鄂尔多斯北部巴汗淖地区奥陶系马家沟组马五6-8沉积相研究

发布时间：2018-06-16 09:57

本文选题：碳酸盐岩 + 沉积微相　；参考：《西北大学》2015年硕士论文

【摘要】：本文以鄂尔多斯北部巴汗淖地区奥陶系马家沟组马五8、7、6亚段为研究对象,在综合前人研究成果的基础上,以沉积学基本原理为指导,结合地球物理学、地球化学等方法,通过露头、岩心、薄片、地化等资料,明确马五8、7、6段地层分布特征,对古地貌进行恢复并掌握当时海平面变化规律,通过研究目的层相标志预判沉积相后,利用单因素分析多因素综合法绘制单因素图并进行碳酸盐岩原岩恢复,综合上述研究成果精确划相并得出三段目的层沉积相展布特征,为后期研究提供有益参考。巴汗淖地区马五8、7、6各亚段地层由东南向西北尖灭,厚度随之平缓减薄,由老至新沉积区面积逐步向东南方缩小,各层厚度均稳定在25m左右。古地貌由西北的岩溶高地过渡为中部的岩溶台地后转变为东南的岩溶斜坡,整体呈现西北高东南低的特征。碳氧同位素分析结果显示由马五8至马五6亚段δ1.C、δ18O含量总体呈先上升后下降的趋势,反映该时期海平面先升高后降低,推测气候由湿热过渡为湿润后再次转为湿热。三段目的层均发育大量云岩,马五8、6亚段灰岩含量较低以次生灰岩为主,含少量泥质和膏质。马五7亚段整体灰岩含量升高,次生灰岩含量降低,原生灰岩含量有所增加,未见泥质及膏质成分。巴汗淖地区奥陶系马家沟组马五8亚段属于局限海台地相中靠近潮上的区域,随着海平面上升马五7亚段过渡到局限海台地的潮上带下部或潮间带上部,之后海平面下降,至马五6期回归到局限海台地相中靠近潮上的区域。
[Abstract]:In this paper, based on the previous research results, the Ordovician Majiagou member of Majiagou formation of the Ordovician Majiagou formation is taken as the research object. The basic principles of sedimentology are combined with geophysics, geochemistry and so on. Based on the data of outcrop, core, thin slice, geochemistry and so on, the stratigraphic distribution characteristics of the 6 member of Mawuan7jiao formation are determined, the paleogeomorphology is restored and the law of sea level change at that time is grasped, and the sedimentary facies are forecasted by studying the target facies mark. Single factor analysis and multifactor synthesis method are used to draw single factor map and recover carbonate original rock. By combining the above research results, the sedimentary facies distribution characteristics of the three target layers are obtained, which provides a useful reference for the later study. In Bahannao area, the strata of each submember of Mawuan7yao 6 are destroyed from southeast to northwest, and the thickness is gradually thinned, and the area of the old to the new sedimentary area is gradually reduced to the southeast, and the thickness of each layer is stable at about 25m. The paleogeomorphology changed from the karst highlands in the northwest to the karst terraces in the central part of the country to the karst slopes in the southeast, showing the characteristics of high, southeast and low in the northwest. The results of carbon and oxygen isotopic analysis show that 未 1. C and 未 18 O contents in the submember from Ma 58 to Ma Wu 6 generally increased first and then decreased, indicating that the sea level first rose and then decreased during this period, and it was assumed that the climate changed from humid heat to humid heat and then to humid heat again. A large amount of dolomite is developed in the three target layers, and the limestone content of the Mawuyao 6 submember is lower than that of the secondary limestone, with a small amount of muddy and gypsum. The total limestone content increased, the secondary limestone content decreased, and the primary limestone content increased, but no muddy and gypsum components were found. The Ma5.8 submember of the Ordovician Majiagou formation in the Bahannao area belongs to the area near the tide in the confined platform facies. With the rise of sea level, the Ma 57 submember is transitioning to the upper tidal belt or the upper intertidal zone of the restricted platform, and then the sea level drops. To Ma 56 stage returns to the area near the tide in the limited sea platform.
【学位授予单位】：西北大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P618.13

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