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A set of nearly NS-trending rifts developed in the Himalayan orogen and southern Tibet, which are the large-scale extensional structures formed under the continuous compression of the Indo-Eurasia continent, playing a significant role in revealing the post-collisional evolution of the Tibetan Plateau. Different predictions have been made on the spatiotemporal distribution of these rifts through the existing hypothesis models, constituting the key factors constraining the formation system of the rifts. In this study we synthesized previous studies on the initiation time of rifting, and further clarified the spatiotemporal trend. The analysis results showed that the rifting initiated progressively earlier westward, which is consistent with the evolution of post-collisional magmatism in the Lhasa Terrain. Moreover, combined with the geophysical observations, it is inferred that the geodynamic mechanism of the nearly NS-trending rifts accords closely with the hypothesis model concerning the eastward-propagating lateral detachment of the subducted Indian slab. The Indian slab detachment resulted in asynchronous gravitational potential energy gradients, which drove the lithosphere flow eastward and eventually caused the eastward development of the rifting.

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. Plain Language Summary: 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. Key Points: 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 [ABSTRACT FROM AUTHOR]

The geology of Tian Shan provides an excellent example for understanding the intracontinental orogeny in the context of Indian–Eurasian convergence. Previous studies leave much space in basinfill deposition process to be assessed in the regions west to the Talas–Fergana fault (TFF). We improve the understanding by conducting new investigations on sedimentology and magnetostratigraphy in the Tierekesazi section of the foreland region of south West Tian Shan. Four lithofacies have been identified, (i) marine lithofacies from the Aertashi to Bashibulake Formations, (ii) lacustrine to fluvial (plain) lithofacies from the Keziluoyi to the middle Pakabulake Formations, (iii) alluvial sand–gravel sheet lithofacies in the upper Pakabulake Formation, and (iv) conglomerate lithofacies from the Atushi to Xiyu Formations. Magnetostratigraphic analysis, accompanied with biostratigraphic correlation, indicates that four lithofacies cover age intervals of ca. 65 Ma to 34 Ma, ca. 22.1 Ma to 12 Ma, 12 Ma to 5.2 Ma, and 5.2 Ma to approximately present (?), with the sediment accumulation rates increasing from ca. 2.4/3.3–3.5 (compacted/decompacted) cm/ka in the lithofacies (i), to 12.3/16–17 cm/ka in the lithofacies (ii), to 16.3/19.5–20.6 cm/ka in the lithofacies (iii), and finally to > 22.8/> 22.8 cm/ka in the lithofacies (iv). These results suggest three episodes of sedimentary events. Combined with previous results, these episodes of sedimentary events are attributed to tectonic activities that are widespread along south Tian Shan. We speculate that the Oligo-Miocene boundary event more directly and likely marks the initial underthrusting of the Tarim block beneath the south Tian Shan. The mid-Miocene and Mio-Pliocene boundary events, although approximately synchronous between the regions east and west to the TFF, have different structural expressions in the two regions. Such difference is proposed to cause the dextral slipping of the TFF, and more fundamentally, likely be driven by the northward indentation of the Pamir at this time. [ABSTRACT FROM AUTHOR]

The western Kunlun Mountains and the adjacent southwestern Tarim Basin define the northwestern boundary of the intensely deformed Cenozoic Tibetan Plateau, and thus should bear important information on the growth processes of the NW Tibetan Plateau. In this study, the integration of a stratigraphic investigation of the Cenozoic Keliyang succession section and a seismostratigraphic analysis on the seismic reflection profile reveal the sedimentary evolution and basin-filling processes of the southwestern Tarim Basin. Our results suggest a significant depositional shift from marine facies during the depositional periods of the Aertashi to Bashibulake Formations to continental facies during the depositional periods of the Keziluoyi to Xiyu Formations. This shift, which corresponds to southward depositional thickening, has been attributed to the uplift of South Kunlun and the onset of foreland basin subsidence along the southwestern Tarim Basin. Strata from the Keziluoyi to Xiyu Formations form an upward-coarsening sequence that is interrupted by a subordinate upward-thinning sequence in the Anjuan Formation. These results, in combination with the northward migration of the depocenter by at least ~56 km since the depositional period of the Artux Formation and previous studies on basinward deformation propagation, demonstrate that the tectonic loading of the western Kunlun has propagated northward to North Kunlun, which suggest expansion of the NW Tibetan Plateau since this period. We posit that the upper-crustal boundary between western Kunlun along the NW Tibetan Plateau and the Tarim Basin is a northward movable feature. This would support the hypothesis that the substantial lower Tarim Plate (>~56 km if calculated from the magnitude of the northward depocenter migration) has underthrusted southward beneath western Kunlun. • Onset of Cenozoic SW Tarim foreland basin since the Keziluoyi period. • Foredeep of the foreland basin migrating northward by >~56 km. • Upper crustal Tarim/W. Kunlun boundary is a northward movable feature. • >~56 km lower Tarim Plate has underthrusted southwards beneath W. Kunlun. [ABSTRACT FROM AUTHOR]