太行山北段赤瓦屋铜钨矿化区花岗质岩石的锆石U-Pb年龄及其地质意义

太行山北段位于华北克拉通中部,以发育中生代中酸性岩浆岩及多个大中型斑岩-矽卡岩铜钼矿床和金矿床为主要特征,最近在南部赤瓦屋岩体内部发现新类型铜钨矿体。文章选择赤瓦屋岩体为对象,开展不同岩相详细的野外地质和锆石U-Pb测年工作,确定赤瓦屋岩体不同岩性的成岩时代,探讨其地质意义。研究表明,赤瓦屋岩体有边缘相石英闪长岩、边缘相花岗闪长岩和中心相斑状花岗闪长岩及晚期中酸性岩脉,其中铜钨矿化主要发育于中心相斑状花岗闪长岩。石英闪长岩、花岗闪长岩、斑状花岗闪长岩和花岗闪长斑岩脉的锆石U-Pb谐和年龄分别为(134±1)Ma、(133±1)Ma、(131±2)Ma和(128±1)Ma,表明赤瓦屋岩体不同岩相体形成于早白垩世(134~131Ma)。结合区域年代学资料,提出太行山北段晚中生代至少存在两期岩浆-成矿事件。

Zircon U-Pb age of granitoid from the Chiwawu Cu-Woccurence Northern Taihang Mountain and its implications

The Northern Taihang Mountain is located in the central part of North China Carton, characterized by Mesozoic intermediate-acid magmatic rocks and plenty of important porphyry-skarn Cu-Mo deposits and hydrothernal gold deposits. A new Cu-W orebody within the Chiwawu granitoid was recently discovered in the southernmost part. The authors conducted field survey and zircon U-Pb dating of different granitic petrofacies from the Chiwawu Cu-W ore district, and then used the data obtained to constrain the timing and origin of granitc rocks. The Chiwawu pluton shows obviously textural and compositional variation from the inner part to the outer part, ranging from porphyritic granodiorite at the inner part, granodiorite at the transition part to quartz diorite at the periphery and several porphyry dykes. These new zircon LA-ICPMS U-Pb analyses of quartz diorite, granodiorite, porphyritic granodiorite and granodiorite porphyry dyke yielded excellent concordant ages of 134±1 Ma, 133±1 Ma,131±2 Ma and 128±1 Ma, respectively, indicating that the Chiwawu pluton was formed during the Early Cretaceous period (134-131 Ma). Combined with available chronologic data, the authors recognized two regional magmatic-metallogenic events during the Mesozoic time in Northern Taihang Mountain.