本文選題：成礦過程 + 流體組成��； 參考：《蘭州大學(xué)》2015年碩士論文

【摘要】：峨眉山大火成巖省產(chǎn)出了Fe-Ti-V氧化物和Ni-Cu-PGE硫化物兩種類型完全不同的巖漿礦床,其成礦巖漿的氧化還原環(huán)境完全不同。白馬寨鎳銅硫化物礦床為富銅鎳-貧PGE型地幔柱巖漿通道礦床,成礦巖體以塊狀硫化物為中心,依次以斜方輝石巖、二輝巖和輝長巖筒狀分布,是認識巖漿通道成礦這種世界超大型鎳銅硫化物礦床的主要成礦作用的理想地區(qū)。白馬寨巖漿礦床相關(guān)成礦巖漿過程的流體組成系統(tǒng)研究可完善巖石地球化學(xué)對礦床形成過程中S飽和以及成礦元素富集的認識。本文以白馬寨鎳銅硫化物礦床主要成礦巖體(3號)中斜方輝石巖、二輝巖和輝長巖等3種主要巖石類型,分選輝石單礦物,采用分步加熱質(zhì)譜法開展了流體組份化學(xué)組成與碳同位素組成分析,探討地幔柱成礦巖漿起源流體環(huán)境及硫飽和過程,取得了如下認識：1.白馬寨鎳銅硫化物礦床成礦巖體斜方輝石巖、二輝巖和輝長巖中主要巖漿礦物輝石中流體揮發(fā)份主要在200-400、400-900和900-1100℃三個溫度段釋出,流體釋出總量分別為136.64、19870.50和996.54 mm3/g,化學(xué)組成主要以H20為主(89%),其次為CO2、H2、O2和C2H6等組分。2.從斜方輝石巖、二輝巖到輝長巖400-900℃的流體揮發(fā)份總量逐漸降低,依次為23243.3、19585.7和16782.43mm3/g,化學(xué)組成為H20、CO2、H2和O2。H2O和O2的平均含量逐漸降低,而CO2和H2的平均含量逐漸增加。3.白馬寨礦床成礦巖體含碳流體揮發(fā)份的碳同位素組成變化范圍較大,200-400℃溫度段釋出CO2和CH4的δ13CCO2介于-21.2～-9.6%o,δ13CCH4介于-54.5--34.0‰。400-900℃釋出CO2和CH4的δ13CCO2介于-21.2～-9.5‰,δ13CCH4介于-49.7～-23.3‰。900-1200℃釋出CO2和CH4的A13CCO2=-22.9～-0.7%o,δ13CCH4=-53.3～-20.6‰。CH4同系物碳同位素組成隨碳數(shù)具有正序分布模式。4.白馬寨巖體中巖漿流體組成(400-900℃)指示巖漿起源于H2O為主流體介質(zhì)中,可能為賦含H2還原性流體揮發(fā)份的環(huán)境。流體揮發(fā)份中H2O、CO2和H2與Cu和Ni的含量具有正相關(guān)關(guān)系,表明大量的H2O促使源區(qū)大規(guī)模高程度部分熔融,使Cu和Ni進入成礦巖漿,CO2也有可能聚集Cu和Ni成礦金屬。5.在硫化物礦體的位置H2S含量降低,H2含量相對較多,表明硫飽和促使硫化物熔離,S2-與成礦金屬結(jié)合消耗了大量的硫。CO2的含量在成礦階段有所升高,造成Fe和Ti氧化物結(jié)晶,從而降低S的溶解度,使硫化物更容易結(jié)晶。
[Abstract]:The Fe-Ti-V oxide and Ni-Cu-PGE sulfide magmatic deposits were produced in Emeishan great igneous province, and the redox environment of the ore-forming magma was completely different. The Baimazhai nickel-copper sulphide deposit is a copper-nickel-poor PGE type mantle plume magmatic channel deposit. The ore-forming rock mass is dominated by massive sulphide, followed by clinophorite, ergite and gabbro. It is an ideal area to recognize magmatic channel mineralization, which is the main metallogenic process of the world's super large nickel copper sulphide deposits. A systematic study on the fluid composition of the associated ore-forming magma process of the Baimazhai magmatic deposit can improve the understanding of the petrogeochemistry of S saturation and ore-forming element enrichment during the formation of the deposit. In this paper, the main ore-forming rock bodies (No. 3) of the Baimazhai nickel copper sulfide deposit are divided into three main rock types, I. e., metaconorite, ergite and gabbro, to separate pyroxene single minerals. The chemical composition and carbon isotopic composition of the fluid were analyzed by means of step heating mass spectrometry, and the fluid environment and sulfur saturation process of mantle plume magma were discussed. The results are as follows: 1. The magmatic pyroxene, the major magmatic mineral pyroxene in the baimazhai nickel-copper sulphide deposit, the major magmatic pyroxenes, and the fluid volatilities of the major magmatic minerals in the baimazhai nickel copper sulphide deposit were mainly released at the temperatures of 200-400400-900 and 900-1100 鈩，

本文編號：2018805