摘要
通过沉积相特征识别、砂体宏观特征观察、古流向分析、砂岩镜下骨架颗粒统计,并结合沉积速率法、镜质组反射率法、Dickinson图解等方法探讨宁武—静乐盆地物源区的位置、母岩组合及其构造背景。研究结果表明:宁武—静乐盆地侏罗系砂岩类型主要为石英砂岩、长石砂岩和岩屑长石砂岩;砂岩骨架颗粒类型及其量比关系表明其物源区主要为大面积的花岗质侵入岩(细粒花岗岩、闪长花岗岩等)广泛出露,并有一定量的变质岩(云母片岩、千枚岩、石英岩等)和沉积岩(砂岩、富含燧石结核或条带的碳酸盐)分布;砂体中古流向数据均值介于158°~204°,反映了物源区是位于该盆地以北的阴山—燕山一带;Dickinson三角图解结果表明物源区总体上处于华北板块北缘陆内隆升的构造背景,且中侏罗世晚期可能伴随有火山作用;天池河组地层原始沉积厚度为269.4~308.0 m,155 Ma左右,区域地层抬升遭受剥蚀,其剥蚀厚度为148.1~207.0 m,剥蚀速率为1.8~2.1 m/Ma,结合镜质组反射率法,侏罗系地层最大埋深时该地区古地温梯度明显偏高,反映了宁武—静乐一带受到燕山运动构造热事件的显著影响。
The provenance location,parent rock and tectonic setting of Jurassic strata in Ningwu-Jingle basin were funded out with the methods of sedimentary facies identification,deposition rate method,vitrinite reflectance method,paleocurrent direction measurement,sandstone skeleton mineral particles statistics,Dickinson diagram and so on. The results show that Jurassic sandstones are mainly quartz sandstone,feldspar sandstone and lithic-feldspar sandstone. The sandstone skeleton particle types and its ratio reveal that there was widely exposed a large area of granitic plutonic intrusive rocks( granite,dioritic granite and so on) and senior metamorphic rocks( mica schist,phyllite,quartzite and so on) in the provenance. And there was also a small amount of sedimentary rocks( sandstone,carbonate rock that are rich in flint tuberculosis or stripes). The paleocurrent direction in Jurassic sand bodies generally focus on the 158° ~ 204° interval that reveals that the provenance is located in the north of the basin,which is Yinshan-Yanshan orogenic belt today. And it is Dickinson diagram that reveals the provenance was under the background of intracontinental uplift on the north edge of North China Plate,with volcanic activity in late Middle Jurassic. The original thickness of sedimentary strata in the Tianchihe formation is 269. 4 ~ 308. 0 m. About155 Ma,the strata begun to uplift and denude. The erosion-thickness is 148. 1 ~ 207. 0 m with the denudation rate of 1. 8 ~ 2. 1 m/Ma. With the method of vitrinite reflectance,the maximum paleogeothermal gradient is distinctly high when the maximum depth of the Jurassic strata was buried,reflecting the Ningwu jingle region was significantly affected by the heat event of Yanshan tectonic movement.
出处
《科学技术与工程》
北大核心
2018年第6期31-38,共8页
Science Technology and Engineering
基金
山西省应用基础研究项目(201601D21138)资助
