桃山复式花岗岩体单颗粒锆石U-Pb年龄及地质意义

桃山岩体为产铀复式花岗岩体,主要由漳灌岩体、蔡江岩体、黄陂岩体、打鼓寨岩体和钓峰岩体组成。漳灌岩体单颗粒锆石LA-MC-ICPMS U-Pb一致线年龄为(409.2±1.8)Ma,成岩期为加里东晚期。蔡江岩体单颗粒锆石SHRIMPⅡU-Pb一致线年龄为(230.0±2)Ma,成岩期为印支中期。黄陂岩体、打鼓寨岩体、钓峰岩体单颗粒锆石SHRIMPⅡU-Pb一致线年龄分别为(164±3)Ma、(163±3)和(168±11)Ma、(164±2)Ma,成岩期相同,为燕山中早期。打鼓寨岩体两种岩性中粒斑状黑云母花岗岩与中粒斑状二云母花岗岩几乎同一期次形成,后者为前者后期白云母化蚀变产物。桃山复式岩体中新岩体内有老岩体残留。桃山岩体是一个多期次岩浆演化的复式岩体。

The simple grained zircon U-Pb dating and its geological significance of Taoshan compound granite massif

Taoshan granite massif is a uranium deposit bearing compound granite massif, Zhangguan granite, Caijiang granite, Huangpi granite, Daguzhai granite and Diaofeng composed of granite. The simple grained zircon LA-MC-ICPMS U-Pb Concordia age of Zhangguan granite is （409.2±1.8） Ma, which falls into late Caledonian. The simple graineded zircon SHRIMP 11 U-Pb Concordia age of Caijiang granite is （230.0±2） Ma, which belongs to Middle Indosinion. The simple grained zircon SHRIMP I1 U-Pb Concordia ages of Huangpi granite, Daguzhai granite and Diaofeng granite are（164±3）Ma, （163±3） and（168±11）Ma, （164±2） Ma, respectively which shows that they formed nearly at the same time in Early-Middle Yanshanian. The diagenetic time of medium-grained porphyritic biotite granite and medium-grained porphyritic two-mica granite is almost the same, indicating that the latter is the product of muscovitization alteration by the former. The new granite massif concludes the residule mineral of the old granite massif. Taoshan granite massif is a multiple- periodic magmatogenetic evolutionary compound granite massif.