Classification and petrological and geochemical characteristics of Antarctic meteorites found by 1st, 2nd and 3rd KOREAMET

Abstract

Using petrological characteristics and oxygen isotopic compositions, we classified 29 Antarctic meteorites found in blue ice fields near Thiel Mountains, West Antarctica by three Korea Expedition for Antarctic Meteorites (KOREAMET) programs. Among them 20 meteorites are ordinary chondrites, 11 H-group and 9 L-group without LL and all of them are equilibrated having petrological type ？‰？4. Two CV3 and two CM2 chondrites were found: both CV and CM chondrites are possibly pairs since two meteorites in each group were not only found at very close locations but also have very similar petrological characteristics. Two CV3 chondrites, TIL 07003 and TIL 07007, have elongated chondrules, CAIs, and AOIs. The CM2 chondrites, TIL 07008 and TIL 08007, experienced heavy aqueous alteration that changed most of primary phases into low temperature secondary minerals. One enstatite chondrite, TIL 07009 is heavily altered by terrestrial weathering. No clear chondrule texture survived by thermal metamorphism;it contains ferroan alabandite, thus classified as EL6. TIL 07012 has petrological and oxygen isotopic characteristics of acapulcoite-lodranite clan. The meteorite is heterogenous in mineralogy but contains abundant plagioclase, thus assigned as acapulcoite. TIL 07014 is monomict breccia of basaltic and gabbroic eucrites. Two pallasites, TIL 07016 and TIL 08004 are similar with Thiel Mountains pallasite in texture and siderophile element compositions, thus likely they are pairs.