松辽盆地开鲁坳陷钱家店地区姚家组砂岩地球化学特征及物源和构造背景分析  

Geochemistry of the Yaojia Formation Sandstone in the Kailu Depression,Songliao Basin:Implications for its Provenance and Tectonic Setting

作　　者：徐增连 张博 里宏亮 李建国 曾辉 朱强 曹民强[2] 魏佳林 XU Zeng-lian;ZHANG Bo;LI Hong-liang;LI Jian-guo;ZENG Hui;ZHU Qiang;CAO Min-qiang;WEI Jia-lin(Tianjin Centre,China Geological Survey,Tianjin 300170,China;Development Company of New Energy Sources of Liaohe Petroleum Exploration Bureau,CNPC,Panjin Liaoning 124010,China)

机构地区：[1]中国地质调查局天津地质调查中心,天津300170 [2]辽河石油勘探局新能源开发公司,辽宁盘锦124010

出　　处：《矿物岩石地球化学通报》2019年第3期572-586,共15页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家重点基础研究发展计划项目(2015CB453000);中国地质调查项目(20160128,20190121)

摘　　要：为了开展钱家店铀矿床砂岩型铀矿的进一步找矿工作,对采集到的上白垩统姚家组19件砂岩样品进行了主、微量和稀土元素分析,并结合前人成果,对姚家组的沉积物源及源岩构造背景进行了探讨。结果表明,姚家组砂岩主要为长石砂岩,矿物成分主要为石英、钾长石和斜长石等;其轻重稀土比为6.96~14.66,均值为10.17;LaN/YbN为7.58~20.95,均值为11.74,说明轻稀土元素相对重稀土元素明显富集,分馏明显。稀土元素配分模式曲线高度一致,也表明姚家组砂岩具有同源性;其ICV值为0.86~2.78,平均值1.34,大部分大于1,表现为未成熟的性质,为初次旋回的沉积物;修正后的CIA均值62.5,暗示源岩经历中等化学风化作用;砂岩碎屑为近源的第一次旋回沉积物,受沉积分选和再循环作用影响不大;姚家组源岩以火山弧物质和大陆上地壳长英质物质为主,源岩主要形成于大陆边缘和大陆岛弧环境;开鲁坳陷形成于早白垩世随着古太平洋板块向欧亚板块俯冲速度的减小而在东北地区出现的北西-南东向拉张构造环境中,并接受盆地西部大兴安岭南段海西期和燕山期岩浆岩、火山岩沉积。In order to guide further prospecting,major,trace and rare earth elements of 19 samples from the Yaojia Formation were analyzed. Combining previous research achievements,the provenance and tectonic setting were discussed.Sandstones from the Yaojia Formation mainly comprise of feldspar sandstone and minor greywacke,with mineral assemblage of quartz,K-feldspar and plagioclase. All sandstone samples have similar REE pattern. They are enriched in LREE relative to HREE,with LREE/HREE of 6. 96-14. 66( averaging 10. 17) and LaN/YbNof 7. 58-20. 95( averaging11. 74),indicating that sandstones are relatively homologous and their chemical compositions are mainly controlled by source rock. The index of the chemistry variation( ICV) of 0. 86-2. 78( averaging 1. 34) indicates the immature nature of the Yaojia Formation sandstones,which resulted from the first cycle of sediments. The corrected chemical index of alteration( CIA correct) is 62. 5 in average,illustrating source rocks underwent moderate degree of chemical weathering. The rock fragments contain first cycle materials. The Yaojia formation sandstones were mainly derived from volcanic arcs and felsic igneous rocks of upper crust. The source material of Yaojia Formation were mainly from continental margin and continental arc setting. The Kailu Depression was formed in the NW-SE extensional tectonic environment due to the decrease ofsubduction speed of the Pacific plate beneath the Eurasian plate in early Cretaceous,and deposited the materials from the Hercynian and Yanshanian magmatic rocks,volcanic deposits of the Great Xing’an Ranges.

关 键 词：松辽盆地 开鲁坳陷 地球化学 物源 构造背景 

分 类 号：P588.212.3[天文地球—岩石学]