Rb-Sr ISOTOPE CHRONOLOGY OF THE MESOZOIC VOLCANICS NORTHWESTERN ZHJIANG PROVINCE
Zhang Wanlin;Wang Jianfeng;Wang Youxiang;Liu Feng
The volcanic complex of Northwestern Zhejiang were previously classified as Jiande Group (upper Jurassic)which wes subdivided into Laocun, Huangjian, Shouchang and Henshan formation. We have got the age from the acid volcanic samples of these formations i. e. 132Ma, 107Ma and 93Ma respectively. The results reflect that Laocun and Huangjian formations should belong to lower Cretaceous, but Shouchang formation should be classified as upper Cretaceous. The initial ~(87)Sr/~(86)Sr value, in the range of 0. 70561--0.71434, showed the volcanic rocks are the anatexisic product of middle-lower sialic crust, and mixed with a little some of the mantle materials since there is individual lower value of ~(87)Sr/~(86)Sr.