柳江盆地上寒武统崮山组微量元素地球化学特征及古环境指示意义

Geochemical Characteristics of Trace Elements of the Upper Cambrian Kushan Formation in the Liujiang Basin and Paleonvironmental Implications

柳江盆地记录了从太古代至新生代华北地台乃至全球地壳运动、岩浆活动、沉积环境、气候演化以及生物进化和发展等各种重要地质事件与地质现象,是研究不同时期古环境恢复的极佳选择。通过对秦皇岛柳江盆地上寒武统崮山组的野外考察和不同层段岩石全元素的测定,分析了各元素富集的丰度。运用微量元素地球化学指标体系研究了古盐度、古气候以及氧化还原环境,根据Sr/Ba和Th/U等指标分析,认为研究区域是淡水-半咸水环境,其盐度从下至上逐渐降低;Sr/Cu、Rb/Sr数据表明研究区为温暖潮湿的气候;依据δU、U/Th、V/Cr、Ni/Co和Ce/Ce^(*)等指标分析,研究区为氧化环境。

The Liujiang Basin records a wide range of important geological events and phenomena from the Archaeozoic to the Cenozoic in the North China Plateau and even the Globe,including crustal movements,magmatic activity,sedimentary environments,climatic evolution and biological evolution and development,making it an excellent choice for the study of palaeoenvironmental recovery in different periods.Based on the fieldwork of the Upper Cambrian Mountains Formation in Liujiang Basin of Qinhuangdao and the determination of full elements of rocks in different layers,the abundance of each element enrichment is analyzed.Using the index system of trace element geochemical indicators,paleosalinity,paleoclimate and redox environment are studied.The analysis shows that the values of Sr/Ba and Th/U indicate that the study area is a freshwater-semisaline environment,and the salinity decreases from bottom to top.Sr/Cu and Rb/Sr data indicate that the study area is a warm and humid climate.δU,U/Th,V/Cr,Ni/Co and Ce/Ce^(*) values indicate that the study area is an oxidizing environment.