鄂尔多斯盆地中南部晚三叠世延长期区域构造环境转变的沉积响应  

Sedimentary response of regional tectonic transformation in Late Triassic Yanchang period at the central and southern Ordos Basin

作　　者：王建强[1,2] 刘池洋[1,2] 郭真[1,2] 张东东[1,2] 

机构地区：[1]西北大学大陆动力学国家重点实验室 [2]西北大学地质学系,陕西西安710069

出　　处：《地学前缘》2015年第3期194-204,共11页Earth Science Frontiers

基　　金：国家自然科学基金项目(41102067;41330315;91214301);西北大学大陆动力学国家重点实验室科学技术部专项;国家科技重大专项(2011ZX05001004-001);中国地质调查局项目(12120113039900;12120114009201)

摘　　要：以大量砂岩碎屑矿物定量鉴定资料为基础,通过对砂岩碎屑组分特征及其变化的综合分析,系统剖析了鄂尔多斯盆地中南部延长组长10—长1层砂岩类型、骨架轻矿物、岩屑组分等在平、剖面上的分布规律和变化特点。研究揭示,盆地在延长组长8与长7层沉积期间,出现了明显的沉积变革事件。在砂岩类型、矿物组分及源区大地构造背景等方面,大致以华池—黄陵一线为界,长7期以来盆地西南与东北沉积区差异显著,开始出现与长7期之前明显不同的沉积分区。结合盆地发育的构造背景及其他沉积-构造事件等研究认为,延长期沉积变革事件与中晚三叠世华北与扬子克拉通拼接碰撞,秦岭洋最终闭合联系密切,是对秦岭全面碰撞造山和强烈隆升剥蚀事件的响应。本研究对进一步分析延长期盆地物源区构造属性的变化和盆内沉积体系划分、砂体展布、有利储层预测提供了科学依据,为中生代盆-山耦合关系、沉积建造与改造响应提供了新的证据和重要线索。Based on a large number of mineral quantitative identification data, the plane and vertical distribution and changing characteristics of the sandstone types, light minerals, lithic components, etc. have been systematically analyzed in the Group Chang 10 - Chang 1 Yanchang Formation at the central and southern Ordos Basin. The study revealed that during the deposition of Group Chang 8 and Group Chang 7, the Ordos Basin had undergone an obvious sedimentary changing event. Since the Period Chang 7, the deposition zones of southwest and northeast in the basin had became very different in the types of sandstone, the components of minerals and tectonic background of source region, but there was no such difference before Period Chang 7. The boundary of the two regions has been confirmed to be along the Huachi and Huangling line. Considering the tectonic setting of the development and other sedimentary and tectonic events in Ordos Basin, we proposed that the sedimentary changing event in Yanchang Period was closely related to the splicing and collision of North China and Yangtze Craton in the Mid-Late Triassic, causing the closure of Qinling Ocean. In other words, this event is the sedimentary response to the fully collision, strong uplift and denudation of Qingling Orogenic Belt. The study can provide scientific basis for further analyzing the tectonic property of source region, the sedimentary system division in basin, the distribution of sand bodies as well as the prediction of favorable reservoirs in Yanchang Formation. Meanwhile, new evidences and important clues for the construction and reformation of basin evolution and basin-range coupling in the Mesozoic are provided.

关 键 词：鄂尔多斯盆地 延长组 砂岩碎屑组分 构造环境 沉积响应 

分 类 号：P512.2[天文地球—地质学]