Lacustrine sediments and underlying fluvial gravels related with Xigeda paleo-lake outcrop in the Panzhihua area, west of Yangtze platform. High concentrations of SiO2 and high SiO2/ A12O 3 ratios with the lacustrine sediments suggest high maturity and long distance transportation. The geochemical characteristics of major, REE and trace elements allocate the provenance of lacustrine sediments to a continental island-arc environment, and most probably derived from the granitoid region of Yidun island arc in the Songpan-Ganze orogenic belt. Eu/La-Yb/La signatures and Zr/Y ratios provide further information on the provenance of the lacustrine sediments, from both catchments of the Jinsha River and the Yalong River. This suggests that the upstream of Jinsha River was captured during the period of Xigeda paleo-lake formation. The geochemical characteristics of REE and trace elements in the fluvial gravels underlying Xigeda lacustrine sediments suggest formation in a tectonic setting of passive continental margin, and most probably in the west part of Yangtze platform, in the catchment of Yalong River. The different provenance features between the lacustrine sediments and the underlying fluvial gravels imply a significant change of the course of the Jingsha River in the period of Xigeda paleo-lake formation.
|Number of pages||16|
|Journal||Scientia Geologica Sinica|
|Publication status||Published - 2009|
- Fluvial gravel
- Jinsha River
- Xigeda formation