MINERALOGY OF ANTARCTIC BASALTIC SHERGOTTITE QUEEN-ALEXANDRA-RANGE-94201 - SIMILARITIES TO ELEPHANT MORAINE A79001 (LITHOLOGY-B) MARTIAN METEORITE

Antarctic meteorite QUE 94201 is a new basaltic shergottite that is ma inly composed of subequal amounts of maskelynite and pyroxenes (pigeon ite and augite) plus abundant merrillite and accessory phases. It also contains impact melt. Complex zoning patterns in QUE 94201 pyroxenes revealed by elemental map analyses using an electron microprobe sugges t a crystallization sequence from Mg-rich pigeonite (En(62)Fs(30)Wo(8) ) to extremely Fe-rich pigeonite (En(5)Fs(81)Wo(l4)) via {110} Mg-rich augite bands (En(44)Fs(20)Wo(36)) in a single crystal. These textures , along with the abundant plagioclase (maskelynite), indicates single- stage rapid cooling (>5 degrees C/year) of this rock from a supercoole d magma. Transition from Mg-rich augite to Fe-rich pigeonite reflects the onset of plagioclase crystallization. Enrichment of late-stage pha ses in QUE 94201 implies crystallization from an evolved magma and sug gests a different parent magma composition from the other basaltic she rgottites. Lithology B of EETA79001 basaltic shergottite contains pyro xenes that show complex zoning with augite bands similar to those in Q UE 94201 pyroxene, which suggests similar one-stage rapid cooling. Lit hology B of EETA79001 also resembles QUE 94201 in its coarse-grained t exture of silicates and its high abundance of maskelynite, although QU E 94201 probably crystallized from a more fractionated magma. We also note that some Apollo lunar mare basalts (e.g., 12020 and 12021) have similar mineralogy and petrology to QUE 94201, especially in pyroxene zoning. All these basaltic rocks with complex pyroxene zoning suggest rapid metastable crystallization from supercooled magmas.