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A Discussion on the Two‐stage Mineralization of the Baguamiao ‐Shuangwang Gold Orefield, Shaanxi Province, China
Author(s) -
Haishan WANG,
Xun LIU
Publication year - 2004
Publication title -
acta geologica sinica ‐ english edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.444
H-Index - 61
eISSN - 1755-6724
pISSN - 1000-9515
DOI - 10.1111/j.1755-6724.2004.tb00157.x
Subject(s) - geology , geochemistry , mineralization (soil science) , meteoric water , hydrothermal circulation , shear zone , structural basin , fluid inclusions , mineralogy , geomorphology , seismology , tectonics , soil science , soil water
The gold orefield studied is located on the south border of the underthrust‐collision zone of the Qinling microplate and the North China microplate in the Indosinian epoch. The main ore deposits localized in the area where the WNW‐trending compression‐shear type fault of the Indosinian epoch intersected the NE‐trending tenso‐shear type fault of the Yanshanian epoch. The orebody appeared in a chambered or wedged form. The mineral composition is relatively complex. On the southeastern border of the orefield there have developed intermediate‐acid anatectic magmatites of the Mesozoic Era. Three‐phase inclusions (Lco 2 , Vco 2 and L NaCl‐H2O ) comprise over 50%, associated with vapor phase consisting of H 2 O, CO 2 , CO, CH 4 , N 2 and H 2 . The ore‐forming fluids can be divided into 2 stages (the early and the late). The samples are projected in the area of mixture of initial magmatic and meteoric water on the δD‐δ 18 O diagram, suggesting two types of mineralization, i.e. the re‐equilibrated magmatic‐hydrothermal type and the circulating geothermal water type of a meteoric water source. The mineralization occurring in this orefield might be a superimposition of 2 tectono‐magmatic activities (the Indosinian and Yanshanian movements). Therefore, it is considered a superimposed B‐S type gold orefield.