新疆奇台县黄羊山石墨矿床特征、物质来源及成因

黄羊山石墨矿床位于新疆东准噶尔造山带南部的卡拉麦里地区东南段，是近年来新发现的国内外首个产于花岗岩体中的超大型石墨矿床。成矿地质条件、矿床地质特征研究表明，该矿床与黄羊山碱性花岗岩体具有密切的时空及成因联系，矿石具独特的球状构造，球体中石墨与长英质矿物及磁黄铁矿、黄铜矿等金属硫化物密切共生。为确定黄羊山石墨矿床的成因和成矿物质来源，本文开展了球状矿石中的石墨拉曼光谱分析和C同位素测试，对与石墨密切共生的金属硫化物开展S-Pb同位素分析。结果表明，黄羊山矿床球状矿石不同部位石墨的拉曼谱峰相似，显示具有很高的结晶程度，估算结晶温度为750~800℃；7件石墨样品的δ¹³C值在-19.27‰~-19.90‰，分布非常集中，介于岩浆碳值和有机碳值之间，表明具有两者的混合来源。4件磁黄铁矿样品的δ³⁴S值集中在-2.3‰~-2.9‰之间，接近原始地幔值；在Pb同位素构造环境判别图解上，Pb同位素比值（²⁰⁶Pb/²⁰⁴Pb=18.114~19.040，²⁰⁷Pb/²⁰⁴Pb=15.448~15.543，²⁰⁸Pb/²⁰⁴Pb=38.253~38.915）显示较好的线性关系，延伸方向与地幔演化曲线的延伸方向基本一致；S-Pb同位素测试结果表明，与石墨共生金属硫化物具有幔源特征。综合黄羊山矿床成矿地质条件、成矿特征、石墨及共生硫化物的物质来源等研究结果，本文初步认为，黄羊山石墨矿床形成于碱性花岗岩的岩浆作用阶段，矿石中的金属硫化物来自岩浆混合作用中的幔源基性端元，碳质由于岩浆同化混染作用达到饱和，在硫化物的催化下沉积形成石墨。

Characteristics, ore sources and genesis of Huangyangshan graphite deposit in Qitai County, Xinjiang

The recently discovered Huangyangshan graphite deposit is tectonically located in the southeastern part of the Kalamari region in the southern Junggar orogenic belt. Due to its close spatial, temporal and genetic relationship with the Huangyangshan alkaline granite, this deposit can be defined as the first super-large graphite deposit hosted in granitoids in the world. Moreover, because the graphite ores in Huangyangshan deposit have unique spherical structures and closely coexist with felsic minerals and sulfides such as pyrrhotite and chalcopyrite, this deposit has been well-known ever since its discovery. In order to determine the ore genesis and sources of the Huangyangshan graphite deposit, ore-forming geological condition and deposit geology have been studied by using Raman spectroscopy and C isotope analysis upon the graphite from the spherical ore and S-Pb isotope analysis upon metal sulfides associated with the graphite. The results show that the Raman spectrum peaks of graphite in different parts of the Huangyangshan deposit are similar, and all have a high degree of crystallization. The crystallization temperature is estimated to be 750~800℃. The δ13C values of seven graphite samples are -19.27‰~-19.90‰, which are concentrated in between the values of magma-derived carbon and organic carbon, indicating a mixed source of them. The δ34S values of four pyrrhotite samples concentrated in between -2.3‰~-2.9‰, which is close to the values of the original mantle; their Pb isotope compositions (206Pb/204Pb=18.114~19.040, 207Pb/204Pb=15.448~15.543, 208Pb/204Pb=38.253~38.915) show a good linear relationship on the tectonic evolution figures of Pb isotope. The trends are consistent with that of mantle evolution line. The S-Pb isotopes compositions indicate the metal sulfides coexisted with graphite are of mantle source. Combined with the research results of the geological conditions, metallogenic characteristics, sources of graphite and symbiotic sulfides in the Huangyangshan graphite deposit, it can be concluded that the Huangyangshan graphite deposit is formed during the magmatism stage of the alkaline granite. The metal sulfides in the ore come from the mantle derived basic end-members in magma mixing. Carbon was saturated due to magma assimilation and contamination, and formed graphite under the catalysis of sulfides.