运城盐湖沉积环境演化

运城盐湖位于山西地堑系运城断陷盆地内的次一级深断陷内。本文通过分析运城盆地新构造运动和运城盐湖区的地层,认为新构造运动对湖盆的形成和湖水、盐份和沉积物的补给起着很重要的作用;盐类矿物的沉积与气候变干有密切的关系;运城盐湖是特殊的构造和气候条件下的产物,是更新世早期古湖的残余。

ENVIRONMENTAL EVOLUTION OF YUNCHENG DALINE LAKE(SHANXI, CHINA)

The Yuncheng Saline Lake is located in a sub-faulted-down area in the Yuncheng faulted basin on the south part of the Shanxi Graben Systems.The evolution of the lake is controlled byneotectonic movement and climate changes.The water suppiies to the lake were greatly reduced at the end of the Middle Pliestocene E-poch because of the uplifting of the Mingtiaogang horst and the abandonment of the ancientFenhe River channel which connected the Yuncheng Basin with the Houma basin before. Duringthe late Pliestocene Epoch,the Mingtiaogang horst,which is north of the lake,uplifted gradually from northeast to southwest and forced the Sushui River migrate westward,and finally separatedthe Yuncheng Lake from the Sushui River.The supplies of water and salt and deposits to theYuncheng Lake were reduced,The reduction of the sediment supplies caused that the sedimentation could not catch up with the faulted down movment,and the basin became deeper and deeper;the reduction of water srpplies contributed the inspisstion of water and sedimentation of salt.The late Quaternery strata,about 150 metres thick,are salt rich silt and mud beds interbeding with salt few silt beds．The salt minerals are dominated by mirabilites,gypsum bloedites andhaiites. The beddings with few salts contain fossils of mollusks,ostracads and marls. Accorddingto the minerals and the fossils,the curve of the salinity changes was established, and it is recognized that the salinity curve is comparable with the curves of climate changes.Most of drill cores show that there are continuous Quatermary lacustrine deposits in theYuncheng Lake area.This indecates that the Yuncheng Lake is the relic of the ancient great lakeof the early Quaternary under specific neotectonic and climatic condition.