湘中龙山地区变形序列及金锑矿控矿构造  

Deformation sequences and ore-controlling structuresof Au—Sb deposits in the Longshan area in central Hunan Province

作　　者：柏道远 李彬 金华 曾广乾 BAI Daoyuan;LI Bin;JIN Hua;ZENG Guangqian(Hunan Institute of Geology Survey,Changsha,410016;State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang,330013;Hunan Xinlong Mining Company with Limited Liability,Xinshao,Hunan,422900;Institute of Geomechanics,Chinese Academy of Geological Sciences,Beijing,100081)

机构地区：[1]湖南省地质调查所,长沙410016 [2]东华理工大学核资源与环境国家重点实验室,南昌330013 [3]湖南新龙矿业有限责任公司,湖南新邵422900 [4]中国地质科学院地质力学研究所,北京100081

出　　处：《地质论评》2023年第1期88-112,共25页Geological Review

基　　金：湖南省地质院科研项目“雪峰金矿带成矿背景和控矿构造研究与成矿预测”(编号:201917)的成果。

摘　　要：龙山金锑矿区位于湘中盆地龙山穹窿内。关于湘中地区上古生界中不同方向褶皱和龙山穹窿的形成时代均存在多种观点,对龙山金锑矿区内含矿断裂的运动学特征和时代背景等缺乏观测和认识。鉴此,笔者等根据大量地表和井下露头构造观测和解析,结合区域构造特征、矿床地质特征和已有区域构造事件研究成果,厘定了龙山金锑矿及邻区的构造变形序列以及上古生界中褶皱和龙山穹窿的形成时代,探讨了构造控矿规律及动力学机制。主要成果认识如下:(1)研究区自早至晚经历了奥陶纪末—志留纪NW向挤压、中三叠世晚期NW向挤压、晚三叠世SN向—NNE向挤压、中侏罗世晚期NWW向挤压、白垩纪区域NW—SE向伸展和古近纪中晚期NE向挤压6期主要变形事件;(2)上古生界中NE向褶皱形成于中三叠世晚期,EW向褶皱形成于晚三叠世,NNE向褶皱形成于中侏罗世晚期;龙山穹窿形成于中三叠世晚期NE向复背斜与晚三叠世EW向复背斜的叠加;(3)两期复背斜核部因应力集中而更易形成导矿、容矿断裂,加之穹窿构造常伴随隐伏花岗岩体,导致龙山金锑矿定位于龙山穹窿的中部。龙山金锑矿的导矿构造为两期复背斜相关的NE向和EW向隐伏逆冲断裂;容矿构造为中三叠晚期形成的NWW向右行走滑断裂,晚三叠世形成的NNE向和NE左行走滑断裂、NW向右行走滑断裂;(4)区内矿体的高角度侧伏与含矿断裂运动方向低角度倾斜有关,而后者与盖层单向滑移导致区域最大主压应力倾斜有关。Objectives: The Longshan Au—Sb mining area is located in the Longshan uplift of Xiangzhong basin. In the past, there were many views on the formation ages of the folds in the upper Paleozoic and on Longshan dome in central Hunan Province, and there is a lack of observation and understanding on the kinematic characteristics and ages of ore-bearing faults in Longshan Au—Sb mining area. Methods: In view of this, this study performed detailed structural observation and analysis of outcrops and in pits in the Longshan deposit and its surrounding areas, and then combined with the regional structural characteristics, Geological characteristics of the deposit and the previous research results of regional tectonics, distinguished the deformation sequences and the formation ages of the folds in the upper Paleozoic and of Longshan dome, and discussed the structural ore-controlling regularity and mechanism. Conclusions: The main achievements are as follows:(1)The study area has experienced six main deformation events: Regional NW compression during late Ordovician to Silurian;Regional NW compression in the late Middle Triassic;Regional SN—NNE compression in the Late Triassic;Regional NWW compression in the late Middle Jurassic;Regional NW—SE extension in the Cretaceous;Regional NE compression in the middle—late Paleogene.(2)The NE-trending folds in the upper Paleozoic were formed in the late Middle Triassic, the EW-trending folds were formed in the Late Triassic, and the NNE-trending folds were formed in the late Middle Jurassic;The Longshan dome was formed by the superposition of NE-trending anticlinorium of late Middle Triassic and EWtrending anticlinorium of Late Triassic.(3)It was likely to form ore-guiding and ore-bearing faults in the core of the two stages of anticlinoriums due to stress concentration, in addition, the dome is accompanied by a hidden granite body, which resulted in the location of Longshan Au—Sb deposit in the middle of Longshan dome. The ore-guiding structures of Longshan Au—Sb deposit

关 键 词：龙山金锑矿床 变形序列 褶皱时代 控矿构造 动力机制 湘中 

分 类 号：P618.51[天文地球—矿床学] P618.66[天文地球—地质学]