Abstract:
Melt fragments in melt breccias from the Gardnos impact crater, Norway, contain abundant carbon. A high proportion of the carbon present in the original melt was preserved. The stripping of hydrogen from carbon during melting prevents later hydrocarbon formation, hence the carbon is fixed in place rather than volatilized. Underlying lithic breccias that were not melted record hydrocarbon generation as a response to less extreme heating. Despite the high-temperature history of the melt, the carbon from the Gardnos impact crater is highly disordered, rather than ordered crystalline graphite, and in this respect, it is comparable with carbon in chondrite chondrules. Disordered carbon bears functional groups upon weathering, and, therefore, carbon preserved through impact or other melting may be available for reworking into biologically relevant organic molecules. © 2006 Geological Society of America.
