Research On Sedimentary Environment Of Mohair Salt Lake In Quaternary In The Qaidam Basin Qinghai Province

Mohair basin is located in the eastern region of the western part of the Qaidam Basin, are formed by folding and faulting movement a sub basin. The region from west to east and south than in the north of terrain features, making major river basins surrounding mohair and salt together in the northeast of the basin, namely the center of Salt Lake deposit. Salt Lake sedimentary evolution is an important controlling factor mohair area mineralization.This article mainly through to the ZKT1 drilling, ZKT3 drilling logging drawing histogram of two drilling, and combined with lithology, saline minerals form characteristics of sediment and the combination, tectonic setting and other indicators, divided into formation s of mohair basin since the early pleistocene climate and environment changes are discussed in this paper.Mohair salt lakes in the quaternary period of the sedimentary facies are mainly fluvial facies, lakeshore facies, shallow lake and salt lake facies. Early pleistocene period mohair, moderate and moist climate region rainfall is rich, water power is stronger, more sediment is given priority to with sand and gravel, as typical blunt-pluvial phase; In addition, in the bottom of the hole, the phenomenon of the small sedimentary rhythm overlap, each small sedimentary rhythm of lithology combination(from bottom to top) : containing gravel sand- sand- containing silty clay- clay, this suggests that the intermittent flood flow dynamics is strong by the weak repeated many times. Since the middle pleistocene climate gradually dry, cream rock material began to deposit; the more is given priority to with lakeshore facies and shallow lake facies. Period of late pleistocene, the climate is extreme drought, mohair basin water recharge greatly reduced, in such an environment, mohair lakes gradually shrink, to fully dry the holocene period, formed the broad dry salt flats.Salt lake sedimentary environment is different in different lithofacies in the same place as the lake expansion, contraction, migration and appear alternatel y. The advance and retreat of cyclical alternates, lake sedimentary rhythm changes frequently, reflects the periodical change of fresh water, salt water. The periodic change and the periodical change of arid climate and lake basin is closely related to the surrounding areas of freshwater supply.Mohair is qaidam basin under the background of "mountain deep basin" always a secondary basin, the evolution of it has been under the influence of the qinghai-tibet plateau neotectonic movement. The main characteristic of the qinghai-tibet plateau neotectonic movement is the overall uplift and strong uplift of large area, strong subsidence in the northern qaidam basin, accept salt deposit. Neotectonic movement in the late, due to the influence of the structure of the cold lake makes mohair basin is a completely isolated closed lake basin. During this mohair lake basin evolution has experienced the occurrence, development, shrinkage, collapse and dies five stages, constitute a complete sedimentary tectonic cycle.