【作者】 范效仁；

【导师】 吴延之；

【作者基本信息】 中南大学 ， 矿产普查与勘探， 2001， 博士

【摘要】 秦岭造山带巍峨磅礴，雄伟壮丽，介于华北板块与扬子板块之间，横亘于中国大陆腹地，是世界著名的大陆造山带和多金属成矿带。西秦岭作为其重要组成部分，具有漫长的地质演化历史，在不同的地质发展阶段以不同的构造体制演化，产生了独特而复杂的岩石圈组成，造就了具流变学分层的“立交桥”式三维结构，形成了丰富的矿产资源。继70—80年代在西成地区探明厂坝—李家沟、邓家山、毕家山等大型铅锌矿床之后，于90年代又相继发现了一大批金矿床（点），目前尚有许多矿点和异常有待评价，找矿前景极为乐观。引起了国内外地质学界的广泛关注。 针对西秦岭构造演化的复杂性和成矿作用的特殊性，本文重点对西秦岭区域地质特征和大地构造演化、成矿盆地形成的动力学机制及其性质、喷流沉积成矿作用过程及其特点、金与铅锌成矿的地质地球化学特征及其成因进行了研究，揭示了秦岭构造演化、喷流成矿及金与铅锌矿化的时空关系和本质联系，主要取得如下成果： 1．在系统分析了西秦岭构造带地层展布、变形变质、岩浆作用和地球物理、地球化学、遥感影像以及深部结构特征的基础上，以宝鸡—栾川深大断裂和武山—丹凤缝合带为界，将其划分为华北板块南缘构造带、北秦岭构造带和南秦岭构造带（秦岭微板块）三大地质构造单元。 2．深入研究了西秦岭泥盆系的岩石特征、生物组合和沉积环境，深化了对西成盆地有利的成矿背景和条件的认识，提出西成盆地是一个复杂的裂陷盆地，属秦岭早海西期裂陷带的一部分，为华北板块、秦岭微板块和扬子板块共同作用的结果。其四周分别为近东西向和北东向断裂构造所限，经历了从狭窄裂谷到宽阔凹陷的演化过程，早期以被动裂陷为主，具有传统裂陷盆地之特征；晚期叠加了主动裂陷作用，逐渐向上拆离盆地转化。 3．厘定了本区构造成矿演化历程，提出西秦岭造山带经历了六大构造演化阶段，是一个以不同构造体制发展演化而形成的复合型大陆造山带。主造山期3个板块沿2个缝合带俯冲消减、碰撞造山之后，燕山—喜山期又发生了强烈的陆内造山作用。其板块运动遵循非威尔逊旋回，具有“多岛洋、 中南大学博上学位论文：西秦岭构造演化与喷流成矿研究软碰撞、多旋回”之特点。 4．对喷流沉积矿床进行了重新厘定，根据大地构造环境、沉积建造及成矿元素组合，把其划分为2类6亚类。成矿受三级构造盆地控制，矿体常出两部分组成，上部以热液沉积作用为主，形成层状、似层状、透镜状矿体，与地层整合接触：下部以热液充填交代作用为主，形成网脉状及角砾状矿体。 5．总结了铅锌矿床的成矿地质特征，认为区内铅锌矿带严格受秦岭早海西期裂陷带的控制，矿床为断陷盆地、同生断裂及海底热液活动共同作用的结果，明显受地层、岩相和时代的控制。矿体呈层状、似层状，以沉积及低温热液矿物组合为特征，沉积组构发育，喷流岩广介，成矿发生于盆地最大扩张裂陷期。 6．首次系统研究了西成地区金的成矿地质特征。金矿床均赋存于中泥盆统西汉水组细碎屑岩一硅质岩一碳酸盐岩建造顶部的浅变质细碎屑岩中，受断陷盆地、地层、岩相、岩浆活动和断裂构造的控制，矿化程度与改造作用的方式及强烈程度有关，属喷流沉积改造型。依据其产出特征，又可划分为石英脉型、石英（十铁碳酸盐）细脉型、细脉浸染型和构造蚀变岩型四种类型。 7．深入探讨了金与铅锌成矿的关系。金矿床与铅锌矿床均为喷流沉积成矿作用的产物，赋存于同一三级构造盆地之中，在空问上密切共生，相伴产出。含矿建造具有双层结构，下部（早期）为台地相碳酸盐岩建造，因强烈的喷流作用而形成大规模的铅锌矿床；上部（晚期）为盆地裂陷而形成的浊流相细碎屑岩建造，以发育较高的金异常为特征，因后期改造作用而形成许多独立的金矿床。与铅锌相比，金的赋矿层位较高，成矿时代较晚，金矿体中贱金属罕见，金与铅锌矿化明显分离。 巴．研究了金与铅锌共生及分离地球化学成矿机制。成矿地球化学特征研究表明，成矿金属元素主要来自于基底岩系，成矿流体以下渗海水和地层水为主，并以海水硫占绝对优势。含矿热卤水以低温高软度为特征，在喷出海底后随着物理化学条件的改变和与海水的混合，形成成矿元素的分带和金与铅锌矿化的分离。 9．根据矿床所处的构造环境、沉积建造、成矿作用方式和矿床发展演化历史，分别建立了区内铅锌矿床与金矿床的成矿模式。更多还原

【Abstract】 tween the North China plate and the Yangtze plate, the grand and lofty Qinling orogen., lying across the center of the China,is a famous continental orogen and a polymetalic minerogenic belt in the world. As an important part of it, the western Qinling orogenic belt enriched in mineral resources, with a long geologic evolutionary history, which is divided into several distinct stages characterized by different tectonic regimes, has unique and complex lithospheric composition and structure. A lot of gold deposits were found at Xihe-Chengxian (Xi-Cheng) region in 90 after Changba-Lijiagou,Dengjiasan,Bijiasan et al. Large-scale Pb-Zn deposits explored between 70 and 80 . Today there are many geochemical anomalies and ore spots will be appraised. The mine prospects very well.Under the direction of modern mineralization theory, the Pb-Zn deposits are formed by sedimentary-exhalative(sedex) metallization after extensive contrast and thorough study of geological features of the ore deposits.According to the complicated tectonic evolution and special mineralization in the western Qinling orogenic belt, this paper stresses the studies of the regional geological features, the nature and dynamic mechanism of mineral-formation basins, the geological and geochemical characteristics and origin of Pb-Zn ore deposits. The space-time and essential relations between Au,Pb-Zn ore deposits and sedex mineralization are revealed. The main results and achievements are as follows:1.Based on the synthetics analyses of strata sequence, deformation and metamorphism, magmatism and features of geophysics,geochemistry,remote sensing image and deep crust structure, the western Qinling orogenic belt is divided into three crustal-scale tectonic elements which contain the North China craton southern margin zone,the Northern Qinling zone and the southern Qinling zone(the Qinling microplate).2.By deep study of rocks, biocoenosium composition and sedimentary environment of the Western Qinling Devonian, this paper first put forward that Xi-Cheng basin is a complex rift basin having experienced a process from narrow rift to wide rift. In early period it formed mostly by passiverifting, which had features of rift basins. In late Period it transPOrted tosupradetaChInent because of piling up active rifting.3. The western Qinling orogenic belt with 6 tectono-development Periods is atypical composite continental orogenic belt evolved by different systems. Itwas formed by collision mountain-building movement that three platessubduct along two suture zones in main mountain-building Period.Not to beignored was also the strong intracontinental mountain-building movement inYallshan-Xishan period.Plate tectonics of the Qinling orogenic belt ensuesmainly the Non-Wilson Cycle charaterized by archiPelagic ocean,softcollision and multicyclicity.4. According to the tectono-envorimeni, sedimentary formation andore-forming elements association, the sedex type ore depoisits are dividedinto 6 subtyPe.5. Early Hercynian rift controlled the occurrence of the regional metallogeneticbelt.Rift basins, structural movements, synsedimentary faults and seafloorhydrothermal activities determined the distribution of the dePOsits.Sedirnentary facies and environments constrained the emplacement of theorebodies. The main orebodies are conformable bedded or bedway developedsyndepositional fabrics and hydrothermal mineral assemblage.There aremany kinds of seafloof hydrothermal sedimentary rocks,such as silicaroc k, al bi ti te, bari tite, c hl o riti te in the area.6. A preliminary study on gold metallogenetic featUres in Xi-Cheng areaindicate tha gold dePOsits which can be divided into 4 types are controlledby strata, rock facies and structUres. Its origin is reformed sedex. The goldore-forming relate to the method and extent of refOrmation.7. The nature relation betWeen Au and Pb-Zn deposits is probed. Au and Pb-ZndePOsits with the sarne sedex origin occurs in sarne geological unit. However,更多还原