岩、矿石显微组构特征对水银洞金矿成因的指示作用

1、岩、矿石显微组构特征对水银洞金矿成因的指示作用        【中文摘要】水银洞金矿床位于灰家堡金、汞、铊矿带东段,是黔西南金矿矿集区发现较晚、规模较大、品位较高的隐伏岩金矿床。矿床赋存于上二叠统龙潭组煤系地层及其与下伏的茅口组石灰岩之上的炭硅质岩(俗称“大厂层”)中,矿床由若干矿体组成,多个矿层垂直空间上下重叠,矿体产于构造高点上。单个矿体呈层状、似层状、透镜状、扁豆状,顺层产于地层中,矿体产状与围岩产状一致。选择该矿床对其成因进行研究,有助于总结成矿地质条件及找矿方向、为区内同类型金矿找矿提供基础资料,具重要的

2、经济意义及理论意义。本文共分七个章节,首先对水银洞金矿的区域地质、水银洞金矿矿床地质特征进行简介,然后重点对水银洞金矿岩、矿石特征及显微组构研究,对水银洞金矿形成作用讨论,并初步建立了水银洞金矿成矿模型。在此基础上,对区内找矿远景作出初步讨论分析。从前人对水银洞金矿研究最薄弱的环节岩、矿石显微组构研究,作为切进点;系统采集水银洞金矿ZK810、ZK802(+1)钻孔及其它几个辅助研究钻孔、岩矿生产坑道的岩矿样品共计150多件,作岩、矿石显微组构的系统研究,辅以岩、矿石地球化学特征,收集前人作的电子探针资料等来讨论水银洞金矿的形成条件,主要得出了以下结论:(1)水银洞金矿床由矿体群组成,单个矿体

3、呈层状、似层状、透镜状、扁豆状顺层产出,单个矿体厚度0.472.50m,厚度变化系数47118%,为厚度变化均匀较均匀矿床;矿体品位4.5513.5×10(-6),品位变化系数51.4564%,为品位变化均匀矿床。(2)水银洞金矿控制#金矿体产出的炭硅质岩为沉积岩,控制#、#诸多矿体的不纯碳酸盐岩为沉积岩,夹于其间的硅质灰岩中硅质与钙质同生沉积;与金矿化有关围岩中硅质为胶体SiO_2陈化玉髓自生石英,为沉积成岩成因。(3)水银洞金矿体寄主岩石多为不纯灰岩,其中富含生物碎屑及玄武岩屑,为龙潭煤系中成分复杂的碳酸盐岩夹层。(4)产于龙潭组底部茅口灰岩顶部岩溶不整合介面上的硅质岩,为喷流沉

4、积成因。(5)金矿石具再生边组构,粒内孔隙组构,铸模孔隙组构,镶边式生物矿化组构,铸模式生物矿化组构,反映沉积成岩期矿石组构特征,是典型的沉积成岩组构。(6)硫同位素、岩石化学组分、微量元素组合、特征元素(Sc、TiO_2)、元素对比值(Sr/Ba、Th/U)、稀土元素均显示了区内龙潭组为泻湖潮坪碳酸盐台地频繁交替的沉积环境,沉积时有玄武质的加进;金矿石物质来源于地层。(7)水银洞金矿产于“大厂层”及龙潭组中,水银洞金矿晚二叠世龙潭期为一局限的泻湖潮坪浅海碳酸盐台地沉积环境,西部频临峨眉山玄武岩频繁喷发,水下有热泉活动,使龙潭组及“大厂层”形成金高背景地层。(8)沉积岩成岩作用演化成的富金成矿

5、溶液是巨量的。(9)沉积岩中金矿就位于古地下水排泄地段。(10)水银洞金矿床具备了充足的成矿物质供给的先天条件;具备了古地下水因承压作用导致成矿流体长期循环的能量支撑条件;具备了成矿溶液长期集中输送及集中排泄条件;具备了成矿空间较局限,使矿质沉淀形成相对均匀富矿条件;因此可形成特大型金矿床。(11)建立了水银洞金矿床成矿模型框图。(12)指出龙潭期及以后地质时期的古地质构造的高点、同生断裂、古地热带及古潜山为水银洞金矿沉淀就位地带。进一步找矿除传统的矿床学研究外,应研究分析古水文单元,单个古水文地质单元的补给径流排泄区;综合利用地质物探远感,在古水文单元的排泄区域寻找新的“水银洞式”金矿。&#

6、39;);【Abstract】 The Shuiyindong gold deposit,discovered in recent years,is located in the east of Huijiabao Au,Hg,Tl mineralizeation trend and exhibits comparatively large scale and high grade typical for most Carlin-type gold deposits,in southwestern Guizhou province.The deposit is hosted in the co

7、al measures strata in the upper Permian Longtan Formation and the carbonaceous silicalite above the subjacent limestone of Permian Maokou Formation,which composed of a number of orebody,multiple ledge overlapped vertical space from top to bottom,the orebodies locate the high point of geological stru

8、cture.The single orebody is stratiform,atoid structure,lentoid, lenticular,existed in strata,its occurrence is consistent with the adjacent rock.Studies the genesis of Shuiyindong gold deposit,which is helpful in the summary mineralization geological condition and the prospecting direction,and provi

9、des the basic data to prospecting of the same type gold deposit in the area,which has the vital economic significance and the theory significance.This * is divided seven chapters,first makes synopsis to the regional geology and the gold deposit geological feature.Next key research the micro fabric o

10、f stone and ore,and discuss the forming process of deposit,and built the model of ore-formation of Shuiyindong gold deposit. Finally,* preliminary analysis and discussion to prospecting prospect in the area.The breakthrough point of this * is the research of the micro fabric of stone and ore.The aut

11、hor has gathered more than 150 samples,these samples picks from ZK810,ZK802(+1) borehole, auxiliary research borehole and produces saps.First systematically make the research of the micro fabric of stone and ore.Next auxiliary research the geochemistry characteristic of stone and ore. Simultaneously

12、,the author has gathered the electron probe material researched by predecessor.We discuss the mineralization geological condition of he Shuiyindong gold deposit through above material,having make the following progress.(1) Shuiyindong gold deposit is composed of a number of orebody.The single orebod

13、y is stratiform,atoid structure,lentoid,lenticular,existed in strata.The thickness of single orebody is 0.472.50m,variation factor of thickness is 47118%,grade of orebody is 4.5513.5×10(-6), variation factor of grade is 51.4564%.(2) The carbonaceous silicalite which controlled# orebody is sedim

14、entary rock,and the impure carbonatite which controlled#,# and other orebody is sedimentary rock.The silicalite with the gold mineralization related is colloid SiO_2agingchalcedonyself-engendered quartz.Which shows the genesis of sedimentdiagenesis.(3) The host stone of Shuiyindong gold deposit is t

15、he impure carbonatite,which contains richly biodetritus and basalt debris.The host stone is intricate carbonatite band of ingredient in Longtan Formation.(4) The silicalite which exists above the subjacent limestone of Permian Maokou Formation is the genesis of cascade sediment.(5) The gold ores hav

16、e reborn margin fabric,intragranular porosity fabric,mould porosity fabric, emborder biological mineralization fabric,mouldic biological mineralization fabric,which reflects the fabric of sedimentdiagenesis.(6) Depositional environment of Longtan Formation is frequent alternant lagoontide flatcarbon

17、ate platform,the conclusion is reflected through sulfur isotopic,petrochemistry constituent, trace element assemble,eigen element(Sc、TiO_2),pair of element ratio(Sr/Ba、Th/U),rare earth element.The gold ore matter come from strata.(7) The Shuiyindong gold deposit produces in the carbonaceous silicali

18、te strata and Longtan Formation.The depositional environment of Longtan Formation is lagoontide flatcarbonate platform.Emei mountains basalt ejected continually in the west of the deposit,which forms the gold high background value strata.(8) Mineralization liquor contained richly gold which come from diagenesis of sedimentary rock is abundant.(9) Gold in the sedimentary rock located the place of the fossil groundwater evacuation.(10) The Suiyindong gold deposit have enough mineralization material,enoug