本文選題：金礦化 + 流體包裹體�。� 參考：《大地構(gòu)造與成礦學(xué)》2017年02期

【摘要】：賀蘭山北段牛頭溝金礦床為華北克拉通西北緣新發(fā)現(xiàn)的金礦床,包括構(gòu)造破碎帶蝕變巖型和石英脈型兩種礦化類型,后者可進一步細(xì)分為低緩石英脈型和陡窄石英脈型2個亞類。礦區(qū)所有礦體均賦存在古元古界賀蘭山群變質(zhì)雜巖和混合花崗巖內(nèi),受主干斷裂F_1及其上盤次級斷裂體系控制。綜合本文及前人研究成果表明,破碎帶蝕變巖型石英流體包裹體以純液相水溶液包裹體為主,而低緩石英脈型和陡窄石英脈型石英流體包裹體則以氣液兩相水溶液包裹體為主,不同礦化類型成礦流體均為中低溫(160~210℃)、中低鹽度(6%~12%NaCl_(eq))的H_2O-NaCl流體。對礦區(qū)內(nèi)3種礦化類型石英流體包裹體和硫化物分別開展的H-O和S-Pb同位素研究顯示:破碎帶蝕變巖型和陡窄石英脈型流體包裹體δD_(H2O)組成相近,分別為-75.2‰~-89.3‰和-87.0‰~-93.8‰,而低緩石英脈型流體包裹體則具有較高的δD_(H2O)值(-45.7‰~-67.7‰);流體包裹體δ~(18)O_(H2O)值則由破碎帶蝕變巖型(3.7‰~4.4‰)→低緩石英脈型(1.9‰~3.3‰)→陡窄石英脈型(0.5‰~0.9‰)依次降低。破碎帶蝕變巖型和陡窄石英脈型δ~(34)S組成均為正值,分別為1.3‰~6.9‰和2.2‰~5.8‰,而低緩石英脈型則具有較低的δ~(34)S值(-5.1‰~-2.6‰)。低緩石英脈型金礦具有明顯不同的δD_(H2O)和δ~(34)S組成,可能與含礦斷裂性質(zhì)及其距離導(dǎo)礦構(gòu)造F_1斷裂較遠(yuǎn)等因素所共同導(dǎo)致的成礦流體氧逸度升高有關(guān)。3種礦化類型對應(yīng)的礦石均表現(xiàn)出明顯富集Th放射成因Pb的特點,~(206)Pb/~(204)Pb(16.467~17.994)和~(207)Pb/~(204)Pb(15.382~15.582)組成相對均一,而~(208)Pb/~(204)Pb變化較大(37.413~42.345)�？傮w上,石英流體包裹體H-O同位素組成表明成礦流體均為巖漿水和大氣降水形成的混合流體,其大氣降水比例自破碎帶蝕變巖型→低緩石英脈型→陡窄石英脈型依次升高;礦石S-Pb同位素指示成礦物質(zhì)為深部巖漿和具有高Th/U比的基底圍巖雙重來源。結(jié)合區(qū)域構(gòu)造 巖漿演化,筆者將牛頭溝金礦床成礦過程概括為晚古生代裂陷盆地形成階段、中晚侏羅世區(qū)域擠壓推覆階段和晚侏羅世至早白堊世巖漿熱液活動階段等3個階段。
[Abstract]:The Niutougou gold deposit in the northern part of Helanshan is a newly discovered gold deposit in the northwest margin of North China Craton, which includes two types of mineralization: altered rock type and quartz vein type. The latter can be further subdivided into two subtypes: low slow quartz vein type and steep narrow quartz vein type. All orebodies are located in metamorphic complex and migmatite of the Paleoproterozoic Helanshan Group, controlled by the main fault F-1 and its secondary fault system. In this paper and previous research results, it is shown that the fluid inclusions of quartz fluid in altered rocks in the fractured zone are mainly composed of pure liquid aqueous solution inclusions, while those in low-slow quartz veins and steeply narrow quartz veins are mainly gas-liquid two-phase aqueous fluid inclusions. The ore-forming fluids of different mineralization types are H_2O-NaCl fluids with moderate and low temperature of 160 ~ 210 鈩，

本文編號：1784101