【摘要】 东南极格罗夫山变质基性岩的地球化学研究表明,该区存在两类玄武岩,即洋岛型玄武岩(OIB)和洋中脊型玄武岩(MORB)。OIB型具有大体类似的地球化学性质,它们均富集Ti(TiO2-2.68％)、REE(=202μg/g)、LREE[(La/Yb)N=4.8]、Ti/Y(=343)、Zr/Y(=3.1),具洋岛玄武岩的特征,推测岩浆来源于富集地幔源区(EM)。而MORB型以低Ti(TiO2=1.1％～1.31％),明显低于OIB的P的含量(P2O5=0.1％～0.2％),低REE(47～93μg/g)、LREE/HREE(2.27～2.54)、(La/Yb)N(=1.30～1.62)为特征,具洋中脊玄武岩的特征。MORB和OIB组合的出现说明在泛非期该区可能存在过洋盆。更多还原

【Abstract】 Based on geochemical signatures of metabasic volcanic rocks, two types of basalt in the Grove Mountains arerecognized, namely, oceanic island basalt (OIB) and Mid-oceanic ridge basalt (MORE). Type 1 rocks have similar geochemical characteristics, with high Ti (TiO2 = 2. 68%), REE ( = 202μg/g), LREE [(La/Yb)N = 4. 8], Ti/Y ( = 343) and Zr/Ti ( = 3. 1), which are similar to those of OIB, and are considered to be products of magma from enriched mantle sources (EM). Type 2 rocks are characterized by low Ti (TiO2 = l. 1%~1. 31%), REE (47~93μg/g), LREE/HREE (2. 27 -2. 54 ), (La/Yb)N( = l. 30-1. 62) and lower P (P2O5 = 0. 1% -0. 2%) than those of OIB, which are similar to those of MORE. The presence of such rock assemblages suggests the existence of an ocean basin in this region during Pan-African ages.更多还原