滇西—湾甸地区奥陶系沉积地层及沉积相特征研究

发布时间：2018-04-10 21:50

本文选题：奥陶系 + 沉积地层　；参考：《成都理工大学》2017年硕士论文

【摘要】：研究区在大地构造单元上属于特体斯-喜马拉雅构造带(域),存在于冈瓦纳大陆与劳亚大陆之间,该区的西部与保山地块东缘相邻,中间地带是扬子西缘多岛-弧盆系昌宁混杂岩带,兰坪-思茅前陆盆地在研究区的东部;在中国西南板块运动学、动力学和板块边缘造山与成岩成矿作用的研究中是最理想的场所。湾甸坝地区奥陶系地层是昌宁-孟连带西侧保山-镇康地块的组成部分,地层出露连续,是研究该区奥陶系沉积环境的良好载体。本文是在云南保山-龙陵地区湾甸坝、勐统街等5幅区域地质矿产调查野外工作的基础上,搜集并整理前人在本研究区以及在邻区的相关研究资料,最后对本研究区内奥陶系地层老尖山组、施甸组、蒲缥组和仁和桥组地层的资料分析研究后完成的。以前人的相关研究为基础,通过对湾甸坝地区奥陶系地层沉积相的确定及沉积环境演化的研究,主要取得以下几点认识:首先查明了滇西-湾甸坝地区的奥陶系地层都为碎屑岩建造。然后通过对湾甸坝地区奥陶系地层沉积相特征的综合研究得出:老尖山组是滨海相,从上往下分为潮上带、高潮泥坪带、潮间带;施甸组为浅海陆棚相,过渡带亚相;蒲漂组是浅海陆棚相,滨外陆棚亚相;仁和桥组是台盆相。综合奥陶系构造演化分析沉积环境演化:保山-镇康地块区域性拗陷,沉积奥陶系至中志留统地层,后区域隆升。晚寒武世主要是一套浅海-开阔台地相粉砂-泥质及碳酸盐沉积,海平面沉降于晚寒武世晚期,而在早奥陶世晚期开始出现新一轮海侵,并在仁和桥组之后进入高水位体系域的稳定沉积。最后得到研究区内只有老尖山组保存有海退的层序,其余施甸组和蒲缥组基本为海进的结构,说明该研究区内奥陶系除了老尖山组经历过完整的海水进退过程,施甸组和蒲缥组只经历了奥陶纪早期海侵的扩张,古陆边缘淹没的过程,至中期海侵停滞。
[Abstract]:The study area belongs to the Teties-Himalayan tectonic belt on the tectonic unit, which exists between Gondwana continent and Laoya continent. The western part of the study area is adjacent to the eastern margin of the Baoshan massif.The middle zone is the Changning melange belt of multi-island-arc basin system in the western margin of Yangtze. The Lanping Simao Foreland basin is in the east of the study area.Dynamics and plate margin orogeny and diagenesis are the most ideal places.Ordovician strata in Wandianba area are part of Baoshan-Zhenkang block on the west side of Changning-Menglian belt, and the strata are exposed continuously, which is a good carrier to study the sedimentary environment of Ordovician in this area.Based on the field investigation of five regional geological and mineral resources in Baoshan-Longling area, Yunnan Province, this paper collects and collates the relevant research data of predecessors in this research area and adjacent areas.Finally, the stratigraphic data of the Ordovician strata of Laojianshan formation, Shidian formation, Pubian formation and Renheqiao formation in this area were analyzed and studied.On the basis of previous studies, the determination of the sedimentary facies of Ordovician strata and the evolution of sedimentary environment in Wandianba area were studied.The main results are as follows: firstly, it is found that Ordovician strata in West Yunnan-Wandianba area are all clastic formations.Then through the comprehensive study on the sedimentary facies characteristics of Ordovician strata in Wandanba area, it is concluded that the Laojianshan formation is coastal facies, which is divided into upper tide belt, high tide mud flat zone and intertidal zone from top to bottom, and Shidian formation is shallow sea shelf facies, transitional zone subfacies;Pupiao formation is shallow-sea shelf facies, off-shore shelf subfacies, Renheqiao formation is platform basin facies.Comprehensive analysis of structural evolution of Ordovician the evolution of sedimentary environment: regional depression of Baoshan-Zhenkang block sedimentary Ordovician to Middle Silurian strata and post-regional uplift.The late Cambrian was mainly composed of a set of shallow-open platform silt, muddy and carbonate deposits, and sea level subsidence occurred in the late late Cambrian, and a new round of transgression began to occur in the late early Ordovician.And after the Renheqiao formation entered into the stable deposition of high water level system tract.Finally, only the Laojianshan formation is preserved in the study area, and the rest of the Shidian and Pubiao formations are basically oceanic, indicating that the Ordovician has experienced a complete process of seawater advance and retreat except the Laojianshan formation in the study area.The Shidian and Puyue formations only experienced transgression in the early Ordovician and submergence of paleocontinent margin until the middle period of transgression stagnation.
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P512.2;P534.42

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