Algal-bacterial fabrics of ores and their genetic implications in the longtang lead-zinc deposit at Yanbian,Sichuan |
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Authors: | Shuai Dequan Zhang Shouting Hu Xiaoqiang |
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Institution: | (1) Chengdu Institute of Technology, 610059 Chengdu |
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Abstract: | The Longtang Pb-Zn deposit occurs in the Upper Sinian Guanyinyan Formation. The host rocks include sandy shale, cherty limestone
and dolomitic limestone. The deposit is a typical one of thallogen origin.
The mineral assemblage in the ore is made up of sphalerite, galena, pyrite, enargite, tennantite, seligmannite, asphalt, etc.
The ore-forming process is possessed of multiepisode and multi-stage characters. Generally, sphalerites exhibit algal stromatolitic,
bacterial and algal colloidal textures, providing evidence for the direct involvement of algae and bacteria in mineralization
of ore-forming elements during sedimentary diagenesis. This is the first transmigration of ore-forming elements. However,
pyrite embracing bacteria and galena replacing/filling trichomes are typical organic textures, which are related to organic
carbon and bitumen that can adsorb or reduce ore-forming elements. This is an indirect process of organic mineralization,
i.e., the second transmigration of ore-forming elements. δ34S values are all greater than 5%., indicating the dominance of the heavy sulfur isotopes. The ore-forming temperature deduced
from fluid inclusions ranges from 100°C to 150°C±. All this goes to show that the Longtang Pb-Zn deposit is of thallogen origin.
This project was granted by the National Natural Science Foundation of China. |
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Keywords: | Longtang Pb-Zn deposit algal-bacterial fabrics algal stromatolite biomineralization |
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