【摘要】：五龍溝礦集區(qū)位于青海省都蘭縣,大地構(gòu)造位置位于東昆侖造山帶中段北緣,區(qū)內(nèi)礦產(chǎn)資源豐富,成礦地質(zhì)條件優(yōu)越。五龍溝礦集區(qū)主要包括7個(gè)金礦區(qū):石灰溝礦區(qū)、紅旗溝礦區(qū)、深水潭礦區(qū)、淡水溝礦區(qū)、水閘東溝礦區(qū)、打柴溝礦區(qū)和中支溝礦區(qū)。本文以近年取得重大找礦突破的深水潭礦區(qū)為主要研究對象,查明其地質(zhì)地球化學(xué)特征及成因。礦區(qū)出露地層主要有中元古代長城紀(jì)小廟組(Chx)、新元古代青白口紀(jì)丘吉東溝組(Qbqj)、早古生代奧陶紀(jì)祁曼塔格群變火山巖組(OQb)及第四紀(jì)(Q),礦體主要產(chǎn)出于丘吉東溝組和祁曼塔格群變火山巖組與各時(shí)期花崗質(zhì)侵入巖的接觸帶處。礦區(qū)內(nèi)斷裂構(gòu)造十分發(fā)育,一系列NW向斷層為主要的控礦和容礦構(gòu)造。深水潭礦區(qū)主要受Ⅺ號(hào)斷裂帶控制,從螢石溝一直延伸至水閘東溝,礦區(qū)由3個(gè)礦體集中分布區(qū)段組成,自東向西分別為:水閘東溝礦段、黃龍溝礦段、黑石溝礦段,共圈定金礦體120條。深水潭金礦熱液成礦作用主要可以分為石英硫化物階段和方解石硫化物階段,以前者為主。礦石礦物主要為黃鐵礦、磁黃鐵礦和毒砂,部分礦段可見少量閃鋅礦、方鉛礦和黃銅礦,脈石礦物主要為石英、長石、角閃石、絹云母、黑云母,部分礦段可見方解石。礦石結(jié)構(gòu)主要為碎裂結(jié)構(gòu)和交代殘余結(jié)構(gòu),礦石構(gòu)造主要為塊狀構(gòu)造、浸染狀構(gòu)造和脈狀構(gòu)造。圍巖蝕變類型主要為硅化、絹云母化和少量碳酸鹽化等。深水潭礦區(qū)樣品流體包裹體顯微測溫結(jié)果顯示,石英硫化物階段成礦流體均一溫度范圍為146.8~393.7℃,峰值區(qū)間210~280℃,鹽度范圍為1.56~13.44 wt%NaCl,峰值區(qū)間7~13wt%NaCl,流體密度范圍為0.59~0.99g/cm3。激光拉曼光譜成分分析結(jié)果顯示,流體包裹體中氣相除H2O外,也檢測到了少量CO2和N2。由此認(rèn)為成礦流體為一套H2O-NaCl-CO2±N2體系,具有中低溫、中低鹽度、低密度的特征。H-O同位素測試結(jié)果顯示,石英硫化物階段礦化石英脈中石英δ18O值為9.7~15.9‰,估算流體δ18OH2O值為0.3~6.5‰;流體包裹體氫同位素組成范圍δD值為-117.3~-87.4‰。分析認(rèn)為深水潭礦區(qū)的成礦流體主要為變質(zhì)水和大氣水的混合,并且隨著成礦作用的進(jìn)行大氣降水逐漸占據(jù)主導(dǎo)地位。石英硫化物階段礦石中硫化物硫同位素測試結(jié)果顯示,其δ34SV-CDT值為0.4‰~8.5‰,平均4.18‰,絕大多數(shù)值在3‰到6‰之間,分析表明硫來源不是單純的巖漿硫來源,推斷為成礦熱液從圍巖中萃取了各類地殼來源硫的混合硫。石英硫化物階段礦石中硫化物鉛同位素測試結(jié)果顯示,206Pb/204Pb比值為18.1516~18.4985,207Pb/204Pb比值15.4943~15.6320,208Pb/204Pb值為38.3430~39.8076,反映了礦床鉛主要來自造山環(huán)境中圍巖鉛。最后,我們認(rèn)為,深水潭金礦的成礦年代不會(huì)早于成礦前閃長玢巖的成巖年齡215Ma,即晚三疊世末期。其成因類型屬造山型金礦床。印支晚期的后碰撞造山作用形成了一系列區(qū)域性深大斷裂和大型剪切帶及次級(jí)斷裂構(gòu)造,成礦流體可通過這些斷裂和剪切帶上升并與大氣水混合,最終在其內(nèi)充填交代成礦。
[Abstract]:The five-long-ditch ore-collecting area is located in Duanxian County, Qinghai Province. The geotectonic position is located in the northern margin of the middle section of the East Kunlun orogenic belt. The mineral resources in the region are rich and the ore-forming geological conditions are superior. The five-long ditch mine is mainly composed of seven gold mining areas: the lime-ditch mining area, the red flag-ditch mining area, the deep-water-pool mining area, the fresh-water-ditch mining area, the Donggou mining area of the water gate, the coal-making ditch mining area and the middle-branch ditch mining area. In this paper, the geological and geochemical characteristics and genesis of the deep-water-tan mining area, which has made a major exploration breakthrough in recent years, are studied. In the mining area, there are mainly the Middle Proterozoic, the Great Wall and the small temple group (Chx), the Neoproterozoic Qingbaikou (Qbqj), the early Palaeozoic and the OQb and the Quaternary (Q), The ore body is mainly produced in the contact zone of the volcanic group and the granitoid intrusive rock in the Group of the Donggou Formation of the Chuji and the Zimmerman Group. The fault structure in the mining area is very developed, and a series of NW-trending faults are the main control and ore-bearing structures. The deep-water-pool mining area is mainly controlled by the No. 1 fault zone, and extends from the fluorite ditch to the Donggou of the water gate. The mining area is composed of three concentrated distribution area sections of the ore body. From the east to the west, the Donggou ore section, the Huanglong ditch mine section and the Heishigou Mine section of the water gate are respectively used to delineate the gold orebody 120. The hydrothermal mineralization of the deep-water-tan gold deposit can be divided into the quartz-sulfide phase and the calcite-sulfide stage, and the former is the former. The ore minerals are mainly pyrite, pyrrhotite and arsenopyrite, and a small amount of sphalerite, galena and chalcopyrite are found in some ore sections. The gangue minerals are mainly quartz, feldspar, hornblende, sericite, biotite, and some of the mineral sections can be seen as calcite. The ore structure is mainly of the fracture structure and the metasomatic residual structure, and the ore structure is mainly of massive structure, disseminated structure and vein structure. The type of alteration of surrounding rock is mainly silicon, sericite and a small amount of carbonate. The micro-temperature measurement of the fluid inclusions in the deep water-pool area shows that the temperature range of the ore-forming fluid in the quartz-sulfide stage is 146.8-397.degree. C., the peak interval is 210-280 鈩，

本文編號(hào)：2362003