青藏高原东北部湟水流域新近纪风尘堆积源区分析

Identification of Dust Sources of the Miocene-Pliocene Red Clay Deposit in the Northeastern Tibetan Plateau

对青藏高原东北部湟水流域河流阶地上的中新世厚层风成堆积与黄土高原中部新近纪红黏土堆积的地球化学元素和磁性矿物特征进行了对比分析,结果表明,湟水流域中新世风尘堆积物与黄土高原风尘堆积物的源区存在差异。位于高原季风与东亚季风交汇区的湟水流域风尘堆积物可能有一部分来源于青藏高原中-西部干旱地区的风化细粒物质。因此,中中新世以来湟水流域风尘堆积物的存在可能表明了青藏高原中西部在那时已经较为干旱。

In this work, the late Cenozoic aeolian deposits at Huangshui catchment, the northeastern Tibetan Plateau, is investigated on geochemistry distribution and magnetic property, and, they are compared with that of the aeolian sediment in the Central Loess Plateau. It shows that the dust sources of the aeolian deposit in Huangshui catachment are different from that of the aeolian deposits in the Central Loess Plateau. The arid and/or semiarid region in the middle and west parts of the Tibetan Plateau may be a potential dust source for the aeolian deposit of the northeastern Tibetan Plateau. Therefore, the existence of the late Cenozoic aeolian deposit demonstrates that the middle and west parts of the Tibetan Plateau have been dry since the middle Miocene time.