蚌埠凤阳地区推覆构造特征及年代学分析
发布时间：2019-01-30 19:12
【摘要】：蚌埠隆起位于华北板块南缘,其受到华北、扬子板块碰撞及之后燕山运动的影响,记录了重要的构造信息,值得开展构造解析研究。近期我们在蚌埠凤阳地区发现了一条近东西走向的逆冲推覆构造,本文运用多种方法,对该逆冲推覆构造的几何学、运动学、形成年代与环境进行了精细的研究和探讨,经过对马山、小红山以及西芦山三条横过推覆构造的剖面进行系统的测量、采样、分析和研究得出以下几点共识：(1)蚌埠凤阳地区的逆冲推覆构造具有由南向北推覆的运动学特征；(2)利用应力场软件对研究区进行应力状态分析,得出凤阳地区受到近南北向和北西-南东向两种方向的挤压力,与石英颗粒涡度分析所显示的挤压背景一致；(3)从推覆构造带内两期不同的变形特征、两组代表性面理182°∠10°和142°-∠33。,再结合推覆构造内石英ESR测年得到268.6±25.0～208.3±20.0Ma和163.4±16.0～151.5±15.0Ma的年龄,推测此逆冲推覆经过两期构造,一期受到印支期阶段华北板块与扬子板块完全碰撞近南北向的挤压；另一期受到早-中燕山阶段,太平洋板块与亚洲陆块碰撞近北西向的挤压。(4)利用角闪-斜长温压计、二长温度计及多硅白云母压力计测得凤阳逆冲推覆形成的温度在300～490℃之间,对应的压力在0.28-0.63GPa,属于中低温中压环境。由于凤阳地区风化较严重,岩石出露极少,所以研究程度有限,有很多问题还没能彻底研究清楚,包括推覆距离及具体规模等,有待于进一步的研究确定。
[Abstract]:Bengbu uplift is located in the southern margin of the North China plate, which is influenced by the collision of North China and Yangtze plates and the Yanshanian movement, which records important tectonic information and deserves to be studied by tectonic analysis. Recently, we found a near east-west thrust nappe structure in Fengyang area of Bengbu. In this paper, the geometry, kinematics, age and environment of the thrust nappe structure are studied and discussed in detail by using various methods. After systematic measurement and sampling of three sections across the nappe structure in Ma Shan, Xiao Hong Shan and Xilushan, The conclusions are as follows: (1) the thrust nappe structure in Bengbu Fengyang area has the kinematic characteristics of thrusting from south to north; (2) using the software of stress field to analyze the stress state in the study area, it is concluded that the Fengyang area is subjected to extrusion pressure in the direction of NNE and NW-SE, which is consistent with the extrusion background of quartz particle vorticity analysis. (3) according to the different deformation characteristics of two stages in the nappe tectonic belt, the two groups of representative planes 182 掳~ 10 掳and 142 掳~ 33. Combined with the ESR dating of quartz in the nappe structure, the ages of 268.6 卤25.0U 208.3 卤20.0Ma and 163.4 卤16.0U 151.5 卤15.0Ma are obtained. It is inferred that the thrust-nappe passed through two stages of tectonics. The first stage was squeezed by the collision between North China plate and Yangtze plate in the Indosinian period. The other stage is squeezed by the collision of the Pacific plate with the Asian continent block in the early and middle Yanshanian stage. (4) using the hornblender-oblique long temperature and pressure meter, Two long thermometers and polysilicon Muscovite pressure gauges show that the temperature of the thrust nappe of Fengyang is between 300 ~ 490 鈩，
本文编号：2418420
[Abstract]:Bengbu uplift is located in the southern margin of the North China plate, which is influenced by the collision of North China and Yangtze plates and the Yanshanian movement, which records important tectonic information and deserves to be studied by tectonic analysis. Recently, we found a near east-west thrust nappe structure in Fengyang area of Bengbu. In this paper, the geometry, kinematics, age and environment of the thrust nappe structure are studied and discussed in detail by using various methods. After systematic measurement and sampling of three sections across the nappe structure in Ma Shan, Xiao Hong Shan and Xilushan, The conclusions are as follows: (1) the thrust nappe structure in Bengbu Fengyang area has the kinematic characteristics of thrusting from south to north; (2) using the software of stress field to analyze the stress state in the study area, it is concluded that the Fengyang area is subjected to extrusion pressure in the direction of NNE and NW-SE, which is consistent with the extrusion background of quartz particle vorticity analysis. (3) according to the different deformation characteristics of two stages in the nappe tectonic belt, the two groups of representative planes 182 掳~ 10 掳and 142 掳~ 33. Combined with the ESR dating of quartz in the nappe structure, the ages of 268.6 卤25.0U 208.3 卤20.0Ma and 163.4 卤16.0U 151.5 卤15.0Ma are obtained. It is inferred that the thrust-nappe passed through two stages of tectonics. The first stage was squeezed by the collision between North China plate and Yangtze plate in the Indosinian period. The other stage is squeezed by the collision of the Pacific plate with the Asian continent block in the early and middle Yanshanian stage. (4) using the hornblender-oblique long temperature and pressure meter, Two long thermometers and polysilicon Muscovite pressure gauges show that the temperature of the thrust nappe of Fengyang is between 300 ~ 490 鈩，
本文编号：2418420
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