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Geochemistry of Platinum Group and Rare Earth Elements of the Polymetallic Layer in the Lower Cambrian, Weng'an, Guizhou Province
Author(s) -
FU Yong,
WU Chaodong,
GUAN Ping,
QU Wenjun,
CHEN Jiafu
Publication year - 2009
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.1755-6724.2009.00044.x
Subject(s) - platinum group , geochemistry , geology , mineralization (soil science) , hydrothermal circulation , chondrite , sedimentary depositional environment , chemistry , platinum , meteorite , catalysis , astrobiology , paleontology , structural basin , biochemistry , physics , seismology , soil science , soil water
The black shales of the Lower Cambrian Niutitang Formation in Weng'an, on the Yangtze platform of south China, contain voluminous polymetallic sulfide deposits. A comprehensive geochemical investigation of trace, rare earth, and platinum group elements (PGE) has been undertaken in order to discuss its ore genesis and correlation with the tectono‐depositional setting. The ore‐bearing layers enrich molybdenum (Mo), nickel (Ni), vanadium (V), lead (Pb), strontium (Sr), barium (Ba), uranium (U), arsenic (As), and rare earth elements (REE) in abundance. High uranium/thorium (U/Th) ratios (U/Th>1) indicated that mineralization was mainly influenced by the hydrothermal process. The δU value was above 1.9, showing a reducing sedimentary condition. The REE patterns showed high enrichment in light rare earth elements (LREE) (heavy rare earth elements (HREE) (LREE/HREE=5–17), slightly negative europium (Eu) and cerium (Ce) anomalies (δEu=0.81–0.93), and positive Ce anomalies (δCe=0.76–1.12). PGE abundance was characterized by the PGE‐type distribution patterns, enriching platinum (Pt), palladium (Pd), ruthenium (Ru) and osmium (Os). The Pt/Pd ratio was 0.8, which is close to the ratios of seawater and ultramafic rocks. All of these geochemical features suggest that the mineralization was triggered by hydrothermal activity in an extensional setting in the context of break‐up of the Rodinian supercontinent.