摘要
双溪坞群中酸性火山岩为浙皖赣晚元古代活动带的组成部分。其 REE 分布曲线较平滑,具 Eu 异常,有不太明显的轻重稀土分馏,(Ce/Yb)_N 平均为3.49。这些特征均与现代板块敛合边界,尤其是岛弧区的同类火山岩类似。所有样品均具有 Ce 亏损,Ce/Ce~*=0.84—0.91,平均0.88。对研究区晚元古代构造格局以及海水成分的认识表明,双溪坞火山岩的 Ce 亏损与现代板块敛合边界火山岩 Ce 亏损具有同样的岩石成因意义,指示岩浆起源于俯冲洋壳,与洋壳上覆的深海沉积物及海水蚀变玄武岩的部分熔融有关。
The volcanic rock series of the Shuangxiwu Group is part of the Late Proterozoic mobilebelt in the border area of Zhejiang,Anhui and Jiangxi provinces.REE characteristics of theShuangxiwu Group are comparable with those of the equivalent rocks occurring on the modernconvergent plate boundaries,especially those in island arc areas,e.g.smooth REE distributionpatterns,small negative Eu anomalies,and slight fractionation of LREE and HREE as in-dicated by an average(Ce/Yb)_N value of 3.49.All the analyzed samples possess negative Ceanomalies,with Ce/Ce~* ratios varyiung from 0.84 to 0.91(0.88 on average).From the tectonicframework of the studied area and the composition of Proterozoic sea water,it is concluded thatCe depletion in Shuangxiwu volcanic rocks has the same petrogenetic significance as in thevolcanic rocks occurring on the modern convergent plate boundaries.This indicates that themagma was originated from the subducted ocean crust and is also related to partial meltingof deep-sea sediments and sea water-altered basalts spread on the ocean crust.
出处
《地球化学》
CAS
CSCD
北大核心
1993年第3期269-274,共6页
Geochimica
基金
国家自然科学基金
