Recent explorations of the oldest known rocks of marine sedimentary origin from the southwestern coast of Greenland suggest that they preserve a biogeochemical record of early life. On the basis of the age of these rocks, the emergence of the biosphere appears to overlap with a period of intense global bombardment. This finding could also be consistent with evidence from molecular biology that ...

[1] Sedimentary molybdenum, [Mo]s, has been widely used as a proxy for benthic redox potential owing to its generally strong enrichment in organic-rich marine facies deposited under oxygen-depleted conditions. A detailed analysis of [Mo]s–total organic carbon (TOC) covariation in modern anoxic marine environments and its relationship to ambient water chemistry suggests that (1) [Mo]s, while use...