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新疆巴里坤湖沉积物的碳酸盐分析

期刊名称：海洋地质与第四纪地质
时间：0
页码：125-131
语言：中文
分类：P595[天文地球—地球化学;天文地球—地质学]
作者机构：[1]兰州大学西部环境教育部重点实验室,兰州730000
相关基金：国家自然科学基金项目（40721061 40871006）
相关项目：新疆东部托勒库勒湖泊全新世气候环境演变研究

关键词：碳酸盐, 湖泊沉积物, 干旱区, 巴里坤湖, Lake Balikun, carbonate, lake sediment, arid area

中文摘要：

干旱区湖泊沉积物中的碳酸盐来源复杂,对于封闭的巴里坤湖而言,风力搬运入湖的碳酸盐含量不可忽视。根据计算,在湖泊的中间区域外源风成碳酸盐含量小于总碳酸盐含量的10%,X射线衍射半定量分析结果也支持这一结论。巴里坤湖泊表层沉积物碳酸盐矿物主要以文石和方解石为主,存在一定量的镁方解石,部分方解石为外源风成碳酸盐。生物活动、风场变化、水位变化以及湖泊水物理化学性质控制着湖泊碳酸盐分布的格局。因此,在利用碳酸盐重建古气候记录时需综合考虑。

英文摘要：

The Lake Balikun of Xinjiang is a saline lake in an arid and semi-arid region of northwest China. The source of carbonates of the lake includes authigenic and allochthonous carbonates. Based on the data of grain-size and X-ray diffraction, and taking the dry climate and regional landscape into account, it is believed that the aeolian carbonate is the major component of the allochthonous carbonates, and the carbonate from rivers is limited. However, the aeolian carbonate is less than 10% of the total carbonate in the central part of the Lake. Dusts were collected from April to June in 2009 from three sites. Mineralogical examination suggests that the carbonate in the dust is predominated by calcite, and the main components of lacustrine carbonates are calcite （Mg-calcite） and aragonite. It suggests that only a part of calcite of the lake sediments is aeolian and the rest is authigenic. The quantitative change in lacustrine carbonates is related to biological activity, especially the activity of algae and brine shrimps. Algae bloom in spring before surface brine water formed. The fecal pellets of brine shrimp are aragonite, calcite and gypsum. The Lake Balikun includes three depositional sub-environments： lake margin and shallow water sub-environment, transitional sub-environment and lake center lacustrine sub-environment. And the content of carbonate is different in sub-environments. In this regard, the boundary conditions of the sub-environment, including the physical and chemical properties of the water body, biological activities, wind and lake level, are the factors in control over the distribution pattern of carbonates in the lake. Authigenic minerals, such as chlorides （halite）, sulphates （gypsum, anhydrite, mirabilite thenardite） and carbonates （calcite, aragonite）, are derived from the seasonal change of surface brine water rich in Na-SO4-Cl-Mg. As the result, the composition of authigenic minerals is different in different sub-environments. Generally, the amount of calcite is opposed to