浙江省丽水地区白垩纪红层盆地火山岩年龄及其构造意义

Geochronology of Volcanic Rocks in Cretaceous Red-bed Basin in Lishui,Zhejiang Province and Its Geological Significance

为查明丽水地区火山活动与盆地形成、演化之间的关系,在碧湖盆地、章村盆地、丽水盆地等红层盆地区域地质调查基础上,对盆地内中性-酸性火山岩夹层进行了精确测年和岩石化学分析,火山岩岩石地球化学表明,碧湖盆地、丽水盆地、章村盆地岩石化学成分基本一致。火山岩LA-ICP-MS锆石U-Pb测年表明:碧湖盆地朝川组火山岩年龄为(123±2)Ma,章村盆地馆头组火山岩年龄为(111±3)Ma,丽水盆地塘上组火山岩年龄为(95±1)Ma。该地区盆地间火山岩夹层存在28 Ma时差,反映了丽水—余姚断裂带的活动延续性。

The geochemistry characteristics of volcanic rocks in three basins indicate that the basins of Bihu, Lishui, Zhangcun have the same composition of the petrochemistry, and that the three basins mentioned above were formed in volcanic island arc. From LA-ICP-MS zircon found that the volcanic age of Chaochuan Formation in Bihu U-Pb data of volcanic rocks in three basins, we basin was （123 ±2） Ma, Guantou Formation in Zhangcun basin was （ 111 ± 3 ） Ma, Tangshang Formation in Lishui basin was （95 ± 1 ） Ma. The age data for those volcanic rocks in three basins show that the time of volcanic activity continued 28 Ma or so, and those data also reflect the activity continuation of Lishui-Yuyao fault.