攀钢西昌钒钛钢铁新基地昔格达组构造变形特征及形成机制研究

发布时间：2019-03-15 21:14

【摘要】：昔格达组地层广泛分布于我国青藏高原东南缘各大江大河及其支流的河谷地区,由于该区特殊地理位置,人类工程经济活动频繁,加之这一地区构造变形复杂,昔格达组的形成机制尚存在争议。因此研究该区昔格达地层构造变形特征对昔格达组地层沉积的控制作用,对揭示昔格达组地层成因以及了解这一地区的区域地质构造演化历史,尤其是青藏高原的隆升过程,以及指导这一地区工程建设活动均具有重要意义。本文以攀钢西昌钒钛钢铁新基地工程区昔格达组地层为研究对象,以工程区的区域地质背景、昔格达组分布及规律、昔格达组变形特征以及昔格达组成因浅析等为研究内容,采用文献调研及工程地质调查分析方法,在大量现场调查及室内资料分析整理基础上,结合已有昔格达地层构造及成因研究,从构造变形类型、构造变形几何学、构造变形运动学、构造变形史等方面讨论了场区昔格达组地层的构造变形特征,反演工程区构造演化过程,揭示昔格达组的成因机制,主要获得以下几点认识：(1)不同地区昔格达组沉积环境差异较大,泸定剖面所反映过水湖泊或沼泽环境,大渡河汉源富林昔格达则反映了河流相沉积,安宁河西昌～德昌昔格达在不同地段则反映了更多的沼泽相、河流-沼泽相沉积环境,而攀枝花的昔格达组则更多的反映了该区属于湖沼相沉积。(2)根据工程区开挖揭露剖面发现该区昔格达组岩层主要的同生变形构造类型是滑塌构造和昔格达组内部的角度不整合接触,受地震影响工程区揭露的沉积剖面表明昔格达组岩层具有软沉积结构特征。(3)不同地区昔格达组地层构造变形的差异性主要受沉积非均质性及距离活动断裂和震源远近的影响,而工程区开挖昔格达剖面素描图显示工程区昔格达组地层主要受近东西向压应力的挤压作用,受力方向与区域构造安宁河断裂带及则木河断裂带主构造方向近于垂直,反映了工程区构造活动与地震作用有关。(4)构成昔格达组主体的各沉积单元可能是河流相(如,河床比降很小的辫状水系)、湖泊相、沼泽相,更可能包括三种沉积环境间的过渡环境—河湖相、河沼相、湖沼相及河-湖-沼泽相,而非冰川堆积作用形成。(5)基于工程区及外围的地貌、岩性、构造特征,初步推断工程区可能大致经历了4个阶段的构造运动,晚更新世以来昔格达在接受不同沉积相沉积及现代河流沉积过程中受区域及近场断裂和地震活动的影响,昔格达组地层发生了复杂的构造变形,而且构造变形特征具有时空分布的非均质性,一定程度上反映了攀西昔格达组地层沉积过程的复杂性。
[Abstract]:The Xigda formation strata are widely distributed in the valleys of the great rivers and their tributaries on the southeastern edge of the Qinghai-Xizang Plateau in China. Due to the special geographical location in this area, the human engineering and economic activities are frequent and the tectonic deformation in this area is complicated. The formation mechanism of Xigda formation is still controversial. Therefore, the control of the tectonic deformation characteristics of Xigeda formation on the strata deposition of Xigeda formation in this area is studied, which can reveal the formation of Xigeda formation and understand the evolution history of regional geological structure in this area, especially the uplift process of Qinghai-Xizang Plateau. It is of great significance to guide the project construction activities in this area. In this paper, the Xigeda formation stratum in Xichang new base of Panzhihua Iron and Steel Company is taken as the research object, and the regional geological background of the engineering area, the distribution and regularity of the Xigda formation, the deformation characteristics of the Xichang formation and the analysis of the factors of Xigeda composition, etc., are taken as the research objects. Based on a great deal of on-the-spot investigation and indoor data analysis and combining with the study on the structure and genesis of Xigeda strata, this paper adopts the methods of literature investigation and engineering geological investigation and analyzes the structure deformation type, structure deformation geometry, and so on. In the aspects of tectonic deformation kinematics and history of tectonic deformation, the tectonic deformation characteristics of Xigeda formation in field area are discussed, the structural evolution process of engineering area is inversed, and the genetic mechanism of Xigeda formation is revealed. The main results are as follows: (1) the sedimentary environment of Xigeda formation varies greatly in different areas. The overflowing lake or swamp environment is reflected in the Luding profile, while the fluvial facies deposit is reflected in the Hanyuan Fulin Xigda formation of the Dadu River. Anning River Xichang-de Changxigda reflected more swamp facies, river-swamp facies sedimentary environment in different areas. However, Xigda formation in Panzhihua more reflects that this area belongs to lacustrine facies deposits. (2) according to the excavation exposure profile of the engineering area, it is found that the main syngenetic deformation structure types of Xigda formation in this area are collapse structure and Xigeda structure. Angle unconformable contact within the group, The sedimentary profiles exposed by the earthquake-affected engineering area indicate that the strata of Xigeda formation have the characteristics of soft sedimentary structure. (3) the difference of tectonic deformation of Xigeda formation in different areas is mainly due to sedimentary heterogeneity and distance active faults. And the far and near effects of the source, However, the sketch of Xigeda profile in the engineering area shows that the strata of Xigeda formation in the engineering area are mainly squeezed by near-east-west compressive stress, and the stress direction is close to vertical to the main tectonic direction of Anning River fault zone and Zemuhe fault zone of regional tectonics. The tectonic activity in the engineering area is related to seismic action. (4) the sedimentary units that make up the main body of Xigda formation may be fluvial facies (for example, braided water system with very small river bed ratio), lacustrine facies and swampy facies. It is more likely to include the transitional environment between the three sedimentary environments-the river-lake facies, the river-marsh facies, the lake-marsh facies and the river-lake-swamp facies, rather than the glacier accumulation. (5) based on the geomorphology, lithology and structural characteristics of the engineering area and its periphery, It is inferred that the engineering area may have undergone four stages of tectonic movement. Since the late Pleistocene, Xigeda was affected by regional and near-field faults and seismic activities in the process of accepting different sedimentary facies and modern river deposits. The complex structural deformation occurred in Xigeda formation, and the structural deformation characteristic has the heterogeneity of space-time distribution, which to some extent reflects the complexity of the sedimentary process in Panxixigda formation.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P542

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