The Indosinian Pulang superlarge porphyry copper deposit in Yunnan,China:Petrology and chronology.
The Indosinian Pulang superlarge porphyry copper deposit in Yunnan,China:Petrology and chronology.
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发表时间：
2006
影响因子：
1.8
通讯作者：
Zeng Pu;Lingbao Weng
中科院分区：
文献类型：
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作者：
Zeng Pu;Lingbao Weng
普朗斑岩铜矿床位于西南三江(金沙江、澜沧江、怒江)中部中国地区云南西北部的中甸岛弧带(ZIAB)中，属于扬子准地台义墩岛弧带南段。在义墩岛弧带内，北段产有库鲁型(嘎村式)块状硫化物矿床。南段为斑岩型铜矿床，以普朗超大型斑岩铜矿床为代表，是我国最重要的斑岩铜矿床之一。普朗斑岩铜矿床由南北两个复式岩体(地块)组成，代表相对独立的斑岩铜矿中心。两个地块均由受北西向构造控制的一系列石英闪长斑岩和石英二长斑岩组成。其中，南段是普朗地区已完成首采区勘探的主要矿体，已探明铜矿量160吨，平均含铜量0.57%Cu1.14Mt；金28.8t，金0.18g/t，钼6399t，钼0.004%。南区块铜矿资源量334~400mt，初步确定为超大型斑岩型铜矿床。在地球化学特征上，普朗斑岩的赋矿岩石为洋壳俯冲形成的I型埃达克岩，SiO_2>56%，MgO 1.34%~2.73%，锶661×10~(-6)~90×10~(-6)。Y10.78×10~(-6)~17.92×10~(-6)，Yb1.07×10~(-6)~1.87×10~(-6)，富LREE，δEu0.83~0.93，锶/Y比22~，K_2O/Na_2O比0.52。首次系统地确定了斑岩铜矿的成矿时代。K-Ar法测定的斑岩硅酸盐(黑云母、钾长石)蚀变热活动持续时间为235.4±2.4 Ma~221.5±2.0 Ma，辉钼矿Re-Os法测定的石英-辉钼矿成矿年龄为≈213±3.8 Ma，黑云母与主要含铜矿体分离的坪年龄为214.58±0.91 Ma~216.0±1 Ma，普朗地区含铜钼矿体为晚三叠世诺里期。这些资料与Re-Os测年结果相吻合，表明普朗斑岩铜矿形成于印支期。
The Pulang porphyry copper deposit is located in the Zhongdian island arc belt(ZIAB)in the NW Yunnan of the middle part of the Southwest Sanjiang(i.e.the Jinsha River,the Lancang River,and the Nujiang River)region in China,which belongs to the south segment of the Yidun island arc belt of the Yangtze paraplatform.Within the Yidun island arc belt,there are Kuro-type (Gacun style)massive sulfide deposits in the north segment,whereas in the south segment there are porphyry copper deposits among which the Pulang superlarge porphyry copper deposit is representative and become one of the most important porphyry copper deposits in China.The Pulang porphyry copper deposit is consists of the two composite rock bodies(blocks)in the north and the south,which represent relatively dependent porphyry copper centers.Both blocks are comprise of a series of quartz diorite porphyry and quartz monzonite porphyry stocks controlled by the NW-trend structures.Of which,the south one is the main orebodies in the Pulang district that the exploration of the initiate mining area has been finished and has proved copper ore 160 Mt with copper 0.57% average, Cu 1.14 Mt;associated gold 28.8t with Au 0.18g/t average,and molybdenum 6399t with Mo 0.004%.Within the south block,it is inferred that the copper resources(334)up to 400 Mt potential.The Pulang porphyry copper deposit has been initially determined is a superlarge porphyry copper deposit.Geochemially,the host rocks of the Pulang porphyry is characteristics of I-type adakite formed by subduction of the oceanic crust,for its SiO_2＞56%,MgO 1.34%～2.73%,Sr 661×10~(-6)～90×10~(-6),Y 10.78×10~(-6)～17.92×10~(-6),Yb 1.07×10~(-6)～1.87×10~(-6),LREE rich,δEu 0.83～0.93,Sr/Y ratios of 22～64,K_2O/Na _2O ratios of 0.52.By Re-Os dating for molybdenite and K-Ar,Ar-Ar dating for thermal minerals,such as biotite and orthoclase,and whole rock from Pulang Porphyry Copper,the timing of mineralization of porphyry copper has systematically been determined first time.The duration of thermal activity involving patassic silicates(biotite and K-feldspar)alteration is ranging from 235.4±2.4Ma to 221.5±2.0Ma determined by K-Ar dating,and the timing of the quartz-molybdenite stage is≈213±3.8 Ma by molybdenite Re-Os dating,the plateau ages 214.58±0.91Ma to 216.0±1Ma of Ar-Ar dating of the biotite separates from the main Cu-bearing orebody and Cu-Mo-bearing orebody of the Pulang district are Late Triassic Norian,consistent with the Re-Os dating.These data suggest that the ore-forming of Pulang porphyry copper is developed in Indosinian.