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Organics preserved in anhydrous interplanetary dust particles: Pristine or not?
Author(s) -
Chan Queenie H. S.,
Franchi Ian A.,
Zhao Xuchao,
Stephant Alice,
Wright Ian P.,
Alexander Conel M. O'D.
Publication year - 2020
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/maps.13414
Subject(s) - interplanetary dust cloud , anhydrous , organic matter , raman spectroscopy , parent body , chemistry , chondrite , astrobiology , astrophysics , analytical chemistry (journal) , mineralogy , solar system , environmental chemistry , meteorite , physics , optics , organic chemistry
The chondritic‐porous subset of interplanetary dust particles ( CP ‐ IDP s) are thought to have a cometary origin. Since the CP ‐ IDP s are anhydrous and unaltered by aqueous processes that are common to chondritic organic matter ( OM ), they represent the most pristine material of the solar system. However, the study of IDP OM might be hindered by their further alteration by flash heating during atmospheric entry, and we have limited understanding on how short‐term heating influences their organic content. In order to investigate this problem, five CP ‐ IDP s were studied for their OM contents, distributions, and isotopic compositions at the submicro‐ to nanoscale levels. The OM contained in the IDP s in this study spans the spectrum from primitive OM to that which has been significantly processed by heat. Similarities in the Raman D bands of the meteoritic and IDP OM s indicate that the overall gain in the sizes of crystalline domains in response to heating is similar. However, the Raman Γ G values of the OM in all of the five IDP s clearly deviate from those of chondritic OM that had been processed during a prolonged episode of parent body heating. Such disparity suggests that the nonaromatic contents of the OM are different. Short duration heating further increases the H/C ratio and reduces the δ 13 C and δD values of the IDP OM . Our findings suggest that IDP OM contains a significant proportion of disordered C with low H content, such as sp 2 olefinic C=C, sp 3 C–C, and/or carbonyl contents as bridging material.