藏北申扎羊湖河谷140ka B.P.以来古环境的初步研究

ENVIRONMENTAL CHANGES IN THE YANG LAKE AREA OF SHENGZHA COUNTY, NORTH TIBET SINCE 140ka B.P.

通过对藏北羊湖河谷第四纪沉积成分、地貌、年龄值、孢粉和氧化物等的测试、研究 ,确定了本区 1 4 0kaB .P .以来沉积序列和 1个河流阶地、3个河湖积台地的地貌状况 ,并得到1 4 0kaB .P.以来本区至少经历了 4个半干 -湿气候旋回 ,目前正处于干旱期。同时通过不同时期的阶地、台地的不同高程使我们得以了解地壳相对抬升趋势 ,从 98.5kaB .P .以来地壳抬升速率为 2 .2 1mm a,总体显示抬升速率低的特征。

In the Yang Lake area of North Tibet, a sedimentary sequence since 140ka B.P. was established on the basis of sediment components, geomorphic features, ages, sporapollen, and oxides, and at the same time 1 terrace and 3 fluviolacustrine platforms were recognized. This area at last had 4.5 climate cycles, shifted from arid to humid and is now in an arid period. The crust uplift rate there was 2.21 mm/a since 98.5ka B.P., a relatively low rate.