Biomarker evidence for green and purple sulphur bacteria in a stratified Palaeoproterozoic sea
- J. Brocks, G. Love, R. Summons, A. Knoll, G. Logan, S. Bowden
- Environmental Science, GeographyNature
- 6 October 2005
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.
A Stratified Redox Model for the Ediacaran Ocean
- Chao Li, G. Love, T. Lyons, D. Fike, A. Sessions, X. Chu
- Environmental Science, GeographyScience
- 2 April 2010
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.
Photic Zone Euxinia During the Permian-Triassic Superanoxic Event
- K. Grice, C. Cao, Yu-gan Jin
- Environmental Science, GeographyScience
- 4 February 2005
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.
Fossil steroids record the appearance of Demospongiae during the Cryogenian period
- G. Love, E. Grosjean, R. Summons
- Geography, Environmental ScienceNature
- 5 February 2009
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.
Widespread iron-rich conditions in the mid-Proterozoic ocean
- N. Planavsky, P. McGoldrick, T. Lyons
- Environmental ScienceNature
- 22 September 2011
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.
Snowball Earth climate dynamics and Cryogenian geology-geobiology
- P. Hoffman, D. Abbot, S. Warren
- Environmental Science, GeographyScience Advances
- 1 November 2017
Modeling shows that the small thermal inertia of a globally frozen surface reverses the annual mean tropical atmospheric circulation, producing an equatorial desert and net snow and frost accumulation elsewhere, and that the evolutionary legacy of Snowball Earth is perceptible in fossils and living organisms.
Reappraisal of hydrocarbon biomarkers in Archean rocks
- K. French, C. Hallmann, R. Summons
- GeologyProceedings of the National Academy of Sciences
- 27 April 2015
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.
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