本文關(guān)鍵詞： 礦床成因 成礦規(guī)律 找礦方向 三峰山銅礦床 北山地區(qū) 新疆　出處：《中國地質(zhì)大學(xué)(北京)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：三峰山銅礦床位于塔里木板塊東北緣的北山造山帶南部地區(qū),產(chǎn)于石炭紀(jì)變質(zhì)火山-沉積巖系中。近年來,前人主要針對該礦床的地質(zhì)特征進行了初步研究,對于成礦背景,礦床成因和成礦規(guī)律等方面尚未開展詳細(xì)的研究工作,很大程度上制約了礦體深部與外圍的找礦進程。本文在詳細(xì)野外地質(zhì)調(diào)查基礎(chǔ)上,系統(tǒng)研究了三峰山銅礦床的賦礦巖系與礦化特征、成礦流體地球化學(xué)、同位素地球化學(xué)和成巖成礦年代學(xué)等,厘定了礦床的成礦地質(zhì)背景與礦床成因類型,總結(jié)了成礦規(guī)律,為礦區(qū)找礦勘查工作提供了依據(jù)。礦床產(chǎn)于下石炭統(tǒng)紅柳園組下段,含礦巖性為淺變質(zhì)玄武巖和少量綠泥石-絹云母片巖。賦礦玄武巖地球化學(xué)特征顯示為一套鈉質(zhì)拉斑玄武巖,具有較為平坦的稀土配分模式,無明顯高場強元素虧損,Ti/V和Th/Nb值較低。巖漿主要來源于虧損的軟流圈地幔大程度部分熔融,并受到了俯沖板片流體的交代影響,形成于古亞洲洋南向俯沖背景下的弧前環(huán)境。礦體多呈似層狀、扁豆?fàn)罨蛲哥R狀展布,與賦礦地層產(chǎn)狀一致。原生礦石類型包括紋層狀、角礫狀、條帶狀、塊狀和浸染狀礦石,金屬礦物以黃鐵礦、黃銅礦和閃鋅礦為主。圍巖蝕變包括硅化、綠泥石化、綠簾石化、絹云母化和碳酸鹽化等,呈帶狀分布,下盤蝕變相對上盤更加強烈,蝕變過程中MgO和Fe2O3T大量遷入、Na2O遷出,代表了斜長石、鈉長石等礦物的分解和綠泥石、黃鐵礦的形成,這一過程與成礦關(guān)系最為密切。礦區(qū)廣泛分布含鐵錳硅質(zhì)巖,呈條帶狀、塊狀或角礫狀與硫化物礦石共生,地球化學(xué)特征顯示為熱水沉積成因,形成于大洋中脊環(huán)境。礦床的形成演化主要經(jīng)歷了同生沉積期、變質(zhì)改造-熱液疊加期以及表生期共3個時期。流體包裹體與同位素研究表明,成礦物質(zhì)主要來自幔源巖漿,可能通過火山脫氣或海水熱液在循環(huán)過程中從賦礦玄武巖中淋濾而來。成礦流體屬于中高溫(182℃~360℃)、低鹽度(0.7%~4.0%)的H2O-NaCl體系,流體來源可能為下滲的海水,巖漿流體對成礦貢獻相對較少。礦床的形成時代為早石炭世(353Ma),與賦礦玄武巖噴發(fā)時間(350 Ma)較為一致。綜合研究認(rèn)為,三峰山銅礦床為典型的塞浦路斯型火山噴流塊狀硫化物(VMS)礦床,形成于早石炭世北山造山帶的弧前環(huán)境。礦床的形成及產(chǎn)出受拉張性構(gòu)造背景、賦礦火山巖及同生斷裂構(gòu)造等因素控制。在此基礎(chǔ)上,總結(jié)了礦床形成機制及在成礦時空背景、含礦巖系、礦化分帶和圍巖蝕變等方面的規(guī)律,確定了找礦標(biāo)志,并指出了下一步找礦方向。
[Abstract]:The Sanfengshan copper deposit is located in the southern part of the Beishan orogenic belt on the northeast margin of the Tarim plate and occurs in the Carboniferous metamorphic volcano-sedimentary rock series. For the metallogenic background, ore deposit genesis and metallogenic law and other aspects have not been carried out detailed research work, to a large extent restricted the orebody deep and peripheral prospecting process. This paper on the basis of detailed field geological survey. The ore-bearing rock series and mineralization characteristics, ore-forming fluid geochemistry, isotopic geochemistry and diagenetic metallogenic chronology of the Sanfengshan copper deposit are systematically studied, and the metallogenic geological background and genetic types of the deposit are determined. The metallogenic regularity is summarized, which provides the basis for the prospecting and exploration of the ore area. The deposit occurs in the lower member of Hongliuyuan formation of Lower Carboniferous. The ore-bearing basalts are of shallow metamorphic basalt and a small amount of chlorite sericite schist. The geochemical characteristics of ore-bearing basalt show a set of sodium tholeiite with a flat REE distribution model. The magma is mainly derived from the depleted asthenospheric mantle to a large extent and is affected by the metasomatism of subduction plate fluids. The orebodies are stratiform, lentil or lentil like, consistent with ore-bearing strata. The primary ore types include lamellar, breccia and banded. The main metallic minerals are pyrite, chalcopyrite and sphalerite. The wall rock alteration includes silicification, green mud, green curtain, sericite and carbonation, etc. During the process of alteration, MgO and Fe2O3T migrated in and out of Na2O, representing the decomposition of plagioclase, albite and the formation of chlorite and pyrite. This process is most closely related to metallogeny. Ferromanganese siliceous rocks are widely distributed in the mining area, which are banded, massive or breccia associated with sulphide ores, and geochemical characteristics show hydrothermal sedimentary origin. It was formed in the middle oceanic ridge environment. The formation and evolution of the deposit mainly experienced three periods: synsedimentary period, metamorphic metamorphic hydrothermal superposition period and superposition period. The fluid inclusions and isotopes were studied. The ore-forming material mainly comes from mantle-derived magma and may be leached from the ore-bearing basalt during the circulation by volcanic degassing or seawater hydrothermal solution. The ore-forming fluid belongs to mid-high temperature (182 鈩，

本文編號：1445877