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ABSTRACT Characterising the spatial and temporal distribution of the S‐N‐trending rift in southern Tibet is crucial for elucidating the dynamics of E‐W extension within the Tibetan Plateau since the Miocene. The Kung Co–Tangra Yumco rift, located in the central part of the rift system, was initiated at the peak of rifting development. While the initiation of rifting has been ascertained through low‐temperature thermochronology, direct timing constraints remain absent for the Gangga Graben in the southernmost region. Utilising the quartz electron spin resonance (ESR) dating technique, we ascertained the onset age of the eastern boundary fault of the Gangga Graben to be 12.00 ± 1.80 Ma, with an accelerated activity phase at 9.17 ± 1.19 Ma, and an activity age for the western boundary fault at 2.22 ± 0.24 Ma. U‐series dating conducted on the western boundary disclosed a time span of 20–13 ka for hot spring fissure activity. Seismic evidence, inclusive of those from the Gongdapu Horst, indicates persistent activity of the Gangga Graben since the Pleistocene. Comparative analysis of age data from the Kung Co–Tangra Yumco rift suggests that it commenced almost synchronously along its strike at ~14.5–12 Ma. Considering the rifts trending from west to east in southern Tibet and the genetic mechanism of leucogranite, we propose an E‐W extension mechanism in southern Tibet. At ~26–14 Ma, the lithosphere experienced weakened delamination and asthenosphere upwelling, leading to a series of magmatic activities and onset of E‐W extension in southern Tibet. At ~17–7 Ma, as the basal shearing of the underthrusting Indian Plate increased, it marked the peak phase of rifting in southern Tibet. [ABSTRACT FROM AUTHOR]

The study of sedimentary mélanges holds pivotal importance in understanding orogenic processes and unveiling geodynamic mechanisms. In this study, we present findings on zircon U‐Pb isotopes and whole‐rock elemental data concerning the recently uncovered Zongzhuo Formation sedimentary mélanges within the Dingri area. Field observations reveal the predominant composition of the Zongzhuo Formation, characterized by a matrix of sandstone‐mudstone mixed with sand‐conglomerates within native blocks exhibiting soft sediment deformation. Moreover, exotic blocks originating from littoral–neritic seas display evidence of landslide deformation. Our study identifies the depositional environment of the Zongzhuo Formation in Dingri as a slope turbidite fan, with its provenance traced back to the passive continental margin. Notably, this contrasts with the Zongzhuo Formation found in the Jiangzi–Langkazi area. Based on existing data, we conclude that the Zongzhuo Formation in the Dingri area was influenced by the Dingri–Gamba fault and emerged within a fault basin of the passive continental margin due to Neo‐Tethys oceanic subduction during the Late Cretaceous period. Its provenance can be attributed to the littoral–neritic sea of the northern Tethys Himalaya region. This study holds significant implications for understanding the tectonic evolution of Tethys Himalaya and for reevaluating the activity of the Dingri–Gamba fault, as it controls the active deposition of the Zongzhuo Formation. [ABSTRACT FROM AUTHOR]

ABSTRACT The tectonic evolution of the Palaeocene–Eocene Tethys Himalayan foreland basin plays a crucial role in reshaping the collisional orogenic process of the Yarlung–Tsangpo oceanic basin. However, studies examining the sedimentary response during the tectonic evolution of the foreland basin are lacking. In this study, through a detailed field investigation and analysis of Palaeocene–Eocene strata in the Tingri area, we clarified the evolution of the Tethys Himalayan tectonic regions and its sedimentary response. Carbon and oxygen isotopes, geochemistry and detrital zircon U–Pb dating demonstrated that the lower Palaeocene Jidula Formation and upper Palaeocene–lower Eocene Zongpu Formation were deposited in a coastal–shallow marine environment, with the detritus sourced from the northern Indian passive margin. The upper Eocene Pengqu Formation was deposited in a deltaic environment, with its detritus sourced from the Gangdese arc and the Yarlung–Tsangpo suture zone at the active continental margin. Combined with the nearshore subaqueous fan branch channel of the Jidula Formation and the slump deformation of the Zongpu Formation, the Palaeocene–Early Eocene southern Tethys Himalaya in the Tingri area was located in the forebulge of the peripheral foreland basin. The marine–continental interactive delta of the Pengqu Formation and its provenance from the Gangdese magmatic arc indicate that the Tingri area was situated in the foredeep of the peripheral foreland basin during the Late Eocene. The study provides valuable insights into the collisional orogenic processes between the Indian and Eurasian plates. [ABSTRACT FROM AUTHOR]