| 内蒙古正镶白旗贡淖尔地区中二叠统额里图组下段 细碎屑岩地球化学特征及意义 |
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| 关键词:Elitu Formation fine clastic rocks geochemistry tectonic background Inner Mongolia |
| 基金项目:中国地质调查局项目“二连盆地及外围石炭-二叠系油气地质调查”(编号: 202016000000180202);中央级公益性科研院所基本科研业务费专项(编号: KK2005);国家自然科学基金项目“兴蒙地区晚二叠世海相沉积的古环境重建”(编号: 41572098) |
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| Geochemistry and Significance of Siliciclastic Rocks from the Lowest Elitu Formation of Middle Permian in the Gongnaoer Area, Zhengxiangbaiqi, Inner Mongolia |
| The Elitu Formation of Middle Permian is widely developed in Zhengxiangbaiqi and its adjacent areas in Inner Mongolia and in the junction area of Xingmeng orogenic belt and North China plate. In recent years, it has been considered as a potential oil and gas bearing Upper Paleozoic strata in the northern China. This formation is characterized by marine siliciclastic rocks in the lowest member, tuff-cemented bryozoan reef limestone in the upper part, and shallow marine eruptive rocks in the second member. We measured the Gongnaoer profile of the Elitu formation in Zhengxiangbaiqi and conducted detailed microscopic petrographic studies on the lower section of the profile. Whole rock geochemistry, including the major elements, trace elements, and rare earth elements (REEs), of the fine-grained siliciclastic rocks widely developed in the lower section was analyzed. The results show that (1) the sorting of sandstone is poor, with angular sand grains. The particles are mainly composed of volcanic rock debris, quartz particles, feldspar, and chert. The cement is tuffaceous material and argillaceous matrix. Overall, it is a low-maturity lithic feldspar greywacke with near-source rapid accumulation. (2) The paleoclimatic conditions of the source area of fine clastic rocks has an evolving trend of slightly cold and dry→warm and humid→slightly cold and dry→warm and humid→slightly cold and dry, which is a generally warm and humid climate environment. (3) Most of the fine clastic rocks belong to the sediments of the first cycle in the active tectonic area, and the source area is mainly composed of felsic igneous rocks and quartziferous sedimentary rocks from the upper crust. (4) The tectonic background of the source region is the active continental margin and continental island arc environment, and the sedimentary basin is the back-arc basin. |
| WANG Biao,SHI Li-zhi,RUAN Zhuang,HUANG Jing-yi,LUO Li-yan.2022.Geochemistry and Significance of Siliciclastic Rocks from the Lowest Elitu Formation of Middle Permian in the Gongnaoer Area, Zhengxiangbaiqi, Inner Mongolia[J].Acta Geoscientica Sinica,43(4):569-583. |
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