Sedimentology and Chronology of Paleogene Coarse Clastic Rocks in East‐Central Tibet and Their Relationship to Early Tectonic Uplift

Abstract

A systematic sedimentological and chronological study of typical Paleogene basins in east‐central Tibet suggests that the depositional characteristics of extensively developed huge‐bedded, purplish‐red coarse clastic rocks formed in a tectonic setting of regional thrusting and strike‐slipping represent a typical dry and hot subaerial alluvial fan environment formed in a proximal and rapid‐accumulating sediment body in debris flows and a fan‐surface braided river. Combining results from basin‐fill sequences, sequences of coarse clastic rocks, fauna and sporo‐pollen associations and thermochronological data, it is concluded that the coarse clastic rocks formed in the period of 54.2–24.1 Ma, nearly coeval with the formation of Paleogene basins in the northern (Nangqĉn‐Yushu thrust belt), middle (Batang‐Lijiang fault belt), and disintegration of large basins in the southern (Lanping‐Simao fold belt) segments of Tibet. The widespread massive‐bedded coarse clastic rocks, fold thrusting and strike‐slip, thrust shortening, and igneous activities in the Paleogene basins of east‐central Tibet indicate that an early diachronous tectonic uplift might have occurred in the Tibetan Plateau from Middle Eocene to Oligocene, related to the initial stage of collision of the Indian and Asian plates.

A Late Quaternary Climate Record Based on Multi‐Proxies Analysis from the Jiaochang Loess Section in the Eastern Tibetan Plateau, China

“…Understanding the paleoclimatic evolution and its mechanism in the Tibetan area is an important topic in the earth history study and is also critical for predicting changes of regional and global climate, since the uplift of the Tibetan Plateau plays an important role in the formation and evolution of global atmospheric circulation pattern and climate changes (Zhang et al, 1988;Chen et al, 2005;Zhou et al, 2007).…”