【作者】 陈祥；

【导师】 於崇文；

【作者基本信息】 中国地质大学（北京） ， 地球化学， 2007， 博士

【摘要】 赣南脉状钨矿床广泛发育“五层楼”(自脉带顶部向下依次是线脉带、细脉带、薄脉带、大脉带和尖灭带)式容矿断裂构造系统。以往对赣南脉状钨矿床容矿断裂构造系统的成因研究大多侧重于区域构造演化对其形成的控制作用,很少考虑花岗岩浆及其演化产物的作用。本文以黄沙脉状钨矿床芭蕉坑组矿脉带为例,通过室内-野外、理论-实验、宏观-微观相结合来研究探讨其形成机理,以期丰富和发展构造、成矿理论。取得如下成果:花岗岩是矿床的成矿母岩,两者之间存在密切的时间、空间和物质组成上的联系。矿床是花岗岩浆结晶分异作用后形成的岩浆热液产物。从花岗岩浆的形成条件、蚀变岩体的水平分带及线脉带形成于高温来看,成矿早期的流体可能由超临界流体演化而成。容矿断裂构造系统局限分布于花岗岩体的正上方,总体呈树枝状放射分布;矿带存在明显的水平、垂直分带,与区域构造极不协调。无论从整个矿区石英脉的空间分布特征,还是从单个容矿断裂的内部结构来看,以及从成矿流体的异常高压来分析,容矿断裂构造系统具有明显的水力断裂的特征。岩石声发射的凯塞效应可以记录岩石所经历的古构造活动。分别采集细脉带、大脉带中的围岩和花岗岩样品进行声发射测试,所获的最大主应力值按大小明显分为两群。细脉带围岩和花岗岩均记录了4次古构造运动,大脉带围岩记录了8次古构造运动。考虑了热应力、重力应力及该测试方法的误差,细脉带中的2个围岩样品和花岗岩这3个样品的4个最大主应力值和大脉带围岩中4个较小的最大主应力值与当今地应力测定结果接近,可能表明由这4个最大主应力值所对应的4次古构造活动记录主要反映了矿床形成以后的区域性构造活动。而大脉带围岩所记录的其余4个最大主应力值较大的古构造活动,由于这4个最大主应力值的大小与成矿流体的异常高压相当,可能反映了4次水力断裂活动的记录(次数)。总之,黄沙脉状钨矿床的容矿断裂构造系统为水力断裂成因,成矿期有4次水力断裂活动,与4个成矿阶段相对应。更多还原

【Abstract】 The vein-type tungsten ore deposit in southern Jiangxi Province exhibit unique“five-storeyed type”morphological vertical as well as horizontal zonality (from top to bottom: thread-vein zone, veinlet zone, thin-vein zone, big vein zone and thinning-out zone).So far the research on the host structures in the vein-type tungsten ore deposits in southern Jiangxi Province has been focused largely on the control of the evolution of the regional structures, and rarely touched upon the important role played by granitic magma and the associated postmagmatic processes. This paper takes the belt of the Bajaoken Group ore vein as major object for studying the mechanisms of formation of the“five-storeyed type”morphological zonality by synthetic approach of combining laboratory experiments and field observations with theoretical analysis,the following results are obtained.Granite is the ore-forming parent rock; it is intimately related with the ore deposit in time, space and composition. The ore deposit is the product of deuteric solutions derived from magmatic crystallization. Judging from the emplacement of granitic magma, the lateral zonality of altered wall-rocks and the thread veins forming under high temperatures, it is highly probable that the mineralizing fluid in the early stage might evolve from supercritical fluids.The system of host structures is situated locally above the granitic rock body and distributed radially like branches of a tree. The ore belt shows conspicuous vertical and horizontal zoning which is not in harmony with regional structures. The distribution of ore-bearing quartz veins in the ore region, the internal structures of single quartz veins and the extremely high pressures of the mineralizing solutions all demonstrate that the host structures belong to hydraulic fracturing.It is well-known that the Kaiser effect of acoustic emission of rocks records the times of paleostructural activities. Detection by acoustic emission for samples taken from country rock of veinlet zone and big vein zone as well as granitic rock body shows that 4, 8 and 4 times of paleostructural activities occurred respectively, corresponding to the three zones. The 4 times of paleostructural activities presented by the country rock of veinlet zone and the granitic rock body having maximum values of principal stress equivalent to the modern geostress indicate that they represent regional paleostructural activities. The sample from country rock of big veins shows 8 times of paleostructural activities, among which 4 times (with smaller maximum values of principal stress) are consistent with that of country rock of veinlet zone and the granite, therefore they reflect the post-metallogenic regional paleostructural activities. The other 4 times of paleostructural activities occurred in country rock of big-vein zone corresponding to maximum values of principal stress equal to the extremely high pressures of mineralizing fluids most probably reflect the times of activities of hydraulic fracturing favorably for ore formation.In short, the genetic nature of host structures in the Huangsha vein-type tungsten ore deposit belongs to hydraulic fracturing, and the times of hydraulic fracturing is four which is consistent with the number of mineralizing stages of ore formation.更多还原