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对安徽月山岩体开展了锆石原位U-Pb测年及Lu-Hf同位素研究。锆石的LA-ICP-MS年代学研究表明,月山闪长岩的U-Pb年龄为(139.3±1.5)Ma,与长江中下游成矿带早白垩世成铜岩体的年龄一致。月山闪长岩中的锆石具有均一的Hf同位素初始比值,介于0.282 430~0.282 491间。这些锆石的ε(Hf)(t)介于-9.05~-6.90间,亏损地幔模式年龄介于1.06~1.17 Ga间。结合长江中下游地区岩浆岩其他地球化学特征,认为月山岩体可能是在俯冲体系下由幔源岩浆经结晶分异作用且局部伴有一定程度的同化混染作用所形成。
In situ zircon U-Pb zircon dating and Lu-Hf isotope studies have been carried out on the Yueshan pluton in Anhui Province. The LA-ICP-MS dating of zircons shows that the U-Pb age of the Yueshan diorite is (139.3 ± 1.5) Ma, consistent with the age of the Early Cretaceous copper-bearing rock mass in the middle and lower reaches of the Yangtze River. The zircons in the Yue Shan diorite have a uniform initial Hf isotopic ratio ranging from 0.282 430 to 0.282 491. The ε (Hf) (t) of these zircons ranged from -9.05 to -6.90, and the depleted mantle models ranged from 1.06 to 1.17 Ga. According to other geochemical characteristics of the magmatic rocks in the middle and lower reaches of the Yangtze River, it is considered that the Yueshan pluton may be formed by the crystallization differentiation of the mantle magma under the subduction system with a certain degree of assimilation and contamination.