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.