| 扬子地台西缘富碱斑岩的岩石地球化学特征及找矿前景 |
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| 关键词:porphyry Cu-Mo-Au deposit alkali-rich porphyry petrology and geochemistry western margin of the Yangtze platform |
| 基金项目:云南省三年地质找矿行动计划专项经费项目(编号: 20090681) |
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| Petrogeochemical Characteristics and Ore-hunting Prospect of Alkali-rich Porphyries on the Western Margin of the Yangtze Platform |
| Along the alkali-rich porphyry belt on the western margin of the Yangtze platform, only a few medium-small size porphyry Cu-Mo deposits and medium-large size Pb deposits were previously found; nevertheless, quite a number of large, medium and small size Au (Ag) deposits have been discovered in recent years, which implies fairly good prospect in search for mineral deposits. The authors systematically collected and analyzed the achievements obtained by previous researchers, summed up such characteristics of alkali-rich porphyries in this area as petrology, petrochemistry, rock alteration, REE partitioning, inclusion geochemistry, stable isotopes and the difference between ore-bearing porphyries and barren ones. On such a basis, the authors hold that that the alkali-rich porphyries in this belt are composed mainly of alkali-rich granite porphyries and alkaline orthophyre, and belong to hypabyssal-ultrahypabyssal intrusive bodies of early-middle Himalayan period. The rocks have somewhat lower Si2O content and rich alkali and high potassium, similar to things of “A” type granites in Australia. The intrusive bodies have basically similar REE total content, LREE/HREE ratios and δEu values, and their REE pattern curves are all steeply right-oblique smooth curves, suggesting that the rock-forming and ore-forming materials were derived from the upper mantle and the lower crust; in addition, the magmatic evolution and genesis of the two types of alkali-rich porphyries show identity. Generally speaking, large size Cu, Mo, Pb, Zn, Au and Ag deposits are likely to be found in the intrusive bodies characterized by comparatively small size, complex shape, somewhat lower alkali, richness of ore-forming elements such as Cu, Mo, Pb, Zn, Au ang Ag and REE alkaline metallic elements like Li, Rb and Cs, varied alteration types, strong alteration, obvious zoning and somewhat higher REE total content(ΣREE). |
| ZHANG Dao-hong,ZHANG Xue-shu,YANG Yan,YAN Jian,YANG Ping.2013.Petrogeochemical Characteristics and Ore-hunting Prospect of Alkali-rich Porphyries on the Western Margin of the Yangtze Platform[J].Acta Geoscientica Sinica,34(s1):168-176. |
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