Title: Geologcal-Geochemcal Features and Genesis of Dugou Gold Deposit of Li County,Gansu Province
Abstract: Controlled by plutons and faults, the Dugou gold deposit is located in the western portion of the Hercynian fold belt in the Qinling Mts., and occurs in the Liba group of the outer contact zone of the Zhongchuan pluton. The natural type of the ore deposit belongs to the structure-alteration rock type. The deposit has already reaches large size. The paper studies geological characteristics of the deposit from ore-bearing strata, ore-control structures, relationship of vein rock and mineralization, ore features and alteration of country rocks. Geochemistry of the Dugou gold deposit has been studied in terms of stable isotopes, ore-forming fluids and REE. The isotopic geochemistry indicates that 34S changes in a small range and shows strong homogeneity, which is related to the emplacement of the Zhongchuan pluton. H and O isotopes fall in between magmatic water and atmosphere water in the δD-δ18O diagram, reflecting that the ore-forming fluid is mixed thermal fluid. Lead isotopes are anomalous lead derived from mixture between U and Pb. This could be genetically in relation with the Zhongchuan pluton rich in U. From the Pb-Sr isotopic analytical results, the main metallogenic period is inferred to be in the early Yanshan orogeny (171.6 Ma~173.4 Ma)close to that of the Zhongchuan pluton (181.5 Ma~219 Ma). The middle Devonian Liba group has Au initial enrichment during its deposit and diagenesis. Faults basically controlled spatial distribution and location of gold ore, while magma is an important thermal dynamic source and a major factor necessary for the deposit. Finally it formed the ore deposit by thermal brine rich in ore-forming materials along the faults. The genetic type for the deposit is the lixiviation composit type of post-magmatic hydrothermal and underground thermal brine. Tectono-dynamics superposed ore layers in 1~5 km range around the pluton are targets for prospecting.
Publication Year: 2007
Publication Date: 2007-01-01
Language: en
Type: article
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Cited By Count: 1
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