【作者】 吕良冀；

【导师】 张达；

【作者基本信息】 中国地质大学（北京） ， 构造地质学， 2011， 硕士

【摘要】 福建省内各类推覆构造是广泛存在的,并具有一定的规模。广平推覆构造位于福建省大田县北部广平—建爱,太华—上京一带,是福建省境内发育最完整,且面积较大的一个推覆构造。推覆构造南北长大于20km,东西宽大于12km,面积大于100 km~2。本文综合运用构造地质学、岩石学、同位素地质年代学、数学建模、统计分析、平衡面积法等多种方法,研究总结了广平推覆构造几何学、运动学、年代学特征并得出初步的动力学模式。得出结论如下:1.广平推覆构造的外来岩系、原地岩系从宏观到微观变形特征不同,外来岩系表现为堆垛式、叠瓦式断层,原地岩系表现为褶皱发育。该区作为闽西南推覆构造的前缘带,受到推覆构造强烈挤压,推覆面波状起伏。2.经过比对汤泉花岗闪长岩岩体和花岗斑岩脉,发现花岗斑岩脉比汤泉岩体对于说明推覆构造的年代学特征更有意义,对花岗斑岩脉进行锆石U-Pb测年研究,本文认为广平推覆构造发生于142±1Ma。3.应用面积平衡方法对原地岩系能干性较差的童子岩组含煤地层做了地层缩短率的估算,并给出计算结果的不确定度。认为缩短率为(10.94±0.32)%。4.研究区内的白云母二长花岗岩在岩石学、岩石地球化学、岩相学、同位素年代学方面与顺昌地区的张坊岩体有着较高的相似性,本文认为张坊岩体很可能是广平推覆构造外来岩系的源头。因此,对外来岩系起源的问题建立数学模型,综合考虑到郑和—大埔断裂的左旋走滑影响,认为广平推覆构造推覆距离介于55~105km之间,方向是北西60°到南北方向之间。5.广平推覆构造是由于燕山期伊佐奈崎板块向欧亚板块俯冲、挤压,中国大陆逆时针旋转,从而使闽西南地区出现大规模的推覆构造。更多还原

【Abstract】 Nappe structure of a certain scale exists extensively in Fujian province. Guangping nappe structure is located in the area of Guangping-Jian’ai and Taihua-Shangjing, in the north of Datian county, Fujian province. It is the most complete nappe structure with large area in Fujian province. It is 20 kilometers from north to south and 12 kilometers from east to west, covering an area of over 100 square kilometers.This paper carries out the theories and methods in structural geology, petrology, isotopic geochronology, mathematical modeling, statistic analysis, area balancing to study the characteristics of geometry, kinematics and chronology of Guangping nappe structure and to work out a preliminary dynamic model. We draw conclusions as follows:1. The allochthone marked by imbricate faults and the autochthone marked by folds of Guangping nappe structure are much different in characteristics of deformation from macroscopic to microcosmic. Located in Southwest Fujian nappe frontal belt, the study area is compressed intensively by the nappe structure, with undulating plane.2. A comparison between the Tangquan granodiorite and the granite porphyry proves it can be more significant to use the age of the granite porphyry to describe the characteristics of chronology of Guangping nappe structure than that of the Tangquan granodiorite. U-Pb dating of zircons from the granite porphyry gives an age of 142±1Ma, indicating the age for the formation of Guangping nappe structure.3. We used the area balancing method to calculate shortening estimates and analyze the errors of the incompetent coal-bearing stratum in the Tongziyan Formation belonging to autochthone. The result is 10.94±0.32% shortening.4. There is good similarity in petrology, lithogeochemistry, facieology and isotopic geochronology between the muscovite monzonitic granite in the study area and the Zhangfang granitoid in Shunchang area. The Zhangfang granitoid is likely to be the source of the autochthone of Guangping nappe structure. In this case, we found mathematical model on the problem of the source of the autochthone. In consideration of the affect of the left-lateral slip of the Zhenghe-Dabu fault, we draw a conclusion that the thrusting distance is between 55 to 105 kilometers, with a direction of N60W to N-S.5. Guangping nappe structure is the result of the subduction and the compression of the Izanagi plate underneath the Eurasian plate, with counter-clockwise rotation of the continent during Yanshanian.更多还原