The Application of Dual Beam FIB Techniques to the Preparation of TEM Sections from Heterogeneous Carbonaceous Chondrites

Content Provider	Semantic Scholar
Author	Chizmadia, Lysa J. Xu, Youren Schwappach, Chris D. Brearley, Adrian J.
Copyright Year	2005
Abstract	CM carbonaceous chondrites have experienced extensive aqueous alteration, prior to their arrival on Earth. The location of this alteration is controversial: models that involve alteration before (preaccretionary alteration) or after (parent-body alteration) the accretion of the final parent asteroid have been proposed. Detailed studies of altered chondrule glass and the corresponding fine-grained rims were conducted on two unbrecciated CM chondrites that experienced differing degrees of alteration, Y791198 and ALH81002. A comparison of these two meteorites demonstrates that elemental exchange had occurred between the chondrules and their rims [1]. In addition, the presence of secondary Fe-rich and Caand P-rich layers at the rim-chondrule interfaces also indicates closed system behavior between the chondrules and their rims [2]. Both of these observations point to the parent-body alteration model. However, micron-sized Fe,Ni metal grains have been observed by SEM [3] and were determined to be pristine (i.e. unaltered). The presence of pristine Fe,Ni metal grains juxtaposed against hydrated rim materials in Y-791198 has been cited as conclusive evidence that unaltered materials must have been mixed into the fine-grained dust that formed rims after aqueous alteration but before accretion of the final parent asteroid. Therefore, it is important to establish whether the Fe,Ni metal grains are pristine or show evidence of alteration at the micron to submicron scale.
Starting Page	1394
Ending Page	1395
Page Count	2
File Format	PDF HTM / HTML
DOI	10.1017/S1431927605504574
Alternate Webpage(s)	https://www.cambridge.org/core/services/aop-cambridge-core/content/view/A8BEFD9E09388DBCE1E7C6CD9B9D9801/S1431927605504574a.pdf/application_of_dual_beam_fib_techniques_to_the_preparation_of_tem_sections_from_heterogeneous_carbonaceous_chondrites.pdf
Alternate Webpage(s)	https://doi.org/10.1017/S1431927605504574
Volume Number	11
Language	English
Access Restriction	Open
Content Type	Text
Resource Type	Article