| 福建行洛坑钨（钼）矿床的成因类型研究 |
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| 引用本文：.1984.A study of the genetic type of Xingluokeng tungsten (molybdenum) deposit, Fujian Province[J].Mineral Deposits,3(1):27~36 |
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| A study of the genetic type of Xingluokeng tungsten (molybdenum) deposit, Fujian Province |
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| Abstract:The Xingluokeng tungsten (molybdenum) ore deposit is well known in China, yet its genesis remains a problem of much controversy. A review is made in this paper concerning the result acquired from the previous research work and on such a base, some geologic criteria are formulated for distinguishing tungsten deposits of granite type from those of porphyry type. Through a comparison between the deposit in question and the typical intrusive-controlled tungsten (molybdenum) deposits in Nanling and neighboring areas in geologic and geochemical characters, the author has come to the conclusion that this deposit should be genetically attributed to the metallogenic series of gramtic tungsten deposit of shallow-source remelting crust type ( transformed corrtinental crust type). Following are the major facts: 1. The Xingluokeng tungsten (molybdenum) deposit and tungsten deposits in southern Jiangxi have analogous regional geologic and structural setting: both lie in Post-Caledonian Uplift of the South China Caledonian Geosyncline Fold System; both underwent approximately the same three major geologic periods; both lie in the same magmatic-tectonic belt, both have the favorable regional geologic and tectonic setting for polycyclic evolution of gianitic tungsten mineralization. 2. Instead of being a hypabyssal or super-hypabassal porphyry or so-called subvolcanic complex, the Xingluokeng igneous complex is composed of granites of hypabyssal to intermediate-abyssal facies generated by multi-stage intrusions of the same magma, as evidenced by the following facts: the rocks are characterized by porphyritoid texture; the intrusive mass has low oxidation coefficient (0.22); the melting experiment and chemical composition of the rocks imply an explacement depth of less than 3km. 3. The intrusive complex seems unrelated to regional volcanism, because no genetically associated co-magmatic volcanic rocks have been found, and the complex does not show crypto-explosive characteristics and no corresponding crypto-explosive breccia is present. 4. δ18Owhole rock is 9.90‰, δ18Oquartz is 12.41‰, Sr87/Sr86 (initial value) are 0.7142 and 0,7213; Rb/Sr is 8.08; Eu anomaly is significant with Eu being 0.33; K/Rb is 157. All these data are in favor of the derivation of the magmatic materials from the sial. 5. The main rock type is made up of biotite granite and leucoganite. Petrochemical composition shows characters of ultra-acidic, alkali-rich evolution with differentiation index (DI) being 87.12-.93.29 and solidification index (SI) 2.39-5.34, the rocks are enriched in F and impoverished in Cl with F/Cl higher than 10; Mb-bearing coefficient of biotite (Km) is 0.34 and Fe-bearing coefficient (Kf) is 0.65; as regards accessory minerals, garnet and monazite are frequently seen, accompanied by xenotime, gadolinite, fergusonite, Nb-, Fe-bearing rutile and some other RE and REE minerals. All these characteristics are in comformity with those of the Nanling granites. 6. The intrusive mass possesses abundant trace elements such as W, Mo, Be, Sn, Nb and Ta; the ore deposit has complicated metallic constituents; molybdenite contains averagely 25ppm Re with Mo/Re ratio 18024; wolframite contains 0.2115% Nb2O5 and 0.018% Ta2O5; pyrite has in it 0.25 g/t gold. These data also bear resemblance with the data obtained from tungsten deposits in Nanling and neighboring areas. 7. Mineralization shows multi-type and multi-stage character. Orebodies are mostly veinlet-stockworks in shape with large vein possessing secondary importance and disseminations found locally. Ore-forming process took place at post-magmatic high- (medium) temperature hydrothermal stage in the form of fissure-filling (replacement). Wall-rock alterations are intensive, dominated by K-feldsparization and greisenization in linear type. No planar type alteration zoning is recognized. Considering that this is a transitional deposit between veinlet zone type and dissemination type tungsten deposits as far as time and mode of formation are concerned, and that it is relatively large in scale and has many features to share with a group of deposits including the Xiatongling tungsten deposit in Jiangxi, the author proposes to classify it as a new type and call it "Xingluokeng type granite veinlet-stockwork tungsten deposit". |
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