The Implication of Elevated Lacustrine Sediments in The Middle Reach of The Yarlung- Tsangpo and Nyang River, Tibet
Abstract
The interaction mechanisms among climate, crustal uplift and related erosion processes in the orogenic belt became one of the popular topics in the past decade, especially in the collisional margin of Eurasian Plate and Indian Plate where stands the most spectacular plateau in the world in terms of elevation and geomorphology. We investigated the outcrops of lacustrine deposits in the lower terraces of the Nyang River and established the stratigraphic column for entire depositional sequence. Woods and charcoals were collected for radiocarbon dating and sands for optical stimulated luminescence (OSL). Based on our observation, the alluvial and lacustrine environments occurred alternatively and represent the evolution of a moraine-induced deposition. We identified at least two coarsening upward sequences of a delta depositional system. Typically, the distinct varve sections were overlain by interbeded sand/silt with abundant ripple cross-beds, parallel laminations, and syndepositional deformations, indicating the transition of depositional environments from pro-delta to beach ridges of the frontal delta-plain. According to the preliminary radiocarbon and OSL dates from the bottom and top of the studied profile, the scenarios of paleolakes took place no younger than very late Pleistocene. The lithology and depositional succession explicate the evolution of the delta and suggest that it has experienced episodic aggradational stages during the late Pleistocene.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2007
- Bibcode:
- 2007AGUFMPP23A1081H
- Keywords:
-
- 1616 Climate variability (1635;
- 3305;
- 3309;
- 4215;
- 4513);
- 1637 Regional climate change;
- 4914 Continental climate records;
- 4928 Global climate models (1626;
- 3337);
- 4950 Paleoecology