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《Geological Review》 1995-03
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LAMPROPHYRE AND GOLD MINERALIZATION AN ASSESSMENT OF OBSERVATIONS AND THEORIES

Li Xianhua(Guangzhou., Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China)and Sun Shensu(Australian Geological Survey Organization, Canberra, Australia)  
The proposal of Rock (1987, 1991) to broaden the term "lamprophyre" from an essentially field-oriented usage to a term covering various rock types other than tholeiites has added confusion to petrogenesis and economic geology. This paper presents a review of various issues related to the alleged genetic connection between mesothermal gold mineralization and lamprophyres. This model is evaluated in terms of the gold contents of fresh and altered lamprophyres and gold mineralization resulting from hydrothermal alteration as well as some theoretical analyses. Altered "lamprophyres", especially those proximal to gold mineralization affected by carbonation, have significantly higher Au contents. Secondary Au enrichment can be identified by a mantle-normalized Cu-PGE-Au diagram, on which Au shows a peak relative to Cu and neighbouring platinum group elements. Thus, those samples with anomalously high gold contents are most likely to be the product of hydrothermal alteration. S-undersaturation is a fundamental condition for concentration of Au, Pd and Pt as incompatible elements in magma during partial melting of the mantle.The relationship between "lamprophyres" and mesothermal gold mineralization varies. In most cases, e. g. in the case of Archean "lamprophyres" associated with gold deposits in the Superior Province, Canada, and Yilgarn region, Western Australia, "lamprophyres" appear unlikely to have contributed significant Au or other components to the mineralization. In contrast, "lamprophyric rocks" (shoshonitic suite) of the Lachlan Fold Belt in SE Australia have produced porphyry and skarn Cu-Au mineralization through magmatic differentiation and release of mag-matic fluids. They also acted as gold sources for later mineralization in shear zones and fault zones in company with deformation and metamorphism.
【Fund】: 国家自然科学基金 (编号49000037)
【CateGory Index】: P618.51
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