Light hydrocarbon gases, C 13, and origin of organic matter in carbonaceous chondrites

Abstract

Analyses for light hydrocarbon gases were carried out on eleven meteorites, including eight carbonaceous chondrites, as well as on terrestrial sediments; detection and identification were performed by gas chromatography. Compounds ranging from C 1 to C 6 were identified. The distribution of compounds was different in the different meteorites studied, both saturated and unsaturated hydrocarbons were detected, and benzene was generally a relatively minor component. It was concluded that the trace constituents identified were present as gases trapped between crystal boundaries, and were not artifacts produced in the course of the analytical work. δC 13 measurements on total meteoritic carbon indicate three possible groupings of the data: values falling below −20‰ characteristic of the ordinary chondrites; values between −7 and −20‰ representing carbonaceous chondrites; and values at about −6‰ representing graphitic carbon. The results imply that equilibrium among the carbon constituents has not been attained.