辽西牛营子—郭家店盆地充填演化及其与构造变形的关系

发布时间：2019-02-24 18:10

【摘要】：燕山造山带是发育在华北板块东北部的一个板内造山带,西起内蒙包头,东到渤海湾,整体构造方向为东西向,造山带东端则转为北东-北北东向。本文研究区牛营子-郭家店盆地位于燕山造山带东段,是一个被后期构造强烈改造的小型盆地。针对该盆地中地层的沉积特征和构造特征,得到以下认识:邓杖子组主要由一套分选性和磨圆度都很差的碳酸盐质砾岩组成,砾岩的成分和结构成熟度都说明它的形成与剧烈的构造活动紧密相关,是研究区内晚三叠世时期强烈构造变动的沉积记录,且与其下伏地层水泉沟组呈整合接触。二者为一套由西向东变新的单斜地层;本文还确定了牛营子-郭家店盆地内邓杖子组所构成的砾岩层中砾石成分的变化规律,并根据砾石成分的不同将邓杖子组分为3段:邓杖子组1段以安山岩砾石为主,沿剖面向上砾岩中安山岩砾石成分减少,而灰岩砾石成分增加,至该段上部砾石成分变为以灰岩砾石为主,该段砾石主要来源于水泉沟组和寒武-奥套系地层;邓杖子组2段砾石成分有灰白-灰色、薄层-中厚层泥晶白云质岩、灰黑色硅质页岩、海绿石石英砂岩和灰绿色辉绿岩,砾石主要来源于青白口系地层;邓杖子组3段砾石以燧石条带灰白-灰色白云岩、白云质灰岩为主,具少量褐红色、褐黄色含Mn白云岩、灰绿色辉绿岩、硅化页岩及石英砂岩,砾石主要来源于蓟县系。邓杖子组砾岩在剖面上具明显的倒序岩屑地层特征,反映了物源区正常的层序地层,并结合盆地周围的地层、构造特征,对牛营子一郭家店盆地邓杖子组砾岩可能的物源区进行了分析和讨论,指出牛营子-郭家店盆地的物源区为盆地西侧。最后本文确定了盆地中部两个近直立的断层(大齐子断层和朱杖子断层)的复杂的变形史:在晚三叠世,元古代地层向南东方向逆冲于邓杖子组之上,随后二者由于再一次的构造作用而发生变形,因此,目前所见到的牛营子-郭家店盆地是一个经历后期强烈构造改造和剥蚀的残余盆地,而不是一个原形盆地。
[Abstract]:Yanshanian orogenic belt is an intraplate orogenic belt developed in the northeast of North China plate. It starts from Baotou in the west and reaches Bohai Bay in the east. The whole tectonic direction is east-west, and the eastern end of the orogenic belt is turned to NE-NNE. The Niuyingzi-Guojiadian basin, located in the eastern section of the Yanshanian orogenic belt, is a small basin which was strongly reformed by late structure. According to the sedimentary and structural characteristics of the middle strata in the basin, the following conclusions have been obtained: the Deng Changzi formation is mainly composed of a set of carbonate conglomerates with poor sorting and roundness. The composition and structural maturity of conglomerate indicate that its formation is closely related to the intense tectonic activity and is a sedimentary record of strong tectonic changes during the late Triassic in the study area and is in integrated contact with the underlying formation of Shuiquangou formation. The two are a set of monocline strata changed from west to east. The variation law of gravel composition in the conglomerate formed by Deng Chang Zi formation in Niuying Zi-Guojiadian Basin is also determined. According to the difference of gravel composition, Deng Chang Zi component is divided into three sections: the first member of Deng Chang Zi formation is dominated by andesite gravel. Along the section, the gravel composition of andesite in the conglomerate decreases, but the gravel composition of the limestone increases, and the gravel composition of the upper part of the section becomes dominated by the limestone gravel, which is mainly derived from the Shuiquangou formation and Cambrian-Ordovician strata. There are gravel-gray, thin-layer and medium-thick mudstone dolomite, grey-black siliceous shale, glauconite quartz sandstone and grey-green diabase in the second member of Dengzangzi formation. The gravel is mainly derived from Qingbaikou strata. In the third member of Dengzhang formation, the gray-gray dolomite is mainly composed of flint stripe, dolomitic limestone with a small amount of brownish-red, brown-yellow Mn dolomite, grey-green diabase, silicified shale and quartz sandstone, and the gravel is mainly derived from Jixian system. The conglomerate of Dengchangzi formation has obvious inverted sequence lithic stratigraphic characteristics in the section, which reflects the normal sequence stratigraphy of the provenance region, and combines with the strata around the basin and structural characteristics. This paper analyzes and discusses the possible provenance of the conglomerate of the Dengchangzi formation in the Niuyingzi-Guojiadian basin, and points out that the source region of the Niuyingzi-Guojiadian basin is the west side of the basin. Finally, the complicated deformation history of two near-vertical faults in the central part of the basin (Dazizi fault and Zhuzangzi fault) has been determined: in the late Triassic, the Proterozoic strata thrust south to east on the Dengzhuzi formation. As a result of the tectonic action again, the Niuyingzi-Guojiadian basin is a residual basin, not a prototype basin, which has undergone a strong tectonic transformation and erosion in the later stage.
【学位授予单位】：中国地质大学(北京)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P548

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