Stromatolite and ooid deposits within the fluvial and lacustrine sediments of the Precambrian Ventersdorp Supergroup of South Africa

Buck, S. G.

doi:10.1016/0301-9268(80)90033-9

Cited by 74 publications

(27 citation statements)

References 19 publications

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“…3). A possible interpretation is that precursor OM of these kerogens thrived in warm waters undergoing intense evaporation, which is consistent with the continental depositional environments proposed for these formations (Buck, 1980;Hunter et al, 1998). …”

Section: Geochemical Perspectives Letterssupporting

confidence: 73%

Warm Archaean oceans reconstructed from oxygen isotope composition of early-life remnants

Tartèse¹,

Chaussidon²,

Gurenko³

et al. 2016

Geochem. Persp. Let.

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doi: 10.7185/geochemlet.1706 Deciphering the surface conditions on the Earth during Archean times (> 2.5 billion years ago -Ga) is crucial to constrain the conditions that promoted the development of life. The progressive shift through time of the oxygen isotopic compositions of Precambrian siliceous sediments -the so-called cherts -has been interpreted as indicating a secular decrease of seawater temperature by 50-80 °C from the early Archean to the present-day. However, this interpretation has been questioned, notably because it assumes that the seawater oxygen isotopic composition has remained globally constant since 3.5 Ga, though this has never been tested by direct isotopic measurements on Archean samples. Here we report measurements of the oxygen isotopic composition of carbonaceous matter indigenous to Precambrian cherts up to ca. 3.5 Ga. These new results demonstrate that the oxygen isotope composition of seawater during most of the Precambrian remained around 0 ± 5 ‰, which is consistent with the composition of present day seawater. Combined with the chert oxygen isotope composition record, this indicates that ca. 3.5 Ga ago ocean bottom-water temperatures were ~50-60 °C higher than today.

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Section: Geochemical Perspectives Letterssupporting

confidence: 73%

Warm Archaean oceans reconstructed from oxygen isotope composition of early-life remnants

Tartèse¹,

Chaussidon²,

Gurenko³

et al. 2016

Geochem. Persp. Let.

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“…Archean terrestrial aquatic environments as old as 2.7 b.y. commonly contained benthic mats (e.g., Buck, 1980;Buick, 1992;Rye and Holland, 2000). Once these mats contained cyanobacteria, they likely developed O 2 oases even at very low net photosynthetic rates, such as the 0.05 µmol O 2 m -2 s -1 observed at 9.8 m in Lake Fryxell.…”

Section: Implications For Archean Oxygen Oasesmentioning

confidence: 99%

Antarctic microbial mats: A modern analog for Archean lacustrine oxygen oases

Sumner

Hawes

Mackey

et al. 2015

Geology

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The evolution of oxygenic photosynthesis was the most important geochemical event in Earth history, causing the Great Oxidation Event (GOE) ~2.4 b.y. ago. However, evidence is mixed as to whether O 2 production occurred locally as much as 2.8 b.y. ago, creating O 2 oases, or initiated just prior to the GOE. The biogeochemical dynamics of possible O 2 oases have been poorly constrained due to the absence of modern analogs. However, cyanobacteria in microbial mats in a perennially anoxic region of Lake Fryxell, Antarctica, create a 1-2 mm O 2 -containing layer in the upper mat during summer, providing the first known modern analog for formation of benthic O 2 oases. In Lake Fryxell, benthic cyanobacteria are present below the oxycline in the lake. Mat photosynthesis rates were slow due to low photon flux rate (1-2 µmol m -2 s -1) under thick ice cover, but photosynthetic O 2 production was sufficient to sustain up to 50 µmol O 2 L -1

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“…3.5 Ga (Hofmann 1973;Allwood et al 2009). Unlike the Archean, where stromatolites have been observed as being limited to shallow-marine evaporitic basins (Lowe 1983;Allwood et al 2006;Schopf 2006), by the Proterozoic, they were present in siliciclastic nearshore, intertidal (Schieber 1999), and carbonate platforms (Beukes 1987), as well as in epicontinental alkaline lakes and rivers, where the mats were commonly dolomitized and silicified (Buck 1980). Morphologically, these ranged from domes and simple columns to elaborately branched and bulbous structures.…”

Section: Introductionmentioning

confidence: 99%

Textural and Geochemical Features of Freshwater Microbialites From Laguna Bacalar, Quintana Roo, Mexico

Castro-Contreras¹,

Gingras²,

Peçoits³

et al. 2014

PALAIOS

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Microbialites provide some of the oldest direct evidence of life on Earth. They reached their peak during the Proterozoic and declined afterward. Their decline has been attributed to grazing and/or burrowing by metazoans, to changes in ocean chemistry, or to competition with other calcifying organisms.The freshwater microbialites at Laguna Bacalar (Mexico) provide an opportunity to better understand microbialite growth in terms of interaction between grazing organisms versus calcium carbonate precipitation. The Laguna Bacalar microbialites are described in terms of their distinct mesostructures. Stromatolites display internal lamination, attributed to the precipitation of calcite and the upward migration of cyanobacteria during periods of low sedimentation. Thrombolitic stromatolites show internal lamination in addition to internal clotting. The clotting is seen as a result of binding and/or trapping of micritic peloids by cyanobacteria and attributed to periods of high sedimentation. The carbonates in both microbialites had similar C-and Ostable-isotopic signatures, both enriched in 13 C relative to bivalves, suggesting photosynthetic CO 2 uptake was the trigger for carbonate precipitation. This implies that the rate of microbialite growth is largely a function of ambient carbonate saturation state, while the texture is especially dependent on accretion rates and sediment deposition on their surface. Importantly, the coexistence with grazing animals suggests no significant inhibition on microbialite growth, thereby calling into question the decline of microbialite as a result of metazoan evolution. Varying sedimentation rates are likely important in controlling the distribution of thrombolite-stromatolite packages in the geological record, given the importance of this factor at Bacalar.

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Stromatolite and ooid deposits within the fluvial and lacustrine sediments of the Precambrian Ventersdorp Supergroup of South Africa

Cited by 74 publications

References 19 publications

Warm Archaean oceans reconstructed from oxygen isotope composition of early-life remnants

Warm Archaean oceans reconstructed from oxygen isotope composition of early-life remnants

Antarctic microbial mats: A modern analog for Archean lacustrine oxygen oases

Textural and Geochemical Features of Freshwater Microbialites From Laguna Bacalar, Quintana Roo, Mexico

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