The metallogenic mechanism of a granite-type uranium deposit in southern China with special reference to its U-Pb isotopic systematics

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Authors:Li Yaosong; Li Xibin
Author Affiliations:Primary:
Beijing Inst. Uranium Geol., Beijing, China
Volume Title:Diqiu Huaxue Geochimica
Source:Diqiu Huaxue = Geochimica, 1985(1), p.20-26. Publisher: Science Press, Beijing, China. ISSN: 0379-1726
Publication Date:1985
Note:In Chinese with English summary. 5 refs.; illus. incl. 4 tables, sketch map
Summary:The uranium deposit occurs in a Precambrian (Xuefengian) granite batholith. The emplacement age of the granite is 760 Ma. The average content of uranium in the granite is 7ppm, but the yield of leached U is higher with an average of about 33.8%. The granitic rocks contain some uraninite. Uranium mineralization mainly takes the form of siliceous veins with an age of 47 Ma. K-feldspar present in the granite and pyrite associated with pitchblende were mass-spectrometrically analysed for Pb isotopic composition. A reasonably linear array can be seen on the 207Pb/204Pb-206Pb/204Pb plot, implying a genetic connection between the rock and the ore, and a derivation of rock-forming materials from a uranium-rich source. According to the continuous-growth model for anomalous lead evolution, two isochrons give the ages of about 764 Ma and 708 Ma for ore-forming materials, close to the emplacement age of the granite batholith. This indicates that the ore-forming materials came from the granite batholith. Eight granite samples collected from the mining area were analysed, but no uranium-lead ages could be worked out because of the progressive destruction of the closed U-Pb isotopic system since granite emplacement, which resulted in the loss of uranium (78%). It can be imagined that in the period of continental weathering the surface water would infiltrate downwards, leaching out large amounts of uranium from the granitic rocks to form infiltration solution. The solution was heated at great depth and then found its way upwards and dissolved U constantly from the rocks to form the uranium deposit. [P.Br.]
Subjects:Absolute age; Batholiths; Dates; Economic geology; Geochronology; Granites; Ground water; Hydrothermal alteration; Igneous rocks; Intrusions; Isotopes; Leaching; Lead; Metal ores; Metals; Metasomatism; Mineral deposits, genesis; Pb-206/Pb-204; Pb-207/Pb-204; Plutonic rocks; Precambrian; Radioactive isotopes; Stable isotopes; U/Pb; Uranium ores; Asia; China; Far East; Hydrothermal processes; Southern China; Xuefengian
Abstract Numbers:86M/1944
Record ID:1985081443
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by National Geological Library, Beijing, China
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