The morphological characteristics of glacial deposits during the Last Glaciation, taking the Parlung Zangbo River Basin as an example

摘要

Moraine morphology is a valuable indicator of climate change.The glacial deposits of ten valleys were selected in the Parlung Zangbo River Basin,southeastern Tibetan Plateau,to study the glacial characteristics of the Last Glaciation and the climate change processes as revealed by these moraines.Investigation revealed that a huge moraine ridge was formed by ancient glacier in the Marine Isotope Stage 2(MIS2),and this main moraine ridge indicates the longest sustained and stable climate.There are at least two smaller moraine ridges that are external extensions of or located at the bottom of the main moraine ridge,indicating that the climate of the glacial stage before MIS2 was severer but the duration was relatively shorter.This distribution may reflect the climate of MIS4 or MIS3b.The glacial valleys show multi-channel,small-scale moraine ridges between the contemporary glacial tongue and the main moraine ridge.Some of these multi-channel moraine ridges might be recessional moraine,indicating the significant glacial advance during the Younger Dryas or the Heinrich event.The moraine ridges of the Neoglaciation and the Little Ice Age are near the ends of the contemporary glaciers.Using high-precision system dating,we can fairly well reconstruct the pattern of climate change by studying the shape,extent,and scale characteristics of glacial deposits in southeastern Tibet.This is valuable research to understand the relationship between regional and global climate change.