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庐枞(庐江~枞阳)盆地是长江中下游地区最重要的火山岩盆地之一。针对该盆地隐伏侵入岩(正长花岗岩),进行的LA-ICP-MS锆石U-Pb定年和Hf同位素研究,获得2组正长花岗岩(ZK2001-900和ZK2001-1100)的锆石U-Pb年龄分别为130.3 Ma±1.8 Ma和131.0 Ma±2.6 Ma,相对应的锆石εHf(t)值介于-7.5~-3.5和-8.3~-1.6。因此,本次研究确定该隐伏侵入的正长花岗岩形成时代为130 Ma,与庐枞盆地内其他火山-侵入岩浆活动的时间(135 Ma~127 Ma)大致相当,都为早白垩世。同时,也暗示它们可能形成于相同的地球动力学条件下,即区域岩石圈伸展背景下岩浆活动的产物。
Luzong (Lujiang ~ Zongyang) basin is one of the most important volcanic basins in the middle and lower reaches of the Yangtze River. According to LA-ICP-MS zircon U-Pb dating and Hf isotopic study of buried volcanic rocks in this basin, zircon U-Pb of two orthorhombic granites (ZK2001-900 and ZK2001-1100) Pb ages are 130.3 Ma ± 1.8 Ma and 131.0 Ma ± 2.6 Ma, respectively, and the εHf (t) values of zircons range from -7.5 to -3.5 and -8.3 to -1.6. Therefore, the present study determined that the age of the intrusive granodiorite was 130 Ma, roughly equivalent to the time of other volcanic-intrusive magmatic activities in the Luzong Basin (135 Ma ~ 127 Ma), all of which were Early Cretaceous. At the same time, it also implies that they may form under the same conditions of geodynamics, that is, the product of magmatic activity in the context of regional lithosphere extension.