【作者】 黄始琪；

【导师】 黄德志；

【作者基本信息】 中南大学 ， 矿产普查与勘探， 2010， 硕士

【摘要】 经中生代印支运动与燕山运动,大巴山形成现今的构造格局。印支运动南北大巴山发生俯冲碰撞；燕山期为陆内造山阶段。野外和室内研究表明,中生代以来大巴山构造带主要经历了NE-SW挤压和NW-SE挤压两期应力作用。印支期和燕山期都为NE-SW挤压,应力场特征为：σ1(40°∠2°)、σ3(175°∠88°)；NW-SE挤压晚于NE-SW挤压,其应力场特征为：σ1(143°∠1°)、σ3(267°∠88°)。根据不同的构造变形特征,NE至SW大巴山可划分为4个不同的构造带：冲断-推覆构造带、基底拆离构造带、盖层滑脱构造带和前陆坳陷带。各构造带发育不同的构造变形样式。NE至SW,变形性质由韧性变形过渡为脆性变形,变形深度和强度逐渐减弱。对大巴山构造带内方解石脉进行了微量稀土元素分析。围岩具有单一的源,反映较稳定的沉积环境。稀土元素具有Eu异常,成脉环境为还原环境。NE-SW挤压过程,活动流体主要为围岩脱水,有富Ba和Rb且稀土元素总量及La/Yb低的流体加入。NW-SE挤压过程,活动流体亦主要来自围岩脱水,同样有富Ba和Rb且稀土元素总量及La/Yb(?)氐的流体加入。更多还原

【Abstract】 The tectonic Framework of Dabashan was fianally formed after Indosinian movement and Yanshan movement. Subduction and collision of south and north Dabashan took place during the Indosinian movement,and during the Yanshan movement intracontinental orogenesis took place in Dabashan area. Two paleotectonic stress fields in Dabashan area during Mesozoic have been obtained By the field and indoor study: NE-SW compression and NW-SE compression. NW-SE compression took place during the Indosinian movement and Yanshan movement and the characters of stress field were:σ1 (40°∠2°)、σ3 (175∠88°) NW-SE compression were later than NE-SW compression,its characters of stress field were:σ1 (143°∠1°)、σ3 (267°∠88°).According to different characters of structural deformation,from NE to SW,Dabashan can be divided into 4 different structural deformation belts:thrust-nappe structural belt, The basement detachment structural belt, cap rock decollement structural belt and forland depression structural belts.There are different tectonic styles in different structural belt. From NE to SW, the patten of deformations are from ductile to brittle and the strength and depth of deformations decrease gradually.Trace elements and REEs of calcite veins filled in fractrures in Dabashan Tectonic belt have been analyzed.The wall-rocks had single origin,indicating the stable sedimentary environment. REEs showed positive Eu anomaly, which indicated environment of the formation of the calcite vein was reductive.The fluids flowed during the NE-SW compression were mainly from wall-rocks,mixing with another kind of fluid with high Ba and Rb and low∑REE and La/Yb. The fluids flowed during the NW-SE compression were mainly from wall-rocks,too,and also mixing with another kind of fluid with high Ba and Rb and low∑REE and La/Yb.更多还原