【作者】 谭红兵； 马海州； 许建新； 肖应凯； 王建国； 李廷伟；

【Author】 TAN Hongbing MA Haizhou XU Jianxin XIAO Yingkai WANG Jianguo LI Tingwei Institute of Salt Lakes,Chinese Academy of Sciences,Xining,Qinghai,810008

【机构】 中国科学院青海盐湖研究所；

【摘要】 我国钾盐资源紧缺,寻找优质大型钾盐矿床一直是国家资源普查的重要目标之一。塔里木盆地在其地史发展过程中,曾与广海相通,多期海水的侵入和间断,以及适宜的构造、古地理环境具备成钾的基本地质条件,因此一直被列为我国寻找古钾矿的重点地区。为了更准确地判断其成盐的海陆相特征,即成盐物质的主要来源,以及岩盐沉积之前的古卤水蒸发浓缩阶段,预测更有前景的成钾远景区,论文选择了蒸发岩沉积序列中的石膏及石盐矿物,分别分析了其硫同位素及氯同位素分布特征。结果表明,非还原环境下沉积的石膏硫同位素可以准确判断盐岩沉积的海相、陆相和海陆交互相沉积特征,氯同位素可以判断岩盐的沉积阶段。应用这两个同位素新指标分析,塔里木盆地西部喀什次级构造凹陷晚白垩世盐岩沉积接近海相沉积类型,而且岩盐沉积阶段较晚,是一最有利成钾远景区。更多还原

【Abstract】 From Late Cretaceous to Early Tertiary,the Paleo-Mediterranean seawater repeatedly invaded into Shaqa subbasin andthen poured into Kuqa subbasin through the Awati strait.With the favorable tectonic and paleoenvironmental conditions,the basindeposited many sequences of thick evaporate beds,especially in its two largest subbasins:Kuqa in the north and Shaqa in the south-west.Therefore,the western Tarim basin has been considered to be a favorable location in search for ancient sylvinite deposits.In or-der to identify its marine or continental sedimentary facies and also the sedimentary stages,the authors selected the late stage evapo-rates of gypsum and salt minerals and measured the values of sulfur and chlorine isotopes.The results show that the sulfur isotopes ofgypsum can be used to distinguish the sedimentary facies of marine or continent whereas chlorine isotopes of salt can be employed todetermine the sedimentary stage.It is thus concluded that Late Cretaceous salts deposited in Kashi depression of southwestern Tarimbasin are close to the marine type,and the sedimentary stage is somewhat later than other regions.Therefore,Kashi depressionshould be regarded as a promising area in prospecting for sylvinite deposits.更多还原