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The Tian Shan is one of the world's largest intracontinental orogens and provides an excellent example for deciphering the intracontinental responses to the tectonics of plate boundaries. Despite its significance, the timing and driving mechanism of the Cenozoic mountain building of the Tian Shan in the context of the India–Eurasia collision remain controversial. In this study, Cenozoic stratigraphy of the Tiereke section along the western Kuqa Depression of the northern Tarim Basin on the south foreland of Eastern Tian Shan (east of 80°E) has been investigated. The results indicate that the Cenozoic deposition of the Tiereke region sequentially experienced a transgression from the Kumugeliemu Group to the Suweiyi Formation and a regression from the Suweiyi to the Kuqa Formations. Based on the contact relationships and conglomerate textures, three stages of high-energy alluvial deposition have been identified in the lower Kumugeliemu Group, upper Jidike and Kangcun–Kuqa Formations, respectively. These sedimentary events were interpreted to represent phases of Eastern Tian Shan mountain building at c. 54 Ma, c. 27 Ma and since c. 9.7 Ma according to previous magnetostratigraphic results, which were possibly related to the initial India–Eurasia collision, the collision between the India and Tarim lithospheric mantles, and the basinward propagation of deformation, respectively. Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change [ABSTRACT FROM AUTHOR]

The convergence of India and Eurasia, which began in the early Cenozoic, established the Tibetan Plateau and the Circum-Tibetan Plateau Basin and Orogen System. When and how the convergence-driving strain propagated into this system is important in deciphering the growth processes of the Tibetan Plateau. We conducted a structural analysis of the West Kunlun–southern Junggar transect along the NW margin of the Tibetan Plateau to establish the propagation of deformation and, through this, to determine the plateau growth processes. Our results suggest a two-phase deformation mode. The first-stage features deformation confined to pre-existing weak zones (e.g. the West Kunlun orogen, the Buchu Uplift and the Tian Shan orogen) during the Paleogene, when the intracontinental strain is speculated to be mainly consumed by shortening of these weak zones. The second stage is characterized by deformation propagating into the foreland regions since the early Miocene, where shortening along the foreland fold–thrust belts on a scale of tens of kilometres and decreasing basinwards had a key role in absorbing intracontinental strain. We suggest that this two-phase deformation mode may reflect a shift in the governing mechanism of the expansion of the Tibetan Plateau from a rigid block to a critical wedge taper style. Thematic collection: This article is part of the Fold-and-thrust belts collection available at: https://www.lyellcollection.org/cc/fold-and-thrust-belts [ABSTRACT FROM AUTHOR]

The northern margin of the Tibetan Plateau is defined by the left‐lateral Altyn Tagh fault. It remains unclear whether the Cenozoic deformation related to the India‐Asia collision has remained stationary along the Altyn Tagh fault or propagated northward into the southeastern Tarim Basin. The Cenozoic Cherchen fault is located in the southeastern Tarim Basin, ∼90–120 km north of the Altyn Tagh fault, and thus, may play a critical role in addressing this issue. Here, we used a densely‐spaced two‐dimensional seismic reflection survey to investigate the geometry and kinematics of the Cherchen fault and understand its role in the expansion of the northern margin of the Tibetan Plateau. Our seismic study shows that the Cenozoic Cherchen fault is a high‐angle left‐lateral transpressional fault. Kinematic analysis of the Cherchen fault suggests that a restraining bend structure has formed along its central segment. Stratigraphic records suggest that the Cherchen fault initiated in the Paleozoic and reactivated during the middle Miocene (ca. 17–15.7 Ma). We infer that the dip‐slip and strike‐slip rates of the Cherchen fault are ∼0.09 mm/a and ∼1.66 mm/a, respectively. A regional cross section reveals that the northward expansion of the plateau is ongoing, but the range is limited to ∼90–120 km. We interpret that middle Miocene tectonic activity throughout the region was also concentrated along the northern plateau margin, defined by both northeast‐directed crustal shortening and northward expansion of the plateau. The Tibetan Plateau is propagating north of the Altyn Tagh fault into the Tarim Basin, evidenced by slip along the Cherchen faultStructural analysis of the Cherchen fault suggests it is a high‐angle transpressional faultThe northward expansion of the Tibetan Plateau is ongoing but limited to ∼90–120 km The Tibetan Plateau is propagating north of the Altyn Tagh fault into the Tarim Basin, evidenced by slip along the Cherchen fault Structural analysis of the Cherchen fault suggests it is a high‐angle transpressional fault The northward expansion of the Tibetan Plateau is ongoing but limited to ∼90–120 km

Bending‐moment faults and flexural‐slip faults (FSFs), as two basic fault styles due to bending‐related tangential longitudinal strain, extensively and prominently crop out as surface scarps in the Pamir‐western Kunlun and southern Tian Shan regions, northwestern China. Characteristic geomorphic expression, favorable formation conditions, and the role in folding accommodation of active FSFs have been systematically summarized in our recent studies. Here we investigate similar properties for well‐developed bending‐moment normal fault (BMnF) scarps at four sites. Our study concludes the following: (i) BMnF scarps are relatively sinuous compared to FSF scarps and probably trend obliquely to the fold hinge. A group of BMnF scarps can delineate a single asymmetric graben or create grabens alternating with horsts. (ii) BMnF scarps primarily overlie poorly‐layered conglomerates. The fold's interlimb angle can range from ~160° to <40°, and the folding kinematics can vary from active‐hinge migration to fixed‐hinge rotation. (iii) The fault‐zone width, fault spacing, and efficiency in folding accommodation significantly decrease with (a) thinner conglomerate beds, (b) a smaller interlimb angle, and (c) the transition of the hinge from migrated to fixed. (iv) Different bed lithologies and fold geometries beneath the surface account for the predominance of BMnF scarps on the western Kunlun piedmont and FSF scarps in the Pamir‐Tian Shan convergent zone. (v) Presence of BMnF scarps on the western Kunlun piedmont indicates that ~4 km of fault slip is transferred northward along a detachment at the base of the Cenozoic and is ultimately absorbed by the Mazatagh Thrust in the Tarim Basin. Bending‐moment normal faults strongly depend on the lithology of underlying beds, and to a lesser extent on the fold geometry and kinematicsFault‐zone width, fault spacing, and efficiency in fold accommodation depend on bed thickness, interlimb angle, and fold kinematicsAbundant bending‐moment normal faults indicate that 4 km of fault slip is likely translated from the western Kunlun piedmont to the Mazatagh

In an orogen‐foreland basin system, syn‐orogenic sedimentation and deformation records within the foreland basin provide critical evidence for understanding uplift and erosion processes of adjacent orogenic belts. Foreland fold‐and‐thrust belts (FTBs) are widely developed around the Tian Shan range, Central Asia. Problem of how crustal shortening accumulates and propagates from the Tian Shan to adjacent foreland basins is essential for understanding the overall dynamics of Tian Shan. In this study, we interpreted three high‐resolution seismic reflection profiles to estimate the magnitude and distribution of Cenozoic shortening across the Eastern Kuqa FTB, South Tian Shan foreland. Combined with well‐dated syntectonic stratigraphy, we further evaluate the timing, rate, and migration of the deformation front of the Kuqa FTB. Our results suggest that the Kuqa FTB's total crustal shortening increases westward. The distribution of crustal shortening across secondary structural belts shows a gradual, basinward decrease, which can be explained by the telescoped mechanism. Propagation rates of the Kuqa FTB's deformation front indicate an episodic propagation of the foreland thrust wedge, with an acceleration after ∼12 Ma. Similar episodic propagation pattern has also been observed in other foreland FTBs around the Tian Shan, but they show significant spatio‐temporal variations in the propagation stages and related rates. The Tian Shan range stretches over 2,500 km from east to west and is one of the Earth's largest intracontinental orogenic belts. As the mountains grew, deformation propagated into foreland basins around the range, forming a series of fold‐and‐thrust belts (FTBs). To better understand the spatial distribution of crustal shortening, and basinward propagation process in foreland FTBs, we interpret and reconstruct three high‐resolution seismic profiles across the Eastern Kuqa FTB, South Tian Shan. Our study indicates that the total crustal shortening of the Eastern Kuqa FTB increases westward. Within the Kuqa FTB, a telescoped distribution pattern of crustal shortening is also observed in frontal thin‐skinned structures above the regional salt décollements. In addition, we find that the basinward propagation of Kuqa FTB is episodic, which is featured by a two‐stage evolution pattern. The Eastern Kuqa fold‐and‐thrust belt shows a westerly increase in total shortening and a telescoped pattern in shortening distributionThe Cenozoic propagation of the Kuqa thrust belt indicates an episodic process that accelerated after ∼12 MaBasinward growth of the Tian Shan orogenic wedge varies spatiotemporally; propagation stages and rates vary in different foreland basins The Eastern Kuqa fold‐and‐thrust belt shows a westerly increase in total shortening and a telescoped pattern in shortening distribution The Cenozoic propagation of the Kuqa thrust belt indicates an episodic process that accelerated after ∼12 Ma Basinward growth of the Tian Shan orogenic wedge varies spatiotemporally; propagation stages and rates vary in different foreland basins

A key issue in the Cenozoic evolution of the Tibetan plateau is the geodynamic drivers for north‐trending rifting in southern Tibet. Recent studies have demonstrated an eastward propagation pattern for rift initiation, but the along‐strike variations remain poorly resolved. Two models that predict different north‐south rift kinematics include northward underthrusting or southward tearing of the Indian lithospheric slab, predicting a northward or southward propagation trend of individual rifts along strike, respectively. The Yadong‐Gulu rift (YGR) is an ideal case to investigate this issue due to its long strike length (∼500 km) and location above proposed slab‐tear structures. Here, we compile constraints on both rift initiation and acceleration, and report new apatite fission track and (U‐Th)/He thermochronological data along the southern segment of YGR. Our main findings are as follows. First, the rifts west of the YGR initiated simultaneously along strike, which we suggest is at odds with predictions of either slab‐tear or slab‐underthrusting models. However, most of these rifts show a northward younging pattern in rift acceleration, which may be governed by low‐angle Indian slab underthrusting released by slab tearing. Second, the initiation timing of the Yadong rift is constrained at ∼13–11 Ma. Combined with published constraints along strike, we demonstrate a clear northward propagation in rift initiation along the YGR. This kinematic pattern may be affected by its orientation of the most oblique northeast‐trending among all rift systems or the outward expansion of the Himalayan arc. The Himalayan‐Tibetan orogen is undergoing active east‐west extension under the continuous compression of the colliding Indo‐Eurasia continents. This extension is manifested by a series of northward oriented (north‐striking) rifts in southern Tibet, the geodynamics of which is critical in revealing the Cenozoic evolution of the Tibetan Plateau. Despite the importance, their development pattern along strike has not been well understood, leaving the mechanisms that emphasize their along‐strike propagation poorly tested, such as the southward slab tearing and northward slab underthrusting models. They predict a southward or northward propagation of rifting along strike, respectively. Therefore, the along‐strike propagation process of individual rifts constitutes the key factor in distinguishing the two mechanisms. In this study, we adopted thermochronological techniques to constrain the propagation of the Yadong‐Gulu rift (YGR) that has the longest strike length. The results suggest that the YGR youngs northward, which is contrary to the situations of each rift system to its west that initiated nearly coevally along strike. This implies that the onset of north‐trending rifts should not be significantly affected by geodynamic process in N‐S direction through either slab tearing or underthrusting, while the northward younging trend of YGR is controlled largely by its oblique striking. Initiation timing of Yadong‐Gulu rift youngs northward (Yadong at ∼13–11 Ma), but each rift system to its west initiated nearly coevally along strikeSlab tearing released subducting slab and activated slab underthrusting that causes northward rifting accelerationExtraordinary earlier initiation of the Yadong rift was related to its most oblique NE‐trending or outward expansion of the Himalayan arc Initiation timing of Yadong‐Gulu rift youngs northward (Yadong at ∼13–11 Ma), but each rift system to its west initiated nearly coevally along strike Slab tearing released subducting slab and activated slab underthrusting that causes northward rifting acceleration Extraordinary earlier initiation of the Yadong rift was related to its most oblique NE‐trending or outward expansion of the Himalayan arc

The Cenozoic North Altyn Fault (NAF) is a major splay of the Altyn Tagh Fault along the northwestern margin of the Tibetan Plateau, but its role in the development of this plateau margin in response to the India‐Eurasia collision is highly debated. Here, we investigate fault geometry, kinematics, and shortening magnitude along the westernmost 120 km of the NAF. Seismic surveys reveal minimal Cenozoic shortening in the subsurface of the Southeast Tarim Basin and support for large‐scale (>120 km) left slip on the NAF. Based on the satellite imagery, two new faults are identified to define the northern boundary of the NAF system, which together with the NAF to the south constitute a narrow transpressional shear zone comprised of three basement‐cored, fault‐bound slivers. Fission track data and thermal modeling indicate that the NAF zone experienced broad reburial during early Cenozoic that was locally interrupted by ∼40 to 35 Ma exhumation proximal to the NAF, followed by widespread but heterogeneous exhumation since ∼17 to 15 Ma associated with ∼9 to 11 km of total shortening across the NAF system via thick‐skinned faulting. We conclude that the NAF initiated as a left‐slip fault at ∼40 to 35 Ma and then became transpressional at ∼17 to 15 Ma during the middle‐Miocene reorganization of the Altyn Tagh Fault system. We find no evidence to support prior inferences of large‐scale (∼100 km) underthrusting of the Tarim Basin beneath the Tibetan Plateau along the NAF. The Cenozoic rise of the Tibetan Plateau has exerted a significant impact on the global climate and migration of Asian hominin. To reveal the growth history of the plateau, geologists rack their brains to learn how the plateau‐bounding faults have evolved in time. Here, we investigate the Cenozoic evolution of the North Altyn Fault (NAF) in the northwestern edge of the Tibetan Plateau, which generates 2–4 km topographic relief between the high plateau and low‐land Tarim Basin. Based on seismic survey, satellite imaging, and geological dating, we find that the NAF initiated with left‐lateral slip at ∼40 to 35 Ma but switched to a transpressional fault accommodating both left‐lateral and dip slips since ∼17 to 15 Ma. Our data show only 9–11 km of shortening across the NAF, which contradicts the prior view that the Tibetan Plateau was thrust over the Tarim Basin by ∼100 km. This study provides independent evidence supporting the reorganization of the Altyn Tagh Fault system at ∼17 to 15 Ma and indicates that the present‐day tectonic and topographic configurations in the northern Tibetan Plateau have developed since the middle Miocene. The North Altyn Fault (NAF) is a transpressional shear zone comprised of narrow fault slivers and has absorbed ∼9 to 11 km of Cenozoic shorteningExtensive early Cenozoic burial was locally interrupted by ∼40 to 35 Ma exhumation, implying onset of left slip on the NAFWidespread and heterogeneous exhumation since ∼17 to 15 Ma manifests a transition from left slip to transpression on the NAF The North Altyn Fault (NAF) is a transpressional shear zone comprised of narrow fault slivers and has absorbed ∼9 to 11 km of Cenozoic shortening Extensive early Cenozoic burial was locally interrupted by ∼40 to 35 Ma exhumation, implying onset of left slip on the NAF Widespread and heterogeneous exhumation since ∼17 to 15 Ma manifests a transition from left slip to transpression on the NAF

This work studies new petrological and geochemical data and zircon U-Pb ages for bimodal intrusive rocks from Xinglong region, Hainan Island. Zircon U-Pb dating yields mean 238U/206Pb ages of 238 ± 2 Ma and 234 ± 2 Ma for diabasic and granitic phases, respectively, representing the Middle Triassic emplacement. The diabase and granite bodies were formed from discrete mafic and acidic magma sources that experienced local mechanical mixing at their mutual contacts. Although SiO2content of intrusions is bimodal, trace element ratios indicate that both were formed in a post-orogenic extensional setting. Sr-Nd isotopic composition reflects a shared EMII type enriched mantle source component, possibly influenced by subduction-fluid metasomatism.