鲕状黄铁矿的热水沉积与微生物成矿作用

Hot-water Deposition and Microbiomineralization of Oolitic Pyrite

鲕状黄铁矿产出在燕山元古代裂陷槽兴隆-宽城次级断陷盆地内的高板河SEDEX块状硫化物矿床中。黄铁矿鲕粒有机质含量1．43％～2．59％，生物标志物，规则类异戊二稀烷烃含量丰富，植烷（Ph）、姥鲛烷（P）含量较高。研究结果表明，鲕状黄铁矿为原生菌藻类沉积结构，在还原环境中，海底热水喷口附近嗜热菌藻类大量繁殖。热水的豚动作用，为黄铁矿鲕粒的形成创造了条件。在热水的脉动作用下，嗜热微生物围绕黄铁矿内碎屑生长，同时吸附热水带来的成矿物质。在这种海底喷气-成矿流体脉动-嗜热微生物吸附与还原作用下，形成鲕状黄铁矿。

Oolitic pyrite ores,a special ore-type,occur in the Gaobanhe massive sullide deposit in the Proterozoic rift in the Yanshan reginn- The pyrite oolides have cores consisting of compacted trangular laminae,cemented by filamentous thermophilous microorganism, of suirur-addicted bacteria and as many as 10-20 incrustations composed of pyrite and lesser galena. In the oolltic pyrite,there are 1. 43 %-2. 59 % of highly sapropelic organic materials, plenty of organism-marking materials, normalized iroamyl dialkene and methyl heptadecyl, and large amounts of phytane and pristane. The oolitic pyrite is similar to hot-water depositions of modern oceanic rifts with respect to its composition of micro and RE E - elements, showing a b acterium or algae- built sedimentary texture under microscope. Further studies indicate these organisms were flourishing in a reduced environment colse to the vents of hot water on sea bdes,essentially because of the suspended regime caused by the vent pulsation. This regime helped the thermophilous microoganism to grow around the pyrite intraclasts and bacterial groups and to take up mineral materials from the vent hot water. In a word,a series of mechanisms including submar8ine ezhalation, vent pulsation, microorganic adsorption and reduction, and the lide contributed considerably to formation of the oolitic pyrite