鄂尔多斯盆地陇东地区二叠系山西组—石盒子组母岩类型和构造背景

发布时间：2018-06-08 11:56

本文选题：岩石学 + 地球化学　；参考：《古地理学报》2017年02期

【摘要】：通过岩石学及地球化学分析方法,对鄂尔多斯盆地陇东地区二叠系山西组1段—石盒子组8段碎屑岩物源区的母岩类型和构造属性进行分析。研究结果表明:山1段和盒8段的砂岩碎屑组成相似,具有基本相同的物源区组成,它们在构造背景、物源及物源特征上具有很好的继承性;砂岩碎屑颗粒镜下特征及石英阴极发光颜色显示母岩主要为变质岩和火成岩;轻矿物特征反映物源与再循环造山带源区中的碰撞缝合线及褶皱—逆掩带物源区密切相关;研究区与北秦岭地区秦岭群和宽坪群斜长石种类一致;构造环境判别图解反映物源区长期受被动大陆边缘物源影响,到晚古生代后期有向主动大陆边缘转换的趋势;源岩判别图解显示物源区主要是长英质岩石;山1段、盒8段沉积岩的REE配分模式均呈右倾型且基本相互平行,与北秦岭地区秦岭群、宽坪群变质岩的稀土元素配分模式相似;锆石U-Pb同位素定年结果显示物源主要来自元古代,有少部分来自晚古生代。综合分析认为研究区主要受被动大陆边缘物源影响,其次为主动大陆边缘物源,母岩主要为北秦岭下元古界秦岭群的片麻岩、石英岩等和中、上元古界宽坪群的绿泥石片岩、阳起石片岩,其次为北秦岭造山带晚古生代岩浆岩。
[Abstract]:By means of petrology and geochemistry analysis, the parent rock types and structural attributes of the source area of clastic rocks of Shanxi member 1 and Shihezi formation 8 of Permian in Longdong area of Ordos Basin are analyzed. The results show that the sandstone clastic compositions of Shan-1 member and Bo8 member are similar and have the same source area composition, and they have good inheritance in tectonic background, provenance and provenance characteristics. The characteristics of sandstone clastic grains and the color of quartz cathodic luminescence show that the parent rocks are mainly metamorphic and igneous rocks, and the light mineral characteristics indicate that the provenance is closely related to the collision suture in the source region of the recirculation orogenic belt and the provenance of the fold-Overthrust belt. The study area is consistent with the type of plagioclase of Qinling Group and Kuanping Group in North Qinling area, and the tectonic environment discriminant diagram shows that the source area is influenced by passive continental margin for a long time, and has a tendency to convert to active continental margin from late Paleozoic to late Paleozoic. The source rocks are mainly felsic rocks, the REE distribution patterns of sedimentary rocks of member 1 and Ke 8 are all right-dip and parallel to each other, which is similar to the REE distribution pattern of metamorphic rocks of Qinling Group and Kuanping Group in North Qinling area. The zircon U-Pb isotopic dating results show that the proterozoic is the main source and a few are from the late Paleozoic. It is considered that the study area is mainly influenced by passive continental margin provenances, followed by active continental margin provenances, and the parent rocks are gneiss of the Lower Proterozoic Qinling Group in the North Qinling Mountains, quartz rocks, and chlorite schists of the Upper Proterozoic Kuanping Group. Yangqinshi schist, followed by the North Qinling orogenic belt late Paleozoic magmatic rocks.
【作者单位】：中国石油大学(北京)地球科学学院;中国石油长庆油田分公司勘探部;
【分类号】：P618.13;P587

【相似文献】