomalously fast convergence of India and Eurasia caused by double subduction[END_REF][START_REF] Jagoutz | Low-latitude arc-continent collision as a driver for global cooling[END_REF][START_REF] Martin | Paleocene latitude of the Kohistan-Ladakh arc indicates multistage India-Eurasia collision[END_REF]. While there likely was a wide pre-collisional lower plate TVZ lithosphere and possibly an intra-oceanic arc [START_REF] Göncüoğlu | A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution[END_REF][START_REF] Göncüoğlu | Oceanization of the northern Neotethys: Geochemical evidence from ophiolitic melange basalts within the İzmir-Ankara suture belt, NW Turkey[END_REF][START_REF] Sarıfakıoğlu | Whole Rock and Mineral Chemistry of Ultramafic-mafic Cumulates from the Orhaneli (Bursa) Ophiolite, NW Anatolia[END_REF][START_REF] Sarıfakıoğlu | New synthesis of the Izmir-Ankara-Erzincan suture zone and the Ankara mélange in northern Anatolia based on new geochemical and geochronological constraints[END_REF], the most recent plate reconstructions require only a few hundred kilometers between the SKZ and TVZ in the early Campanian [START_REF] Van Hinsbergen | Orogenic architecture of the Mediterranean region and kinematic reconstruction of its tectonic evolution since the Triassic[END_REF]. Therefore, these geodynamic mechanisms invoked to explain upper plate shortening deficits and thousands of kilometers of distance between continental domains during initial collisional deformation are not pertinent in western Anatolia. In the remaining part of the discussion, we focus on the three mechanisms that are the most viable for SKZ-TVZ collision.

Slab Breakoff

Slab breakoff is a mechanism commonly employed to explain coeval surface uplift, extension and magmatism (von Blanckenburg & Davies, 1995;Davies & von Blanckenburg, 1995), although its prevalence in the geologic past and its genetic connection to magmatism is questioned [START_REF] Garzanti | Slab breakoff: A critical appraisal of a geological theory as applied in space and time[END_REF][START_REF] Niu | Slab breakoff: a causal mechanism or pure convenience?[END_REF]. In western Anatolia, slab breakoff can explain the manuscript submitted to Geochemistry, Geophysics, Geosystems timing and geochemical signature of ~58-40 Ma magmatism [START_REF] Altunkaynak | Eocene Granitic Magmatism in NW Anatolia (Turkey) revisited: New implications from comparative zircon SHRIMP U-Pb and 40Ar-39Ar geochronology and isotope geochemistry on magma genesis and emplacement[END_REF][START_REF] Dilek | Geochemical and temporal evolution of Cenozoic magmatism in western Turkey: mantle response to collision, slab break-off, and lithospheric tearing in an orogenic belt[END_REF]Ersoy, Akal, et al., 2017;Ersoy, Palmer, et al., 2017;[START_REF] Graham | Graphical representation of particle shape using triangular diagrams: an Excel spreadsheet method[END_REF][START_REF] Kasapoğlu | The petrology of Paleogene volcanism in the Central Sakarya, Nallıhan Region: Implications for the initiation and evolution of post-collisional, slab break-off-related magmatic activity[END_REF]. However this interpretation is debated for four main reasons [START_REF] Ustaömer | Lutetian arc-type magmatism along the southern Eurasian margin: New U-Pb LA-ICPMS and whole-rock geochemical data from Marmara Island, NW Turkey[END_REF]; see also [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF][START_REF] Okay | Blueschists, Eclogites, Ophiolites and Suture Zones in Northwest Turkey: A Review and a Field Excursion Guide[END_REF][START_REF] Okay | Geochronology of Eocene plutonism and metamorphism in northwest[END_REF][START_REF] Van Hinsbergen | Reconciling the geological history of western Turkey with plate circuits and mantle tomography[END_REF]. (1) The TVZ slab was subducted to mantle depths in the Late Cretaceous and the exhumation of blueschists in the Campanian-Maastrichtian suggests slab breakoff was in the Late Cretaceous not Eocene (e.g., [START_REF] Okay | Geochronology of Eocene plutonism and metamorphism in northwest[END_REF]. ( 2) Geodynamic models of slab breakoff predict >1.5 km of surface uplift across several hundreds of kilometers across-strike [START_REF] Göğüş | Postcollisional lithospheric evolution of the Southeast Carpathians: Comparison of geodynamical models and observations[END_REF]). Yet, across the <150 km İAES and CSB width (Figure 2), Paleocene-Eocene marine deposition in the CSB and SB indicates there was not significant surface uplift. ( 3) Magmatism was contemporaneous across three parallel volcano-plutonic belts at the northern margin of the CSB, bisecting the SB, and in the TVZ (e.g., Ersoy, Akal, et al., 2017;Ersoy, Palmer, et al., 2017;[START_REF] Graham | Graphical representation of particle shape using triangular diagrams: an Excel spreadsheet method[END_REF][START_REF] Kasapoğlu | The petrology of Paleogene volcanism in the Central Sakarya, Nallıhan Region: Implications for the initiation and evolution of post-collisional, slab break-off-related magmatic activity[END_REF]. ( 4) There was early Eocene contractional deformation in the SB and no evidence for extension [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF]. Slab breakoff has been inferred in extensional sedimentary basins based on the observation of alternating clastic and lacustrine deposits, an overall fining-upward sedimentary succession, high sedimentation rates, and an absence of contractional growth structures (DeCelles et al., 2011;[START_REF] Leary | Along-strike diachroneity in deposition of the Kailas Formation in central southern Tibet: Implications for Indian slab dynamics[END_REF]. Although the SB contains alternating clastic floodplain and lacustrine limestone deposits and no contractional growth strata, the presence of basement-aged zircons and clasts of quartz, mica and gneiss in coarse-grained fluvial deposits indicate that the Central Sakarya Basement was exposed in the hanging wall of the Tuzaklı-Gümele Thrust in the early Eocene [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF]. The slab break-off model remains a popular interpretation for Eocene magmatism; other explanations include lithospheric delamination [START_REF] Van Hinsbergen | Reconciling the geological history of western Turkey with plate circuits and mantle tomography[END_REF][START_REF] Pourteau | Neotethys closure history of Anatolia: insights from 40 Ar-39 Ar geochronology and P-T estimation in high-pressure metasedimentary rocks[END_REF], arc volcanism from a different subduction zone system [START_REF] Okay | Geochronology of Eocene plutonism and metamorphism in northwest[END_REF], and mid-to-late Eocene orogenic collapse and extension [START_REF] Ustaömer | Lutetian arc-type magmatism along the southern Eurasian margin: New U-Pb LA-ICPMS and whole-rock geochemical data from Marmara Island, NW Turkey[END_REF]. We note that an amagmatic slab breakoff [START_REF] Garzanti | Slab breakoff: A critical appraisal of a geological theory as applied in space and time[END_REF][START_REF] Niu | Slab breakoff: a causal mechanism or pure convenience?[END_REF] occurring ~10 Myr after initial collision, during the 67-58 Ma magmatic lull and Yenipazar section angular unconformity, could partly solve these issues and provide a mechanism to increase plate coupling and contractional deformation and facilitate juvenile magmatism (Figure 10a).

Relict Basin Closure manuscript submitted to Geochemistry, Geophysics, Geosystems

In both the Arabia-Eurasia and India-Asia collisions, the initial collision of upper plate island arcs or continental terranes with the lower plate continental lithosphere results in upper plate backarc basin closure (e.g., [START_REF] Cowgill | Relict basin closure and crustal shortening budgets during continental collision: An example from Caucasus sediment provenance[END_REF][START_REF] Jagoutz | Anomalously fast convergence of India and Eurasia caused by double subduction[END_REF][START_REF] Kapp | Mesozoic-Cenozoic geological evolution of the Himalayan-Tibetan orogen and working tectonic hypotheses[END_REF]. Initial Arabian collision is inferred from the coeval ca. 36 Ma magmatic lull and switch from extension to contraction in the Alborz Mountains of Iran [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF], and increased exhumation rates in the eastern Taurides [START_REF] Darin | Rapid Late Eocene Exhumation of the Sivas Basin (Central Anatolia) Driven by Initial Arabia-Eurasia Collision[END_REF] and central Pontides [START_REF] Ballato | Multiple Exhumation Phases in the Central Pontides (N Turkey): New Temporal Constraints on Major Geodynamic Changes Associated With the Closure of the Neo-Tethys Ocean[END_REF]). Yet initial foreland basin sedimentation [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF], slowed convergence rates [START_REF] Mcquarrie | Cenozoic evolution of Neotethys and implications for the causes of plate motions[END_REF], and increased exhumation near the Bitlis suture zone (Okay et al., 2010) was delayed until at 20-17 Ma. [START_REF] Cowgill | Relict basin closure and crustal shortening budgets during continental collision: An example from Caucasus sediment provenance[END_REF] suggest that significant upper plate deformation from the Arabia-Eurasia collision was delayed by ~15-20 Myr due to northward jumping deformation. In this scenario, collisional stress was transferred through the lithosphere and closed several upper plate basins [START_REF] Cowgill | Relict basin closure and crustal shortening budgets during continental collision: An example from Caucasus sediment provenance[END_REF]. Eocene-Oligocene Arabian collision along the Bitlis-Zagros suture (e.g., [START_REF] Koshnaw | Timing of the Arabia-Eurasia continental collision-Evidence from detrital zircon U-Pb geochronology of the Red Bed Series strata of the northwest Zagros hinterland, Kurdistan region of Iraq[END_REF][START_REF] Mcquarrie | Cenozoic evolution of Neotethys and implications for the causes of plate motions[END_REF][START_REF] Mcquarrie | Retrodeforming the Arabia-Eurasia collision zone: Age of collision versus magnitude of continental subduction[END_REF] initiated subduction in the backarc basin between the Lesser and Greater Caucasus (e.g., [START_REF] Avdeev | Rapid Pliocene exhumation of the central Greater Caucasus constrained by low-temperature thermochronometry[END_REF]; then, completed backarc basin closure around 5 Ma produced a 10-fold increase in Greater Caucasus exhumation rates [START_REF] Avdeev | Rapid Pliocene exhumation of the central Greater Caucasus constrained by low-temperature thermochronometry[END_REF] coincident with foreland basin erosion and non-deposition, mixing of sediment from the upper and lower plates, and provenance signatures of progressive crustal exhumation (e.g., [START_REF] Tye | Sedimentary response to a collision orogeny recorded in detrital zircon provenance of Greater Caucasus foreland basin sediments[END_REF].

In line with this relict basin closure scenario, major collisional deformation from initial TVZ-SKZ underthrusting could be delayed by >20 Myr due to the closure of relict basins to the north or south of the İAES (Figure 10b). The closure of the Intra-Pontide suture zone is a strong candidate to explain this delay because the timing of suturing remains unclear, with proposed ages spanning from the Early Cretaceous [START_REF] Akbayram | Early Cretaceous closure of the Intra-Pontide Ocean in western Pontides (northwestern Turkey)[END_REF], to the Late Cretaceous-Paleocene (Di [START_REF] Rosa | U-Pb zircon geochronology of intrusive rocks from an exotic block in the Late Cretaceous -Paleocene Taraklı Flysch (northern Turkey): Constraints on the tectonics of manuscript submitted to Geochemistry, Geophysics, Geosystems the Intrapontide suture zone[END_REF][START_REF] Göncüoğlu | A Geotraverse Across Northwestern Turkey: Tectonic Units of the Central Sakarya Region and their Tectonic Evolution[END_REF][START_REF] Özcan | Late Cretaceous-Eocene Geological Evolution of the Pontides Based on New Stratigraphic and Palaeontologic Data Between the Black Sea Coast and Bursa (NW Turkey)[END_REF][START_REF] Robertson | Tectonic evolution of the Intra-Pontide suture zone in the Armutlu Peninsula, NW Turkey[END_REF], and to the Paleocene-Eocene [START_REF] Akbayram | The evolution of the intra-Pontide suture; implications of the discovery of late Cretaceous-early Tertiary melanges[END_REF][START_REF] Göncüoğlu | The Arkot Dağ Mélange in Araç area, central Turkey: Evidence of its origin within the geodynamic evolution of the Intra-Pontide suture zone[END_REF][START_REF] Okay | Kinematic history of the opening of the Black Sea and its effect on the surrounding regions[END_REF]. Major contractional deformation could also be delayed by the hypothesized southward-jumping subduction zones synchronously or sequentially facilitating the closure of Neotethyan oceanic basins between Anatolide and Tauride terranes south of the İAES [START_REF] Pourteau | Neotethys closure history of Anatolia: insights from 40 Ar-39 Ar geochronology and P-T estimation in high-pressure metasedimentary rocks[END_REF][START_REF] Pourteau | Neotethyan closure history of western Anatolia: a geodynamic discussion[END_REF]. Resumed or increased continental underthrusting at 54 Ma along the İAES could partly explain the renewal of magmatism without explaining its regional distribution. The manuscript submitted to Geochemistry, Geophysics, Geosystems lack of consensus on the history of Intra-Pontide rifting and suturing makes it difficult to assess the applicability of this mechanism.

Increasing Lithospheric Thickness of the Lower Plate

Another two-stage collision scenario invoked for Tethyan collisions involves the underthrusting of increasing thickness of lower plate passive margin lithosphere (e.g., [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF][START_REF] Darin | Rapid Late Eocene Exhumation of the Sivas Basin (Central Anatolia) Driven by Initial Arabia-Eurasia Collision[END_REF][START_REF] Soret | How Himalayan collision stems from subduction[END_REF]. In the Himalayan sector, the initial collision of India with Asia is generally accepted as 60-55 Ma when the final vestiges of Neotethyan oceanic crust were subducted (Hu et al., 2016 and references therein). In northern Pakistan, Barrovian metamorphism from 47 to 38 Ma is coincident with the formation and exhumation of eclogites [START_REF] Soret | How Himalayan collision stems from subduction[END_REF], a >50% decrease in convergence rates at 50-45 Ma (van Hinsbergen et al., 2011), and increased exhumation in the Himalaya starting around 35 Ma [START_REF] Ding | The India-Asia collision in north Pakistan: Insight from the U-Pb detrital zircon provenance of Cenozoic foreland basin[END_REF].

Following oceanic basin closure, [START_REF] Soret | How Himalayan collision stems from subduction[END_REF] identify the first phase of collision as a period of "continental subduction," which is the slow underthrusting of thinned Indian passive margin lithosphere beneath Asia. Continental subduction is expressed as Barrovian metamorphism and the accommodation of convergence by underplating and tectonic stacking [START_REF] Soret | How Himalayan collision stems from subduction[END_REF]. Then, a second collision phase, "collision initiation," began ca. 38 Ma when increased mechanical coupling between India and Asia significantly increased transpressional deformation (i.e., Main Mantle thrust, Karakorum fault), exhumation, uplift, and erosion rates [START_REF] Soret | How Himalayan collision stems from subduction[END_REF]. Therefore, multi-phase collision in western Anatolia could be attributed to the arrival of progressively thicker, buoyant TVZ continental lithosphere beneath the SKZ (Figure 10c). At 76 Ma, the initial continental subduction," or "soft" collision, of thinned passive margin lithosphere locked the subduction zone megathrust, triggered upper plate shortening, and exhumed the accretionary prism [START_REF] Beaumont | Mechanical model for subductioncollision tectonics of Alpine-type compressional orogens[END_REF][START_REF] Tye | Sedimentary response to a collision orogeny recorded in detrital zircon provenance of Greater Caucasus foreland basin sediments[END_REF]. The appearance of basement-aged zircons in the CSB at 76 Ma is closely followed by a regional unconformity [START_REF] Ocakoğlu | Orta Sakarya Bölgesi Geç Kretase-Paleojen Çökellerinin Sekans Stratigrafisi[END_REF], magmatic lull (67-58 Ma), TVZ Barrovian metamorphism (63-57 Ma; e.g., Whitney et al., 2011), and TVZ exhumation (60 Ma;[START_REF] Seaton | Recrystallization of high-pressure marble (Sivrihisar, Turkey)[END_REF]. Subsequent thick-skinned deformation and basin partitioning by 54 Ma [START_REF] Mueller | Collision Chronology Along the İzmir-Ankara-Erzincan Suture Zone: Insights From the Sarıcakaya Basin, Western Anatolia[END_REF][START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF] would represent the final "collision initiation", or "hard collision," defined by the arrival of full-thickness continental lithosphere along the subduction zone and a more substantial plate coupling manifested as manuscript submitted to Geochemistry, Geophysics, Geosystems widespread regional contractional deformation. A convergence rate of ~5 mm/yr from 76 to 54 Ma (van Hinsbergen et al., 2020) predicts ~110 km of TVZ underthrusting, which is less than estimates for the amount of underthrust thinned, passive margin Arabian lithosphere (~400-480 km; [START_REF] Ballato | Arabia-Eurasia continental collision: Insights from late Tertiary foreland-basin evolution in the Alborz Mountains, northern Iran[END_REF][START_REF] Darin | Rapid Late Eocene Exhumation of the Sivas Basin (Central Anatolia) Driven by Initial Arabia-Eurasia Collision[END_REF]. This mechanism reasonably explains the collisional evolution of the İAES in western Anatolia.

Geodynamic Influence on Mediterranean Biogeography

Even though it remains difficult to pinpoint a specific mechanism for protracted collision and delay in upper plate deformation, our results highlight a direct-and unexpectedgeodynamic and paleogeographic control on the regional fauna. Backarc rifting in the middle Cretaceous isolated the Pontides from Eurasia [START_REF] Akdoğan | Striking Variation in the Provenance of the Lower and Upper Cretaceous Turbidites in the Central Pontides (Northern Turkey) Related to the Opening of the Black Sea[END_REF][START_REF] Okay | Tectonic evolution of the southern margin of Laurasia in the Black Sea region[END_REF], setting the stage for Paleogene endemism. In Cretaceous-Paleogene times, Anatolia was an island archipelago separated from large continental domains (i.e., Afro-Arabia, Europe and Asia) by strands of the Paleotethys and Neotethys oceans [START_REF] Barrier | Palaeotectonic Maps of the Middle East[END_REF][START_REF] Van Hinsbergen | Orogenic architecture of the Mediterranean region and kinematic reconstruction of its tectonic evolution since the Triassic[END_REF]. Gradual Late Cretaceous to early Eocene convergence and collision favored colonization of the Pontides by Gondwanan and Laurasian mammalian clades via "island hopping" across the Neotethyan archipelago [START_REF] Beard | An omomyid primate from the Pontide microcontinent of north-central Anatolia: Implications for sweepstakes dispersal of terrestrial mammals during the Eocene[END_REF][START_REF] Jones | A stem bat (Chiroptera: Palaeochiropterygidae) from the late middle Eocene of northern Anatolia: implications for the dispersal and palaeobiology of early bats[END_REF][START_REF] Kappelman | A new early Tertiary mammalian fauna from Turkey and its paleobiogeographic significance[END_REF][START_REF] Licht | Tectonostratigraphy of the Orhaniye Basin, Turkey: Implications for collision chronology and Paleogene biogeography of central Anatolia[END_REF][START_REF] Métais | Tarsal morphology of the pleuraspidotheriid mammal Hilalia from the middle Eocene of Turkey[END_REF][START_REF] Sen | Dispersal of African mammals in Eurasia during the Cenozoic: Ways and whys[END_REF]. The TVZ-SKZ collision assembled a larger subaerial continental landmass that further promoted in situ diversification of endemic taxa [START_REF] Maas | Enigmatic new ungulates from the Early Middle Eocene of central Anatolia, Turkey[END_REF][START_REF] Métais | Eocene metatherians from Anatolia illuminate the assembly of an island fauna during Deep Time[END_REF]. Endemism persisted until at least the Lutetian (44-43 Ma;[START_REF] Licht | Tectonostratigraphy of the Orhaniye Basin, Turkey: Implications for collision chronology and Paleogene biogeography of central Anatolia[END_REF], a time when much of Anatolia was near sea level (e.g., [START_REF] Licht | Tectonostratigraphy of the Orhaniye Basin, Turkey: Implications for collision chronology and Paleogene biogeography of central Anatolia[END_REF][START_REF] Lygina | Nummulitic facies of the Crimean-Caucasian Region[END_REF][START_REF] Mta | Geological map of Turkey[END_REF][START_REF] Ocakoğlu | Evidence of orbital forcing in lake-level fluctuations in the Middle Eocene oil shale-bearing lacustrine successions in the Mudurnu-Göynük Basin, NW Anatolia (Turkey)[END_REF][START_REF] Özcan | The Ypresian to Lutetian marine record in NW Turkey: a revised biostratigraphy and chronostratigraphy and implications for Eocene paleogeography[END_REF][START_REF] Racey | A review of Eocene nummulite accumulations: Structure, formation and reservoir potential[END_REF].

Therefore, the protracted nature of the collision, especially with respect to evolving plate coupling, is pertinent to the timing and magnitude of crustal thickening and topographic development and might explain the persistence of seaways and faunal isolation until late in the collision timeline [START_REF] Beard | An omomyid primate from the Pontide microcontinent of north-central Anatolia: Implications for sweepstakes dispersal of terrestrial mammals during the Eocene[END_REF][START_REF] Jones | A stem bat (Chiroptera: Palaeochiropterygidae) from the late middle Eocene of northern Anatolia: implications for the dispersal and palaeobiology of early bats[END_REF][START_REF] Licht | Tectonostratigraphy of the Orhaniye Basin, Turkey: Implications for collision chronology and Paleogene biogeography of central Anatolia[END_REF][START_REF] Métais | Eocene metatherians from Anatolia illuminate the assembly of an island fauna during Deep Time[END_REF][START_REF] Sen | Dispersal of African mammals in Eurasia during the Cenozoic: Ways and whys[END_REF]. In this way, the protracted nature of İAES collision is relevant to the evolution of emergent landmasses and exemplifies a direct influence of geodynamics and tectonics on biogeography. manuscript submitted to Geochemistry, Geophysics, Geosystems

Conclusion

The uninterrupted sedimentary record of the forearc-to-foreland Central Sakarya Basin records a complete history of progressive intercontinental collision that can serve as an example for Tethyan collisions. This sedimentary basin highlights how geodynamic mechanisms involving changing plate coupling can reconcile and synthesize collision proxies with seeming 15-40 Myr discrepancies into a holistic model for protracted collisions. During Cenomanian to early Campanian times (94-76 Ma), the CSB forearc basin received detritus from the Pontide volcanic belt, likely located at the southern margin of the CSB. Phase 2 started at 76 Ma with the appearance of recycled basement-aged zircons in CSB strata, northward prograding deltas [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF] and increased in mafic input [START_REF] Açıkalın | Stable isotopes and geochemistry of a Campanian-Maastrichtian pelagic succession, Mudurnu-Göynük Basin, NW Turkey: Implications for palaeoceanography, palaeoclimate and sealevel fluctuations[END_REF], which record İAES uplift and exhumation attributed to the onset of TVZ-SKZ continental collision. Phase 3 began at 54 Ma and is associated with to the onset of thick-skinned deformation, foreland basin partitioning, and regional syn-collisional magmatism.

The shift in deformation regime 20 Myr after initial intercontinental collision emphasizes the protracted nature of the collision. The duration of İAES suturing may be explained by aspects of three multi-phase collision models that implicate a change in plate coupling: slab breakoff, relict basin closure, and underthrusting of progressively thicker lithosphere. Given the debated chronology of relict basin closure and the setting of Eocene magmatism, the underthrusting of progressively thicker lower plate passive margin lithosphere is the best and simplest explanation for protracted collision in western Anatolia. [START_REF] Aksay | Geologic map of Turkey (Zonguldak, Scale[END_REF]Duru & Aksay, 2002;Gedik & Aksay, 2002;[START_REF] Şahin | A case study of compression to escape tectonic transition: Tectonic evolution of the Nallıhan Wedge and comparison with the Tercan Wedge (Eastern Mediterranean, Turkey)[END_REF][START_REF] Timur | Geological map of the Adapazari quadrangle (Sheet H 26[END_REF][START_REF] Turhan | Geologic map of Turkey (Ankara, Scale[END_REF].

See Figure 1 for location. Note that some published Karakaya Complex samples are west of the displayed map area. Cretaceous volcaniclastics are included (see [START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]Duru & Aksay, 2002;Gedik & Aksay, 2002). Adapted from [START_REF] Akdoğan | Provenance of a large Lower Cretaceous turbidite submarine fan complex on the active Laurasian margin: Central Pontides, northern Turkey[END_REF], Ersoy, Akal, et al. (2017), and[START_REF] Okay | TAVSANLI ZONE: THE NORTHERN SUBDUCTED MARGIN OF THE ANATOLIDE-TAURIDE BLOCK[END_REF][START_REF] Okay | Tectonic evolution of the southern margin of Laurasia in the Black Sea region[END_REF] and references therein. [START_REF] Darin | Rapid Late Eocene Exhumation of the Sivas Basin (Central Anatolia) Driven by Initial Arabia-Eurasia Collision[END_REF][START_REF] Rosa | U-Pb zircon geochronology of intrusive rocks from an exotic block in the Late Cretaceous -Paleocene Taraklı Flysch (northern Turkey): Constraints on the tectonics of manuscript submitted to Geochemistry, Geophysics, Geosystems the Intrapontide suture zone[END_REF][START_REF] Göncüoğlu | The Arkot Dağ Mélange in Araç area, central Turkey: Evidence of its origin within the geodynamic evolution of the Intra-Pontide suture zone[END_REF]. Table 1. New and published samples, units, ages, groups, sample types, and sources. DZ: detrital zircon; SP: sandstone petrography. Data sources: 1: [START_REF] Ustaömer | Ion Probe U-Pb Dating of the Central Sakarya Basement: A peri-Gondwana Terrane Intruded by Late Lower Carboniferous Subduction/Collision-related Granitic Rocks[END_REF]2: Ustaömer et al., 2016;3: Campbell, 2017;4: Ocakoğlu et al., 2018;5: Schleiffarth et al., 2018 and references therein;6: Mueller et al., 2019;7: this study.

Figure 5 and

 5 Figure 5 and Figure 6, respectively. To facilitate comparison, distributions are colored according to the ages of known late Neoproterozoic through Eocene plutonic outcrops across the Black Sea region (Figure 3). Sandstone petrography results of new CSB samples are displayed in Figure 7.

  Anatolian volcanic arc is characterized by 30-56 Ma and 67-99 Ma age peaks. The Karakaya Complex samples are characterized by 200-250 and 325 Ma populations, and, additionally, the modern river sample (17RIVER01) draining the İAES contains minor Eocene, Late Cretaceous, Triassic, and Paleozoic populations. The Central Sakarya Basement bedrock samples exhibit a prominent ~325 Ma peak, and the oldest samples include 375-500 Ma age populations; the metasedimentary sample ('SgtMeta' from Ustaömer et al., 2012) contains a range of Proterozoic-Archean zircons with peaks centered around 600 Ma, 1000 Ma, 2000 Ma, and 2650 Ma. The absence of Precambrian-aged zircons in most Central Sakarya Basement manuscript submitted to Geochemistry, Geophysics, Geosystems samples is likely due to sampling bias as most of the samples are orthogneiss and granitoids, with only one metasedimentary sample ('SgtMeta' from Ustaömer et al., 2012). New (n=3199) and published (n=1457) CSB and SB detrital zircon ages (Figure 6) and new sandstone petrography results (Figure 7) characterize sedimentary provenance. The oldest CSB samples are Cenomanian to lower Campanian in age and are characterized by a major 76-110 Ma peak; few zircons are older than 110 Ma (n=22/660, 3%). These samples plot in the volcanic arc and recycled orogen fields. Samples younger than the lower Campanian have prominent Late Cretaceous (67-110 Ma) and Carboniferous (~325 Ma) peaks. The youngest CSB samples also contain a prominent Eocene peak (~41-58 Ma). About half of these samples have major or minor Triassic (~250 Ma), Devonian (375-400 Ma), and Proterozoic peaks around 600 Ma, 1000 Ma and 2000 Ma. The Sarıcakaya Basin samples have a similar distribution of DZ

  ), the presence of this doublet likely indicates sediment sourced from the Karakaya Complex rather than from both Triassic and Carboniferous igneous rocks (e.g., samples 18TBTG and 18TK01).The absence of deposition in the flexural SB before ~53 Ma indicates that the Tuzaklı-Gümele Thrust likely did not expose basement rocks in Phase 2. Therefore, we propose that the basement-age zircons and evolution toward quartz-and sedimentary lithic-rich compositions indicate an unroofing sequence in which poly-cyclic basement-aged zircons appeared in the basin. It is uncertain exactly where sediment recycling occurred or which structures were active, but we suggest it was a southern source for two reasons: (1) Increased mafic/felsic element ratios (i.e., Ni/Zr, Ni/Y, Cr/Zr) in the distal İsmailler section at ca. 73 Ma show the input of ophiolitic material into the CSB, pinpointing the area of exhumation to the İAES where Late Paleozoic-Mesozoic ophiolitic and subduction-accretion units are exposed today. (2) Paleocurrent directions indicating flow from the SW-SE to NE-NW[START_REF] Ocakoğlu | Chronology of subduction and collision along the İzmir-Ankara suture in Western Anatolia: records from the Central Sakarya Basin[END_REF]. Together this indicates that at 76 Ma, the southern margin of the SKZ, including the İAES accretionary complex, began uplifting, exhuming, and creating south-to-north flowing transverse drainage systems.We propose that uplift of the southern Pontide margin marks the onset of initial intercontinental collision. A 76 Ma age of initial collision is supported by a decrease in convergence rates from 28 mm/yr at 110-76 Ma to 5 mm/yr from 76 Ma onwards (rates calculated from plate reconstructions based on paleomagnetic and kinematic data in van[START_REF] Van Hinsbergen | Orogenic architecture of the Mediterranean region and kinematic reconstruction of its tectonic evolution since the Triassic[END_REF]. Moreover, evolved εHf values in 85-70 Ma detrital zircons indicate either crustal thickening, lower plate continental underthrusting, or arc migration into evolved continental crust[START_REF] Campbell | Tectonic Evolution of the Izmir-Ankara Suture Zone in Northwest Turkey using Zircon U-Pb Geochronology and Zircon Lu-Hf Isotopic Tracers (M.S.)[END_REF]. Lastly,[START_REF] Okay | İzmir-Ankara Suture as a Triassic to Cretaceous Plate Boundary-Data From Central Anatolia[END_REF] interpret the 74 Ma onset of the major dextral transpressional Sakarya Shear Zone as initial collision.

Figure 1 .

 1 Figure 1. Simplified terrane map of Anatolia including hypothesized suture zones (dashed lines) modified from Licht et al. (2017). İAES: İzmir-Ankara-Erzincan suture zone; IPS: Intra-Pontide suture zone.

Figure 2 .

 2 Figure 2. Simplified geologic map of northwestern Anatolia (after[START_REF] Aksay | Geologic map of Turkey (Zonguldak, Scale[END_REF] Duru &

Figure 3 .

 3 Figure 3. Outcrops and isotopic ages of Devonian through Eocene plutons. Jurassic metamorphic rocks, Neoproterozoic to Ordovician crystalline basement, and southern CSB Late

Figure 4 .

 4 Figure 4. Simplified Upper Cretaceous through Eocene lithostratigraphic diagram of the Central Sakarya Basin showing formation names and ages, and sample locations. The measured sections, stratigraphic age constraints, and interpreted depositional environments are from Ocakoğlu et al. (2018). Measured sections are schematically oriented in space; see Figure 2 for measured section locations. Grain size: Sh: shale; Ss: sandstone; Cg: conglomerate.

Figure 5 .

 5 Figure 5. Detrital zircon age spectra characterizing potential sediment sources displayed as probability density functions (black lines) and optimized fixed bandwidth kernel density estimates (black lines and color shading). The Pontides volcanic arc ages are from a published compilation of pluton zircon U-Pb ages from the central and eastern Pontides. The Karakaya Complex samples are from Triassic sedimentary rocks and one modern river sample draining the İzmir-Ankara-Erzincan suture zone. The Central Sakarya Basement compilation includes bedrock and metasedimentary zircon U-Pb ages. See Table1for data sources.

Figure 6 .

 6 Figure 6. Detrital zircon age spectra from Central Sakarya Basin (CSB) and Sarıcakaya Basin (SB) detrital zircon samples grouped by basin phase (see main text); Phase 3 is split into CSB and SB groups. Data are displayed as probability density functions (black lines) and optimized

Figure 7 .

 7 Figure 7. Ternary diagrams of sandstone modal composition from the CSB. Samples are grouped by the sedimentary basin phases discussed in the text. Poles: Qt: total quartz; Qm: monocrystalline quartz; F: feldspar; L: lithics; Lm: metamorphic lithics; Ls: sedimentary lithics; Lv: volcanic lithics; Lt: total lithics (L + polycrystalline quartz).

Figure 8 .

 8 Figure 8. Probability density functions (black lines) and optimized fixed bandwidth kernel density estimates (black lines and shading) of all bedrock, modern, and detrital zircon ages grouped by basement terrane, basin, and stratigraphic age. See main text for discussion.

Figure 9 .

 9 Figure 9. All 150 to 30 Ma detrital zircon U-Pb ages from all SB and CSB samples are displayed as a histogram (1 Myr bins) and probability density function. The chronostratigraphic chart and depositional environments of the CSB and SB are after Ocakoğlu et al. (2018) and Mueller et al. (2019), respectively. Shading highlights the three sedimentary basin phases discussed in the text.

Figure 10 .

 10 Figure 10. Schematic diagram of multi-phase collision scenarios (inspired by[START_REF] Darin | Rapid Late Eocene Exhumation of the Sivas Basin (Central Anatolia) Driven by Initial Arabia-Eurasia Collision[END_REF]

  (a) Tavşanlı Zone slab breakoff. (b) Relict basin closure between the Sakarya (SKZ) and Istanbul (IST) Zones in the north and/or the Tavşanlı Zone (TVZ) and Afyon Zone or Tauride terrane (AF-TAU) in the south. (c) Subduction and underthrusting of progressively thicker Tavşanlı Zone continental lithosphere.

Figure 1 .

 1 Figure 1.

Figure 2 .

 2 Figure 2.

Figure 3 .

 3 Figure 3.

  Figure 4.

Figure 5 .

 5 Figure 5.

  Figure 6.

  Figure 7.

Figure 8 .

 8 Figure 8.

  Figure 9.

  Figure 10.

Acknowledgments

We thank Cassandra Brigham, Alison Duvall, Katharine Huntington, Begüm Kurtoğlu, Spencer Mattingly, Çelik Ocakoğlu, Ben Paulson, Aurora Rosenberger, Theresa Schwartz, Tamas Ugrai, and Melissa Wood for prolific discussions and for field and lab assistance. We thank Editor Peter van der Beek and Aral Okay and two anonymous reviewers for providing constructive and thoughtful reviews. This work was supported by NSF EAR-1543684 and Eskişehir Osmangazi University Fund 200715024. Datasets for this research are included in the supplementary information files and archived in a data repository (http://dx.doi.org/10.17632/hz5dxh9vrn.1). manuscript submitted to Geochemistry, Geophysics, Geosystems

Data Source

Sample