In an article that appeared in Science (13 July 2012 issue) on Martian meteorites, abioitic organic carbon in association with small oxide grains within high temperature minerals has been described. The implications on the carbon cycle in the Mars is discussed in the paper.
MSR/16 Aug. 2012
Source: A. Stecle and others (2012) – A Reduced Organic Carbon Comportment in Martian Basalts. Science, v.337, 13 July 2012, pp.212-215.