Carbonate Sedimentation in an Arid Zone Tidal Flat, Nilemah Embayment, Shark Bay, Western Australia

Woods, Peter J.; Brown, Raymond G.

doi:10.1007/978-3-642-88494-8_26

Cited by 11 publications

(4 citation statements)

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“…Though light and dark ooids are found in the same small size fractions and there does not appear to be any spatial separation between the two types of ooids, the differences in their mineralogies indicate different formation mechanisms and transport histories. It is likely that dark ooids spent some time within microbial mats (Davies, 1970; Jahnert & Collins, 2011; Woods & Brown, 1975), where dark grains are common. The nuclei of light ooids often contain carbonate or quartz and do not preserve iron sulfide grains.…”

Section: Discussionmentioning

confidence: 99%

“…that dark ooids spent some time within microbial mats (Davies, 1970;Jahnert & Collins, 2011;Woods & Brown, 1975), where dark grains are common. The nuclei of light ooids often contain carbonate or quartz and do not preserve iron sulfide grains.…”

Section: Interpreting Biosignatures In Ooidsmentioning

confidence: 99%

“…In both the black skeletal grains and the dark ooids, Fe is attributed to the presence of sulfide minerals (Davies, 1970), similar to dark skeletal grains of the Great Barrier Reef (Maiklem, 1967). Dark grains are also trapped and bound by microbial mats in Shark Bay (Woods & Brown, 1975). However, the composition of dark material and the mineralogy of these dark ooid cortices have remained unknown.…”

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confidence: 99%

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Organic‐rich bimineralic ooids record biological processes in Shark Bay, Western Australia

et al. 2023

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Marine ooids have formed in microbially colonized environments for billions of years, but the microbial contributions to mineral formation in ooids continue to be debated. Here we provide evidence of these contributions in ooids from Carbla Beach, Shark Bay, Western Australia. Dark 100–240 μm diameter ooids from Carbla Beach contain two different carbonate minerals. These ooids have 50–100 μm‐diameter dark nuclei that contain aragonite, amorphous iron sulfide, detrital aluminosilicate grains and organic matter, and 10–20 μm‐thick layers of high‐Mg calcite that separate nuclei from aragonitic outer cortices. Raman spectroscopy indicates organic enrichments in the nuclei and high‐Mg calcite layers. Synchrotron‐based microfocused X‐ray fluorescence mapping reveals high‐Mg calcite layers and the presence of iron sulfides and detrital grains in the peloidal nuclei. Iron sulfide grains within the nuclei indicate past sulfate reduction in the presence of iron. The preservation of organic signals in and around high‐Mg calcite layers and the absence of iron sulfide suggest that organics stabilized high‐Mg calcite under less sulfidic conditions. Aragonitic cortices that surround the nuclei and Mg‐calcite layers do not preserve microporosity, iron sulfide minerals nor organic enrichments, indicating growth under more oxidizing conditions. These morphological, compositional, and mineralogical signals of microbial processes in dark ooids from Shark Bay, Western Australia, record the formation of ooid nuclei and the accretion of magnesium‐rich cortical layers in benthic, reducing, microbially colonized areas.

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Section: Discussionmentioning

confidence: 99%

Section: Interpreting Biosignatures In Ooidsmentioning

confidence: 99%

mentioning

confidence: 99%

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Organic‐rich bimineralic ooids record biological processes in Shark Bay, Western Australia

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“…Nas porções mais altas da zona de supramaré foram depositados materiais trazidos por ondas de tempestade que tinham disponíveis, além de areia, fragmentos oriundos de planícies expostas e gretadas. Woods & Brown (1975) reconheceram, em zonas de supramaré do Nilemah Embayment (Shark Bay, Austrália), sedimentos intraclásticos gradando de brechas (clastos de 10 cm a 30 cm) para areias progressivamente mais finas no sentido mar→continente. Tais depósitos seriam originados por retrabalhamento de material por ondas de tempestade.…”

Section: Sítios Deposicionais E Processos De For-maçãounclassified

Sucessão De Fácies Na Camada Porangaba, Grupo Passa Dois, Estado De São Paulo

Matos¹,

Coimbra²

1997

RBG

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FÁCIES SUCCESSION IN PORANGABA BED, PASSA DOIS GROUP, SÃO PAULO STATE Much more than a simple contact between lithostratigraphic units, the surface that separates the Permian Passa Dois and Mesozoic São Bento groups is an important sequence boundary in of the Paraná Basin record, when the old marine sequence was overlain by the triassic continental sequence. The Permian and partially Triassic marine deposition were substituted by aeolian continental deposition just after the final marine regression. The Porangaba Bed, stratigraphically situated in the upper part of Passa Dois Group, represents the final deposition of this retreating epicontinental permian-triassic sea. This bed is composed by breccias, mudrocks, sandstones and calcilutites deposited in tidal flats at the margin of this epicontinental sea, in a site closely to the coastal dunes of the Pirambóia Formation. The Porange Bed facies sequence constancy described in outcrops and in 14 well-drillings of PETROBRÁS, allows the definition of a Ω sucession, constituted upwards by lithofacies with progressive continental influence. This study demonstrated that major correlation of the rocks of the Porangaba Bed with is with rocks of the underlying units, named Corumbataí, Teresina and Rio do Rasto formations, and not with rocks of the overlying Pirambóia Formation.

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Central West Western Australia Region

Short

2019

Australian Coastal Systems

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Carbonate Sedimentation in an Arid Zone Tidal Flat, Nilemah Embayment, Shark Bay, Western Australia

Cited by 11 publications

References 1 publication

Organic‐rich bimineralic ooids record biological processes in Shark Bay, Western Australia

Organic‐rich bimineralic ooids record biological processes in Shark Bay, Western Australia

Sucessão De Fácies Na Camada Porangaba, Grupo Passa Dois, Estado De São Paulo

Central West Western Australia Region

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