The sediments that now comprise the Messel shale1 accumulated 47±2 million years ago in
anaerobic waters at the bottom of a lake2. Subsequent depths of burial have not exceeded …

PORPHYRINS, which are present in most sediments and crude oils, represent the'molecular
fossils' of compounds such as chlorophylls, bacteriochlorophylls and haems in the …

THE organic matter found in sedimentary rocks must derive from many sources; not only
from ancient primary producers but also from consumers and secondary producers. In all of …

The widespread occurrence of extended hopanoids in sediments and petroleums illustrates
the importance of bacterial lipid contributions to geological materials1. In archaebacteria …

THE Black Sea is the world's largest anoxic basin; it is also a contemporary analogue of the
environment in which carbonaceous shales and petroleum source beds formed1. Recently …

THE Black Sea, the world's largest anoxic marine basin, is frequently used as a modern
analogue for the formation of organic-rich sediments and carbonaceous rocks1–3, on the …

Abstract Metasedimentary rocks from Isua, West Greenland (over 3,700 million years old)
contain 13C-depleted carbonaceous compounds, with isotopic ratios that are compatible …

BECAUSE their molecular signatures are often prominent in extracts of sediments, bacteria
are thought to be important contributors to petroleum source beds1. It has been shown …

Modern and ancient sediments contain a multiplicity of organic compounds which record a
partial history of the organisms that contributed them1. Interpretation of this record depends …

Natural hydrocarbons are largely formed by the thermal decomposition of organic matter
(thermogenesis) or by microbial processes (bacteriogenesis). But the discovery of methane …