滇西北中甸松诺含矿斑岩的锆石SHRIMP U-Pb年龄及地质意义  

SHRIMP ZIRCON U-PB DATING OF THE SONGNUO ORE-HOSTED PORPHYRY,ZHONGDIAN,NORTHWEST YUNNAN,CHINA AND ITS GEOLOGICAL IMPLICATION

作　　者：冷成彪[1] 张兴春[1] 王守旭[1] 秦朝建[1] 苟体忠[1] 王外全 

机构地区：[1]中国科学院地球化学研究所矿床地球化学国家重点实验室 [2]云南省地质调查院矿产调查所,云南大理671000

出　　处：《大地构造与成矿学》2008年第1期124-130,共7页Geotectonica et Metallogenia

基　　金：国家自然科学基金项目(40372049);国家“973”项目课题(2002CB412605)资助

摘　　要：位于义敦岛弧南端的中甸岛弧中广泛发育印支期斑岩及斑岩型和矽卡岩型铜矿床。松诺（或称松诺力赞）复式岩体位于东斑岩带中部，由石英闪长玢岩、黑云石英二长斑岩、闪长玢岩和含矿石英二长斑岩组成，其南部为普朗超大型斑岩铜矿床，北部为地苏嘎铜矿点。本文对含矿石英二长斑岩进行了岩相学和锆石SHRIMPU-Pb定年研究，结果表明所有锆石颗粒自形较好且均发育规则的韵律环带，Th含量为180-854μg／g，U含量为270-709μg／g，Th／U比值为0．77-1．24，为典型岩浆成因锆石。获得了含矿石英二长斑岩的侵位年龄为220．9±3．5Ma（n=9，MSWD=1．6），这与中甸岛弧洋壳俯冲造山作用的时限（210-235Ma）相吻合。There are lots of skarn and porphyry copper deposits associated with the Indosinian porphyry bodies in the Zhongdian arc, which is situated in the southern Yidun island arc. The Songnuo （or Songnuolizan） complex, which consists of quartz diorite porphyry, biotite quartz monzonite porphyry, diorite porphyry and ore-bearing quartz monzonite porphyry, is located in the central segment of the eastern Zhongdian porphyry belt. On the basis of the preliminary petrological study, the ore-hosting quartz monzonite porphyry of the Songnuo complex is dated by the zircon SHRIMP U-Pb method. The zircon grains are of typical magmatic origin, characterized by Th of 180-854μg/g , U of 270-709μg/g and Th/U ratios of 0.77-1.24. The zircon SHRIMP U-Pb dating at 220.9±3.5 Ma represents the emplacement age of the ore-hosting quartz monzonite porphyry. It coincides with the age of 210 - 235 Ma, an indicative of the subduction of oceanic crust in the Zhongdian arc.

关 键 词：锆石SHRIMP U-PB年龄 含矿石英二长斑岩 松诺 中旬县 云南省 

分 类 号：P597[天文地球—地球化学] P611[天文地球—地质学]