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5 results on '"Zhang Qihou"'

1. Hydrothermal redistribution of rare-earth elements in Pingxiang Dacite, Guangxi

Author

Wan Guojiang, Zhang Qihou, Gu Shangyi, and Mao Jian-quan

Subjects
chemistry.chemical_compound, chemistry, Geochemistry and Petrology, Heavy mineral, Rare earth, Geochemistry, Carbonate minerals, Carbonate, Weathering, Fractionation, Dacite, Hydrothermal circulation, Geology
Abstract

Distribution of the rare-earth elements (REE) in dacite has been studied so as to get a better understanding of the migration behavior of REE during alteration. Both unaltered and altered samples were collected in an unpolluted area of Guangxi Zhuang Autonomous Region, southwest China. The REE concentrations were analyzed by ICP-MS. It is concluded that the REE were enriched during dacite alteration in varying degrees. The chondrite-normalized REE patterns of altered samples approximately maintain the characteristics of unaltered samples. However, if we normalize the REE concentrations of altered samples with unaltered dacite, fractionation of REE will appear. The LREE are more enriched than HREE in all altered samples with the LREE possibly precipitated as carbonate minerals. Both positive and negative Eu anomalies exist. Enrichment, immobility and depletion are noticed for the element Lu. Heavy mineral alteration, difference in stability constant between carbonate LREE and HREE complexes, downward migration of weathering fluid and microenvironment change may be responsible for the fractionation of REE in the altered dacite.

Published
2002

2. Geochemical studies on Dachang antimony ore deposit in Qinglong, Guizhou Province

Author

Zhang Qihou

Subjects
Basalt, Placer mining, Mineral, Geochemistry, chemistry.chemical_element, Metamorphism, engineering.material, Unconformity, chemistry.chemical_compound, chemistry, Antimony, Geochemistry and Petrology, engineering, Geology, Ilmenite, Magnetite
Abstract

The Dachang antimony deposit in Qinglong, Guizhou Province, is strictly controlled by the “Dachang Layer” which is a complex altered rock occurring at unconformity between the Permian Emeishan basalt and the Maokou limestone. Based on the studies of the hanging- and foot-wall rocks, the trace elements and REE contents of the rocks and ores and heavy placer minerals in the basalt, this paper is focused on the relations between these data and the “Dachang Layer” and its hanging- and foot-wall rocks. The author pointed out that the “Dachang Layer” and basalt are the source-beds of antimony; ilmenite and magnetite are the major mineral carriers of antimony. In the processes of halmyrosis and burial metamorphism of the “Dachang Layer” and basalt, antimony was mobilized along with the mobilization of iron and was preliminarily concentrated in the “Dachang Layer”.

Published
1999

4. Geochemical studies on Dachang antimony ore deposit in Qinglong, Guizhou province.

Author

Zhang Qihou. and Zhang Qihou.

Abstract

The deposit is strictly controlled by a layer of complex, altered rock at the unconformity between the Permian Emeishan basalt and the Maokou limestone. The basalts are the front part of a superalkalic basalt rich in volatile constituents and once intruded into sea water. Together with basalt-conglomerates and tuffs, they were the source beds for the antimony, which was therefore derived from the mantle. Ilmenite and magnetite are the two main Sb-carrying minerals. Both the altered Dachang Layer and the basalt underwent reaction with sea water, during which albite, epidote, zoisite, chlorite, sericite and clay alteration products formed as a result of alkaline metasomatism. During the alteration, Sb was remobilised and found its way into sea water or bond- and pore-water in the rocks as a result of Fe activation. The types of alteration during the following burial metamorphism were similar to those during halmyrolysis, remobilising 15-30% of the ore-forming elements., The deposit is strictly controlled by a layer of complex, altered rock at the unconformity between the Permian Emeishan basalt and the Maokou limestone. The basalts are the front part of a superalkalic basalt rich in volatile constituents and once intruded into sea water. Together with basalt-conglomerates and tuffs, they were the source beds for the antimony, which was therefore derived from the mantle. Ilmenite and magnetite are the two main Sb-carrying minerals. Both the altered Dachang Layer and the basalt underwent reaction with sea water, during which albite, epidote, zoisite, chlorite, sericite and clay alteration products formed as a result of alkaline metasomatism. During the alteration, Sb was remobilised and found its way into sea water or bond- and pore-water in the rocks as a result of Fe activation. The types of alteration during the following burial metamorphism were similar to those during halmyrolysis, remobilising 15-30% of the ore-forming elements.

5. A tentative discussion on the genesis of the Dachang antimony deposit, Qinglong County, Guizhou Province.

Author

Chen Yu, Liu Xiucheng, Zhang Qihou, Chen Yu, Liu Xiucheng, and Zhang Qihou

Abstract

The Dachang stibnite deposit is a typical stratabound deposit. Ore related elements such as F, Cl, S, Fe, Cu, Pb, As, Au and Sb were brought in by a Hercynian basaltic lava flow. The intensive Yenshanian orogeny and geothermal gradient activated antimony as well as other elements and produced a sulphate type hot brine with added meteoritic water at about 300 degrees C. Loaded with antimony and other elements this hot brine moved along the palaeokarst surface of Maokou limestone and filled in exfoliation space, joints, cracks and fractures to form the stibnite deposit at approximately 140 degrees C., The Dachang stibnite deposit is a typical stratabound deposit. Ore related elements such as F, Cl, S, Fe, Cu, Pb, As, Au and Sb were brought in by a Hercynian basaltic lava flow. The intensive Yenshanian orogeny and geothermal gradient activated antimony as well as other elements and produced a sulphate type hot brine with added meteoritic water at about 300 degrees C. Loaded with antimony and other elements this hot brine moved along the palaeokarst surface of Maokou limestone and filled in exfoliation space, joints, cracks and fractures to form the stibnite deposit at approximately 140 degrees C.

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