| Summary: | International audience The recent detection of in situ Martian organic carbon by the SAM instrument onboard the Curiosity rover has confirmed both a novel organic carbon cycle on another planet, as well as opened new opportunities for the correlation of planetary conditions and processes between Earth and Mars. Recently, thiophenes were identified by the Curiosity rover as preserved in 3 billion year old mudstones formed in a lacustrine environment at one of the lowest topographic and stratigraphic points in Gale crater. The presence of these thiophenes suggests that sulfurization aided organic matter preservation in this ancient Martian lacustrine environment. In fact, thiophenes have also been identified in kerogen, microfossils and stromatolites from the oldest sedimentary rocks on Earth as well as in the most pristine objects of the Solar System, e.g., carbonaceous chondrites. Their formation could provide clues to the organic productivity potential in aqueous environments and contributes to the formation of kerogens in sediments. We report here the detection of thiophenes in sedimentary rocks from the Yaxcopoil-1 drill hole in the Chicxulub impact structure in the southern Gulf of Mexico. Selected samples of this drillhole collected at ∼30 m intervals from 404 m to 1511 m were pyrolyzed to 1200∘C for 60 s and the gases and volatiles released were analyzed by gas chromatography-mass spectrometry (GC-MS). The concentration of thiophenes in the sedimentary record varied with ocean surface temperature, and is interpreted to reflect the organic productivity in the Paleo-Gulf of Mexico. These results are compared to the stratigraphic variation of thiophenes in the lacustrine sediments explored by Curiosity from the Yellowknife Bay formation, corresponding to the oldest sediments, to target Highfield at the Vera Rubin ridge, representing the youngest sediments encountered by Curiosity until Sol 2224. Fourteen mudstones and sandstones were analyzed by evolved gas analysis by the SAM quadrupole mass spectrometer ...
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