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ScientificWorldJournal. 2014;2014:780910. doi: 10.1155/2014/780910. Epub 2014 Jul 22.

Distribution, microfabric, and geochemical characteristics of siliceous rocks in central orogenic belt, China: implications for a hydrothermal sedimentation model.

Author information

1
Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China ; Guangdong Provincial Key Lab of Geological Processes and Mineral Resource Survey, Guangzhou 510275, China.
2
Key Laboratory of Mineral Resources, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China.
3
Guangdong Provincial Key Lab of Geological Processes and Mineral Resource Survey, Guangzhou 510275, China ; Department of the Earth Sciences, Sun YAT-SEN University, Guangzhou 510275, China.
4
Department of Mineralogy-Petrology, University of Athens, Athens 15784, Greece.

Abstract

Marine siliceous rocks are widely distributed in the central orogenic belt (COB) of China and have a close connection to the geological evolution and metallogenesis. They display periodic distributions from Mesoproterozoic to Jurassic with positive peaks in the Mesoproterozoic, Cambrian--Ordovician, and Carboniferous--Permian and their deposition is enhanced by the tensional geological settings. The compressional regimes during the Jinning, Caledonian, Hercynian, Indosinian, and Yanshanian orogenies resulted in sudden descent in their distribution. The siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartz, syn-depositional metal sulphides, and scattered carbonate minerals. Their SiO2 content (71.08-95.30%), Ba (42.45-503.0 ppm), and ΣREE (3.28-19.75 ppm) suggest a hydrothermal sedimentation origin. As evidenced by the Al/(Al + Fe + Mn), Sc/Th, (La/Yb) N, and (La/Ce) N ratios and δCe values, the studied siliceous rocks were deposited in a marginal sea basin of a limited ocean. We suggest that the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activities. The hydrothermal sediments of the former stage include metal sulphides and silica, while the latter was mainly composed of silica. Despite the hydrothermal sedimentation of the siliceous rocks, minor terrigenous input, magmatism, and biological activity partly contributed to geochemical features deviating from the typical hydrothermal characteristics.

PMID:
25140349
PMCID:
PMC4130366
DOI:
10.1155/2014/780910
[Indexed for MEDLINE]
Free PMC Article

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