Petrology and chemistry of the picritic shergottite North West Africa 1068 (NWA 1068)

We report on the petrology and chemistry of North West Africa 1068 (NWA 1068), a shergottite recently recovered in Morocco. This meteorite has a total known mass of about 577 g and comprises 23 fragments. The largest fragment is a greenish-brown rock devoid of fusion crust. It displays a porphyritic texture consisting of a fine-grained groundmass and olivine grains. Excluding the impact melt pockets and the minor carbonate veins produced by terrestrial weathering, modal analyses indicate the following mineral proportions: 52 vol% pyroxenes, 22% maskelynite, 21% olivine, 2% phosphates (merrillite and chlorapatite), 2% opaque oxides (mainly ilmenite and chromite) and sulfides, and 1% K-rich mesostasis. Olivines with various habits occur as clusters often associated with chromite, or single crystals ranging in size from 50 mum to 2 millimeters ("megacrysts"). These crystals originate probably from disrupted cumulates with strong affinities with peridotitic shergottites.


Published in:
Geochimica Et Cosmochimica Acta, 66, 3505-3518
Year:
2002
Keywords:
Laboratories:




 Record created 2011-09-29, last modified 2018-12-03


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