齐古断褶带头屯河组—清水河组地球化学特征及古环境

为确定齐古断褶带头屯河组—清水河组地球化学特征及其古环境,利用X射线荧光光谱仪进行元素分析,选取对沉积环境较为敏感的钒（V）、铬（Cr）、镍（Ni）、钴（Co）、锶（Sr）、锆（Zr）、镓（Ga）等元素,系统分析了研究区的古氧化—还原条件、古盐度、古水深及古气候特征。结果表明,研究区头屯河组—清水河组为氧化环境沉积,极个别时期为短暂的弱氧化—弱还原环境。Ga、Sr等敏感元素及Sr/Ba指示,研究区头屯河组—喀拉扎组沉积期以淡水环境为主,局部可能有短暂的半咸水环境;清水河组古盐度波动较为频繁,其沉积期咸水与淡水频繁交替。根据Co元素估算,头屯河组—清水河组沉积期水深为2.05~74.20 m,水体深度波动较大。头屯河组—喀拉扎组沉积期气候由温暖湿润转向炎热干旱,清水河组沉积期又逐渐转向温暖湿润。

Geochemical Characteristics and Paleoenvironment of Toutunhe Formation-Qingshuihe Formation in Qigu Fault-Fold Belt

In order to determine the geochemical characteristics and paleoenvironment of the Toutunhe formation-Qingshuihe formation in the Qigu fault-fold belt of Junggar basin, the element analysis was carried out using the X-ray fluorescence spectrometer. Such elements as vanadium (V), chromium (Cr), nickel (Ni), cobalt (Co), strontium (Sr), zirconium (Zr) and gallium (Ga), which are sensitive to the depositional environment, were selected to systematically analyze the characteristics of paleo-oxidation-reduction conditions, paleosalinity, paleo-water depth, and paleoclimate in the study area. The results show that the Toutunhe formation-Qingshuihe formation in the study area was deposited in an oxidation environment, and occasionally in short-term weak oxidation-weak reduction environment. Sensitive elements (e.g. Ga and Sr) and Sr/Ba value indicate that the Toutunhe formation-Kalazha formation was dominantly deposited in a freshwater environment, and possibly a short-term brackish water environment locally, and the Qingshuihe formation exhibits relatively frequent paleosalinity fluctuation and was deposited in an alternating environment of saltwater and freshwater. According to the Co estimation, the water depth of the Toutunhe formation-Qingshuihe formation rangef from 2.05 to 74.20 m, and fluctuated greatly during the depositional period. The climate changed from warm and humid to arid and hot during the deposition of the Toutunhe formation-Kalazha formation, and shifted to warm and humid during the deposition of the Qingshuihe formation.