鄂尔多斯盆地南部侏罗纪—早白垩世沉降史分析

发布时间：2018-03-26 04:42

本文选题：鄂尔多斯盆地　切入点：去压实校正　出处：《中国地质大学(北京)》2017年硕士论文

【摘要】：盆地沉降史的研究,可以提供沉积盆地构造演化的重要信息,也可作为定量或半定量地划分盆地构造演化阶段的主要参数之一,可为揭示盆地形成机制提供重要的参考依据。晚三叠世-早白垩世是鄂尔多斯盆地发育的主要时代,前人对于盆地晚三叠世沉降史的研究较为详细,然而侏罗纪-早白垩世沉降史的研究仍然较为欠缺。该项研究对我们重新认识鄂尔多斯盆地沉降机制、成因乃至构造活动期次和过程均具有重要意义。为了分析研究鄂尔多斯盆地南部的沉降史,笔者在前人研究的基础之上,收集鄂尔多斯盆地南部钻井数据资料,首先运用测井地质学的相关理论方法解释测井曲线所反映的地层沉积相和沉积岩性,建立研究区地层格架。然后运用盆地模拟的指导思想和技术手段,得到了研究区不同时期的沉降量及其沉降速率信息。然后收集前人对研究区西部,即鄂尔多斯盆地西南部的资料,将研究范围由鄂尔多斯盆地中南部扩大到整个鄂尔多斯盆地南部。通过分析盆地总沉降和构造沉降速率的变化划分了盆地基底沉降演化的期次,并描述每个期次盆地沉降量和沉降中心的位置,恢复各个时期盆地基底的形态,以此来得到鄂尔多斯盆地南部的沉降演化史和沉降中心的分布、迁移规律。鄂尔多斯盆地南部侏罗纪沉降主要受燕山运动的影响,开始于198 Ma,到157 Ma结束。在全盆地经历了印支运动引发的一次短暂的抬升剥蚀之后,盆地南部在早侏罗世开始沉降并接受沉积。鄂尔多斯盆地南部沉降演化史可分为五个阶段:(1)富县期研究区沉降量较小,但盆地西南部地区富县期沉降活动却比研究区剧烈,盆地西南部是整个盆地南部的沉降中心;(2)延安期盆地西南部的沉降速率减缓,而研究区迎来了一个高速沉降的时期,盆地南部的沉降中心已由西部向中部逐渐转移;(3)直罗期盆地西南部沉降更为缓慢,而在研究区,沉降速率变化较小,仍以相对较高的速率沉降,沉降中心完全迁移到了中部;(4)安定期盆地西南部和研究区沉降速率都十分缓慢,沉降中心仍然在中部,前四个时期构造沉降均主导总沉降;(4)志丹期盆地西南部迎来了一个高速沉降的时期,而研究区早白垩世沉降速率则相对较低。构造沉降量已经不是总沉降量的主要部分,失去了主导地位,沉积物压实负载沉降开始主导总沉降量,沉降中心再次迁移到西部。
[Abstract]:The study of basin subsidence history can provide important information for tectonic evolution of sedimentary basins, and can also be used as one of the main parameters for quantitative or semi-quantitative division of tectonic evolution stages of basins. The late Triassic to early Cretaceous is the main period of Ordos basin development, and the previous research on the basin subsidence history of late Triassic is more detailed. However, the study of Jurassic-early Cretaceous subsidence history is still lacking. In order to analyze and study the subsidence history of the southern Ordos Basin, the author collects the drilling data of the southern Ordos Basin on the basis of previous researches. Firstly, the sedimentary facies and sedimentary lithology reflected by the log curve are explained by using the relevant theory and method of logging geology, and the stratigraphic framework of the study area is established, and then the guiding ideology and technical means of basin simulation are used. The settlement amount and subsidence rate in different periods in the study area were obtained. Then, the data of the western part of the study area, that is, the southwest of the Ordos Basin, were collected. The research scope is extended from the central and southern part of the Ordos Basin to the whole southern part of the Ordos Basin. By analyzing the variation of the total subsidence and the rate of tectonic subsidence in the basin, the evolution stages of the basement subsidence in the basin are divided. It also describes the position of subsidence volume and subsidence center in each period, and restores the shape of basin basement in each period, so as to obtain the history of subsidence evolution and the distribution of subsidence center in the southern part of Ordos Basin. Migration pattern. Jurassic subsidence in southern Ordos Basin was mainly influenced by Yanshanian movement, which began at 198Maand ended at 157Ma. After the whole basin experienced a brief uplift and denudation caused by Indosinian movement, The southern part of the basin began to settle and accept sedimentation in the early Jurassic. The history of subsidence evolution in the southern part of Ordos Basin can be divided into five stages: 1) the subsidence in Fuxian period is relatively small, but the subsidence activity in Fuxian period is more intense than that in the study area in the southwestern part of the basin. The southwestern part of the basin is the subsidence center of the southern part of the basin.) during the Yanan period, the subsidence rate of the southwestern part of the basin slowed down, and the study area ushered in a period of high speed subsidence. The subsidence center of the southern part of the basin has been gradually transferred from west to middle. The subsidence of the southwestern part of the Zhiluo basin is more slowly, but in the study area, the rate of subsidence is relatively small, and it is still settling at a relatively high rate. The settlement center moved completely to the central part of the Anji Basin and the settlement rate was very slow in the southwestern part of the Anji Basin and the study area, and the settlement center was still in the middle part of the basin. The early Cretaceous subsidence rate in the study area is relatively low. The tectonic subsidence is no longer the main part of the total subsidence. Without the dominant position, the sedimentation of the sediment compaction load began to dominate the total settlement, and the settlement center moved to the west again.
【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】：2017
【分类号】：P534.5;P542;P618.13

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