In-situ Heating Decrease Kinetics of Aliphatic Hydrocarbons in Tagish Lake Meteorite by Micro-ftir

Introduction: Carbonaceous chondrites are known to contain up to 3wt.% C, the major part of which corresponds to a macromolecular organic fraction [1]. Chondritic organic matter is based on small aromatic units, cross-linked by short aliphatic chains rather than large clusters of polyaromatic structures [2]. Two main characteristic features of those organics measured by FTIR are (1) an equivalent intensity of the asymmetric stretching mode absorptions for CH3 (2960cm) and CH2 (2920cm) and (2) a lack of aromatic CHstretching mode (3040cm-1) [3]. Tagish Lake is a new type of waterand carbon-rich type 2 carbonaceous chondrite [4, 5]. Its total carbon content is ~5 wt%, of which the organic carbon content reaches ~1.3 wt% [4]. Tagish Lake may have never experienced temperatures higher than 120°C after formation of organics based on the disappearance of infrared (IR) organic peaks in step heating experiments [6]. Here we report in-situ kinetic heating experiments of organics in Tagish Lake by micro-FTIR to characterize the nature of aliphatic hydrocarbons and their thermal stabilities.