德令哈盆地尕海湖DG03孔岩芯矿物组合与古环境变化  

Mineral Assemblages and Palaeoenvironmental Changes of Core DG03 of Gahai Lake in Delingha Basin

作　　者：张西营[1] 马海州[1] 韩风清[1] 陈忠[1] 曹广超[1] 王建国[1] 

机构地区：[1]中国科学院青海盐湖研究所,西宁810008

出　　处：《沉积学报》2007年第5期767-773,共7页Acta Sedimentologica Sinica

基　　金：国家重点基础研究发展计划"973计划"(批准号:2004CB720202)资助

摘　　要：对气候敏感区德令哈盆地尕海湖DG03孔岩芯的矿物学分析表明,DG03孔岩芯的矿物主要包括石英、斜长石、微斜长石、绿泥石、伊利石、方解石、文石、白云石、石膏及石盐等。岩芯记录了尕海湖约11ka以来(AMS-14C年龄)的古环境变化。根据矿物、碳酸盐含量及岩性的变化,整个岩芯可划分为三个部分:Ⅰ.约11ka～10kaBP,晚冰期末期;Ⅱ.10ka～4kaBP,全新世早中期;Ⅲ.4ka至今,全新世晚期。矿物组合表明,自晚冰期以来,尕海湖先后经历了湖泊演化的逆向和正向演化阶段,即尕海湖先后经历了晚冰期的干冷气候,早全新世的暖干气候,中全新世的暖湿气候以及晚全新世以来的逐渐干冷的气候。岩性分析还表明,尕海湖沉积环境复杂,存在多种微相沉积。Gahai Lake lies in the conjunction area of some large-scale climatic systems such as East Asian monsoon area, southwest monsoon area and westerly wind and so on. Through studies on some palaeoenvironmental proxies such as minerals, grain size and carbonate content in Core DG03, we have analyzed and discussed the characteristics of palaeoenvironment changes in Gahai Lake, where is a sensitive area for climatic change. The research results show that the main minerals in core DG03 include quartz, plagioclase, microcline, chlorite, illite, calcite, aragonite, dolomite, gypsum and halite. The core records the palaeoenvironmental change information of Gahai Lake since about l lka BP （AMS-14C age）. According to change characteristics of minerals and lithology, the core is divided into three parts： Ⅰ about 11 ka - 10 ka BP, the last period of late-glacial （Younger Dryas event） ; Ⅱ 10 ka -4 ka BP, the early and middle Holocene; Ⅲ 4 ka ～ 0 BP, the late Holocene. The mineral assemblages in different period indicate that the water level of Gahai Lake experiences a process of low-high-low and accordingly salinity high-low-high. Gahai Lake orderly experiences the reverse and forward process of lake evolution. Combining the lithology and grain size, we speculate that Gahai Lake area orderly experienced the cold and dry climate of late-glacial, the warm and dry climate of early Holocene, the warm and wet climate of middle Holocene and the gradually cold and dry climate of late Holocene. The analysis of lithology also shows that there is a complex sedimentary environment and there are some different types of terrestrial deposits in Gahai Lake and the influence of alluvial-proluvial deposition is through the whole Holocene. But we believe that the complex sedimentary environments can better reveal the change characteristics of regional environment.

关 键 词：德令哈盆地 尕海湖 矿物组合 古环境 文石 石膏 

分 类 号：P512.2[天文地球—地质学]