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Bowyer FT, Shore AJ, Wood RA, Alcott LJ, Thomas AL, Butler IB, Curtis A, Hainanan S, Curtis-Walcott S, Penny AM, Poulton SW. Regional nutrient decrease drove redox stabilisation and metazoan diversification in the late Ediacaran Nama Group, Namibia. Sci Rep 2020; 10:2240. [PMID: 32042140 PMCID: PMC7010733 DOI: 10.1038/s41598-020-59335-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/30/2019] [Indexed: 12/01/2022] Open
Abstract
The late Ediacaran witnessed an increase in metazoan diversity and ecological complexity, marking the inception of the Cambrian Explosion. To constrain the drivers of this diversification, we combine redox and nutrient data for two shelf transects, with an inventory of biotic diversity and distribution from the Nama Group, Namibia (~550 to ~538 Million years ago; Ma). Unstable marine redox conditions characterised all water depths in inner to outer ramp settings from ~550 to 547 Ma, when the first skeletal metazoans appeared. However, a marked deepening of the redoxcline and a reduced frequency of anoxic incursions onto the inner to mid-ramp is recorded from ~547 Ma onwards, with full ventilation of the outer ramp by ~542 Ma. Phosphorus speciation data show that, whilst anoxic ferruginous conditions were initially conducive to the drawdown of bioavailable phosphorus, they also permitted a limited degree of phosphorus recycling back to the water column. A long-term decrease in nutrient delivery from continental weathering, coupled with a possible decrease in upwelling, led to the gradual ventilation of the Nama Group basins. This, in turn, further decreased anoxic recycling of bioavailable phosphorus to the water column, promoting the development of stable oxic conditions and the radiation of new mobile taxa.
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Affiliation(s)
- F T Bowyer
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK. .,University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK.
| | - A J Shore
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - R A Wood
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - L J Alcott
- University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK
| | - A L Thomas
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - I B Butler
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - A Curtis
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - S Hainanan
- Ministry of Mines and Energy, 6 Aviation Road, Private Bag, 13297, Windhoek, Namibia
| | | | - A M Penny
- Finnish Museum of Natural History, University of Helsinki, Jyrängöntie 2, 00560, Helsinki, Finland
| | - S W Poulton
- University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK
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Bowyer F, Wood RA, Poulton SW. Controls on the evolution of Ediacaran metazoan ecosystems: A redox perspective. Geobiology 2017; 15:516-551. [PMID: 28387043 PMCID: PMC5485040 DOI: 10.1111/gbi.12232] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Accepted: 01/25/2017] [Indexed: 05/26/2023]
Abstract
A growing number of detailed geochemical studies of Ediacaran (635-541 Ma) marine successions have provided snapshots into the redox environments that played host to the earliest known metazoans. Whilst previous compilations have focused on the global evolution of Ediacaran water column redox chemistry, the inherent heterogeneity evident in palaeogeographically distinct environments demands a more dissected approach to better understand the nature, interactions and evolution of extrinsic controls on the development of early macrobenthic ecosystems. Here, we review available data of local-scale redox conditions within a palaeogeographic and sequence stratigraphic framework, to explore the mechanisms controlling water column redox conditions and their potential impact on the record of metazoans. The openly connected Laurentian margin, North America (632-540 Ma) and Nama basin, Namibia (550-538 Ma), and the variably restricted Yangtze Block, South China (635-520 Ma), show continued redox instability after the first fossil evidence for metazoans. This may support opportunistic benthic colonisation during periods of transient oxygenation amidst episodic upwelling of anoxic waters beneath a very shallow, fluctuating chemocline. The first skeletal metazoans appeared under conditions of continued redox stratification, such as those which characterise the Dengying Formation of the Yangtze Block and the Kuibis Subgroup of the Nama basin. Current data, however, suggests that successful metazoan reef-building demanded more persistent oxia. We propose that cratonic positioning and migration throughout the Ediacaran Period, in combination with gradually increasing dissolved oxygen loading, may have provided a first-order control on redox evolution through regulating circulation mechanisms in the Mirovian Ocean. Some unrestricted lower slope environments from mid-high latitudes benefited from sustained oxygenation via downwelling, whilst transit of isolated cratons towards more equatorial positions stifled pervasive ventilation either through ineffective surface ocean mixing, Ekman-induced upwelling, elevated surface ocean productivity or a combination of these processes.
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Affiliation(s)
- F Bowyer
- School of Geosciences, University of Edinburgh, Edinburgh, UK
| | - R A Wood
- School of Geosciences, University of Edinburgh, Edinburgh, UK
| | - S W Poulton
- School of Earth and Environment, University of Leeds, Leeds, UK
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Clarkson MO, Wood RA, Poulton SW, Richoz S, Newton RJ, Kasemann SA, Bowyer F, Krystyn L. Dynamic anoxic ferruginous conditions during the end-Permian mass extinction and recovery. Nat Commun 2016; 7:12236. [PMID: 27433855 PMCID: PMC4960316 DOI: 10.1038/ncomms12236] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2015] [Accepted: 06/15/2016] [Indexed: 11/09/2022] Open
Abstract
The end-Permian mass extinction, ∼252 million years ago, is notable for a complex recovery period of ∼5 Myr. Widespread euxinic (anoxic and sulfidic) oceanic conditions have been proposed as both extinction mechanism and explanation for the protracted recovery period, yet the vertical distribution of anoxia in the water column and its temporal dynamics through this time period are poorly constrained. Here we utilize Fe–S–C systematics integrated with palaeontological observations to reconstruct a complete ocean redox history for the Late Permian to Early Triassic, using multiple sections across a shelf-to-basin transect on the Arabian Margin (Neo-Tethyan Ocean). In contrast to elsewhere, we show that anoxic non-sulfidic (ferruginous), rather than euxinic, conditions were prevalent in the Neo-Tethys. The Arabian Margin record demonstrates the repeated expansion of ferruginous conditions with the distal slope being the focus of anoxia at these times, as well as short-lived episodes of oxia that supported diverse biota. Oceanic anoxia is invoked for driving the Permo-Triassic Mass Extinction, but the timing, distribution and chemical state are poorly understood. Here, the authors show that fluctuations of anoxic, non-sulfidic (ferruginous) conditions were important for the delayed biotic recovery in the Neo-Tethys.
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Affiliation(s)
- M O Clarkson
- School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh EH9 3FE, UK
| | - R A Wood
- School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh EH9 3FE, UK
| | - S W Poulton
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - S Richoz
- Institute of Earth Sciences, NAWI Graz, University of Graz, Heinrichstraße 26, 8010 Graz, Austria
| | - R J Newton
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - S A Kasemann
- Department of Geosciences and MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany
| | - F Bowyer
- School of GeoSciences, University of Edinburgh, James Hutton Road, Edinburgh EH9 3FE, UK
| | - L Krystyn
- Institute for Palaeontology, Vienna University, Althanstrasse 14, 1090 Vienna, Austria
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Clarkson MO, Kasemann SA, Wood RA, Lenton TM, Daines SJ, Richoz S, Ohnemueller F, Meixner A, Poulton SW, Tipper ET. Ocean acidification and the Permo-Triassic mass extinction. Science 2015; 348:229-32. [PMID: 25859043 DOI: 10.1126/science.aaa0193] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.
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Affiliation(s)
- M O Clarkson
- School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3FE, UK.
| | - S A Kasemann
- Faculty of Geosciences and MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany
| | - R A Wood
- School of Geosciences, University of Edinburgh, West Mains Road, Edinburgh EH9 3FE, UK
| | - T M Lenton
- College of Life and Environmental Sciences, University of Exeter, Laver Building, North Parks Road, Exeter EX4 4QE, UK
| | - S J Daines
- College of Life and Environmental Sciences, University of Exeter, Laver Building, North Parks Road, Exeter EX4 4QE, UK
| | - S Richoz
- Institute of Earth Sciences, NAWI Graz, University of Graz, Heinrichstraße 26, 8010 Graz, Austria
| | - F Ohnemueller
- Faculty of Geosciences and MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany
| | - A Meixner
- Faculty of Geosciences and MARUM-Center for Marine Environmental Sciences, University of Bremen, 28334 Bremen, Germany
| | - S W Poulton
- School of Earth and Environment, University of Leeds, Leeds LS2 9JT, UK
| | - E T Tipper
- Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK
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Poulton SW, Krom MD, van Rijn J, Raiswell R, Bows R. Detection and removal of dissolved hydrogen sulphide in flow-through systems via the sulphidation of hydrous iron (III) oxides. Environ Technol 2003; 24:217-229. [PMID: 12666791 DOI: 10.1080/09593330309385553] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A novel automated warning and removal system for hydrogen sulphide in aqueous flow-through systems has been developed based on the sulphidation of ferrihydrite sorbed to zeolite substrate. The system consists of a small flow-through reaction cartridge with photo-sensors positioned at the base. During the reaction, sulphide is initially oxidised to elemental sulphur by the ferrihydrite, and Fe2+ is subsequently released to solution. This Fe2+ then reacts with additional dissolved sulphide to form solid phase iron monosulphide. The colour change from orange ferrihydrite to black iron monosulphide is continuously monitored by the photo-sensors, which provide a rapid and reproducible response (via a voltage change) to pulses of sulphidic water. The response of the photo-sensors is linear with respect to inflowing sulphide concentration, while the most rapid response to dissolved sulphide occurs at a flow rate of approximately 200 ml min(-1) (equivalent to a hydraulic loading rate of 21 cm min(-1). The presence of phosphate in solution substantially decreases reaction rates due to adsorption to reactive surface sites. However, the response time of the photo-sensors remains sufficient to provide a rapid indication of sulphidic conditions even in systems with high concentrations of dissolved phosphate. The cartridge has the advantage of partially or completely removing sulphide (depending on flow rate and substrate mass) from an initial pulse of water. At the optimal flow rate for the successful use of the cartridge as a sulphide warning system (200 ml min(-1)), required substrate masses for the complete removal of dissolved sulphide (over the experimental range of 0-1000 microM) are relatively small (0.5-2 kg).
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Affiliation(s)
- S W Poulton
- School of Earth Sciences, University of Leeds, Leeds LS2 9JT, UK
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