油气演化与一些金矿床成因的关系

THE EVOLUTION OF OIL AND GAS AND THE GENESIS OF SEDIMENTATION REWORKED GOLD ORE DEPOSITS

石油演化和金属成矿之间的关系是地球化学研究的一个重要方向。通过对贵州部分金矿石中有机质的分析研究,认识到在大部分金矿矿石中均有热变沥青,热成熟度都很高(R°%>1.5)。进一步分析石油中的金含量,发现一些原油中金的含量比较高(最高达106ppb)。实验研究了原油对金的萃取作用、原油对金的溶解及金矿石的淋滤作用,证明了金富集在原油中的过程。经载金原油成矿实验研究,确认油气的破坏过程是金成矿的过程。通过综合分析,我们建立了一个油气演化与金成矿之间的模式,用以进一步研究油气与某些沉积改造金矿床之间的相互关系。

Some gold deposits,especially sedimentation reworked gold deposits,share much in com-mon with oil and gas deposits.They are both strata-bound deposits.They are characterizedby structurelly controlled distribution.Strata-bound gold deposits are high in organic carbon (C_(org)) It has proved that organicmatter in gold ores and source rocks is of sapropelic type or related to its evolutionary productsin the light of organic geochemical study on gold ores and source rocks.In many gold ores,thermally altered bitumens of high maturity are often found.Oil is a mixture of organic compounds which generated in the late stages of lithogenesis.It contains many heteroatomic organic compounds with N,O,S,As and Si,for example,thiols,thiophenes,pyrins,etc.These compounds exist not only in oils,but also in oilfield brines,thuscapable of interacting with gold and gold complexes to form organic compounds of gold.The metal contents of oils from several large basins of China were analysed by INAA andAAS.The results show that the highest value is 0.13 ppm from the Shengli oilfield.The re-sults are similar to those reported from abroad.Experimental studies indicate that oils can absorb gold from solutions.Oils and oilfieldbrines can solve gold from gold ores and pure gold metal.Mineralizing experiments show thatoils are capable of absorbing gold to form gold ores.Oils have an important role to play in gold transport,accumulation and deposition.