摘要
砂岩地球化学特征可以有效反映物源区地质信息。为了探讨查干凹陷下白垩统巴音戈壁组-苏红图组砂岩物源属性与源区构造环境,进行了砂岩显微薄片鉴定和主量元素测定,结果显示,巴音戈壁组砂岩与苏红图组砂岩的岩石学特征较相似,主量元素特征稍有差异。综合研究表明,砂岩成熟度低,杂基含量较高,岩性以岩屑长石砂岩和长石岩屑砂岩为主;物源区母岩主要为中酸性岩类(长英质为主),其次为中性和酸性岩类,也有极少量基性岩成分;研究区总体上长期处于构造活跃地区,气候寒冷干燥,碎屑物质化学风化程度低,源区构造环境以活动大陆边缘和岛弧环境为主,也有少量物源来自被动大陆边缘,基本上没有来自反映稳定构造环境的克拉通内部的物源;主体物源区构造环境以活动大陆边缘为主,其构造环境性质长期保持相对稳定。
Geochemical characteristics of sandstone can effectively provide geological information about source area. Microscopic thin sections of sandstones from Bayin Gehi Formation and Suhongtu Formation of Lower Cretaceous in Chagan sag were analyzed and their major elements were tested, in order to discuss the provenance attributes of sandstones and tectonic settings of their source areas. The analysis results show that the petrological characteristics of sandstones from Bayin Gebi Formation and Suhongtu Formation are similar, and that the characteristics of their major elements vary slightly. Comprehensive research suggests that the sandstones have low maturity and higher matrix contents, and the lithology is mainly composed of feldspathic lithic sandstones and lithic feldspathic sand- stones, and that source rocks mainly comprise intermediate-acidic rocks （main felsic composition）, followed by neu- tral and acidic rocks, and a tiny amount of basites. And it was showed that the research area had generally been lo- cated in a tectonically active region for a long time, where the climate had been cold-and-dry for a long period and the debris had low chemical weathering degree. Provenance analysis shows that the tectonic settings in source areas are mainly active continental margin and island arc, slightly passive continental margin and basically no craton standing for stable tectonic setting, and that the tectonic setting in the main source area is active continental margin, which properties of tectonic setting remain relatively stable for long.
出处
《矿物岩石地球化学通报》
CAS
CSCD
北大核心
2014年第4期517-525,共9页
Bulletin of Mineralogy, Petrology and Geochemistry
基金
中原油田科技攻关项目(2011133)
关键词
下白垩统
查干凹陷
巴音戈壁组苏红图组
元素地球化学
物源
构造环境
Lower Cretaceous
Chagan Sag
Bayin Gebi Formation and Suhongtu Formation
element geochemistry
source
tectonic setting
