摘要
浙西北火山杂岩系原划为侏罗系上统建德群,分为劳村组、黄尖组、寿昌组和横山组。作者在浙西北火山岩带劳村组、黄尖组、寿昌组酸性火山岩中获得了132Ma,107Ma和93Ma的全岩等时线年龄值。这表明,劳村组、黄尖组应划归早白垩世,寿昌组应划归晚白垩世。而这些岩组的火山岩锶同位素初始比值(^(87)Sr/(86)Sr)_0为0.70561—0.71434,火山岩应属硅铝壳中下部物质深熔的产物,个别样品(^(87)Sr/^(86)Sr)_0值表明,抑或有上地幔物质的干扰。
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.
关键词
中生代
火山岩
铷
锶
地质年龄
Northwestern Zhejiang
volcanics
Rb-Sr isotope age
Cretaceous
anatexis
