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Anomalous Enrichment of Silver in Organic Matter of the Songxi Shale‐hosted Ag‐Sb Deposit in Northeastern Guangdong
Author(s) -
Kai HU,
Chensheng YU,
Dongsheng MA,
Jianping ZHAI,
Wenlan ZHANG,
Zhenyu XIAO
Publication year - 2002
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2002.tb00090.x
Subject(s) - organic matter , oil shale , electron microprobe , mineralogy , geology , geochemistry , chemistry , paleontology , organic chemistry
The silver contents of organic matter in the host rocks of the Songxi shale‐hosted Ag‐Sb deposit of northeastern Guangdong, South China, have been directly determined using the electron microprobe technique. The silver contents in two types of organic matter, marine vitrinite and solid bitumen, vary in the range from 100times10 −6 to 350times10 −6 , which are from tens of times to thousands of times higher than those of the host rocks in the ore deposit. The average silver content of the organic matter is also several times higher than the pay grade of silver for commercial mining of the ore deposit. It is quite obvious that the organic matter of the host rocks in the ore district is characterized by an anomalous enrichment of silver. The results of this study indicate that the silver anomalies in the organic matter have been derived from both the host rocks and the silver‐bearing fluids of the Songxi black shale ore source. In the course of sedimentation and later hydrothermal reworking, organic matter was able to entrap the element silver from source rocks and silver‐bearing fluids through complexation and reduction, so that silver could be further enriched (or precipitated) in the solid bitumen. The quantitative assessment in this study suggests that the distribution of solid bitumens in the ore district may be considered an indication for mineral exploration.