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A discussion of characteristics, genesis of lithocaps and their distributions in South China

Citation

Chen, J and Zhou, TF and Zhang, LJ and Sun, Y and White, NC and Li, XX, A discussion of characteristics, genesis of lithocaps and their distributions in South China, Yanshi Xuebao/Acta Petrologica Sinica, 36, (11) pp. 3380-3396. ISSN 1000-0569 (2020) [Refereed Article]

Copyright Statement

Copyright (2020) Science China Press

DOI: doi:10.18654/1000-0569/2020.11.08

Abstract

The lithocap, as first defined by Sillitoe (1995), is a volumetrically significant domain of pyrite-rich rocks with extensive hypogene silicic, advanced argillic and argillic alterations that formed between a paleosurface and a shallow-crustal intrusion. It is helpful for the finding of underlain porphyry mineralizations by a lithocap due to its prominence on the surface. However, the presence of a large lithocap (developed in an area over tens of square kilometres) together with an extensive hydrothermal alteration may obscure the geochemical footprint of the underlying porphyry deposits since it's difficult to further define the location of the underlying intrusive center. The exploration of location of mineralization within, under, or adjacent to a large lithocap must on the basis of detailed geological mapping, including the alteration mapping, with the aid of short-wave infrared spectroscopy (SWIR) analyses. The anomaly of elements in the whole rock geochemistry and mineral chemistry can provide directional indicators for locating the heat source or underlying intrusion. Remote sensing and induced polarization (IP) surveys were used to help site drill holes. Lithocaps in South China are mainly distributed in the Middle-Lower Yangtze Belt (MLYB) and the Coastal Volcanic Belt. Previous studies about Fanshan lithocap in Luzong basin, Anhui Province, indicate that it was formed simultaneously with its host volcanic rocks in Cretaceous. The fluid inclusion study, especially the O-D isotopes of the quartz, proved that the fluids that form the Fanshan lithocap are a mixture of magmatic-hydrothermal fluid with meteoric water, where the fluids reacted with the permeable volcanic rocks, and the lateral outflows help to develop such an extensive silicic and advanced argillic alteration. There are high potentials for finding the high sulfidation epithermal and porphyry deposits in Fanshan and Luzong basin. Another case of a lithocap occured at Zijinshan district, Fujian Province, where the biggest high sulfidation epithermal deposit developed in China. The geological and alteration characteristics of this deposit have been systematic studied, but the underlain porphyry has not been determined by any exploration yet. Lithocaps in Zhejiang Province have provided a large amount of non-metallic resources in China, including alunite, dickite, pyrophyllite and andalusite, however, the relationships between these lithocaps and the metal deposits have not been examined yet. In general, a large amount of lithocaps are distributed in South China, and they have typical alteration characteristics of a lithocap, but the studies of these lithocaps are still limited. The current researches indicate that mineralization related to lithocaps in South China has a tremendous potential, which possibly forms a giant porphyry epithermal metallogenic belt. Further studies should focus on explorations in, below or adjacent to these lithocaps.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Exploration geochemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding knowledge
Objective Field:Expanding knowledge in the earth sciences
UTAS Author:Chen, J (Ms Jing Chen)
UTAS Author:Zhang, LJ (Dr Lejun Zhang)
UTAS Author:Sun, Y (Mr Yi Sun)
UTAS Author:White, NC (Professor Noel White)
ID Code:152735
Year Published:2020
Web of Science® Times Cited:1
Deposited By:Research Performance and Analysis
Deposited On:2022-08-23
Last Modified:2022-09-08
Downloads:0

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