The research outlined in this proposal will address some outstanding questions regarding the origin of solid organic matter (OM) in carbonaceous chondrite meteorites. Although studies of bulk OM…

The research outlined in this proposal will address some outstanding questions regarding the origin of solid organic matter (OM) in carbonaceous chondrite meteorites. Although studies of bulk OM residues extracted from meteorites have provided remarkable data about the characteristics of this material, IT is clear from recent coordinated in situ nanosims, TEM and stxm studies that there is a remarkable isotopic, textural and structural diversity in OM at the micro to nanoscale. We propose to carry out correlated mineralogic, spectroscopic and isotopic studies of organic materials in situ within the matrices of primitive carbonaceous chondritesusing a combination of nanosims-FIB/TEM-stxm techniques. The proposed research brings together individuals with considerable expertise in nanosims analysis, stxm spectroscopy and TEM analysis in a collaborative endeavor to gain new insights into different aspects of the formation and processing of OM. These studies will provide significant new insights into such questions as: a) how OM was distributed in nebular dust, b) the relationships between silicate dust and organic matter prior to accretion and c) how organic material was processed within asteroidal parent bodies. The specific research tasks that we propose will first address the issues of electron beam damage of OM caused by TEM studies that may affect subsequent isotopic and chemical analyses by nanosims and stxm. Second, we will examine the distribution, morphology, grain size and chemistry of isotopically anomalous (d, n, and c) and isotopically normal OM grains in pristine type 3 chondritic meteorites. Our goal will be to understand the diversity of organic materials present in these meteorites, constrain their possible origins and determine whether the different chondrite groups all accreted the same reservoir of organic grains. In addition, we wish to understand if there are morphological, compositional and structural differences between isotopically anomalous and normal OM grains. We will also examine the effects of aqueous alteration on the evolution of OM in CI, CM and CR chondrites to understand if reactions within an aqueous medium result in synthesis of new OM grains or redistribution or modification of existing OM grains. Further we will determine if heterogeneity during the earliest stages of aqueous alteration is the result of localized melting of ICE that was accreted as composite OM/water ICE grains. Finally, we will examine the question of whether d anomalous OM grains exchanged hydrogen isotopes with water to form phyllosilicate phases with elevated d/h ratios during aqueous alteration.