Petrography and classification of Elephant Moraine 14017 (EET 14017): a new primitive LL3.05 ordinary chondrite from Antarctica

Abstract

The mineralogy and petrography of EET 14017 were studied using optical microscope, scanning electron microscope, electron microprobe, and micro-Raman. The mineral chemistry of olivine, pyroxene, plagioclase, spinel, and Fe-Ni metal in EET 14017 is comparable to that of previously studied L/LL3.0x chondrites. In particular, the Cr2O3 2 O 3 content in the ferroan chondrule olivine and the excess silica component, [ ]Si4O8, 4 O 8 , in the plagioclase lead us to conclude that EET 14017 belongs to subtype 3.05. Raman spectral data of carbonaceous matter from the matrix of EET 14017 suggest a higher degree of thermal metamorphism, probably due to terrestrial weathering in Antarctica. EET 14017 and some of the other L/LL3.0x chondrites from the EET region are possibly a pair, since they have similar Cr2O3 2 O 3 contents of ferroan chondrule olivines and Raman spectral data, and moreover they were also found in a restricted region of the blue ice field. The plagioclase in some chondrules is a late crystal phase in the chondrule melt, which may constrain the timing of chondrule formation and cooling rate. If more L/LL3.0x chondrites like EET 14017 from Antarctica are identified, they would be excellent source material for studying the early evolution of the Solar System.