Geochemical characteristics of the metabasic volcanic rocks in the Grove Mountains, East Antarctica.

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.