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Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea
Hydrocarbon biomarkers from a 1.64-Gyr-old basin in northern Australia reveal a marine basin with anoxic, sulphidic, sulphate-poor and permanently stratified deep waters, hostile to eukaryotic algae, and support mounting evidence for a long-lasting Proterozoic world in which oxygen levels remained well below modern levels. Expand
A Stratified Redox Model for the Ediacaran Ocean
A detailed spatial and temporal record of Ediacaran ocean chemistry for the Doushantuo Formation in the Nanhua Basin, South China is presented, finding evidence for a metastable zone of euxinic (anoxic and sulfidic) waters impinging on the continental shelf and sandwiched within ferruginous [Fe(II)-enriched] deep waters. Expand
Fossil steroids record the appearance of Demospongiae during the Cryogenian period
It is suggested that shallow shelf waters in some late Cryogenian ocean basins contained dissolved oxygen in concentrations sufficient to support basal metazoan life at least 100 Myr before the rapid diversification of bilaterians during the Cambrian explosion. Expand
Photic Zone Euxinia During the Permian-Triassic Superanoxic Event
The authors' evidence for widespread photiczone euxinic conditions suggests that sulfide toxicity was a driver of the extinction and a factor in the protracted recovery of the Permian-Triassic superanoxic event. Expand
Widespread iron-rich conditions in the mid-Proterozoic ocean
Results indicate that ferruginous (anoxic and Fe2+-rich) conditions were both spatially and temporally extensive across diverse palaeogeographic settings in the mid-Proterozoic ocean, inviting new models for the temporal distribution of iron formations and the availability of bioessential trace elements during a critical window for eukaryotic evolution. Expand
Biogeochemical evidence for euxinic oceans and ecological disturbance presaging the end-Permian mass extinction event
article i nfo The Permian-Triassic Boundary event at 252.2 Ma marks the largest extinction of marine fauna in the Phanerozoic and there is a wide consensus that the extinction coincided with anExpand
Large-scale fluctuations in Precambrian atmospheric and oceanic oxygen levels from the record of U in shales
The atmosphere–ocean system experienced a progressive change from anoxic to more oxidizing conditions through time. This oxidation is traditionally envisaged to have occurred as two stepwiseExpand
Reappraisal of hydrocarbon biomarkers in Archean rocks
It is reported that hopane and sterane concentrations measured in new ultraclean Archean drill cores from Australia are comparable to blank concentrations, yet their concentrations in the exteriors of conventionally collected cores of stratigraphic equivalence exceed blank concentrations by more than an order of magnitude due to surficial contamination; previous hydrocarbon biomarker reports no longer provide valid evidence for the advent of oxygenic photosynthesis and eukaryotes by ∼2.7 billion years ago. Expand
Evidence for a redox stratified Cryogenian marine basin, Datangpo Formation, South China
Abstract Here, in an effort to explore Cryogenian seawater chemistry, we present chemostratigraphic results for iron, carbon, molybdenum, and sulfur for two outcrop sections for the ca. 663–654 MaExpand
Origin of petroleum in the Neoproterozoic–Cambrian South Oman Salt Basin
Abstract The South Oman Salt Basin (SOSB) is host to the world’s oldest known commercial deposits. Most of the South Oman oils have been proven to be associated with the source rocks of theExpand