江蘇棲霞山鉛鋅礦床地質(zhì)地球化學(xué)特征及成因研究
發(fā)布時(shí)間：2018-03-24 09:12
本文選題：棲霞山鉛鋅礦床 切入點(diǎn)：中低溫?zé)嵋盒?/strong> 出處：《中國地質(zhì)大學(xué)(北京)》2016年碩士論文
【摘要】：棲霞山鉛鋅礦床位于江蘇省南京市棲霞區(qū),礦床自東向西主要由棉花地、平山頭、虎爪山、北象山、甘家巷、西庫等多個(gè)礦段組成,本文以虎爪山礦段深部成礦地質(zhì)特征為重點(diǎn)研究對(duì)象,在整理已有研究成果和進(jìn)行細(xì)致野外地質(zhì)工作的基礎(chǔ)上,進(jìn)行了礦物學(xué)、流體地球化學(xué)、同位素地球化學(xué)等方面的研究,并結(jié)合區(qū)域構(gòu)造演化背景,探討了礦床的成礦機(jī)制,為該礦床的成因分析和深部找礦提供了更多依據(jù)。礦體主要受硅鈣面、縱向斷裂、不整合面、古巖溶構(gòu)造帶及隱伏巖體等多重地質(zhì)要素控制,其中硅鈣面主要為由F2斷裂上下盤地層形成的和由斷碎不整合面上下構(gòu)造層形成的兩種硅鈣面,礦體主要賦存于硅鈣面鈣質(zhì)巖性一側(cè)。礦石礦物主要有黃鐵礦、閃鋅礦、方鉛礦等;脈石礦物主要有石英、方解石、白云石等。礦石的構(gòu)造主要有角礫狀構(gòu)造、浸染狀構(gòu)造、塊狀構(gòu)造,其次為脈狀、網(wǎng)脈狀、團(tuán)塊狀以及條帶狀構(gòu)造等,礦石結(jié)構(gòu)主要有粒狀結(jié)構(gòu)、交代溶蝕結(jié)構(gòu)、骸晶結(jié)構(gòu)、乳滴狀結(jié)構(gòu)、顯微包含結(jié)構(gòu)、網(wǎng)狀結(jié)構(gòu)、碎裂結(jié)構(gòu)和揉皺結(jié)構(gòu)等。通過野外工作和鏡下鑒定,將成礦作用過程分為石英-黃鐵礦階段、閃鋅礦-方鉛礦階段、黃鐵礦-閃鋅礦-方鉛礦階段、碳酸鹽-重晶石-金(銀)階段等四個(gè)階段。通過對(duì)黃鐵礦、閃鋅礦電子探針數(shù)據(jù)的分析,指示虎爪山礦段深部黃鐵礦、閃鋅礦等礦石礦物主要為巖漿熱液成因。流體包裹體研究結(jié)果顯示,礦床主要發(fā)育氣液兩相包裹體,流體包裹體均一溫度變化范圍在125~294℃之間,鹽度變化范圍為1.06~7.59wt%NaCl,密度變化范圍為0.84~0.96g/cm3,激光拉曼探針分析顯示,氣液相成分僅包含H2O和少量CO2,因此礦床成礦流體為中低溫、較低鹽度、較低密度的H2O-NaCl-CO2體系流體。H-O同位素研究表明,成礦熱液主要為巖漿熱液和大氣降水、熱鹵水、有機(jī)水混合的復(fù)雜流體,成礦作用早期以巖漿水為主,晚階段成礦流體類似大氣降水。結(jié)合前人S、Pb同位素的研究,成礦物質(zhì)的來源主要為地幔及地殼深部,即主要來自于礦區(qū)深部推測(cè)隱伏巖體和下伏震旦系地層。綜合研究認(rèn)為,礦床成因類型為與深成巖漿熱液作用有關(guān)的中低溫?zé)嵋盒偷V床。
[Abstract]:Qixiashan Pb-Zn deposit is located in Qixia District, Nanjing City, Jiangsu Province. From east to west, the deposit is mainly composed of several ore sections, such as cotton field, Pingshantou, Hujiashan, North Xiangshan, Ganjiaxiang, Xiku and so on. In this paper, the ore-forming geological characteristics in the deep part of the Hujiushan ore section are taken as the main research objects. On the basis of sorting out the existing research results and carrying out detailed field geological work, the mineralogy, fluid geochemistry, isotope geochemistry and so on have been studied. Combined with the regional tectonic evolution background, the metallogenic mechanism of the deposit is discussed, which provides more basis for the genetic analysis and deep prospecting of the deposit. The paleokarst tectonic belt and concealed rock mass are controlled by many geological elements, in which the calcium siliceous surface is mainly formed by the upper and lower plate strata of the F2 fault and the two kinds of calcium siliceous surfaces formed by the upper and lower tectonic layers of the faulted unconformities. The ore bodies mainly occur on the side of the calcareous lithology of the calcium silicate surface. The ore minerals are mainly pyrite, sphalerite, galena, etc. The gangue minerals are mainly quartz, calcite, dolomite, etc. The ore structure mainly consists of granular structure, metasomatic solution structure, skeleton crystal structure, emulsion droplet structure, microscopic inclusion structure, reticular structure. Through field work and microscopic identification, the metallogenic process is divided into quartz-pyrite stage, sphalerite-galena stage, pyrite -sphalerite-galena stage, etc. Through the analysis of electron probe data of pyrite and sphalerite, the deep pyrite in the Hujiushan ore section is indicated. The ore minerals such as sphalerite are mainly magmatic hydrothermal origin. The results of fluid inclusion study show that gas-liquid two-phase inclusions are mainly developed in the deposit, and the homogenization temperature of fluid inclusions varies from 125 鈩，
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