Neoproterozoic peritidal phosphorite from the Sete Lagoas Formation (Brazil) and the Precambrian phosphorus cycle

Drummond, Justin B. R.; Pufahl, Peir K.; Porto, Claudio G.; Carvalho, Mariana

doi:10.1111/sed.12214

Cited by 53 publications

(35 citation statements)

References 136 publications

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“…Thankfully, many aspects of the depositional imprint can be preserved even where alteration is strong (e.g. Drummond et al ., ; Melezhik et al ., ). Many of the proxies for environmental change are analysed in carbonate rocks and so carbonate diagenesis is of particular interest.…”

Section: Chemical Sedimentology: Atmospheric and Hydrospheric Signalsmentioning

confidence: 97%

Sedimentological perspectives on climatic, atmospheric and environmental change in the Neoproterozoic Era

2016

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Sedimentological insights underpin many of the important recent advances in understanding of Earth system behaviour in the Neoproterozoic Era. This article reviews three main areas: (i) chemical proxies and their preservation, with emphasis on carbonate facies; (ii) glacial and post-glacial facies, including their age constraints; (iii) sedimentary evidence for biotic innovations and responses. Chemostratigraphy plays an important role in ordering Neoproterozoic events and defining disturbances to the carbon cycle. There is increasing attention being paid to assessing the role of diagenetic origination or modification of chemostratigraphic signals. Alongside this, new criteria for identifying primary dolomite and precursor metastable phases such as ikaite have been developed. In respect of oxygenation, geochemical proxies substantiate the concept of a Neoproterozoic Oxygenation Event as a very gradual transition, the ocean being at any one time a heterogeneous assemblage of ferruginous, sulphidic and oxic conditions, with some evidence of increasing deep-sea oxidation through the Ediacaran Period. Techniques such as Fe-speciation need to be supplemented with proxies sensitive to suboxic conditions. More generally, it is predicted that petrographically constrained microanalytical studies will also become more important in reconstructing palaeoenvironmental conditions. The global distribution of Neoproterozoic glacial deposits combined with palaeomagnetic evidence supports the concept of panglaciations in which ice sheets reached sea-level in the tropics. Advances in radiometric dating have demonstrated the synchronous onset of global (Sturtian) glaciation at 717 Ma and the demise of a second (Marinoan) glaciation at 635 Ma, and plausibly indicate long durations for each (55 Myr for Sturtian and 5 to 15 Myr for Marinoan). However, a compilation of radiometric dates indicates ambiguities indicating the need for further improvements to the radiometric and Sr-isotope database to understand events within the Sturtian time frame, the timing of onset of Marinoan glaciations, and the age and synchroneity of individual negative d 13 C anomalies. Sturtian deposits are typically thick, rift-related successions containing a range of environments influenced or dominated by dynamic glaciers, as well as ice-free marine intervals. Marinoan glacial deposits, by contrast, tend to be thin and continental. During the latter interval, oxygen isotope systematics of sulphate demonstrate that atmospheric CO 2 was high, as predicted by Snowball Earth theory, and that sedimentation was influenced by orbital forcing. The Sturtian record, by comparison, needs to be searched for evidence of cold-climate hiatuses on the one hand and orbital forcing on the other. Cap carbonate formation appears to have coincided with rising sea-levels following panglaciations. Snowball theory considers that they formed rapidly in the postglacial greenhouse, but an alternative (2016) 63, 253-306 doi: 10.1111/sed.12261 STATE OF THE SCIENCE model o...

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Section: Chemical Sedimentology: Atmospheric and Hydrospheric Signalsmentioning

confidence: 97%

Sedimentological perspectives on climatic, atmospheric and environmental change in the Neoproterozoic Era

2016

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“…Phosphorites are associated with nearshore oxygen oases ∼610 Ma [91], then shift to greater depths and areal extent ∼570 Ma onwards (e.g. the Doushantuo Formation) [83,91].…”

Section: Sessile Animals and Benthic Matsmentioning

confidence: 99%

The effects of marine eukaryote evolution on phosphorus, carbon and oxygen cycling across the Proterozoic–Phanerozoic transition

Lenton

Daines

2018

Emerging Topics in Life Sciences

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A ‘Neoproterozoic oxygenation event’ is widely invoked as a causal factor in animal evolution, and often attributed to abiotic causes such as post-glacial pulses of phosphorus weathering. However, recent evidence suggests a series of transient ocean oxygenation events ∼660–520 Ma, which do not fit the simple model of a monotonic rise in atmospheric oxygen (pO2). Hence, we consider mechanisms by which the evolution of marine eukaryotes, coupled with biogeochemical and ecological feedbacks, potentially between alternate stable states, could have caused changes in ocean carbon cycling and redox state, phosphorus cycling and atmospheric pO2. We argue that the late Tonian ocean ∼750 Ma was dominated by rapid microbial cycling of dissolved organic matter (DOM) with elevated nutrient (P) levels due to inefficient removal of organic matter to sediments. We suggest the abrupt onset of the eukaryotic algal biomarker record ∼660–640 Ma was linked to an escalation of protozoan predation, which created a ‘biological pump’ of sinking particulate organic matter (POM). The resultant transfer of organic carbon (Corg) and phosphorus to sediments was strengthened by subsequent eukaryotic innovations, including the advent of sessile benthic animals and mobile burrowing animals. Thus, each phase of eukaryote evolution tended to lower P levels and oxygenate the ocean on ∼104 year timescales, but by decreasing Corg/P burial ratios, tended to lower atmospheric pO2 and deoxygenate the ocean again on ∼106 year timescales. This can help explain the transient nature and ∼106 year duration of oceanic oxygenation events through the Cryogenian–Ediacaran–Cambrian.

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“…Iron would have been supplied by clays and/or (oxyhydr)oxides (Jickells et al., ). Phosphorous could have been absorbed to iron‐(oxyhydr)oxides and clays (Filippelli, ; Wang et al., ; Drummond et al., ). Some of these nutrients would have been bioavailable and promoted primary productivity as they do in the modern oceans (Benitez‐Nelson, ; Bressac et al., ).…”

Section: Discussionmentioning

confidence: 99%

Phosphorites, glass ramps and carbonate factories: The evolution of an epicontinental sea and a late Palaeozoic upwelling system (Phosphoria Rock Complex)

Matheson

Frank

2020

Sedimentology

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The Permian Phosphoria Rock Complex of the western USA contains an enigmatic assemblage of bioelemental rocks (i.e. phosphorites and cherts) that accumulated in a depositional system with no modern analogue. This study utilizes detailed sedimentological, stratigraphic and petrographic examination to evaluate the genetic relations of phosphorites, spiculitic chert and carbonates of the Ervay cycle (depositional sequence) and propose a unified oceanographic model for their deposition. The Ervay cycle contains three marine and one terrestrial facies association, each of which composes the bulk of a single lithostratigraphic unit. The marine facies associations include: (i) granular phosphorites (Retort Member); (ii) spiculitic cherty dolostones (Tosi Member); and (iii) marine to peritidal carbonates (Ervay Member). Red beds and intercalated gypsum (Goose Egg Formation) accumulated in the vast desert adjacent to the sea. The three marine members are chronostratigraphically distinct, successive and conformably stacked. They are not coeval facies belts. They reflect the progressive evolution of the epicontinental sea from the location of: (i) authigenic phosphogenesis (lowstand to transgression); to (ii) a glass ramp with biosiliceous (sponge) deposition (transgression); to (iii) a carbonate ramp (regression). This succession of switching biochemical sediment factories records the evolution of sea‐level, nutrient supply, upwelling, oxygenation and dissolved Si. Intense upwelling, potentially coupled with aeolian input, led to sedimentary condensation and phosphogenesis. Decreased upwelling intensity during transgression increased oxygenation sufficiently for a siliceous sponge benthos. Sponges were favoured over biocalcifiers due to elevated dissolved silica and a low carbonate saturation state. The cessation of sponge dominance and transition to a carbonate ramp occurred due to decreasing upwelling intensity, Si drawdown and an increased carbonate saturation state. These results provide insight into the role of Si loading in faunal turnover on glass ramps and highlight how differences in dissolved Si utilizers in pre‐Cretaceous versus post‐Cretaceous upwelling systems influence the resultant deposits.

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Neoproterozoic peritidal phosphorite from the Sete Lagoas Formation (Brazil) and the Precambrian phosphorus cycle

Cited by 53 publications

References 136 publications

Sedimentological perspectives on climatic, atmospheric and environmental change in the Neoproterozoic Era

Sedimentological perspectives on climatic, atmospheric and environmental change in the Neoproterozoic Era

The effects of marine eukaryote evolution on phosphorus, carbon and oxygen cycling across the Proterozoic–Phanerozoic transition

Phosphorites, glass ramps and carbonate factories: The evolution of an epicontinental sea and a late Palaeozoic upwelling system (Phosphoria Rock Complex)

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