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Lüeyang Chengguanzhen, China

Wu J.,China University of Geosciences | Liu J.-J.,China University of Geosciences | Li J.-X.,China University of Geosciences | Jia L.,China University of Geosciences | And 5 more authors.
Geology in China | Year: 2014

The Bikou Group basalt lenticular or banded in form is distributed in tuffs and tuffaceous phyllites of Huachanggou area. Based on detailed field geological survey and systematic laboratory studies including microscope observation, major and trace element analysis and radioactive isotope analysis, the authors investigated the petrological, geochemical and chronological characteristics of the basalt. The result shows that the basalt in Bikou Group has been subjected to metamorphism of greenschist facies, and mainly consists of plagioclase, chlorite and epidote. The basalt exhibits low SiO2 (44.67%-49.76%), TiO2 (1.14%-1.34%) and REE, high TFe2O3(12.03%-15.47%), MgO (7.57%-9.3%) and CaO (7.29%-10.54%), with LREE depletion and HREE enrichment. It originated from asthenosphere, occurred in N-MORB setting and was mixed with the old crust. The basalt sample yielded zircon LA-ICP-MS U-Pb age of (316.3±6.0) Ma (MSWD=0.78; n=7), which indicates that the Bikou Group volcanic rocks are products of at least two periods of volcanic activities, i.e., Neoproterozoic and late Paleozoic. They were formed massively in Neoproterozoic and reformed by the volcanic activity in late Paleozoic. Source


Yang L.-B.,China University of Geosciences | Liu J.-J.,China University of Geosciences | Wang J.-P.,China University of Geosciences | Yang Z.-H.,China University of Geosciences | And 5 more authors.
Geology in China | Year: 2013

Located in Lueyang County of Shaanxi Province, the Huachanggou gold deposit is a small -sized deposit which is currently being mined. The gold deposit occurs in the slightly metamorphosed Middle and Lower Devonian strata composed of mafic volcanic rocks (spilite) and marine carbonate rocks. Gold mineralization is strictly controlled by a fault zone. There are mainly three types of ores : altered spilite gold ore, limestone quartz gold ore and quartz sandstone gold ore. These three types of ores occur respectively in the main ore belt, the north ore belt and the south ore belt, and the south-south ore belt. The S, C, Pb, H and O isotopic compositions show that there is a distinctive difference between the spilite ore and the limestone ore: the ore forming material source of the former ore came from deep source while that of the latter ore was derived from the upper crust. The Q-type cluster analysis of the trace elements and the REE distribution patterns show that the spilite ore and the limestone ore were closely related to the wall rocks. The geochemical characteristics clearly show that the ore-forming material sources came from the mafic volcanic rocks and the marine carbonate rocks. The data obtained also suggest that the ore-forming fluid was derived predominantly from an active meteoric groundwater system with the addition of small amounts of volcanic water. Source


Liu C.,China University of Geosciences | Liu J.,China University of Geosciences | Wang J.,China University of Geosciences | Wu J.,China University of Geosciences | And 5 more authors.
Earth Science Frontiers | Year: 2013

The Huachanggou gold deposit in Shaanxi Province mainly occurs in the submarine basic volcanic effusive spilite. On the basis of a study of the thermoelectric characteristics of pyrite, the authors put forward the following conclusions. The main ore zone is a low-medium temperature gold deposit, whose pyrite crystallization temperature is in the range of 130-330°C. The electric conduct assemblage type of the pyrite changes in the order of N-type to P-type from the early stage to the late stage. The frequence of P-type pyrites gradually decreases from the shallow part to the deep. The high average gold grade corresponds to the high frequence of P-type pyrites and low value of thermoelectrical coefficient dispersions. The characteristics of thermoelectricity imply that the lower to middle parts of the ore body have been exhumed until now, and there exists an extension of the main ore zone in the deep. Furthermore, the authors suggest that the better exploring prospect would be expectable in the depth of exploration line Nos. 0, 2 and Nos. 22-26. Source

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