ORGANICS IN DEEPLY BURIED FOSSIL SOILS CORED DURING THE OCEAN DRILLING PROGRAM (LEG 197): THEIR MODEL FORMATION AND USE AS TEST BEDS FOR MARS SOIL ANALOGUES

摘要

Although no near-surface life has been detected on the surface of Mars, some preservation with depth of past/present organics and life is possible. Organic-poor (C-org = 0.05-0.12%) red paleosoils were drilled during the Ocean Drilling Program (ODP) Leg 197. Fe-oxides/oxyhydroxide-rich horizons of deeply buried red paleosoils (early Tertiary) have a basalt rock derivation and retain a stable isotope signature for mixed organic sources. I suggest a model (i.e., surface formation, deep burial and isolation from the atmosphere and the ocean) based upon literature and new geochemical data which suggests considering these sub-basement fossil soils (46.8 to 309.9 meters below seafloor; mbsf) as test beds samples for Mars soil analogues. Preservation of organic traces in a deep earth system (no sun light, and reducing conditions), which remained isolated and decoupled from the ocean and the atmosphere for millions of years it is relevant to the future search and identification of organic sources in materials recovered from the deep Earth and as model for a possible deep biosphere on Mars.