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East Tibet preserves broad areas of low relief that occur at elevations >3000 m and are dissected by major strike-slip faults that have been repeatedly reactivated since the late Mesozoic. Apatite fission-track samples from these low-relief, high-elevation surfaces indicate Cretaceous cooling (ca. 90 Ma). Fast rock uplift of the 110 °C isotherm and a fossilized partial annealing zone began in the plateau interior of east Tibet in the Miocene. Low denudation rates in the plateau interior during the Cenozoic, which are constrained by thermal history modeling and a consistency in ages from apatite fission tracks, suggest that dip-slip displacement on faults has been minor. Some localized areas have experienced the effects of structurally enhanced rock uplift and denudation or fault-related hydrothermal reheating. Cooling ages in Eocene sediments deposited on the older plateau surface suggest that rapid denudation occurred from the Miocene to Holocene. Other evidence of significant Ceno zoic denudation comes from river valleys, in particular, the Yalong River valley, where incision was initiated in the Oligocene to Miocene (28--12 Ma). Estimated mean denudation in east Tibet during the Cenozoic was ~1--2 km in the low-relief, high-elevation plateau interior and at least 5 km at the highrelief plateau margin in the Longmen Shan. The region south of the Longmen Shan and the Sichuan Basin was not uplifted with the main Tibetan Plateau in the Miocene, but it has undergone enhanced denudation since the Eocene. Due to an orographic effect, most of the denudation in the east Tibetan Plateau interior has occurred in major river valleys. Incision in the major rivers of the Longman Shan occurred simultaneously and has kept pace with surface uplift that began in the middle--late Miocene (12 Ma), with acceleration of denudation rates in the late Miocene (>5 Ma). [ABSTRACT FROM AUTHOR]

The article discusses a study on the Oligocene-Miocene Kailas Formation (KF) along the Indus-Yarlung (IY) suture zone (SZ) in southwestern Tibet. The researchers investigated the effects of the tectonic setting paleography of the Kailas basin on the postcollisional tectonics of the IY suture and southern Tibet. They found that KF stratigraphy is in agreement with deposition in extension basin elongated parallel to the SZ.

Lacustrine strata of the Wudaoliang Group demonstrate that two vast lake complexes covered the central Tibetan Plateau during early Miocene time. The Wudaoliang Group, which is characterized by dolostone, limestone, and marl as thick as 310-350 m, miles horizontally or with a slight dip above Oligocene reddish-brown sandstone, and is covered by upper Miocene and Pliocene mudstone and sandstone. The extensive distribution of this group outlines interconnected lake basins of 5000-15,000 km² or larger in the north-central Tibetan Plateau, such as the Wudaoliang, Beiluhe, Tuotuohe, Tongtianhe, and East Wenquan Basins, and lake basins 2000 km² or larger in the southcentral plateau, such as the Ando, Naqu, Bangoin, Lunpola, and Shuanghu Basins. These lake basins, separated by mountain ranges and islands, were linked by water passages in early Miocene time, when they apparently formed a huge lake complex that covered as much as 100,000 km² in the north-central Tibetan Plateau and another one >50,000 km² in the south-central part of the plateau. Such immense lakes existed for several million years between ca. 23.5 and ca. 13.5 Ma after the Tibetan Plateau rose, and their interconnected basins define the topography during early Miocene time. The fossils contained in these basins indicate a change from the warm, dry climate of the Oligocene to moderately cool and wet conditions at the beginning of the early Miocene, followed by progressive cooling and drying, which suggests continuous uplift during deposition of the Wudaoliang Group. [ABSTRACT FROM AUTHOR]

Metamorphicdomecomplexesoccurwithin the internal structures of the northern Himalaya and southern Tibet. Their origin, deformation, and fault displacement patterns are poorly constrained. We report new field mapping, structural data, and cooling ages from the western flank of the Leo Pargil dome in the northwestern Himalaya in an attempt to characterize its post-middle Miocene structural development. The western flank of the dome is characterized by shallow, west-dipping pervasive foliation and WNW-ESE mineral lineation. Shear-sense indicators demonstrate that it is affected by east-west normal faulting that facilitated exhumation of high-grade metamorphic rocks in a contractional setting. Sustained top-to-northwest normal faulting during exhumation is observed in a progressive transition from ductile to brittle deformation. Garnet and kyanite indicate that the Leo Pargil dome was exhumed from the mid-crust. 40Ar/39Ar mica and apatite fission track (AFT) ages constrain cooling and exhumation pathways from 350 to 60 °C and suggest that the dome cooled in three stages since the middle Miocene. 40Ar/39Ar white mica ages of 16-14 Ma suggest a first phase of rapid cooling and provide minimum estimates for the onset of dome exhumation. AFT ages between 10 and 8 Ma suggest that ductile fault displacement had ceased by then, and AFT track-length data from high-elevation samples indicate that the rate of cooling had decreased significantly. We interpret this to indicate decreased fault displacement along the Leo Pargil shear zone and possibly a transition to the Kaurik-Chango normal fault system between 10 and 6 Ma. AFT ages from lower elevations indicate accelerated cooling since the Pliocene that cannot be related to pure fault displacement, and therefore may reflect more pronounced regionally distributed and erosion-driven exhumation. [ABSTRACT FROM AUTHOR]