Relict magnesian calcite oolite and subsidence of the Amazon shelf

Kumar, Naresh; Damuth, John E.; Gorini, Marcus Aguiar

doi:10.1111/j.1365-3091.1977.tb00124.x

Cited by 15 publications

(10 citation statements)

References 11 publications

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“…When comparing the position of the oolites dated by 8 with the sea-level change curve (Fig. 3), we agree with the observations by 11 about the lack of reliability of oolite materials as indicators of ancient shores on the Amazon margin.…”

Section: Discussionsupporting

confidence: 87%

“…The older dating ages used in 7 were published by 8 and would correspond to the oolites present in the Northern Sector. However 11 , argued that these oolite samples were displaced from their original place of formation and highlighted one should be very careful when using these dated oolite samples to infer reef age and accretion 7 . also stated that the Amazon shelf is mostly covered by muds, a condition which would impede the development of carbonate reefs.…”

Section: Introductionmentioning

confidence: 99%

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Insights on the evolution of the living Great Amazon Reef System, equatorial West Atlantic

Mahiques

Siegle

Francini‐Filho

et al. 2019

Sci Rep

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The Great Amazon Reef (GARS) is an extensive mesophotic reef ecosystem between Brazil and the Caribbean. Despite being considered as one of the most important mesophotic reef ecosystems of the South Atlantic, recent criticism on the existence of a living reef in the Amazon River mouth was raised by some scientists and politicians. The region is coveted for large-scale projects for oil and gas exploration. Here, we add to the increasing knowledge about the GARS by exploring evolutionary aspects of the reef using primary and secondary information on radiocarbon dating from carbonate samples. The results obtained demonstrate that the reef is alive and growing, with living organisms inhabiting the GARS in its totality. Additional studies on net reef growth, habitat diversity, and associated biodiversity are urgently needed to help reconcile economic activities and biodiversity conservation.

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Section: Discussionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Insights on the evolution of the living Great Amazon Reef System, equatorial West Atlantic

Mahiques

Siegle

Francini‐Filho

et al. 2019

Sci Rep

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“…Such rates, however, reflect only short‐term processes. Long‐term accumulation rates are controlled by subsidence rates, which on the Amazon Shelf have averaged about 15–22 cm/ky since the Miocene [ Kumar et al , 1977]. Over shorter periods of time, different localities on the shelf alternate between multicentury intervals of net accretion and multicentury intervals of net erosion [ Nittrouer et al , 1996].…”

Section: Discussionmentioning

confidence: 99%

An Appalachian Amazon? Magnetofossil evidence for the development of a tropical river‐like system in the mid‐Atlantic United States during the Paleocene‐Eocene thermal maximum

et al. 2009

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[1] On the mid-Atlantic Coastal Plain of the United States, Paleocene sands and silts are replaced during the Paleocene-Eocene Thermal Maximum (PETM) by the kaolinite-rich Marlboro Clay. The clay preserves abundant magnetite produced by magnetotactic bacteria and novel, presumptively eukaryotic, ironbiomineralizing microorganisms. Using ferromagnetic resonance spectroscopy and electron microscopy, we map the magnetofossil distribution in the context of stratigraphy and carbon isotope data and identify three magnetic facies in the clay: one characterized by a mix of detrital particles and magnetofossils, a second with a higher magnetofossil-to-detrital ratio, and a third with only transient magnetofossils. The distribution of these facies suggests that suboxic conditions promoting magnetofossil production and preservation occurred throughout inner middle neritic sediments of the Salisbury Embayment but extended only transiently to outer neritic sediments and the flanks of the embayment. Such a distribution is consistent with the development of a system resembling a modern tropical river-dominated shelf.

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“…A detailed survey of the region conducted by the Australian Bureau of Mineral Resources determined the distribution pattern of ooids in the Southern GBR (Marshall, 1977). Since ooids are found throughout this area, but only at depths between 100 to 120 m, we should consider the possibility of secondary transportation of the ooids from shallower sites following their original deposition (eg., Kumar et al, 1977;Kump and Hine, 1986). A source depth shallower than 100 m is not a candidate for the origin of the ooids sands since surface sediments from these depths contain no ooids and the physical oceanography of the area would not have permitted re-deposition (Marshall, 1977).…”

Section: Observed Sea-level From the Ooids And Implication Of Eslmentioning

confidence: 96%

Sea-level during the early deglaciation period in the Great Barrier Reef, Australia

Yokoyama¹,

Purcell²,

Marshall³

et al. 2006

Global and Planetary Change

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Relict magnesian calcite oolite and subsidence of the Amazon shelf

Cited by 15 publications

References 11 publications

Insights on the evolution of the living Great Amazon Reef System, equatorial West Atlantic

Insights on the evolution of the living Great Amazon Reef System, equatorial West Atlantic

An Appalachian Amazon? Magnetofossil evidence for the development of a tropical river‐like system in the mid‐Atlantic United States during the Paleocene‐Eocene thermal maximum

Sea-level during the early deglaciation period in the Great Barrier Reef, Australia

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