浙江磨石山群祝村组岩石SHRIMP锆石U-Pb定年

SHRIMP ZIRCON U-Pb AGES OF THE ZHUCUN FORMATION OF THE MOSHISHAN GROUP IN ZHEJIANG

通过对丽水东郊祝村地区地质调查,在圈定火山机构、岩性岩相划分的基础上,对祝村组的层型剖面进行了岩石同位素定年,对剖面0、8、36层的岩石采用SHRIMP锆石U-Pb测年,取得加权平均年龄值为125.1±2.4Ma、128.6±1.7 Ma、129±2.5 Ma,属早白垩世。与周边火山机构成岩年龄一致,不应单独划为磨石山群的第三旋回,根据岩性岩相、地层层序、同位素年龄,可分解为西山头组、茶湾组和九里坪组。

This paper presents SHRIMP zircon U-Pb ages from the stratotype of the Zhucun Formation in Lishui of Zhejiang Province. SHRIMP zircon U-Pb dating of beds 0, 8, and 36 of the Zhucun Formation gives weighted average ages of 125.1±2.4 Ma, 128.6±1.7 Ma, 129±2.5 Ma, suggesting an Early Creta- ceous age and consistent with the diagenetic age of surrounding volcanic rocks. The Zhucun Formation should not be regarded as the third cycle of the Moshishan Group. On the basis of lithologic facies, strati- graphic sequences, and isotope ages, the Zhucun Formation can be divided into the Xishantou, Chawan, and Jiuliping formations.