【摘要】 罗卜岭斑岩铜钼矿床是紫金山Cu-Au-Mo浅成低温-斑岩矿田内新近发现的大型斑岩铜钼矿床,本文在岩芯及光薄片系统观察的基础上,分析了矿化斑岩锆石LA-ICP-MSU-Pb年龄及锆石Ce4+/Ce3+比值。罗卜岭赋矿斑岩体可分为两期,早期为角闪黑云母花岗闪长斑岩及黑云母花岗闪长斑岩,晚期为黑云母花岗闪长斑岩。早期角闪黑云母花岗闪长斑岩和黑云母花岗闪长斑岩锆石LA-ICP-MSU-Pb年龄分别为103.7±1.2Ma,MSWD=0.33和103.0±0.9Ma,MSWD=1.00;晚期黑云母花岗闪长斑岩锆石LA-ICP-MSU-Pb年龄为97.6±2.1Ma,MSWD=6.00。罗卜岭成矿斑岩基质普遍发育硬石膏,两期成矿斑岩锆石都具较高的Ce4+/Ce3+平均值,在630～770之间,高于区内非成矿花岗岩锆石的Ce4+/Ce3+平均值(182～577),显示罗卜岭斑岩矿床成矿岩浆具有高氧逸度的特征。据罗卜岭斑岩矿床的形成时代、高氧逸度岩浆特征,结合华南地区中生代构造背景,我们初步认为罗卜岭斑岩矿床的形成可能和中生代古太平洋向北西西方向俯冲有关。更多还原

【Abstract】 The Luoboling large porphyry Cu-Mo deposit is a recently discovered deposit in the Zijinshan Cu-Au-Mo ore field. Based on the relationship of the porphyries and the systematically petrographic study, the ore-bearing porphyries can be divided into early stage hornblende biotite granodiorite porphyry and biotite granodiorite porphyry and late stage biotite granodiorite porphyry. The early stage hornblende biotite granodiorite porphyry and biotite granodiorite porphyry has zircon LA-ICP-MS U-Pb age of 103.7±1.2Ma, with MSWD=0.33 and of 103.0±0.9Ma with MSWD=1.00, respectively, and the late stage biotite granodiorite porphyry has zircon LA-ICP-MS U-Pb age of 97.6±2.1Ma with MSWD=6.00. Zircon grains from two stage ore bearing porphyries have much higher average Ce4+/Ce3+ ratios (630~770) than those (182~577) of barren granites in the ore field. Based on the zircon high Ce4+/Ce3+ ratios and the wide occurrence of anhydrite in the ore-bearing porphyries, it is concluded that the ore-bearing magma was characterized by a relatively high oxygen fugacity. According to emplaced age and high oxygen fugacity of ore forming magma, and tectonic setting of the South China in the Mesozoic, the Luoboling ore-bearing porphyries are regarded to be triggered by the westward subduction of paleo-Pacific plate during Mesozoic.更多还原