摘要
为揭示柴达木盆地西缘英东地区上油砂山组含铀砂岩源岩风化程度、物源性质及构造背景,以区内最新发现的工业铀矿孔ZKY01中上油砂山组含矿砂岩为研究对象,通过岩心和显微观察、扫描电镜和地球化学分析,探讨了区内含矿砂岩的岩石学特征、地球化学特征、风化作用特征、物源特征及沉积构造背景,并结合地质特征,初步分析了油气与砂岩型铀成矿的关系。结果显示,上油砂山组含矿砂岩以长石岩屑砂岩为主,铀矿物主要有钒钙铀矿、钒钾铀矿、沥青铀矿和铀石;分异指数CIA和风化指数ICV表明含矿砂岩成分变化程度低,为构造带首次沉积,没有经历沉积再循环过程。物源以中酸性岩浆岩为主,源区具有主动大陆边缘和大陆边缘弧的构造背景;δEu、δCe与U呈微弱正相关,U富集过程由氧化向还原环境转变。结合铀成矿地质条件认为,上油砂山组含矿目的层中铀矿化与油气关系密切,油气的上侵提升了砂体的还原能力,有利于砂岩型铀矿的形成。
In order to reveal the weathering degree, provenance properties, and tectonic background of uranium-bearing sandstone source rocks of the Shangyoushashan Formation in the Yingdong area of the western margin of Qaidam Basin, the ore-bearing sandstone samples of the Shangyoushashan Formation have been collected from drill cores of Hole ZKY01 in the newly discovered industrial uranium ore deposit in the study area to study the lithological characteristics, geochemical characteristics, weathering characteristics, provenance characteristics, and sedimentary tectonic background of the ore-bearing sandstone by using naked-eye observation, microscopic observation, scanning electron microscopy, and geochemical analysis of core samples, and then to preliminarily analyze relationship between the oil and gas and the sandstone type uranium mineralizationwith the combination of geological characteristics of the area. The results show that the ore-bearing sandstone of the Shangyoushashan Formation, dominated by feldspathic lithic sandstone, contains major uranium minerals including tyuyamunite, carnotite, uraninite, and coffinite. The CIA and ICV indexes show that the compositional variation of the ore-bearing sandstone is low and the sandstone was firstly deposited in the tectonic belt with no experience of a sedimentary recycling process. The provenance of the sandstone could be mainly intermediate-acid magmatic rocks in the tectonic settings of active continental margin and continental marginal arc. There are weak positive correlations between δEu values, δCe values and U contents. The U enrichment process had experienced a transition from oxidation to reduction environments. Combined with the comprehensive analysis of uranium metallogenic geological conditions, it is believed that uranium mineralization in the ore-bearing target layer of the Shangyoushashan Formation in the study area is closely related to the movement of oil and gas. The upward movement of oil and gas resulted in the improvement of the reduction ability of the sandstone which is conducive to the formation of sandstone type uranium deposits.
作者
李强
陈擎
王继斌
陈斌
邵恒博
时志浩
龚美鑫
LI Qiang;CHEN Qing;WANG Ji-bin;CHEN Bin;SHAO Heng-bo;SHI Zhi-hao;GONG Mei-xin(No.203 Research Institute of Nuclear Industry,Xi'an 712000,China)
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2022年第6期1145-1164,共20页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
中国铀业有限公司项目(202219)
中国铀业有限公司-东华理工大学核资源与环境国家重点实验室联合创新基金项目(2022NRE-LH-17)。
关键词
砂岩型铀矿
元素地球化学特征
油气还原作用
上油砂山组
柴达木盆地西缘
sandstone type uranium deposits
elemental geochemical characteristics
oil-gas reduction
Shangyoushashan Formation
western margin of the Qaidam Basin
