论文部分内容阅读
陇山群中斜长角闪岩的地质－地球化学特征研究表明，斜长用问岩是分两期形成的，其Sm－Nd等时线年龄分别为983±22Ma和756±97Ma，源区为类似于现在洋中脊型的地幔，说明在中元古代形成的裂谷此时已趋成熟，具有相当的规模。微量元素和稀土元素的特征也支持该认识。作者认为斜长用闪岩的原岩是侵入陇山群的辉绿岩墙或基性岩脉，是800～1000Ma（晋宁期）裂谷作用的产物，裂谷活动的扩张速率为2～5cm／a。
Geophysical and geochemical characteristics of the plagioclase amphibolite in the Longshan Group show that the interbedded plagioclase amphibolite is formed in two phases with Sm-Nd isochron age of 983 ± 22Ma and 756 ± 97Ma, respectively. The source region It is similar to the present mid-ocean ridge mantle, indicating that the rift formed in Mesoproterozoic has now matured and has a considerable scale. The characteristics of trace elements and rare earth elements also support this understanding. The authors consider that plagioclase amphibolite is a diabase wall or basic dyke intrusive into the Longshan Group and is a product of rifting from 800 to 1000 Ma (Jinning Period). The expansion rate of rifting activity is 2 ~ 5cm / a.