摘要
古气候控制着砂岩型铀矿含矿建造的形成,对厘定找矿目的层有重要的指导意义。沉积岩中元素地球化学研究是研究沉积时古气候的有效手段。在总结古气候指示元素含量变化特征基础上,结合十万大山盆地区域构造演化、宏观沉积特征推算了古盐度变化特征,重建了侏罗纪古气候演化。研究表明:沉积旋回转换时往往伴随古气候变化,微量元素含量及比值变化具有旋回性。侏罗纪古水体整体为淡水-微咸水,古气候演化为早侏罗世为潮湿气候,到中侏罗世气候逐渐变为半干旱半潮湿频繁波动,晚侏罗世气候逐渐变为干旱。中侏罗统那荡组发育杂色碎屑岩建造,可作为砂岩型铀矿找矿目的层。
Elemental geochemistry in sedimentary rocks is an effective means to study the paleoclimatology.The Jurassic paleoclimate was reconstructed on the basis of paleosalinity,regional tectonic evolution and sedimentary features in Shiwandashan basin.The paleosalinity was calculated on the basis of studying the variation pattern of paleoclimatic indicator element content.Paleoclimate controls the formation of sandstone type uranium ore-bearing formation,which has important guiding significance for determining the strata of ore-prospecting targets.The results showed that the transformation of sedimentary cycle is often accompanied by the periodic change of paleoclimate,trace element content and their ratio.Water body hosting the Jurassic sediment was fresh–brackish.The paleoclimate evolved from the humid in early Jurassic through semi-arid with frequent fluctuation in the middle Jurassic to the dry gradually in the Late Jurassic.The Middle Jurassic Nadang Formation with well-developed clastic rock formation was believed the target layer for sandstone-type uranium deposit.
作者
王小明
朱小兵
彭新发
WANG Xiaoming;ZHU Xiaobing;PENG Xinfa(Research Institute No.230,CNNC,Changsha,Hunan 410007,China)
出处
《铀矿地质》
CAS
CSCD
2021年第5期834-842,共9页
Uranium Geology
基金
青海省柴达木盆地东部铀矿资源调查评价项目(编号:202018-2)资助。
关键词
十万大山盆地
侏罗系
元素地球化学
古气候
那荡组
Shiwandashan basin
Jurassic Strata
geochemistry
paleoclimate
Nadang Formation
