Tianyi Shen
email: shenty@cug.edu.cn

G Wang

A Replumaz

L Husson

A A G Webb

M Bernet

P H Leloup

P Zhang

G Mahéo

K Zhang

Miocene subsidence and surface uplift of southernmost Tibet induced by Indian subduction dynamics

 Gangdese batholith experienced reheating between ~28 and 20 Ma, followed by rapid cooling between 20-17 Ma at a rate of ~50 °C/Myr  The northward migration of the Indian continent created a wave of dynamic topography that caused the successive subsidence and uplift  The Kailas basin is a unique occurrence of a perched basin that owes its existence to dynamic deflection within a mountain belt

Introduction

The continent-continent collision between the Indian and Eurasian plates, following the northward movement of the Indian plate since the early Cenozoic, formed the Tibetan Plateau [START_REF] Dewey | Extensional collapse of orogens[END_REF][START_REF] Najman | Timing of India-Asia collision: Geological, biostratigraphic, and palaeomagnetic constraints[END_REF][START_REF] Decelles | Paleocene-Eocene foreland basin evolution in the Himalaya of southern Tibet and Nepal: Implications for the age of initial India-Asia collision[END_REF][START_REF] Hu | The timing of India-Asia collision onset -Facts, theories, controversies[END_REF]. The orogenic deformation front has migrated both northward and southward from the initial collision zone at the Yarlung-Tsangpo suture zone [START_REF] Tapponnier | Oblique Stepwise Rise and Growth of the Tibet Plateau[END_REF][START_REF] Replumaz | Reconstruction of the deformed collision zone between India and Asia by backward motion of lithospheric blocks[END_REF][START_REF] Yin | Cenozoic tectonic evolution of Asia: A preliminary synthesis[END_REF][START_REF] Kapp | Mesozoic-Cenozoic geological evolution of the Himalayan-Tibetan orogen and working tectonic hypotheses[END_REF]. In the center of this large Cenozoic continental collision zone, thick conglomerate layers were deposited during the Oligocene to Miocene and are exposed along strike to the north of the Indus-Yarlung suture zone with an east-west extension of more than 1000 km but with a north-south width of less than 10 km [START_REF] Heim | Central Himalayan geological observations of the Swiss expedition[END_REF][START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]. These rocks have been referred to as the Kailas Formation, named after the most famous holy mountain in Tibet, Mt. Kailas [START_REF] Cheng | Geologic Map of the Gaize Region with Report: Tibetan Bureau of Geology and Mineral Resources[END_REF], which is located in western Tibet and is composed of subhorizontal conglomerates [e.g., [START_REF] Lacassin | Large-scale geometry, offset and kinematic evolution of the Karakorum fault, Tibet[END_REF][START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]. The sediments of the current 6566-m-high peak have been buried to a depth of ~4-7 km during the early Miocene and have experienced significant exhumation at 17

Ma [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF]. In other places, the Kailas Formation experienced variable rates of accumulation, burial, exhumation and deformation [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF][START_REF] Sanchez | Tectonic evolution of the India-Asia suture zone since Middle Eocene time, Lopukangri area, south-central Tibet[END_REF]Leary et al., 2016a]. Therefore, it could provide critical information for understanding the processes of India-Asian continental collision during the Cenozoic. However, the tectonic context of the conglomerates is still debated, with points of view including a foreland basin related to the southward-thrusting Gangdese Thrust (GT) [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF], a flexural basin associated with the termination or renewal of India-Asia collision [START_REF] Aitchison | When and where did India and Asia collide[END_REF][START_REF] Wang | Flexural bending of southern Tibet in a retro foreland setting[END_REF], and an extensional basin due to Indian slab rollback [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]Leary et al., 2016a]. The successive burial and exhumation processes in the early Miocene have highlighted significant uncertainty regarding the surface geological evolution and mantle dynamics in the collision zone since the Oligocene [e.g., [START_REF] Replumaz | Indian continental subduction and slab break-off during Tertiary collision[END_REF][START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF]Leary et al., 2016a;[START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF], which has renewed interest in the study of the geodynamics and mechanisms of the collision.

Disturbances in the subduction zone alter mantle flow, which in turn vertically deflects the surface of the Earth, thereby providing a simple mechanism to explain the formation of deep intracontinental basins [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF][START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF]. This process is commonly referred to as dynamic topography: viscously flowing mantle imposes vertical stresses underneath the lithosphere, and these stresses are counterbalanced by a dynamic deflection of the surface of the Earth [START_REF] Husson | Unraveling topography around subduction zones from laboratory models[END_REF]. In regions where the structure of the mantle quickly evolves (typically subduction zones), transient dynamic topography is expected to respond efficiently, and to be detectable in the geological record. Several theoretical [e.g. [START_REF] Gurnis | Generation of long wavelength heterogeneity in the mantle by the dynamic interaction between plates and convection[END_REF][START_REF] Husson | Unraveling topography around subduction zones from laboratory models[END_REF] and case studies [e.g., [START_REF] Husson | Dynamic topography above retreating subduction zones[END_REF] point to kilometer-scale dynamic deflections in the topography above subduction zones. Such deflections are commonly transient, and the fast-changing Indian subduction dynamics are no exception. The northward motion of the Indian plate relative to its own slab [e.g. [START_REF] Van Der Voo | Tethyan subducted slabs under India[END_REF][START_REF] Replumaz | Indian continental subduction and slab break-off during Tertiary collision[END_REF] has been shown to be accompanied by a migration of the deflection above the mass anomaly in the mantle [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF]. At the surface, this process manifests as a southward-migrating wave of subsidence followed by a southward-migrating wave of uplift, already studied from the Himalaya towards the Ganges basin. These short-lived episodes explain both the Miocene surface uplift of the Himalaya and subsidence in the Ganges basin [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF][START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF], as well as the formation of sedimentary basins on the NW Indian plate [START_REF] Najman | The Late Eocene-Early Miocene Unconformities of the NW Indian Intraplate Basins and Himalayan Foreland: A Record of Tectonics or Mantle Dynamics?[END_REF]. This model offers a simple, single mechanism that explains a range of first-order observations. Thus, this interpretation represents an alternative to a more complex combination of processes involving removal of the mantle lithosphere [START_REF] Harrison | Raising Tibet[END_REF][START_REF] Molnar | Mantle dynamics, uplift of the Tibetan Plateau, and the Indian monsoon[END_REF], elastic flexure of the lithosphere [START_REF] Lyon-Caen | Constraints on the structure of the Himalaya from an analysis of gravity-anomalies and a flexural model of the lithosphere[END_REF], and extension triggered by slab rollback [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]Leary et al., 2016a].

In this paper, we further test the dynamic topography model by exploring whether the predicted southward-migrating waves of subsidence and uplift are recorded to the north of the Himalaya range and in southern Tibet. We revisit the spatial extent of the burial and exhumation experienced by the Kailas Formation and underlying rocks by reporting new in situ zircon fission-track (ZFT) and apatite fission-track (AFT) data and thermal modeling for the Gangdese batholith immediately to the north of the main preserved body of Kailas Formation rocks in the Mt. Kailas region in western Tibet. We focus on the succession of subsidence and exhumation and use numerical simulations to show that transient dynamic topography in response to mantle loading and unloading successfully reconciles structural, sedimentological, and thermochronological data in southern Tibet.

Geological settings

Regional geology

The Indus-Yarlung suture zone represents the site of the India-Asia continent-continent collision that began at ca. 60 Ma [e.g. [START_REF] Najman | Timing of India-Asia collision: Geological, biostratigraphic, and palaeomagnetic constraints[END_REF][START_REF] Decelles | Paleocene-Eocene foreland basin evolution in the Himalaya of southern Tibet and Nepal: Implications for the age of initial India-Asia collision[END_REF][START_REF] Hu | The timing of India-Asia collision onset -Facts, theories, controversies[END_REF] and separates the Lhasa terrane to the north and the Tethyan Himalaya to the south [START_REF] Yin | Geologic evolution of the Himalayan-Tibetan orogen[END_REF]. Late Jurassic and early Cretaceous volcano-sedimentary rocks are widely distributed to the north of the suture zone in the Lhasa terrane and are related to the northward subduction of the Neo-Tethys oceanic lithosphere [START_REF] Zhu | The Lhasa Terrane: Record of a microcontinent and its histories of drift and growth[END_REF]. The Gangdese magmatic arc is located along the southern margin of the Lhasa terrane (Fig. 1) and is related to the end of oceanic subduction and removal of the slab at the onset of collision [e.g. [START_REF] Mahéo | A slab breakoff model for the Neogene thermal evolution of South Karakorum and South Tibet[END_REF][START_REF] Mahéo | Partial Melting of Mantle and Crustal Sources beneath South Karakorum, Pakistan: Implications for the Miocene Geodynamic Evolution of the IndiaAsia Convergence Zone[END_REF]. This arc consists of the Linzizong volcanic rocks (with crystallization ages between ~65 and 45 Ma), the coeval Gangdese batholith (with crystallization ages between ~60 and 40 Ma) [START_REF] Harrison | The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet[END_REF]Mo et al., 2008, and references therein], and calc-alkaline and potassicultrapotassic volcanic rocks that formed in an Oligocene-Miocene stage [START_REF] Chung | Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism[END_REF]. Some studies interpreted the last group of rocks as the products of a second slab breakoff, of the Indian lithosphere slab [e.g. [START_REF] Mahéo | A slab breakoff model for the Neogene thermal evolution of South Karakorum and South Tibet[END_REF][START_REF] Mahéo | Partial Melting of Mantle and Crustal Sources beneath South Karakorum, Pakistan: Implications for the Miocene Geodynamic Evolution of the IndiaAsia Convergence Zone[END_REF]. Given the ages of the magmatic and volcanic rocks (K-Ar age of lamprophyres from the Karakorum range, NE Pakistan [START_REF] Rex | The geochemical and tectonic evolution of the Central Karakoram, North Pakistan[END_REF], U-Pb and 40 Ar/ 39 Ar ages of adakitic volcanic rocks in western Tibet [START_REF] Miller | Post-collisional potassic and ultrapotassic magmatism in SW Tibet: Geochemical and Sr-Nd-Pb-O isotopic constraints for mantle source characteristics and petrogenesis[END_REF][START_REF] Kapp | Mesozoic and Cenozoic tectonic evolution of the Shiquanhe area of western Tibet[END_REF]Willams et al., 2004;[START_REF] Gourbet | Western Tibet relief evolution since the Oligo-Miocene[END_REF], and the U-Pb age of an adakite in eastern Tibet [START_REF] Zhang | Southern Tibetan Oligocene-Miocene adakites: A record of Indian slab tearing[END_REF], Fig. 1), breakoff is thought to have initiated at ~25 Ma at the western and eastern ends of the slab [e.g. [START_REF] Replumaz | Indian continental subduction and slab break-off during Tertiary collision[END_REF][START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF][START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF].

The exhumation history of the Gangdese batholith has been highly debated over the past 20 years. In the eastern part of the batholith, near the city of Lhasa, 40 Ar/ 39 Ar thermochronological analyses have shown that the Gangdese batholith locally experienced two cooling stages, at 30-25 and 20-15 Ma [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]Harisson et al., 2000]. They have been interpreted as due to upper crustal thickening, in between the southward thrusting along the Gangdese Thrust (GT) (30-25 Ma) and northward thrusting along the Great Counter Thrust (GCT) (20-15 Ma), two major thrust faults described south of the Kailas Formation [START_REF] Heim | Central Himalayan geological observations of the Swiss expedition[END_REF][START_REF] Burg | Structure and metamorphism of a tectonically thickened continental crust: The Yalu Tsangpo suture zone (Tibet)[END_REF][START_REF] Ratschbacher | Distributed deformation in southern and western Tibet during and after the India-Asian collision[END_REF][START_REF] Yin | Tertiary structural evolution of the Gangdese thrust system, southeastern Tibet[END_REF][START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF][START_REF] Kapp | The Gangdese retroarc thrust belt revealed[END_REF]. The north-dipping GT is mainly exposed along the eastern part of the Indus-Yarlung suture zone (between the Zedong and Xigaze) and was active during the Oligocene [START_REF] Yin | Tertiary structural evolution of the Gangdese thrust system, southeastern Tibet[END_REF][START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]. The south-dipping GCT was active during 19-16 Ma [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]Harrison et al., 2000;[START_REF] Laskowski | Tectonic evolution of the Yarlung suture zone, Lopu Range region, southern Tibet[END_REF] and juxtaposed rocks associated with the Tethyan Himalaya, Gangdese forearc basin and accretionary wedge atop the Gangdese magmatic arc and Kailas Formation [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF][START_REF] Murphy | Structural evolution and sequence of thrusting in the Tethyan fold-thrust belt and Indus-Yalu suture zone, southwest Tibet[END_REF]. Low-temperature thermochronological analyses (fission-track and (U-Th)/He) detected the second stage of cooling, which has been explained via a diverse range of interpretations, such as movement along the GT [START_REF] Copeland | Thermal evolution of the Gangdese batholith, southern Tibet -a history of episodic unroofing[END_REF], surface uplift [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF][START_REF] Tremblay | Erosion in southern Tibet shut down at similar to 10 Ma due to enhanced rock uplift within the Himalaya[END_REF], and north-dipping duplex development beneath the Gangdese magmatic arc [START_REF] Laskowski | Gangdese culmination model: Oligocene-Miocene duplexing along the India-Asia suture zone, Lazi region, southern Tibet[END_REF].

In western Tibet, the dextral Karakorum strike-slip fault has been shown to be a transpressive flower structure, producing thrusting in the south of the Kailas basin. The fault is connected to arc-perpendicular normal faults, such as the Xiao Gurla and Gurla Mandhata faults that have formed since ~15 to 9 Ma [e.g. [START_REF] Murphy | Structural evolution and sequence of thrusting in the Tethyan fold-thrust belt and Indus-Yalu suture zone, southwest Tibet[END_REF][START_REF] Lacassin | Large-scale geometry, offset and kinematic evolution of the Karakorum fault, Tibet[END_REF][START_REF] Chevalier | Slip-rate measurements on the Karakorum Fault may imply secular variations in fault motion[END_REF][START_REF] Valli | Twenty million years of continuous deformation along the Karakorum fault, western Tibet: A thermochronological analysis[END_REF][START_REF] Pullen | Cenozoic anatexis and exhumation of Tethyan Sequence rocks in the Xiao Curia Range, Southwest Tibet[END_REF][START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF][START_REF] Shen | Controls on Cenozoic exhumation of the Tethyan Himalaya from fissiontrack thermochronology and detrital zircon U-Pb geochronology in the Gyirong basin area, southern Tibet[END_REF] (Fig. 1). Along the southern front of the Himalaya, sole thrusts are propagating towards the foreland, forming an orogenic wedge, and include duplex systems associated with the Main Central Thrust (MCT, active during the early Miocene), the Main Boundary Thrust (MBT, active during the late Miocene), and the Main Frontal Thrust (MFT, active during the Quaternary) [e.g., Kohn et al., 2000;[START_REF] Coutand | Geometry and kinematics of the Main Himalayan Thrust and Neogene crustal exhumation in the Bhutanese Himalaya derived from inversion of multithermochronologic data[END_REF] (Fig. 1).

Oligocene-Miocene sedimentary rocks deposition along the Gangdese magmatic arc

Deposition of the Kailas Formation to the south of the magmatic arc occurred earlier in the west (near the Kailas peak) between 26 and 21 Ma, between 25 and 22 Ma near Xigaze, and later eastward (near Zedong-Lhasa), between 23 and 18 Ma [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Decelles | Oligocene-Miocene Great Lakes in the India-Asia Collision Zone[END_REF]Leary et al., 2016a;[START_REF] Ai | The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane[END_REF]. Detailed sedimentary analysis suggests that the formation in the Mt. Kailas area consists of a lower coarse-grained proximal conglomerate, a more distal fluvial sandstone member, a lacustrine shale and sandstone member, and an upper redbed clastic member [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]. Most of the sediments were derived from the Gangdese magmatic arc to the north, with the exception of the uppermost redbed member [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]Leary et al., 2016a]. Previous study suggested that the Kailas basin was never more than 20 km wide [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]. However, several isolated outcrops of the formation are observed overlying the Gangdese batholith to the north of the present-day northern basin boundary (Fig. 2), indicating that the Kailas Formation extended farther north than previously thought [START_REF] Shen | Long-term exhumation history of the Gangdese magmatic arc: Implications for the evolution of the Kailas Basin, western Tibet[END_REF]. The layers near the Mt. Kailas area are nearly horizontal and the thickness of exposed stratigraphy is over 1500 m [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Ai | The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane[END_REF]Shen et al., 2019]. AFT and zircon (U-Th)/He ages from the Kailas Formation at the depth of ~1000 m in the stratigraphic column near the Kailas peak are younger than the depositional age and require between 4 and 7 km of burial followed by rapid cooling and exhumation starting at 17 ± 1 Ma with a cooling rate of ca. 50 °C/Myr [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF]. The movement along the GCT deformed the southernmost fringe of the Kailas Formation [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]. However, the subhorizontal stratigraphy of Mt. Kailas in the northern part of the basin also implies that crustal shortening and deformation have not affected the whole basin [e.g. [START_REF] Lacassin | Large-scale geometry, offset and kinematic evolution of the Karakorum fault, Tibet[END_REF][START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]. Further east in the Xigaze area, the Kailas Formation is ~1000 m thick [Leary et al., 2016a], and a thermochronologic study also suggests burial between 4 and 7 km after the deposition according to a granite sample beneath ~900 m thick Kailas Formation [START_REF] Ge | Oligocene-Miocene burial and exhumation of the southernmost Gangdese mountains from sedimentary and thermochronological evidence[END_REF].

South of the Indus-Yarlung suture zone, in the central part of southern Tibet, deposition continued to the early Miocene with the Liuqu Formation exposed near Xigaze [Li et al., 2015b;Leary 2016b] (Fig. 1). Leary et al. [2016b] suggested the Liuqu Formation represented a wedgetop basin of the northward thrusting of the GCT during or immediately after Indian slab breakoff, as contractional deformation resumed in the suture zone. However, clumped isotope thermometry of the Liuqu Formation revealed that it was buried between 2.9 and 3.3 km [START_REF] Ning | The burial and exhumation history of the Liuqu Conglomerate in the Yarlung Zangbo suture zone, southern Tibet: Insights from clumped isotope thermometry[END_REF], followed by rapid exhumation between 12-10 Ma [Li et al., 2015b], indicating similar subsidence and uplift processes as for the Kailas Formation.

Oligocene-Miocene deposition to the north of the Gangdese magmatic arc has been little discussed so-far. The Rigongla Formation (Fig. 1), with alluvial fan, fluvial-channel and lacustrine facies, outcrops discontinuously at several locations within the central Lhasa terrane between Shiquanhe and Xigaze [START_REF] Wu | Tertiary of the Tibet[END_REF][START_REF] Kapp | Mesozoic and Cenozoic tectonic evolution of the Shiquanhe area of western Tibet[END_REF][START_REF] Zhu | Oligo-Mioence depositional facies of the Wuyu basin, southern Tibetan Plateau[END_REF][START_REF] Zhao | Stratigraphy of the Tibetan Plateau[END_REF][START_REF] Wang | Cenozoic geological map of the Tibetan Plateau and adjacent areas[END_REF][START_REF] Zhang | Palaeogene-Neogene stratigraphic sequences of the Tibetan Plateau and their response to plateau uplift[END_REF][START_REF] Currie | Multiproxy paleoaltimetry of the late Oligocene-Pliocene Oiyug basin, southern Tibet[END_REF][START_REF] Gourbet | Western Tibet relief evolution since the Oligo-Miocene[END_REF][START_REF] Bai | The discovery and significance of the sporopollen assemblages from the Oliogene Rigongla Formation in the Lunggar region Zhongba Xizang[END_REF]. The Rigongla Formation consists overall of an over 500-m-thick fining-upward sequence of conglomerates, sandstones and mudstones derived from the surrounding Cretaceous volcanic rocks (interbedded dacite to andesite) [START_REF] Currie | Multiproxy paleoaltimetry of the late Oligocene-Pliocene Oiyug basin, southern Tibet[END_REF]. Dacites in the lower Rigongla Formation yielded a K-Ar age of 31.4 Ma [START_REF] Zhao | Stratigraphy of the Tibetan Plateau[END_REF][START_REF] Wang | Cenozoic geological map of the Tibetan Plateau and adjacent areas[END_REF], providing a maximum age of deposition for the unit. Vitrinite reflectance values indicate that the rocks were buried to maximum temperatures of 95-125 °C [START_REF] Currie | Multiproxy paleoaltimetry of the late Oligocene-Pliocene Oiyug basin, southern Tibet[END_REF], corresponding to a depth between 3 and 4 km with an estimated thermal gradient of 30 °C/km.

Controversies associated with the formation of the Kailas basin

Several models have been proposed for the tectonic context of the Kailas basin deposition based on geological observations, all with major shortcomings or inconsistencies. [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF] suggest that the Kailas Formation was deposited in a foreland basin system related to the uplift and erosion of the Gangdese magmatic arc to the north of the basin. The basin was uplifted by the top-to-the-south GT below the batholith, which is blind in the Kailas region but emergent to the east in the Zedong region, possibly active between ~31 and 24 Ma [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF][START_REF] Harrison | The Zedong Window: A record of superposed Tertiary convergence in southeastern Tibet[END_REF]. Both the absence of the GT in the Mt. Kailas region and the proposed timing for the onset of the fault (5 Ma earlier than the deposition of the Kailas Formation) argue against this model. [START_REF] Wang | Flexural bending of southern Tibet in a retro foreland setting[END_REF] proposed another compressional model, which interpreted the basin as a flexural foredeep basin loaded, to the south in this case, by the top-to-the-north GCT, which bounded the basin to the south. However, the onset of the GCT (19-16 Ma) after the main deposition phase of the Kailas Formation (26-21 Ma), as well as the northern provenance of the sediments, challenge this interpretation [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Laskowski | Tectonic evolution of the Yarlung suture zone, Lopu Range region, southern Tibet[END_REF].

Finally, based on sedimentary and thermochronology studies, it has been suggested that the Kailas Formation was deposited in an extensional context during relative southward rollback of the Indian slab below southern Tibet prior to Miocene slab breakoff [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF]Leary et al., 2016a;[START_REF] Laskowski | Tectonic evolution of the Yarlung suture zone, Lopu Range region, southern Tibet[END_REF][START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF]. In this model, the northern edge of the Indian slab reached the northern Lhasa terrane between 30 and ~26 Myr ago [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Kapp | Mesozoic-Cenozoic geological evolution of the Himalayan-Tibetan orogen and working tectonic hypotheses[END_REF]. The subsequent, long-range slab rollback is interpreted to be represented by a coeval southward migration of volcanism across the Lhasa terrane. During sediment deposition, the Kailas basin would have been bounded to the south by a normal fault and was later disrupted by thrusting on the GCT. The Kailas basin was then subsequently exhumed in response to renewed Indian plate underthrusting following slab detachment. However, at the scale of the Tibetan plateau, there are only three volcanic belts [START_REF] Chung | Tibetan tectonic evolution inferred from spatial and temporal variations in post-collisional magmatism[END_REF], which have been interpreted as related to subduction events. The main belt is the Gangdese magmatic arc following the Indus-Yarlung suture, related to the northward subduction of the Indian plate. Another belt is following the Jinsha suture, related to the southward subduction of the Asian lithosphere in an early phase of collision [e.g. [START_REF] Horton | Paleocene-Eocene syncontractional sedimentation in narrow, lacustrine-dominated basins of east-central Tibet[END_REF][START_REF] Spurlin | Structural evolution of the Yushu-Nangqian region and its relationship to syncollisional igneous activity east-central Tibet[END_REF][START_REF] Goussin | Carbonated inheritance in the Eastern Tibetan lithospheric mantle: Petrological evidences and geodynamic implications[END_REF]. Finally, one belt follows the Kunlun suture, related to on-going southward Asian lithosphere subduction since ~15 Ma (Fig. 1). In between the Indus-Yarlung and the Jinsha sutures, volcanism is sparse in the Qiangtang and the Lhasa terranes, where its spatial pattern does not appear consistent with a continuous southward migration wave associate to a slab-roll-back (Fig. 1). Furthermore, this scenario relies on unsupported geodynamic and structural inferences and unlikely mechanical behavior.

Structurally the extensional setting is only indirectly inferred from the large-scale architecture of the basin, which is interpreted as growth-strata. No clear evidence of normal faulting is reported [Leary et al., 2016a]. The mechanical impact of slab rollback within a sustained collisional setting, as advocated in this model, may be misinterpreted. While the slab continued to roll back during the deposition of the Kailas Formation, the still-converging Indian and Eurasian plates sustained compression in the Himalaya, and potentially caused extension in the mantle wedge above the slab. Only compressionnot extensionis expected between the colliding lithospheres [START_REF] Replumaz | Asian collisional subduction: A key process driving formation of the Tibetan Plateau[END_REF][START_REF] Pitard | Mantle kinematics driving collisional subduction: Insights from analogue modeling[END_REF]. Therefore, both the absence of unambiguous extensional structures and a problematic geodynamic framework weakens this interpretation.

Thermochronology

Samples and dating results

We collected six bedrock samples from the Gangdese batholith along two transects, one 20 km and another ~80 km east of Mt. Kailas (Fig. 2), for AFT, ZFT and zircon U-Pb dating.

Detailed analytical procedures for zircon U-Pb, ZFT and AFT dating are presented in the Supporting Text S1. The zircon U-Pb ages are 41.0 ± 1.1 Ma (13T02) and 50.8 ± 1.6 Ma (14T05) (see Table S1 for details), with Pb/U concordia diagrams created using Isoplot (v. 3.75) [START_REF] Ludwig | User's manual for Isoplot 3[END_REF] shown in Figure 3. ZFT analysis yielded cooling ages between 19.6 ± 2.0 and 24.1 ± 3.3 Ma (±2σ) (Table 1), and AFT analysis yielded cooling ages between 16.3 ± 1.9 and 11.5 ± 2.1 Ma (±2σ) (Table 3). Detailed fission-track data are provided in the Appendix A1. These ages do not show significant correlation with sample elevation (Fig. 4A). For samples 13T01 and 13T02, 135 and 77 apatite confined track lengths are measured (Table 3), providing mean AFT c-axis projected length of 13.89 ± 1.32 and 13.74 ± 1.38 μm (with 1 standard deviation), respectively. The samples 14T01 and 14T05 each yielded less than 50 measured track lengths, with mean values of 14.22 ± 1.09 and 14.59 ± 1.14 μm.

One modern river sand sample was collected to the north of the Gangdese magmatic arc, approximately 90 km east of Shiquanhe (Fig. 5), and subjected to ZFT analysis. The river originated from the Mt. Kailas area to the south, running mostly northward through the Linzizong volcanic rocks and belonging to the Indus drainage system. The Linzizong volcanic rocks cover most of the drainage area; therefore, the sediment sample could be used to reveal the long-term exhumation history of the Linzizong volcanic rocks in the northern part of the Gangdese magmatic arc. Central and peak ages of the sample are determined and plotted with the RadialPlotter by [START_REF] Vermeesch | RadialPlotter: A Java application for fission track, luminescence and other radial plots[END_REF] and presented in Table 4 andFig

Thermochronological modeling

Fission-track data, including AFT ages, AFT lengths and ZFT ages, are modeled using the QTQt software (v. 5.5.0) [START_REF] Gallagher | Transdimensional inverse thermal history modeling for quantitative thermochronology[END_REF] to extract thermal history models. We only performed modeling for samples from the western transect (sample 13T series) because samples from the other transect provided insufficient AFT length data for modeling. The two zircon U-Pb ages from the Gangdese batholith of 41. 0 ± 1.1 Ma (13T02) and50.8 ± 1.6 Ma (14T05), interpreted as the age of the batholith intrusion and crystallization, have been introduced into the model as a thermal constraint of 750 ± 100 °C [START_REF] Harrison | Temperature spectra of zircon crystallization in plutonic rocks[END_REF][START_REF] Valley | Comment on "Heterogeneous Hadean hafnium: Evidence of continental crust at 4.4 to 4.5 Ga[END_REF] between 50 and 40 Ma. The fact that the Kailas Formation was deposited unconformably on the granite means that the top of the batholith was at the surface before deposition started, i.e., at ~26 Ma at the location of the Kailas basin [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF]. This condition has been introduced as a second thermal constraint with a low temperature (0-400 °C) between 32 and 26 Ma to take into account the shallow depth range of the samples before Kailas Formation deposition (Table 1 and Fig. 4B) and the present-day surface temperature of 0 ± 10 °C (mean annual surface temperature from 1961 to 2000 on the Tibetan Plateau, [START_REF] Yang | Permafrost degradation and its environmental effects on the Tibetan Plateau: A review of recent research[END_REF]).

After discarding the initial 50,000 burn-in iterations, 200,000 iterations of the model are run. For fission-track annealing kinetics, the multi-kinetic annealing model of [START_REF] Ketcham | Improved measurement of fission-track annealing in apatite using c-axis projection[END_REF] was chosen for AFT data, and the kinetics of [START_REF] Yamada | Statistical modelling of annealing kinetics of fission tracks in zircon; Reassessment of laboratory experiments[END_REF] are chosen for ZFT data. Compositionally dependent initial track lengths are calculated based on a Dpar value for each apatite grain, calibrated against the Durango apatite standard. Detailed QTQt modeling parameters are shown in Table 1, and all the data used for QTQt modeling are shown in Supplementary Table S2. The Eocene post-magmatic cooling is constrained by the two thermal constraints imposed on the model, resulting in rapid cooling between ~40 Ma and ~28 Ma, compatible with the published K-feldspar 40 Ar/ 39 Ar age of 31.33±0.26 Ma (Fig. 4A) from the nearby granite sample 95-6-11 (Fig. 2) [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]. For the fission track data, the best fit inversion model obtained with QTQt shows a 3-stage thermal history (Fig. 4B): 1) heating from ~200 °C (60-350 °C with 95% confidence interval) to ~380 °C (320-420 °C with 95% confidence interval) between ~28-26 and ~20 Ma (16-40 °C/Myr), 2) rapid cooling from ~380 °C (320-420 °C with 95% confidence interval) to ~100 °C (30-120 °C with 95% confidence interval) between 21-20 and 17 Ma with a minimum cooling rate of ~50 °C/Myr , and 3) relatively slow cooling since ~6 Ma after a ~10 Myr residence time in the AFT partial annealing zone. The model-predicted ages and track length are plotted in Figure 4C, and the individual sample predictions by QTQt are provided in Appendix A2.

Dynamic topography modeling

We modeled changes in dynamic topography to decipher the link between first-order geomorphic changes and deep slab movements. We model the viscous flow beneath the Indian-Eurasian convergence zone following the Stokeslets approximation [START_REF] Morgan | Gravity anomalies and convection currents: 1. A sphere and cylinder sinking beneath the surface of a viscous fluid[END_REF][START_REF] Harper | Mantle flow due to internal vertical forces[END_REF], which has proven successful in global [e.g. [START_REF] Ricard | A geodynamic model of mantle density heterogeneity[END_REF]] and more regional [START_REF] Guillaume | Neogene uplift of central eastern Patagonia: Dynamic response to active spreading ridge subduction?[END_REF] models. The density field is discretized into point masses, and each point mass i induces an elementary flow for which the stream function is known [e.g. [START_REF] Batchelor | An Introduction to Fluid Mechanics[END_REF], which can be written as follows:

Ψ 𝑖 = ∆ρ𝜐 𝑖 g 8πη 𝑟 𝑖𝑗 sin 2 𝜃 𝑖𝑗
where ∆ρ𝜐 𝑖 is the mass anomaly associated with each point mass, g is the acceleration of gravity, η is the viscosity, 𝑟 𝑖𝑗 is the distance from the point mass i to a point j at the surface, and 𝜃 𝑖𝑗 is the angle between the vector ij and g. The normal stress is computed following the image technique, as in [START_REF] Morgan | Gravity anomalies and convection currents: 1. A sphere and cylinder sinking beneath the surface of a viscous fluid[END_REF]:

𝐹 𝑖𝑗 = 3∆ρ𝜐 𝑖 g𝑧 𝑖 3 π𝑟 𝑖𝑗 5
where 𝑧 𝑖 is the depth of the point mass. For a stress-free surface, the normal stress is compensated by an opposite surface load. That surface load is a deflection of the surface (dynamic topography):

ℎ 𝑖𝑗 = 𝐹 𝑖𝑗 (𝜌 𝑚 -ρ)g
where 𝜌 𝑚 is the density of the mantle and ρ is the density of water in immersed domains, air in subaerial domains (as in the Himalaya for instance) or sediments in sedimentary plains (such as the Indo-Gangetic plain). The total deflection 𝐻 𝑖𝑗 is the sum of all individual deflections, and the dynamic topography at a given location is given by the following:

𝐻 𝑖𝑗 = 3∆ρ𝜐 𝑖 g𝑧 𝑖 3 π𝑟 𝑖𝑗 5 (𝜌 𝑚 -ρ)
Here, we take advantage of this semianalytical formalism to explore the dynamic topography (as in [START_REF] Husson | Dynamic topography above retreating subduction zones[END_REF]) above a flowing mantle around reconstructed idealized slab geometries.

We computed models of dynamic topography from our reconstructed geometries at intervals of 5 Myr, and only updating the slab geometry between 30 and 25 Ma in order to account for shortening and slab relocation beneath the Himalaya. Slab geometries at each time are reconstructed as described in [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF] and [START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF], based on geophysical observations for present-day, and geological arguments for past reconstructions in the past complemented by lessons from numerical and analogue models. In practice, slab geometries are simplified as down-dipping surfaces. Slabs are linear at the surface and distorted at depth. That distortion is defined by a laterally variable dip along the trench. Over time, the slab overall rotates from a north-dipping to a south-dipping slab over 25 Myr period. In addition, the slab gradually detaches from the edges towards the center over the same period. Last, the slab is offset with respect to the trench, by an amount that decreases over time, to account for relative rollback. Detailed geometries are accessible in [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF].

Slabs at each time step are discretized into individual Stokeslets (or point masses). The negative buoyancy of the slab at any time is computed assuming that an unstretched section of slab has a thickness of 110 km and a density contrast with the mantle of 60 kg m -3 . The total buoyancy of the slab in the upper mantle is assumed to be uniform per unit trench length at each time step. Because the lithosphere stretches as it gets closer to the edges, its thickness decreases.

Thus, the absolute buoyancy of the individual point masses decreases, and we adjust the values accordingly. In these models, we only consider the density anomaly of the slab; hence, the net density anomaly is positive. This implicitly corresponds to the assumptions that opposing buoyancy anomalies (to restore a neutral net buoyancy) are either uniformly distributed in the mantle or too remotely located to produce any effect in the area. In both cases, there is no impact on the model predictions. Summing up individual flows of each Stokeslet yields the entire flow, from which the vertical stress beneath the surface can be computed.

The vertical stress is compensated by a long-wavelength (100s of km) deflection, either filled with air, sediments, or water. This is critical because the magnitude of the deflection scales with the density contrast between the mantle and the filling material, namely, sediments in the Indo-Ganges plain and Kailas basin (corresponding to a density contrast of 500 kg m -3 ) and air in the Himalayan belt (corresponding to a density contrast of 3200 kg m -3 ). Note that the deflection has a very low aspect ratio (amplitude over wavelength) which implies that its geometry remains insensitive to the elasticity of the lithosphere, regardless of its compensation. We therefore predict air-compensated deflections δza and sediment-compensated deflections δzs (and their temporal variations, i.e., uplift and subsidence; Fig. 6). Because air-compensated topographic change by default assumes no erosion, we also computed the values of surface uplift with an amount of equivalent erosion in order for the elevation to remain constant throughout while maintaining isostasy. This scenario represents the maximum bound for bulk exhumation of the Gangdese batholith and Kailas basin caused by dynamic surface uplift.

As the slab remains stationary underneath the northward-drifting Indian plate, our model predicts a wave of dynamic subsidence migrating from the Lhasa terrane to the south (from ~30

to 26 Ma, Fig. 6) towards its current southern location, where it now explains the deflection of the foreland basin (see also [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF]). If compensated by sediments, as we hypothesize for the Kailas basin, the predicted deflection amounts to about 4 to 7 km (note that it would be only ~1 km in the absence of sedimentary infill, i.e., if the stresses were compensated by air instead of sediments). As the slab migrates southward relative to the Himalaya, the mantle load and dynamic deflection relocate southward and the topography bounces back. In the absence of erosion, our model predicts a surface uplift of ~1 km. If this surface uplift were instantaneously compensated by erosion, the amount of rock uplift could be as high as 5-6 km. explanations involve removal of the mantle lithosphere [e.g., [START_REF] Harrison | Raising Tibet[END_REF][START_REF] Molnar | Mantle dynamics, uplift of the Tibetan Plateau, and the Indian monsoon[END_REF] and elastic flexure of the lithosphere [e.g., Lyon-Caen and [START_REF] Lyon-Caen | Constraints on the structure of the Himalaya from an analysis of gravity-anomalies and a flexural model of the lithosphere[END_REF]. While each process is independently mechanically plausible, they are somewhat incompatible: if lithospheric unloading by removal of the lithospheric mantle in southern Tibet is invoked to explain the mid-Miocene uplift of southern Tibet and the High Himalaya, it implies that the vertical load exerted by the overriding lithosphere decreases. Removing the dense mantle lithosphere would counteract the overloading effect of the thickened crust and the net result would arguably be to unload the overriding lithosphere. The flexural response of the subducting plate would adjust accordingly, and the unloaded overriding lithosphere would be incapable to increase the deflection, but would perhaps decrease it. It follows that if delamination prevails in the upper plate, it therefore simultaneously rules out the lithospheric flexure hypothesis under an increased load at the plate boundary to explain the synchronous development of the foreland basin. In contrast, transient dynamic topography is a simple mechanism that provides a single explanation for these first-order observations. Here, we show that deposition and erosion of the Kailas Formation in the southern Lhasa terrane are further evidence of the same process.

Other explanations [e.g., [START_REF] Wang | Flexural bending of southern Tibet in a retro foreland setting[END_REF] invoke elasticity in the upper plate. Such a model would work if elasticity could prevail over long time scales (i.e., that of an orogen). We deem this hypothesis unlikely because the tectonically disrupted lithosphere and the high thermal regime suggest that viscous relaxation should quickly take over. Importantly, our model is conversely insensitive to the elasticity of the upper plate; the dynamic deflection only owes its origin to viscous fluxes in the mantle, and its cessation to the release of the viscous traction underneath the surface. The subsequent rebound (Fig. 6) is not due to any elastic rebound, but only to the restoration of isostatic equilibrium.

Transient subsidence across the Lhasa terrane

The best-fit line of thermal history shows the granites of the Gangdese batholith north of the Kailas basin after crystallization (50-40 Ma), began with a cooling to ~200 °C (60-350 °C with 95% confidence interval) during ~40 to ~28 Ma followed by a reheating phase between 28-26 and 21-20 Ma with temperature increasing to 320-420 °C, in the Kailas area (Fig. 4B). This reheating is coeval with the heating of the Kailas Formation during its deposition between ~26 and ~21 Ma [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF], suggesting that both the deeper sedimentary rocks of the basin and the underlying batholith were heated by the burial below thick sedimentation in a rapidly subsiding basin. Such burial is in agreement with our inversion of the thermal data showing that the batholith has been reheated to temperatures in excess of 320-420 °C (Fig. 4B).

This implies that subsidence was not restricted to the present-day exposure of the Kailas basin but spanned a broader region including the current Gangdese batholith exposures, which also experienced burial. Isolated exposures of conglomerates atop the batholith (Fig. 2) have been interpreted as local remnants of such a more extended Kailas Formation [START_REF] Shen | Long-term exhumation history of the Gangdese magmatic arc: Implications for the evolution of the Kailas Basin, western Tibet[END_REF] (Fig.

2).

Our dynamic models show that the southward-migrating wave of dynamic topography implies a phase of dynamic subsidence. The initiation of deposition could have occurred north of the Gangdese magmatic arc south of the Lhasa terrane above the Indian slab, subducted since ~35 Ma after the Neo-Tethyan slab breakoff at ~45 Ma [START_REF] Guillot | Reconstructing the total shortening history of the NW Himalaya[END_REF][START_REF] Replumaz | The coupling of Indian subduction and Asian continental tectonics[END_REF]. The deposition of the Rigongla Formation at ~31 Ma along the northern margin of the Gangdese magmatic arc between Shiquanhe and Xigaze could correspond to this initial subsidence (Fig. 6A). Dynamic topography modeling estimates subsidence amounting to ca. 4 km, compatible with the amount of sediment thickness between 3 and 4 km estimated for Rigongla Formation in Namling [START_REF] Currie | Multiproxy paleoaltimetry of the late Oligocene-Pliocene Oiyug basin, southern Tibet[END_REF]. Afterwards, subsidence migrated southwards as the northward-drifting Indian plate moved above its own stationary slab, leading to an overturned geometry (Fig. 6). During the Oligocene to Miocene (between 26 and 21 Ma), subsidence occurred in the Gangdese magmatic arc and Indus-Yarlung suture zone, yielding a maximum subsidence of ~ 6 km between the magmatic arc and suture zone (Fig. 6B). The current extent of the Kailas basin probably represents the location of the depocenter, which experienced ca. 4-7 km of burial [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF], and the magnitude of burial shallowed northward, with ca. 4 km of burial in the Gangdese batholith according to our thermal modeling (Fig. 6B). Moreover, according to the thermal model in this study, the 16-40 °C/Myr heating rate is compatible with a sediment accumulation rate of 0.5-1.3 km/Myr, which is consistent with the 4-7 km burial during 26-21 Ma at a deposition rate of 0.8-1.4 km/Myr [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF].

Importantly, the dynamic deflection did not create the basin by itself: the southward increase in mantle traction during sedimentation only manifested as a southward tilt of the upper plate. For the deflection to be filled by water and sediments at an elevation of 1500-2900 m above sea level [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Ai | The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane[END_REF], the basin thus needed to be capable of storing sediments. This inference implies that the dynamic deflection could be recorded only in sedimentary basins in which the outlets of the drainage system were partly hindered by surrounding topographic highs (Fig. 7 A and 7B). Indeed a paleoaltitude analysis has suggested that the Gangdese magmatic arc was slightly higher (~4500 m) than the area to the north (<3000 m) [START_REF] Ding | The Andean-type Gangdese Mountains: Paleo elevation record from the Paleocene-Eocene Linzhou Basin[END_REF], which provided ideal conditions for the deposition of the Rigongla Formation (Fig. 6A). South of the Indus-Yarlung suture, even though the Himalaya range had not reached its highest elevations [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Decelles | Oligocene-Miocene Great Lakes in the India-Asia Collision Zone[END_REF][START_REF] Ai | The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane[END_REF], the sediments deposited in the foreland basin in Nepal during the Oligocene [START_REF] Decelles | Detrital geochronology and geochemistry of Cretaceous-Early Miocene strata of Nepal: implications for timing and diachroneity of initial Himalayan orogenesis[END_REF][START_REF] Najman | Provenance of Eocene foreland basin sediments, Nepal: Constraints to the timing and diachroneity of early Himalayan orogenesis[END_REF], are indicative of some relief in the Himalaya, with elevation exceeded 3600 m at the late Miocene [START_REF] Chen | Lower-altitude of the Himalayas before the mid-Pliocene as constrained by hydrological and thermal conditions[END_REF]. These ranges could have circumscribed an interior drainage system around the Kailas basin (Fig. 7B). It follows that the dimensions of the Kailas basin were not exclusively set by the dynamic deflection itself but also by the elevations of the drainage outlets with respect to the depocenter. This difference in elevation dictated the thickness of the sedimentary layer that could be deposited at that time and, consequently, the extent of the Kailas basin in all directions. Geometrically, the basin thickens southward towards the Himalaya. This is attested by the fan-shape of the formation, which has previously been interpreted as growth strata [e.g. Leary et al., 2016a]. These rare conditions for sediment storage (instead of sediment export) explain why the extent of the sedimentary basin (possibly up to a maximum north-south width of 50 km at the time of deposition) is much narrower than the bulk dynamic deflection (several 100s of km) (Fig. 7B and 7 D). Additionally, the dynamic deflection not only caused subsidence but also the subsequent uplift (see following section), which means that with the southward migration of the deflection, uplifted areas to the north would be exhumed and eroded, which provided sediments southward to the subsided Kailas basin. This implies the formation of proximal sedimentary facies in the subsiding basin, at least along its northern margin, is consistent with the alluvial fan lithofacies of the Kailas Formation in the early stage [DeCelles et al., 2011]. Moreover, the ZFT peak age of the modern river sand from the central Lhasa terrane suggests that the volcanic rocks to the north of the Gangdese magmatic arc experienced exhumation at ~ 27.3±1.3 Ma (Fig. 5). This timing is coincident with the initial reheating of the Gangdese batholith to the south according to the thermal modeling (Fig. 4) and with the subsequent deposition in the Kailas basin. Volcanic gravel clasts, not granite, dominate the conglomerate clasts in the Kailas Formation, further indicating that the main source of the sediments was the Linzizong volcanic rocks to the north, not the Gangdese batholith [DeCelles et al., 2011;[START_REF] Shen | Long-term exhumation history of the Gangdese magmatic arc: Implications for the evolution of the Kailas Basin, western Tibet[END_REF]. Sedimentation ceased when the efficient river incision and evacuation of material from southern Tibet by the paleo-Yarlung River and Indus River occurred during the early to middle Miocene [START_REF] Carrapa | Tectonic and erosional history of southern Tibet recorded by detrital chronological signatures along the Yarlung River drainage[END_REF].

Middle Miocene uplift in southern Tibet

The period of subsidence in the sampled region was followed by a period of exhumation between 20 and 17 Ma. Considering a thermal gradient of 30 °C/km during this exhumation phase, the cooling is estimated to correspond to a minimum of 6.6 km of exhumation (6.6-13 km considering 95% confidence interval, according to the thermal model) (Fig. 4). Similar magnitudes of exhumation are recorded during the same time interval across the Ladakh batholith [START_REF] Kirstein | Rapid early Miocene exhumation of the Ladakh batholith, western Himalaya[END_REF], Kailas basin [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF], Gyirong basin [START_REF] Shen | Controls on Cenozoic exhumation of the Tethyan Himalaya from fissiontrack thermochronology and detrital zircon U-Pb geochronology in the Gyirong basin area, southern Tibet[END_REF], Xigaze area [Dai et al., 2013;[START_REF] Ge | Cenozoic thermo-tectonic evolution of the Gangdese batholith constrained by low-temperature thermochronology[END_REF][START_REF] Ge | Oligocene-Miocene burial and exhumation of the southernmost Gangdese mountains from sedimentary and thermochronological evidence[END_REF] and eastern Tibet [START_REF] Tremblay | Erosion in southern Tibet shut down at similar to 10 Ma due to enhanced rock uplift within the Himalaya[END_REF]Li et al., 2015a] (Fig. 1 and8). The elevation of southern Tibet was still relatively low (1500-2900 m) during the time of deposition (26-21 Ma) of the Kailas Formation [DeCelles et al., 2011[START_REF] Decelles | Oligocene-Miocene Great Lakes in the India-Asia Collision Zone[END_REF][START_REF] Ai | The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane[END_REF], while after the phase of exhumation (20-17 Ma) the Namling basin attained elevations of approximately 4000 m [START_REF] Spicer | Constant elevation of southern Tibet over the past 15 million years[END_REF]. Moreover, no major thrust faults or major deformation events are observed to be directly associated with the surface uplift of the Kailas basin, which lies in the footwall of the GCT, rests unconformably on the Gangdese batholith to the north (Fig. 2), and has a well-preserved, seemingly isopachous stratigraphy [e.g. [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]. Besides, the rapid river incision along the Yarlung-Tsangpo River mainly occurred after 15 Ma and was almost confined at the east of the Xigaze area [e.g., et al., 2012;Dai et al., 2013;Li et al., 2015a], so that it also cannot account for the exhumation between 20 and 17 Ma across the southern Tibet.

Rohormann

In the absence of clear evidence for horizontal tectonics, our dynamic model provides an Topographic subsidence may have bypassed the Himalaya itself, or was perhaps diminished across the range. This could occur due to development of the orogenic wedge (i.e., the MCT active during the early Miocene, the MBT active during the late Miocene, and the MFT active during the Quaternary [e.g., Kohn et al., 2000;[START_REF] Coutand | Geometry and kinematics of the Main Himalayan Thrust and Neogene crustal exhumation in the Bhutanese Himalaya derived from inversion of multithermochronologic data[END_REF]), such that tectonic shortening and concomitant crustal thickening (e.g., duplex systems) could have compensated for the otherwise predicted topographic deflection [START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF]. Further exploration of the impacts of the relative southwards motion of the slab on the thrust tectonics, topography, and climate across the Himalayan orogenic wedge are presented in [START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF].

The model-predicted dynamic surface uplift amounts to approximately 1 km. This value is consistent with the estimated increase in elevation before and after rock cooling, according to fossil leaf evidence, which suggested a 1500-2900 m elevation for the Kailas basin at ~23 Ma [START_REF] Ai | The uppermost Oligocene Kailas flora from southern Tibetan Plateau and its implications for the uplift history of the southern Lhasa terrane[END_REF] and a 4638±847 m elevation for southern Tibet at 15 Ma [START_REF] Spicer | Constant elevation of southern Tibet over the past 15 million years[END_REF]. The associated exhumation rates can be computed, to the first order, by assuming that isostatic equilibrium is restored when the elevation remains constant. This yields at maximum approximately 6 km of exhumation (Fig. 6C), which is comparable to data from the Gangdese batholith. This exhumation was accompanied by intense surface erosion, reducing the presentday preserved thickness of the Kailas Formation [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Decelles | Oligocene-Miocene Great Lakes in the India-Asia Collision Zone[END_REF] (Fig. 7D). In practice, exhumation does not strictly result in a constant elevation, and some of the surface uplift is not compensated by erosion. The remainder has uplifted the Kailas basin in southern Tibet from its basin surface elevation during deposition (1500-2900 m), to its modern elevation of 4500-6700 m.

Along-strike dynamic deflection

Along the Himalayan arc, the present-day dynamic deflection center (more than 6 km of sediment compensated deflection in the foreland) is located in the middle of the range, with no deflection below the eastern syntaxis, and a smaller amplitude to the west (-2 km), as shown by [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF] (Fig. 8A). It is due to the geometry of the slab, whose center of mass is located below the middle of the Himalayan range along the arc-parallel direction [e.g. [START_REF] Replumaz | Indian continental subduction and slab break-off during Tertiary collision[END_REF][START_REF] Replumaz | The coupling of Indian subduction and Asian continental tectonics[END_REF]. It has been similar since the Miocene time, with about 8 km of sediments deposited in the middle of the foreland basin along the arc-parallel direction, and less than 1 km close to the eastern and western syntaxes [Husson et al., 2014, and references therein].

Thermochronologic data reveal a similar longitudinal pattern for the Kailas formation, whose depocenter was located above the center of mass of the subducting slab, in the middle of the suture in the arc-parallel direction (Fig. 8A). In the Mt. Kailas area, rapid exhumation occurred at ca. 20-17 Ma for the Kailas Formation [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF] with AFT ages mostly younger than ~20 Ma (Fig. 8B). To the east, in the Xigaze area, rapid exhumation occurred at ca.

16-14 Ma for the Kailas Formation [START_REF] Ge | Oligocene-Miocene burial and exhumation of the southernmost Gangdese mountains from sedimentary and thermochronological evidence[END_REF] and 16-10 Ma for the Liuqu Formation [Li et al., 2015b], with also AFT ages younger than ~20 Ma (Fig. 8C). Between the Kailas Formation to the north and the Liuqu Formation to the south, the rocks from the Xigaze basin also experienced rapid exhumation at ca. 16-15 Ma showing < 20 Ma AFT (Fig. 8C) [START_REF] Li | India-Asia convergence: Insights from burial and exhumation of the Xigaze fore-arc basin, south Tibet[END_REF].In the Zedong area, thermal modeling also suggests rapid exhumation at 20-17 Ma for the Kailas Formation with AFT ages younger than 20 Ma [Li et al., 2015a] (Fig. 8 D). These thermochronologic data suggest all the late Oligocene to early Miocene deposits exposed south of the Gangdese magmatic arc have been experienced rapid exhumation around 20-15 Ma.

However, the AFT ages of the Gangdese batholith are not fully confined to younger than 20 Ma, except in the Mt. Kailas area (this study) (Fig. 8B). In the Xigaze area, granitic rocks located ~50 km north of the suture zone have AFT cooling ages at around 25 Ma, and the <20 Ma ages are mostly limited close to the Kailas Formation (Fig. 8C). The AFT ages of granitic rocks in the Zedong area are scatter from 60 to 15 Ma and most of them are older than 20 Ma (Fig. 8D),

indicating that the cooling ages of these granitic rocks were not reset by the deposition of the Kailas Formation probably due to shallow burial. This lack of young ages to the east of Tibet (Fig. 8) and of the Himalaya [START_REF] Webb | The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification[END_REF], corresponding to a low amount of sedimentation in the Ganges basin (Fig. 8A), suggests that the dynamic deflection center was in the Mt. Kailas area during the deposition of the Kailas formation (26-21 Ma) and in the Ganges basin (since 15 Ma) [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF]. The maximum of dynamic deflection result in deep subsidence and rapid uplift of both the Kailas Formation and the Gangdese batholith. To the east, the relatively old cooling ages of the Gangdese batholith and the young cooling ages of the Kailas Formation indicate shallow burial and reduced width of the Kailas Formation, implying a relatively small amplitude of deflection.

Conclusions

Geodynamic models attempting to explain the India-Asia collision process must incorporate a mechanism that allows the southern fringe of the upper plate plateau to be topographically depressed during collision. Our new thermochronological data and modeling of samples from the Gangdese batholith in southwestern Tibet illustrate that not only the Kailas basin but also over a relatively large region in southern Tibet was topographically depressed.

After being exposed at the surface, the Gangdese batholith experienced reheating during burial beneath the Kailas Formation between ~28-26 and 21-20 Ma, followed by rapid cooling between 20 and 17 Ma. This thermal history is compatible with the results of dynamic topography modeling based on mantle dynamics. We show that the northward migration at the surface of the Indian continent above its own stationary slab, induced a wave of dynamic topography, accompanied by a phase of subsidence in southern Tibet followed by a phase of uplift, as the dynamic deflection migrated southward to the Ganges basin. The computed estimate of the dynamic topography in the upper plate predicts approximately ~4 km of dynamic subsidence, followed by ~6 km of exhumation and 1 km of surface uplift in the southern Gangdese batholith, which are compatible with sedimentary and thermochronology observations.

The large-scale accumulation of sediments in the Kailas basin required conditions in which the sediments were not entirely transported out of the system by rivers at that time. The rivers draining the Gangdese batholith to the south did not cross the Himalaya range, which was rising during this period, thus providing the rare conditions necessary to block sediments in the interior of this elevated region. In fact, the very existence of the Kailas basin is itself surprising: dynamic deflection alone is not sufficient; the sediments must have been able to settle instead of being washed out. The Kailas basin is thus perhaps the unique occurrence of a perched basin that owes its existence to dynamic topography, which temporarily offered the appropriate conditions for sediment storage, while most intermontane basins are likely explained by lateral variations of crustal tectonics. program Isoplot [START_REF] Ludwig | User's manual for Isoplot 3[END_REF]. The data reduction procedures are described in [START_REF] Liu | In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[END_REF][START_REF] Liu | Continental and oceanic crust recycling-induced melt-peridotite interactions in the Trans-North China Orogen: U-Pb dating, Hf isotopes and trace elements in zircons of mantle xenoliths[END_REF] with GJ-1 zircon standards [START_REF] Jackson | The application of laser ablation-inductively coupled plasma-mass spectrometry to in situ U-Pb zircon geochronology[END_REF]. [START_REF] Ketcham | Improved measurement of fission-track annealing in apatite using c-axis projection[END_REF], and the black boxes are geological constraints on the modeling (see the text and Table 1 for details). surface uplift (red) and subsidence (blue) at present day as well as the depth contours of the foreland basin (yellow) [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF]. The contour values (km) are for a sediment compensation of dynamic subsidence (blue) or erosion compensated dynamic surface uplift (red). In the absence of erosion or surface uplift, the magnitude should be divided by a factor of ~6 (see [START_REF] Husson | Dynamic ups and downs of the Himalaya[END_REF] for details). The age of magmatism contours by Goussin et al.

[2020] are also illustrated. (B-D) AFT, AHe and ZHe ages of the Kailas Formation, Gangdese batholith and Xigaze basin against the distance from Indus-Yarlung suture zone in different locations. The data are summarized from [START_REF] Pan | Thermal and unroofing history of the Lhasa area, southern Tibetevidence from apatite fission track thermochronology[END_REF], [START_REF] Copeland | Thermal evolution of the Gangdese batholith, southern Tibet -a history of episodic unroofing[END_REF], Yang et al.

[1999], [START_REF] Wang | Cooling history and tectonic exhumation stages of the south-central Tibetan Plateau (China): constrained by 40 Ar/ 39 Ar and apatite fission track thermochronology[END_REF], Dai et al. [2013], [START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF], [START_REF] Wang | Flexural bending of southern Tibet in a retro foreland setting[END_REF], Li et al. [2015aLi et al. [ , 2015b[START_REF] Currie | Multiproxy paleoaltimetry of the late Oligocene-Pliocene Oiyug basin, southern Tibet[END_REF][START_REF] Li | India-Asia convergence: Insights from burial and exhumation of the Xigaze fore-arc basin, south Tibet[END_REF], [START_REF] Tremblay | Erosion in southern Tibet shut down at similar to 10 Ma due to enhanced rock uplift within the Himalaya[END_REF], J. Zhao et al. [2015], [START_REF] Ge | Cenozoic thermo-tectonic evolution of the Gangdese batholith constrained by low-temperature thermochronology[END_REF][START_REF] Ge | Oligocene-Miocene burial and exhumation of the southernmost Gangdese mountains from sedimentary and thermochronological evidence[END_REF],

and this study.

X X X 13T02 X X X 13T04 X X

Data treatment

The AFT lengths are measured from cf tracks and using c-axis projected lengths [START_REF] Ketcham | Improved measurement of fission-track annealing in apatite using c-axis projection[END_REF], with initial track length of 16.3 μm. The term for the kinetic parameter is Dpar [START_REF] Donelick | Apatite fission-track analysis[END_REF][START_REF] Ketcham | Variability of apatite fission-track annealing kinetics: III. Extrapolation to geological time scales[END_REF].

The AFT ages and lengths are combined in one data set for an individual sample, while the ZFT ages were regarded as another data input file for the same sample, with the same GPS information but different annealing parameters. These data were modeled as an age-elevation profile.

Additional geologic information

Assumption Explanation and data source

At a surface temperature of 0 ± 10 °C by 0 Ma

Based on the annual mean surface temperature of the Tibetan Plateau for the years from 1961 to 2000 [START_REF] Yang | Permafrost degradation and its environmental effects on the Tibetan Plateau: A review of recent research[END_REF] At a near-surface level during 32-26 Ma, assuming a temperature of 200 ± 200 °C

The Gangdese batholith was exposed at the surface before deposition of the Kailas Formation [START_REF] Decelles | Oligocene-Miocene Kailas basin, southwestern Tibet: Record of postcollisional upper-plate extension in the Indus-Yarlung suture zone[END_REF][START_REF] Carrapa | Miocene burial and exhumation of the India-Asia collision zone in southern Tibet: Response to slab dynamics and erosion[END_REF]. Available 40 Ar/ 39 Ar ages of K-feldspar for the Gangdese batholith in the Mt. Kailas area, close to our profile (ca. 15 to the west), suggest that the rocks experienced cooling after 32 Ma [START_REF] Yin | Tertiary deformation history of southeastern and southwestern Tibet during the Indo-Asian collision[END_REF]. Modeling begins at temperatures of 750-850 °C at 41.0±1.1 Ma According to the U-Pb dating of sample 13T02 in this study

System-and model-specific parameters

AFT annealing model: [START_REF] Ketcham | Improved measurement of fission-track annealing in apatite using c-axis projection[END_REF] ZFT annealing model: [START_REF] Yamada | Statistical modelling of annealing kinetics of fission tracks in zircon; Reassessment of laboratory experiments[END_REF] Note: All the samples were counted with a zeta calibration factor [START_REF] Hurford | A users' guide to fission track dating calibration[END_REF]] ξ = 125.66 ± 1.86 for glass dosimeter IRMM541. N = total number of grains counted; binomial peak-ages are given ± 2SE. The percentage of grains in a specific peak is also given. P(χ 2 ), χ 2 probability that the single grain ages represent one population. Note: All the samples were counted with a zeta calibration factor ξ = 247.47 ± 6.05 for glass dosimeter IRMM540R. N = total number of grains counted; binomial peak-ages are given ± 2SE. The percentage of grains in a specific peak is also given. P(χ 2 ), χ 2 probability that the single grain ages represent one population. n = number of horizontal confined track length measured; MTL, mean track length (with ± 1 Std. Dev., standard deviation). MTLc, mean track length of c-axis projected. All apatite samples for track length measurements were irradiated by a collimated beam of heavy ions released from a 252Cf source at the University of Melbourne (Australia) [START_REF] Donelick | Enhanced TINT fission-track densities in low spontaneous track density apatites using cf-252-derived fission fragment tracks -a model and experimental-observations[END_REF].

  5. The detrital ZFT grains ages range from 15.0 to 96.0 Ma, and three peak ages of 27.3 ± 1.3, 40.5 ± 2.3 and 70.0 ± 8.1 Ma are obtained.

5

  Discussion: dynamic subsidence and surface uplift in southernmost Tibet Multiple unrelated processes have been invoked in the past to explain several observations of vertical land motion that cannot be explained by horizontal shortening or extension. Classic examples include the mid-Miocene uplift of southern Tibet and the Himalaya and the coeval onset of rapid deposition of the Siwalik series in the foreland basin. Canonical

  explanation. Once the downward deflection associated with the slab migrated to southern locations, the topography uplifted towards an isostatically compensated elevation (Figs.6B and 7A). The wave of surface uplift first occurred in the northern Gangdese magmatic arc, according to the young ZFT peak age of modern river sand from the central Lhasa terrane, showing exhumation at ~ 27.3±1.3 Ma (Fig.5), then migrated southward. As the deflection migrated south of the Kailas basin it first starved then eventually exhumed and eroded from 20 Ma onwards, while subsidence started in the Himalayan foreland basin (Figs.6C and 7C).

Figure 1 .

 1 Figure 1. Schematic structural framework of southern Tibet and the Himalaya. Age data of magmatism are from the Tibetan Magmatism Database (https://www.jaychapman.org/tibetmagmatism-database.html) by Chapman & Kapp [2017], with contours from Goussin et al. [2020]. Thermochronological data are cited from 1) Kirstein et al. [2006]; 2) Carrapa et al. [2014]; 3) Tremblay et al. [2015]; 4) Li et al. [2015a]; 5) Li et al. [2015b]; 6) Shen et al. [2016]. The yellow box indicates the location of Figure 2, and the green box indicates the location of Figure 5. JRS: Jinsha suture; BNS: Banggong-Nujiang suture; IYS: Indus-Yarlung suture; GCT: Great Counter Thrust; KF: Kunlun Fault; KKF: Karakorum Fault; STF: South Tibetan Fault; MCT: Main Central Thrust; MBT: Main Boundary Thrust; MFT: Main Front Thrust; GM: Gurla Mandhata.

Figure 2 .

 2 Figure 2. Detailed geological map of the Mt. Kailas area, showing the sample locations and previous thermochronological data in study area: grey, Yin et al. [1999]); violet, DeCelles et al. [2011]; yellow, Pullen et al. [2011]; cyan, Carrapa et al. [2014]. Cross-sections with sample locations are shown below the map.

Figure 3 .

 3 Figure 3. U-Pb concordia diagrams of sample 13T02 (top) and 14T05 (bottom) using the

Figure 4 .

 4 Figure 4. A. Age-elevation plots for dated samples and selected previous 40 Ar/ 39 Ar datum [Yin et al., 1999]. Samples with red labels are used for QTQt modeling. B. QTQt model results taking samples 13T01, 13T02 and 13T04 as a profile. The red line corresponds to the path of the hottest (lowest elevation) sample (with the 95% credible interval range in magenta); the blue line corresponds to the coolest (highest elevation) sample (with the 95% credible interval range in cyan); intermediate samples are shown in grey. C. The predicted data by the QTQt modeling compared with observed data. The red box is the general prior time-temperature box, which was set to a temperature of 200 ± 200 °C[START_REF] Ketcham | Improved measurement of fission-track annealing in apatite using c-axis projection[END_REF], and the black boxes are geological

Figure 5 .

 5 Figure 5. Drainage network related to the modern river sand sample (red star). Main lithologic units of the northern Gangdese magmatic arc are shown in the figure. Inset figure illustrates the RadialPlotter plot of the ZFT data from the modern river sand.

Figure 6 .Figure 7 .

 67 Figure 6. Simplified geodynamic evolution of Indian subduction, the Himalaya and southern Tibet. Green curves above cross-sections (left) and map views (right) of the modeled dynamic surface uplift and subsidence (differences in dynamic topography over the time frames) for an idealized Indian-Eurasian subduction zone, with dynamic surface uplift (air compensated), dynamic subsidence (sediment compensated), or equivalent erosion (assuming steady elevation). Slab geometries at each time are based on geophysical observations for present-day, and geological arguments for past reconstructions in the past complemented by lessons from numerical and analogue models (left). The black line is the zero isocontour, representing 0 uplift/subsidence

Figure 8 .

 8 Figure 8. Compilation of the existing thermochronologic data in southern Tibet with the presentday dynamic deflection [Husson et al., 2014]. (A) Distribution of the AFT and AHe data of the Kailas Formation, Gangdese batholith and Xigaze basin with the model-predicted dynamic

Figure 2 .

 2 Figure 2.

  Figure 3.

  Figure 4.

  Figure 5.

Table 1 .

 1 Thermal history input table for the QTQt modeling

Table 2 .

 2 Bedrock ZFT results from the Gangdese batholith

Table 3 .

 3 Bedrock AFT results from the Gangdese batholith

Table 4 .

 4 Detrital zircon fission-track data from sample T44-1

Table 1 1019 1 . Thermochronologic Data Samples and data used in modeling

 11

	Sample	AFT ages	lengths AFT	ZFT ages
	13T01

Table 2

 2

	No.	GPS	Elevation (m)	Lithology	ρ s	N s	ρ i	N i	ρ d	N d	N	P(χ 2 )	Dispersion	Pooled age (Ma)	U±2σ (ppm)
	13T01	81.58389 31.08029	5447	Granite	8.11×10 6 1581 6.35×10 6 1239 2.54×10 5 3161 20	80.4%	1.2%	20.3±1.7	1253±78
	13T02	81.58159 31.07923	5317	Granite	6.10×10 6	992	4.94×10 6	804	2.54×10 5 3161 20	65.7%	1.0%	19.6±2.0	974±73
	13T04	81.53824 31.04565	5044	Granite	3.54×10 6	647	2.60×10 6	475	2.54×10 5 3161 19	97.6%	0.3%	21.7±2.7	513±49
	14T01	82.05073 30.83476	5493	Diorite	5.43×10 6 1324 3.79×10 6	926	2.54×10 5 3161 20	98.4%	0.2%	22.7±2.1	748±53
	14T03	82.02802 30.83046	5291	Diorite	2.78×10 6	550	1.83×10 6	362	2.54×10 5 3161 18	88.6%	0.6%	24.1±3.3	361±39
	14T05	82.00145 30.82388	5104	Diorite	5.50×10 6 1197 4.08×10 6	887	2.54×10 5 3162 20	98.1%	0.4%	21.5±2.0	805±58

Table 3

 3

	No.	ρ s	N s	ρ i	N i	ρ d	N d	N	P(χ 2 )	Dispersion	Pooled age (Ma)	U±2σ (ppm)	n	MTL (μm)	MTLc (μm)
	13T01	3.50×10 5	403	2.83×10 6	3256	1.07×10 6	3394 20	98.0%	0.2%	16.3±1.9	40±2	135	12.70±1.83	13.89±1.32
	13T02	2.31×10 5	275	2.24×10 6	2664	1.07×10 5	3405 20	91.9%	0.3%	13.7±1.8	31±2	77	12.60±1.87	13.74±1.38
	13T04	9.77×10 4	84	1.08×10 6	926	1.07×10 6	3417 20	99.0%	0.1%	12.0±2.8	15±1
	14T01	1.31×10 5	162	1.18×10 6	1451	1.08×10 6	3428 24	75.7%	1.6%	14.9±2.5	16±1	41	13.13±1.57	14.22±1.09
	14T03	1.46×10 5	72	1.51×10 6	745	1.08×10 6	3440 21	100.0%	0.1%	12.9±3.2	21±2
	14T05	1.43×10 5	141	1.67×10 6	1648	1.08×10 6	3451 30	99.9%	0.1%	11.5±2.1	23±1	37	13.76±1.54	14.59±1.14

Table 4 1037 1038

 41038

	Sample No.	GPS location	N	ρd×10 5 cm -2 (N d )	Ρs×10 6 cm -2 (N s )	Ρi×10 6 cm -2 (N i )	U (ugg -1 )	P(χ 2 ) Dispersion	Age range (Ma)	P1 Age (Ma±1σ)	P2 Age (Ma±1σ)	P3 Age (Ma±1σ)	Central Age (Ma±1σ)
	T44-1	81.08881 32.39525	100	3.837 (2686)	4.17 (3689)	3.02 (2669)	313	0	28%	15.0-96.0	27.3±1.3 (39.9±9.3%)	40.5±2.3 (50.7±8.6%)	70±8.1 (9±13%)	36.0±1.2

Acknowledgments

This work has been supported by National Natural Science Foundation of China (41702208 and 41672195), and the China Geological Survey (Grant Nos. 1212011121261).

Bowen Song, Junliang Ji, Keke Ai, and Gaolei Jiang provided support during fieldwork. Melanie Balvay is acknowledged for help during the AFT and ZFT sample preparation. We also thank the suggestions by Djordje Grujic, Feng Cheng, Jonas Ruh, Giuditta Fellin, Barbara Carrapa, Devon A. Orme, Andrew Laskowski, and Peter G. DeCelles which helped to significantly improve the manuscript. All the new thermochronological data are archived in Figshare repository (https://doi.org/10.6084/m9.figshare.11626053.v1).