Xiangjiang Yu

The Cenozoic thermal evolution of the North China Craton (NCC) provides important constraints on understanding the development of intracontinental basins and mountains. Based on newly acquired apatite fission-track (AFT) data, burial–erosion histories, geothermal data, published geophysical data, and lithospheric thermal-structure simulations, this study reconstructs the thermal evolution along the Ordos Basin–northern Taihang Mountains–Jizhong Depression profile since the late Eocene (ca. 35 Ma). The results show that the Jizhong Depression experienced extensional reactivation and reached a thermal peak at ca. 25 Ma, with a mantle-dominated heat-flow contribution. The northern Taihang Mountains reached a later thermal peak at ca. 20 Ma, but crustal heat flow remained dominant. The Ordos Basin shows no comparable thermal peak, and the thermal structure of the lithosphere has remained relatively stable. After their respective thermal peaks, the Jizhong Depression experienced prolonged and incomplete cooling and thermal-lithosphere thickening, whereas the northern Taihang Mountains cooled rapidly and thickened significantly. These differences may have been controlled by the deep thermo-tectonic setting associated with the western Pacific subduction system, including slab rollback and back-arc extension, together with inherited lithospheric architecture. The India–Eurasia collision mainly affected regional deformation through far-field stress transfer and reactivation of inherited faults. These results indicate that rifting and post-rift subsidence in the Jizhong Depression, uplift and exhumation of the northern Taihang Mountains, and preservation of the Ordos Basin resulted from the domain-dependent thermo-mechanical evolution of the lithosphere, highlighting the temporal and spatial heterogeneity of the NCC basin–mountain system.

The Paleogene sedimentary basins of southeastern Tibet record sediment dispersal patterns associated with crustal deformation during the early stages of the India–Asia collision. We present detrital zircon U–Pb geochronology, tourmaline geochemistry, and petrographic data from the Gonjo and Mangkang basins that suggest a reginal interconnected paleodrainage during the Paleocene–Eocene. Sediments were likely sourced from the distal Songpan–Ganzi and proximal northern Qiangtang terranes. Stratigraphic relationships and paleoelevation estimates support the interpretation of a paleodrainage system that may have extended toward the Lanping–Simao region and northern Vietnam. This system appears to have been disrupted in the late Eocene, possibly due to sinistral shearing along the Ailao Shan–Red River fault zone. These findings offer new insights into sediment routing and landscape evolution along the southeastern margin of the Tibetan Plateau during the early Cenozoic.

The Cenozoic development of the Tibetan Plateau is one of the most remarkable events in the geosciences. The southern boundary of the Qilian Mountains is a spectacular basin-mountain boundary in the northern Tibetan Plateau offering a valuable opportunity to investigate the growth processes and mechanisms of the Tibetan Plateau. Structural activity is significantly variable across the northern Qaidam basin, and the underlying reason for these differences remains uncertain. To address this issue, we undertook an analysis of two main watersheds—the Tataleng and Yuqia River watersheds—encompassing the middle section of the northern Qaidam basin. This study utilized a multidisciplinary approach combining fluvial geomorphology, low-temperature thermochronology, and seismic data to comprehensively investigate the structural activity within the northern Qaidam basin. The high channel steepness index, young low-temperature thermochronologic ages, concentrated earthquakes, and numerous knickpoints along the piedmont area of the Qaidam Shan collectively suggest that this region is among the most structurally active areas along the southern boundary of the Qilian Mountains. The varying levels of structural activity in the northern Qaidam basin could be linked to the intense glacial erosion in the Qaidam Shan during the Quaternary. Moreover, the flow orientation observed in the bedrock mountains is consistent with the N-S compressional stress field in the northern Qaidam basin during the early Cenozoic, representing a stark contrast to the modern NE-SW stress field. In this way, this research supports the understanding that river geomorphic parameters, including river steepness index and flow direction, are valuable tools for unveiling the regional tectonic evolution in bedrock mountain areas.

The Jurassic is one of the most important periods generating hydrocarbon source rocks and coals in Northwest China, and the Qaidam Basin is an important petroliferous and coal-forming basin. However, a series of explorations in the Qaidam Basin targeting Jurassic source rocks have failed over the past several years. These failures were mainly caused by missing the targeted Jurassic strata, suggesting that the current understanding of the Jurassic distribution in the Qaidam Basin is still limited. Therefore, this study conducts detailed analyses of the drilling wells and seismic data in the middle segment of the northern Qaidam Basin. The seismic profiles and borehole data indicate a rifting tectonic setting with discontinuous deposition and rapid facies transition during the Jurassic. A well-preserved buried rift valley proved in the Hongnan region reveals that the Jurassic deposits are mainly restricted in the narrow rift system. Therefore, further exploration targeting the Jurassic source rocks should focus on delineating the distribution of the Jurassic rift system in the Qaidam Basin, combined with the recovery of the complex Cenozoic tectonic overprinting. Graphic abstract

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 Yingxiong Range is the largest anticlinal belt within the triangular overlapping zone between the Altyn Tagh Fault and the Eastern Kunlun Fault and thus records the critical information concerning the strike-slip superimposition between the two large-scale left-slip faults. The detailed structural analysis on the basis of 3D seismic data shows that the Shizigou (SZG) and Youshashan (YSS) structures in the Yingxiong Range are controlled by NE-dipping low-angle thrust faults at shallow depth and three groups of faults including the NW-striking inverted faults, the WNW-striking XI fault and the N–S-striking Shidong fault zone at deep levels. The inverted faults were right-stepping en-échelon sinistral transtensional normal faults in the Eocene. Fracture analysis on cores of the U. Xiaganchaigou Formation shows the existence of syn-sedimentary normal faults which indicate Eocene extension deformation in the Yingxiong Range. The Eocene transtensional normal faults constituted a half-graben structural system and controlled the formation of the SZG sag. In the early Miocene, the XI fault obliquely superimposed the pre-existing Eocene transtensional normal faults, causing the reactivation of these faults in a reverse sense. Simultaneously, the Shidong fault zone started to develop as a dextral tear fault. The oblique strike-slip superimposition from transtension to transpression in the Yingxiong Range reflects the differential controlling effects of the asynchronous initiation of the Altyn Tagh Fault and the Eastern Kunlun Fault on the structural evolution and oil-gas reservoir development in the western Qaidam Basin. Graphic Abstract

Accumulating sediments is an inherent attribute of endorheic basins. Overall aggradational stratigraphic architecture can be predicted in endorheic basins, whereas the offlap process can be regarded as an important geological indicator in closed basins. This study theoretically proposes the possible offlap process in endorheic basins, and then explores the actual pattern of the offlap process in the Qaidam basin, the largest endorheic basin in the northern Tibetan Plateau. According to the interpretation of drilling well data and seismic reflection profiles, widespread offlap is identified at all the three boundaries of the Qaidam basin since the late Miocene. The offlap process in endorheic basins is controlled by newborn faults or new isostatic flexures inside the previous basin margin. Interpretation of seismic reflection profiles reflects that the rigid Qaidam block was gradually broken during the India‐Eurasian collision and the plateau progressively expanded from pre-existing mountains to basins. Graphical abstract