贵州三岔河硫铁矿矿床中假象黄铁矿的发现及其成因意义

贵州三岔河硫铁矿矿床是西南硫矿带内大型矿床之一。矿床产在二叠系龙潭煤系底部，矿体呈层状，与地层产状一致。在矿床的下部发现一层由假象黄铁矿组成的矿石。柱状假象黄铁矿的特点是：Ａｓ含量高，ＣＯ／Ｎｉ值＞１，Ｓ／Ｓｅ值＜２００００，且交代结构明显。通过假象黄铁矿物性特征、主微量元素、硫同位素的研究，证明它系成岩过程中Ｈ２Ｓ交代火山物质中的辉石或间石类矿物的产物。西南硫矿带煤系硫铁矿的形成与火山作用有关。成矿物质源于峨眉山玄武岩喷发期后气液，经沉积－成岩作用形成黄铁矿床。

DISCOVERY OF PSEUDOMORPHOUS PYRITE IN THE SANCHAHE PYRITE DEPOSIT,GUIZHOU PROVINCE,AND ITS IMPLICATION OF MINERALIZATION

Abstract The Sanchahe pyrite deposit is one of the large-sized pyrite occurrences developed along the southwest sulfur belt at the bottom of the Permian Longtan coal series and stratified with beddings identical to the regional stratigraphic sink. At the lower part of the deposit, pseudomorphous pyrites are recognized as a single beam featuring prismatic structure, typical metasomatic texture, arsenic-high content, Co to Ni ratio more than l, and S to Se ratio less than 20, 000. Case studies on the unusual sulfide piece with regards to mineralogy, trace elements and sulfur isotopes reveal that it resulted possibly from replacement of pyroxene or hornblende minerals in volcanic materials by H2S during diagenetic evolution. In fact, volcanic processes,took also a important Part in formation of the pyrite deposits associated with the coal series throughout the southwest sulfur belt as the eruption of the Emeishan basalt brought up a large amount of productive hydrothermal solution which later precipitated to form deposits at the same time as diagenesis conducted.