【作者】 王少怀；

【导师】 裴荣富； 闫学义； 陈景河； 邱小平；

【作者基本信息】 中国地质科学院 ， 矿产普查与勘探， 2007， 博士

【摘要】 福建省上杭县紫金山矿集区位于NE向松溪—上杭火山喷发带与NW向上杭—云霄构造岩浆活动带叠加部位,并以上杭县紫金山金铜矿为中心,总面积约达3500km2。本文对该矿集区内主要构造带的特征及形成、发展、演化和主要矿产类型及其特征作了总结,对该区构造―岩浆―成矿进行了深入分析。另外,还结合矿集区中生代火山—侵入岩中花岗岩的时空分布、地质、地球化学特征,以及中生代火山-潜火山作用对成矿的控制进行了系统的研究。在矿集区开展的大比例尺成矿预测中,在对区内矿床(点)聚类分析的基础上,主要是利用地球化学块体的谱系树追索成矿物质浓集轨迹,达到逐步缩小靶区的目的。同时,通过物探电法和钻探工程验证其异常,达到增加资源储量为目的。研究成果获得以下主要进展和认识:1.对紫金山矿集区与成矿有关地质构造提出“构造的构造”(tectonic structure)的认识。紫金山矿集区的区域背景构造为位于中国东南沿海中生代火山活动带西侧,闽西南拗陷带西南缘,即为夹持于东侧的NE向长乐—南澳(东山)地壳断裂带和西侧的政和—长汀岩石圈断裂带之间。其间次级构造也依从两深大断裂派生为NE向松溪—上杭拗陷带与NW向上杭一云霄深断裂互为衔接的“断—陷”部位。区域“断—陷”背景构造是区域成矿宏观制约;而矿集区内矿田的控矿构造则为受背景构造的响应下,形成NE向和NW向两组断裂相互交切的,并使矿田呈现NE成“行”、NW成“列”,两向交切成“汇”的“行、列、汇”样式的棋盘格子状控矿构造;而矿田中的紫金山及其他几个裂隙—中心式火山机构则为“行、列、汇”控矿构造中的成矿构造。三个级次构造的相互叠置,即背景构造—控矿构造和成矿构造的有机耦合是紫金山矿集区与成矿密切相关地质构造成因(tectonogeneses)演化的新认识。2.对紫金山矿集区与成矿有关火山―侵入岩提出“体中体”(body in body)的认识。矿集区地质构造经历了加里东、华力西一印支、燕山及喜马拉雅四个构造旋回的形成发展过程,形变构造复杂,以形成多期叠加的复杂构造带为特征。紫金山矿集区产出的火山―潜火山―岩浆岩多为复式岩体。它们在空间的式样多呈在垂向上或侧列方向上的岩体中岩体,即“体中体”的复式岩体产状,并被区域性NE、NW向断裂限制于矿集区的中部。前人研究在时间上,它们分属晚侏罗世—早白垩世两个时期;它们形成的时序自老至新是:紫金山序列复式岩体(晚侏罗世花岗岩)→才溪岩体(晚侏罗世～早白垩世花岗岩)→上杭-碧田火山盆地(早白垩世火山岩)→四坊岩体(早白垩世花岗闪长岩)→紫金山火山机构(早白垩世火山岩―隐爆角砾岩―潜火山岩―斑岩)→罗卜岭岩体(早白垩世花岗闪长斑岩)。在空间上,它们则分别属于更大区域范围的NE向侏罗纪火山—侵入岩带和NW向早白垩世火山—侵入岩带的成员。也表现为从区域挤压向区域拉伸转换的构造机制。体中体及其构造动力转换机制是紫金山火山—侵入岩成矿的新认识。3.对紫金山矿集区与成矿流体有关的蚀变作用提出“蚀变的蚀变”(altered alteration)的新认识。紫金山矿集区内成矿流体及其围岩蚀变划分为四期:(1)岩浆期后热液蚀变期:(2)次火山热液蚀变期(包括英安玢岩岩浆期后热液蚀变阶段、早期隐爆蚀变阶段、晚期隐爆蚀变阶段、热水溶液(热泉)蚀变阶段和残余热水溶液蚀变阶段):(3)斑岩型热液蚀变期:(4)表生蚀变期。四期作用反映为“蚀变的蚀变”,并在空间分布上受北西向断裂构造和火山机构的双重控制,表现为裂隙—中心式。蚀变分带从宏观上可划分为石英、地开石一明矶石带;石英一绢云母地开石带和石英绢云母带等3个蚀变带(黄铁矿化因分布普遍,不具划分蚀变分带的意义);在时间上与成矿的相关关系可划分为前蚀变、同蚀变和后蚀变,但它们在时间和空间上多为相互叠置关系。4.提出紫金山矿集区为火山—侵入岩的“一梯多层楼”成矿模式(multi-floor building modle)。紫金山矿集区大型铜金矿床是我国大陆发现的首例高硫浅成低温热液型(石英一明矾石)矿床。在该矿床的深部和外围相继发现了斑岩铜(钼)矿、大型中低温热液型铜矿、大型低硫浅成热液型(绢云母一冰长石)银(金、铜)矿床和铀矿床。各类型均属同一地热体系的不同衍生相,其空间产出按垂向或侧列方向从上到下形成了不同矿种在空间上的叠置关系,具体表现为“矿化的矿化”(minerlized minerlization)U、Ag→Au→Au、Cu→Cu→Cu、Mo→W、Sn“一梯多层楼”式的矿种组合特征。据此“多层楼”产出模式将启示这一地区找矿新的时空领域。5.在上述对矿集区构造、火山—侵入岩和成矿流体深化认识的基础上,开展了矿集区中比例尺成矿预测。首先综合利用区域水系沉积物地球化学填图成果圈定地球化学块体和子块体。根据地球化学块体内已探明的矿产储量与该块体内的金属量(假定1km厚度)确定各级地球化学块体成矿率。利用这样的成矿率来预测整个研究(矿集)区内资源潜力,并给出潜在资源量。根据成矿物质逐步浓集的轨迹,利用地球化学块体筛选原则,确定矿集区内最有利于成矿物质汇聚的部位,达到逐步缩小的目的。据此提出了最有望的成矿远景区26个(其中:A级成矿远景区7个、B级成矿远景区8个、C级成矿远景区11个),为矿集区进行地质找矿规划提供地质依据。6.通过找矿靶区的区域比较和综合评价问题的探索和对紫金山矿田及其外围矿床(点)的地质矿产特征的研究,在对已知矿床进行模式化研究的基础上,提出了找矿靶区预测准则、找矿标志,并结合地质、地球物理、地球化学和遥感地质特征进行优选,在紫金山矿田及其外围共计优选找矿靶区共15个,并根据不同的成矿条件划分了A、B、C三类(其中:A类6个、B类8个、C类1个),从而达到大比例尺成矿预测之目的,为紫金山矿田进一步开展矿产勘查提供科学依据。7.本研究课题邀请了安徽省321地质队物化探所在紫金山矿区西北矿段330运输平巷、龙江亭铜矿区及温屋三个勘查区进行物探电法剖面测量,取得了各地段的激电法成果资料,指出了验证钻孔的孔位。通过紫金矿业集团实施了钻探工程,验证了激电法成果所确定的矿致异常实属矿体,获得了较为明显的找矿效果,指导了矿山地质勘查,达到了增加资源储量的目的。更多还原

【Abstract】 The study area, Zijinshan ore concentrated area of Shanghang county, Fujian province, is located at the overlapped zone of NE trending Songxi-Shanghang volcanics belt and NW trending Shanghang-Yunxiao tectonomagmatic activities belt with focus on Zijinshan gold-copper deposits and has an area about 3500km2. The characteristics , formation, development and evolvement of main structures and ore deposits are completely summarized in the study area and the relationships of teconomagmatic activities and metallogeny (were)are explained detaily. Furthermore, the controlled factors of ore-forming are studied systematically , integrated with the temporal and spatial distribution, geological and geochemical features of Mesozoic granitoids and volcanics and their correlation to Au-Cu mineralization Based on the cluster analysis of ore deposits in the study area, the enrichment path of ore materials are traced by use of the hierarchical dendrogram of geochemical block to reduce the prospect target gradually in metallogenic forecasting of large scale in the ore concentrated area,. In addition, the storage of resources has increased by verifying the potential geochemical and geophysical abnormities and farther drilling . The important improvement and cognition during this work are as follows:1.New improvement was is made“tectonic structure”is put forward about the geological strusture related to the minerallization within the Zijinshan ore cluster. Tectonically, the Zijinshan ore cluster is located at the western part of Mesozoic volcanics belt which spreads along the southeastern margin of China and at the southwestern margin of Minxinan depression. It lies between NE trending Changle-Nanao crustal fault on east and Zhenghe-changding lithospheric fault on west. The secondary structures belong to inclined meeting part between NE trending Songxi-Shanghang fault and NW trending Shanghang-Yunxiao deep fault. In the ore field, the ore-controlled strutures are mainly displayed as crossing of two suits of faults with NE trending and NW trending, which make a grid frame. The response among these tectonic structures is coupling of background tectonic-controlling structure and metallogenic structure. 2.“body in body”is put forward about the magmatic rocks related to metallogeny within Zijinshan ore cluster. The study area goes through multiple cycles, namely,Jialidong、Hualixi-Yinzhi、Yanshan and Himalaya four structural cycles and then the structure in the study area is complex and is characterized by multiple overlaping. Within the ore cluster, the intrusions related to minerallization are multiple and the ore body occurs in the granule granite of Zijinshan composite batholith, which forms the manner of“body in body”. Temporally, the Mesozoic magmatic rocks are restricted in late Jurassic and early Cretaceous and the sequence of formation from morning till night is:Zijinshan complex (late Jurassic granite)→Caixi pluton (late Jurassic to early Cretaceous granite)→Shanghang-Bitian volcanic basin (early Cretaceous volcanics)→Sifang pluton (early Cretaceous granodiorite)→Zijinshan volcanic apparatus (early Cretaceous volcanics-cryptoexplosion breccias-subvolcanics -porphyry)→Ruoboling pluton (early Cretaceous granodiorite porphyry). Spatially, it is belongs to NE trending Jurassic and NW trending early Cretaceous magmatic belt. The mechanism behave as transition from extrusion to extention regionally.3.“altered alteration”is brought forward about the alteration relevant to minerallization within Zijinshan ore cluster. From late Jurassic to early Cretaceous, the wall rock alteration in Zijinshan ore cluster are classified as four phases: (1) the postmagmatic hydrothermal alteration; (2) subvolcanic hydrothermal alteration including dacite porphyry hydrothermal alteration, earlier cryptoexplosive alteration, later cryptoexplosive alteration epoch, hydrothermal alteration epoch and residue hydrothermal alteration epoch; (3)porphyry hydrothermal alteration; (4) superficial alteration. The action of four stage can be thought as“alteration of alteration”,and the distribution of alteration is controlled by both NW trending fault and volcanic .mechanism, which is in the model of fracture-center.The altered zone can be classified as quartz-dacite-alunite assemblage, quartz-sericite-dacite assemblage and quartz-dacite assemblage. Accrding to the relationship of the alteration and the minerallization, pre-minerallization, accompanied minerallization and post-minerallization alteration can be identified.4. Multi-floor building metallogenic mode of volcano-intruded rock was put forward in the Zijinshan ore cluster. Zijinshan large-scale Cu-Au deposit is the first high-sulphur epithermal type deposit found in China mainland. Porphyry Cu-Mo deposit, large-scale mesothemral Cu deposit, large-scale low-sulphur type epithermal Ag-Au-Cu deposit and U deposit were discovered on after the other at the deep part of Zijinshan ore district and its periphery area. These deposits , mineralized mineralization, were controlled by same geothermal system and overlapped reciprocally in space from the top down.Specifically, it is thought as“minerlized minerlization”, namely,the U、Ag→Au→Au、Cu→Cu→Cu、Mo→W、Sn assembled features of different deposits display as multi-floor building.5. Middle-scale metallogenic forecast in the ore cluster is developed based on new understandings of structure, volcano-intruded rock, and ore-forming fluid. Geochemical blocks and secondary geochemical blocks were outlined by use of regional stream sedimentary geochemical mapping data. Mineralization coefficients in each grading geochemical block is calculated based on the ore reserve and the whole metal capacities of geochemical blocks. The resource potential was forecast by use of the mineralization coefficients. The prospect target reduced gradually by tracing the enrichment route of ore-forming materials and fixing on the parts which are favorable to gathering the materials of ore-forming by use of filter principle of geochemical blocks. Twenty-six targets are outlined including seven targets of A level, eight targets of B level, eleven targets of C level, which offers the geological rules for programming of geological ore-seeking.6. Based on mode study on known deposits, the ore-finding target forecast rules, ore-finding signs are put forward by use of regional comparison and synthesize evaluation of targets and study on characteristics of geology and mineral resources of zijinshan ore-field and its periphery area. , and the 15 targets , which are classified as level A, B, C by different metallogenic condition ,are selected by advantage of multiple data , namely, geological, geophysical, geochemical and remote geological characteristics in zijinshan ore-field and its periphery area. , thus, we can get the aim, large-scale ore-forming forecast, which can offer scientific rules for further ore seeking in zijinshan ore-field7. Geophysical survey and farther drilling are developed for the potential abnormities. Three-electrical-sections measurement is carried out in 330m level sap of northwestern segment in Zijinshan mining district, Longjinting copper ore district and Wenwu exploration district during this work,and the induced eletriccal data are gained and indicated the place of validated drilling hole . Drilling carried out of zijin mining group validated that the electrical abnormities are aroused by orebodies, which gets obvious effect.of ore-seeking and directs geological exploration and has the reserve increased .更多还原