【作者】 雷时斌；

【导师】 邓军；

【作者基本信息】 中国地质大学（北京） ， 矿物学、岩石学、矿床学， 2011， 博士

【摘要】 阳山金矿带位于秦岭造山带西段的南亚带中南部边缘,目前探获金资源/储量大于320 t,是我国川陕甘“金三角”最重要的金矿带。笔者通过大量的野外第一手资料和较详细室内测试、综合分析,重点研究了阳山金矿带的区域成岩成矿背景,控矿构造系统,脉岩成岩环境与时代,构造-岩浆成矿作用,探讨了构造控岩控矿的动力学机理和勘查找矿方向。通过对阳山金矿带构造地质现象的构造解析,厘定了控矿构造系统,并结合西秦岭地区构造演化历史,认为阳山金矿带的基本构造格局成生于印支期陆-陆碰撞造山运动,其构造演化序列:1)华力西期陆内伸展裂陷沉积三河口群岩层,之后隆升伸展发生顺层韧性剪切变形,形成顺层紧闭同斜褶皱,并伴有强烈构造置换,形成区域性透入性面理S1;2)印支期陆-陆碰撞造山,在SN向收缩挤压背景下,形成了一些列弧形构造带,阳山金矿带为弧顶和东翼褶皱-断裂系,并伴有同期和期后的中酸性脉岩侵入;3)燕山早期变形以脆性构造为主,主要继承早期构造发育逆冲推覆和碎裂岩系,以及派生的层间断裂等;燕山中晚期隆升伸展形成早白垩世箕形断陷盆地、正断层,并伴有燕山期斜长花岗岩侵入,直至喜马拉雅期主要处于伸展作用环境。对构造带空间结构、构造样式和构造变形组构的研究表明,汤卜沟—观音坝断裂带是西秦岭南亚带重要控岩控矿构造,经历了不同层次构造变形。早期在中深层次下以逆冲、左行走滑韧性变形为主;晚期处于浅部层次,叠加于韧性变形之上发生脆性变形形成的碎裂岩系。韧性变形的后期和脆性变形均伴有较强烈岩浆活动和热液成矿作用。为探求岩浆活动对金成矿的制约作用,在对阳山金矿带广泛分布的中酸性脉岩的岩石学、岩石化学和地球化学的研究基础上,开展了脉岩锆石SHRIMP U-Pb年龄成岩年代学研究:1)阳山金矿带发育的中酸性脉岩主要活动时间印支期和燕山期;2)印支期脉岩开始侵位于220 Ma左右,为陆-陆碰撞造山运动末期,在210 Ma左右期后的隆升伸展环境发生强烈活动,并延续至190 Ma左右;3)首次在阳山金矿带发现燕山期脉岩锆石U-Pb年龄(115.8±1.6)Ma,形成于陆内伸展环境;4)多期岩浆叠加成矿活动制约着阳山超大型金矿床的形成。对构造-岩浆活动与金成矿作用的研究表明:阳山金矿带主体受近EW-NEE向区域性断裂控制,矿体主要赋存于汤卜沟—观音坝区域性断裂的主干构造和其伴派生次断裂内,矿体产状严格受断裂控制;大型、特大型矿床形成多受断裂-褶皱-多期次岩浆活动联合控制。同时在控矿断裂几何学和运动学研究基础上,探讨构造控岩控矿机理,建立了阳山金矿带构造岩浆成矿模式,认为阳山金矿带的岩脉侵入、矿体定位与主干断裂在成矿期活动时形成的扩容空间关系密切。以构造-岩浆控矿规律研究为基础,综合地质、物探、化探、遥感等信息,开展了以证据权法为主的综合信息找矿预测研究,圈定了安坝里西段深部和安坝北带2个找矿靶区,以及汤卜沟、柏林坪等找矿远景区。其中安坝北带靶区经钻探工程验证,发现1个中型规模金矿床。此外,本次工作提出的安坝―葛条湾矿段的主要容矿构造为汤卜沟—观音坝区域性断裂的主干构造(F2、F3),以及其产状在中浅部向南反倾的认识,为该区段金矿勘查指明了方向,为矿体圈连和报告通过评审提供了地质依据。更多还原

【Abstract】 The Yangshan Gold Belt locates in the mid-south part of south sub-belt in western Qinling orogenic belt; the current gold resources/reserves of Yangshan belt were more than 320 tons. In this paper, using a large number of field data and integrated test and analysis as the support, the regional diagenesis and mineralization background, environment and age of dike formation, ore-controlling structural system and structural-magmatic mineralization were studied, and the dynamics mechanism of structural control and exploration direction in Yangshan gold belt were discussed.Based the structral analysis for structral geological phenomenon in Yangshan gold belt and study of Western Qinling tectonic evolution history, we comformed that the ore-controlling structure system of Yangshan gold belt, and considered that basic structure pattern in this area were formed during the continent-continent collision of Indosinian period. The regional tectonic evolution sequences of Yangshan gold belt were as follows: 1) the extension of Hercynian intracontinental rift caused the sediment of Sanhekou Group, later on the uplift background, bedding ductile shear deformation occurred and closed oblique fold formed in this area which accompanied by strong structural replacement, then regional penetrative foliation(S1) formed; 2) a series of arc structural belts were formed under the background of SN strike compression caused by the continent-continent collision in the Indosinian period. The Yangshan gold belt was the tip-arc and folds-faults system in its east part; and associated with the homochronous or post-Indosinian mid-acidic dykes intruded; 3) the deformation were mainly brittle structure in early Yanshanian period, including succeed thrust fault and derived bedding fracture, etc.; the regional extension caused the dustpan-shaped rift basin and normal faults formed in the late Yanshanian period, accompanied by the plagio-granite intrusion of the Yanshanian period; the structual setting of the Yangshan gold belt were mainly extension in Himalayan period.The study of spatial structure of belt, structural styles and deformation fabrics showed that the Tangbogou-Guanyinba fault was the important ore-controlling structure in south sub-zone of West Qinling fault zone, and had undergone different levels of deformation. Early deformation mainly thrust fault, left-slip falut deformation in deep, later deformation were cataclastic rocks system which caused by brittle deformation superposed to ductile deformation. The later ductile deformation and brittle desormation were accompanied by strong magmatic activity and hydrothermal mineralization.To find out the restriction rule of magmagic activity to gold mineralization, the SHRIMP U-Pb zircon geochronology of dykes were carried out based on the study of petrology, petrochemistry and geochemistry for mid-acidic dykes. The results showed that: 1) the mid-acidic dykes occurred in Yangshan gold belt formed major in Indosinian and Yanshanian period; 2) Indosinian dykes intruduction started at the end of continent-continent collision (about 220Ma), activitied at uplift-extend environment (about 210Ma) and continue until about 190Ma; 3) the Yanshanian dikes were first discovered in this area(U-Pb zircon age of 115.8±1.6Ma), indicating that magmatic activity occurred in the intracontinental extension phase; 4) superposition of multi-period magmatic activity and mineralization restricted the formation of the Yangshan super-large gold deposit.The studies of magmatic activity and gold mineralization suggest that: the Yangshan gold belt was controlled mainly by near EW-NEE strike regional faults, the ore bodies occurred in the Tangbogou-Guanyinba regional fault and its derived sub-fault, and the ore occurrence controlled by faults strictly. The formation of large, super-large scale deposits were controlled by fault-fold-magmatic activity. This paper pinpointed the ore-controlling mechanism of structural and established the tectonic-magmatic mineralization model of Yangshan gold belt based on the study of geometry and kinematics analysis for ore-controlling faults, the dike intrusion and ore body position in Yangshan gold belt had close relationship with expanded space formed in mineralization period.The metallogenic prediction using weights-of-evidence method was carried from integrated imformation (include geological, geophysical, geochemical and remote sensing) based on structure-magma ore-controlling law. Two prospecting targets were delineated (deep in west Anbali and north area of Anba), some prospecting areas were submitted (including Tangbogou and Bolinping). A middle scale gold deposit was discovered by drilling in north area of Anba.This paper recognizing that main ore-bearing structure in Anba-Getiaowan ore section were trunk structure (F2, F3) of Tangbogou-Guanyinba fault, and its occurrence dip to south in shallow. This pointed out the direction for the gold exploration in this area and provided geological evidence for circle ore body and appraises report.更多还原