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Noble gases in enstatite chondrites II: The trapped component
Author(s) -
Patzer Andrea,
Schultz Ludolf
Publication year - 2002
Publication title -
meteoritics and planetary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.09
H-Index - 100
eISSN - 1945-5100
pISSN - 1086-9379
DOI - 10.1111/j.1945-5100.2002.tb00841.x
Subject(s) - chondrite , enstatite , chondrule , meteorite , noble gas , breccia , regolith , parent body , geology , achondrite , astrobiology , geochemistry , mineralogy , chemistry , physics , organic chemistry
— The trapped noble gas record of 57 enstatite chondrites (E chondrites) has been investigated. Basically, two different gas patterns have been identified dependent on the petrologic type. All E chondrites of type 4 to 6 show a mixture of trapped common chondritic rare gases (Q) and a subsolar component (range of elemental ratios for E4–6 chondrites: 36 Ar/ 132 Xe = 582 ± 270 and 36 Ar/ 84 Kr = 242 ± 88). E3 chondrites usually contain Q gases, but also a composition with lower 36 Ar/ 132 Xe and 36 Ar/ 84 Kr ratios, which we call sub‐Q ( 36 Ar/ 132 Xe = 37.0 ± 18.0 and 36 Ar/ 84 Kr = 41.7 ± 18.1). The presence of either the subsolar or the sub‐Q signature in particular petrologic types cannot be readily explained by parent body metamorphism as postulated for ordinary chondrites. We therefore present a different model that can explain the bimodal distribution and composition of trapped heavy noble gases in E chondrites. Trapped solar noble gases have been observed only in some E3 chondrites. About 30% of each group, EH3 and EL3 chondrites, amounting to 9% of all analyzed E chondrites show the solar signature. Notably, only one of those meteorites has been explicitly described as a regolith breccia.