摘要
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。
Geological and geochemical characteristics of amphibolites of the Longshan Group in eastern GansuProvince show that there are two kinds of amphibolites with Sm-Nd isochron ages of 983 ±22Ma and 756 ±97Ma respetively, which were derived from magma sources similar to the MORB-type mantle. The information about trace elements and REE provides similar evidence. We also come to the conclusion that the original rocks of amphiboites were diabase dikes or veins, and they were proclucts of rift magmatism during800 ~ 1000Ma (Jinning Movement), and the rift is of considerable scale with an expanding rate of 2 ~ 5cm/a.
出处
《地质地球化学》
CSCD
北大核心
2000年第2期45-50,共6页
Geology-Geochemistry
关键词
甘肃
陇山群
斜长角闪岩
形成时代
构造背景
Longshan Group
amphibolite
Sm-Nd isochron age
geochemistry
tectonic setting
eastern Gansu Province
