陕西省洛南地区二叠系石盒子组砂岩特征及物源区探讨  

Discussion on sandstone characteristic and provenance of Permian Shihezi Formation in Luonan,Shaanxi Province

作　　者：陈高潮[1] 李玉宏[1] 韩伟[1] 牛亚卓[1] 张乔 Chen Gaochao;Li Yuhong;Han Wei;Niu Yazhuo;Zhang Qiao(Xi'an Center of Geological Survey,China Geological Survey,Xi'an 710054)

机构地区：[1]中国地质调查局西安地质调查中心,西安710054

出　　处：《地质科学》2020年第4期1001-1011,共11页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：地质矿产调查评价基金项目(编号:21201011000150014,DD20190103)资助。

摘　　要：为了认识陕西省洛南地区二叠系石盒子组砂岩特征及其物源,给探索渭河盆地前新生代基底组成提供依据,本文综合分析了洛南二叠系石盒子组砂岩组分和重矿物特征。结果表明,砂岩物源区主要为再旋回造山带和克拉通地块,物源区与北秦岭造山带的演化关系密切,南秦岭构造带北部下古生界也为石盒子组提供部分物源,中二叠世晚期华北、秦岭板块面接触碰撞,北秦岭构造带快速隆升,南秦岭物源区提供物源减少,砂岩物源主要为中酸性岩浆岩+低级变质岩+沉积岩。二叠纪鄂尔多斯盆地南缘向南延至洛南—栾川断裂附近,洛南地区二叠系石盒子组河流沼泽相含煤岩系沉积应该属于鄂尔多斯盆地南缘沉积,结合渭北—渭河—洛南地区晚古生代地层对比成果,认为渭河地区二叠纪至少曾沉积过二叠系石盒子组地层,渭河新生代盆地基底具有残存二叠系的可能。In order to better understand the characteristic and source of sandstones in Permian Shihezi Formation in Luonan,Shaanxi Province,China and provide evidence for the exploration of pre-Cenozoic basement composition in Weihe Basin,this study analyzed the compositions and heavy minerals features of the sandstones synthetically.It was indicated that sandstones in Shihezi Formation mainly came from reworking orogenic belt and craton block,which were closely related with the evolution of North Qinling orogenic belt.Besides,the Lower Paleozoic strata in the north of South Qinling orogenic belt also provide partial provenance for the sandstones.In Late Mid-Permian,the surface contact collision occurred between North China Block and Qinling orogenic belt caused that northern Qinling belt uplifted rapidly and the provenance from southern Qinling belt decreased.It was suggested that the provenance of sandstones in Permian Shihezi Formation mainly includes intermediate-acid igneous rocks,low-grade metamorphic rocks and sedimentary rocks.During Permian,Ordos Basin southward extended to the area near the Luonan-Luanchuan fault,therefore,Permian coal-bearing rock series deposition of Shihezi Formation with fluvial-swamp facies in Luonan must be part of deposition in the southern margin of Ordos Basin.Combined with the stratigraphic correlation of Late-Paleozoic strata in Weibei,Weihe and Luonan area,it suggested that Permian Shihezi Formation should ever deposited in the Weihe area,that is to say,it was probable that Permian strata exist in the basement of Weihe Cenozoic Basin at present.

关 键 词：洛南 石盒子组 轻矿物 重矿物 物源 

分 类 号：P534.46[天文地球—古生物学与地层学] P539.2[天文地球—地质学]