黔西南簸箕田卡林型金矿中含砷黄铁矿和毒砂的赋金特征研究  

Gold-bearing Characteristics of Arsenian Pyrites and Arsenopyrites in the Bojitian Carlin-type Gold Deposits,Southwestern Guizhou Province, Southwest China

作　　者：潘谋成[1] 胡凯[1] 曹剑[1] 韩善楚[1] 

机构地区：[1]南京大学内生金属矿床成矿机制研究国家重点实验室地球科学与工程学院,南京210093

出　　处：《高校地质学报》2013年第2期293-306,共14页Geological Journal of China Universities

基　　金：国家自然科学重点基金课题(40638042);南京大学内生金属矿床成矿机制研究国家重点实验室自主研究课题(黔西南卡林型金矿与古油藏同生共储关系研究)资助

摘　　要：黔西南簸箕田金矿是新近发现的一个中型卡林型金矿。该文在显微镜矿相学观察的基础上,采用电子探针显微分析,包括背散射电子图像、点分析和面分析,对金矿中的赋金矿物展开了基本特征和赋金状态研究,发现含砷黄铁矿和毒砂是主要的赋金矿物。赋金黄铁矿又以环带状和细粒自形为主,莓球状、粗粒以及条带状次之。这些黄铁矿成因复杂,并且可能普遍受到热液蚀变作用影响。环带状黄铁矿核部中的金可能主要以"不可见"超显微包裹金(纳米级自然金,Au0)的形式赋存,而环带部分中的金可能以固溶体金(Au+)的形式赋存,并也可能存在纳米级自然金(Au0)。相比而言,莓球状、粗粒和条带状黄铁矿中的金既可能含有纳米级自然金(Au0),也可能含有固溶体金(Au+)。对于毒砂,单独的毒砂和黄铁矿-毒砂集合体中的毒砂均为热液成因,都赋存金,但以单独的毒砂为主,金以"不可见"超显微包裹金(纳米级自然金,Au0)的形式存在。The recently discovered Bojitian carlin-type gold deposits are located in the southwestern Guizhou Province and are middle in scale. In this study, we investigated the mineral＇s gold-bearing characteristics based on integrated studies of microscope observations and electron-probe back-scattered image, element spot and element map analyses. Analytical results show that arsenian pyrites and arsenopyrites are major gold-bearing minerals. The gold-bearing pyrites are dominated by zoned arsenian pyrites and fine-grained arsenian pyrites, followed by framboidal pyrites, coarse-grained pyrites, and banded pyrites. These pyrites have complex origins and most of them may hare undergone hydrothermal alterations. The gold in the cores of the zoned arsenian pyrites occurs as ＂invisible＂ microscopic inclusions of gold grains （nanoparticles of native gold, Au^0）. In contrast, the gold in the rims of the zoned arsenian pyrites occurs in solid solution （Au^＋） and may occur as nanoparticles of native gold （Au^0）. With respect to the gold in framboidal pyrites, coarse-grained pyrites, and banded pyrites, it occurs as nanoparticles of native gold （Au^0） or in the solid solution （Au^＋）. The arsenopyrites in the individual arsenopyrites and aggregations of pyrite-arsenopyrite are of hydrothermal origin. The gold occurs mainly in the former phase and is generally ＂invisible＂ microscopic inclusions of gold grains （nanoparticles of native gold, Au^0）.

关 键 词：簸箕田金矿 含砷黄铁矿 毒砂 电子探针 赋金特征 卡林型金矿 

分 类 号：P599[天文地球—地球化学] P618.51[天文地球—地质学]