The Genetic Relationship between Carlin-Type Gold Deposits and Paleo-Petroleum Reservoirs in SW Guizhou, China: Evidence from Organic Petrography
详细信息
- 责任者：Gu Xuexiang (School of Earth Sciences and Resources ; China University of Geosciences ; Beijing 100083 ; China) ; Zhang Yongmei
- 刊名：Earth Science Frontiers
- 出版年：2013
- 卷期：20(1)
- 关键词：金矿 ; gold ores ; 油气藏形成 ; reservoir formation ; 贵州 ; Guizhou Province
- 页码：p.92-106
- 图表：illus., 1 table, 37 refs.
- 分类号：1001
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
Two principal types of organic matter are present in the Carlin-type gold deposits in SW-Guizhou: In situ alginite and hydrothermally migrated bitumen/pyrobitumen.Autochthonous alginite disseminates in both gold ores and host sedimentary rocks and typically appears as lamellae or bands always parallel to bedding planes.Bitumen appears as discrete grains dispersed in altered and mineralized rocks and is particularly prevalent in proximal zones of high grade ores,but is absent in barren sedimentary rocks.In general,bitumen is intimately associated and/or intergrown with the main stage jasperoidal quartz patches,arsenian pyrite,and arsenopyrite.It also occurs as discrete grains enclosed by the main and late stage quartz,calcite and realgar.Bitumen in gold ores has higher contents of ore-associated trace elements As(4.90%-7.88%) and S(typically 7.48%-15.24%),compared to autochthonous alginite with negligible As and lower S concentrations(2.72%-7.18%).Hydrocarbon fluid inclusions,ranging from those filled only by vapor hydrocarbons(CH4) to inclusions consisting of a vapor hydrocarbon phase(CH4) and an aqueous liquid phase,are common in hydrothermal minerals.Bitumen in paleo-petroleum reservoirs is commonly observed filling open spaces(pores and fractures) in Permian reef carbonate rocks,occurring either alone or associated with calcite.It commonly shows fine mosaic texture,suggesting a high thermal maturity.Organic petrographic evidence suggests that gold originated and migrated along with the hydrocarbons in an immiscible,ore-and hydrocarbon-bearing,basinal fluid system.The gold mineralization and hydrocarbon accumulation took place by different depositional and trapping mechanisms.