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Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath.

Song H, Wignall PB, Chu D, Tong J, Sun Y, Song H, He W, Tian L - Sci Rep (2014)

Bottom Line: The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery.Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters.Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.

ABSTRACT
The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

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The evolution of the mid-water refuge zone during the Early Triassic.Carbon isotope data3729, sulfur isotope data3031, temperature data35, and conodont ΩCe data showing redox conditions22 are all from South China. Environmental data in the Changhsingian and PTB strata are from Meishan section whereas those in the Lower and Middle Triassic are from Nanpanjiang Basin. Age data are from Figure S1. Abbreviation: G. = Griesbachian, D. = Dienerian, S. = Smithian, OMZ = oxygen minimum zone, LPE = latest Permian extinction, ETE = earliest Triassic extinction, and SSE = Smithian-Spathian extinction.
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f4: The evolution of the mid-water refuge zone during the Early Triassic.Carbon isotope data3729, sulfur isotope data3031, temperature data35, and conodont ΩCe data showing redox conditions22 are all from South China. Environmental data in the Changhsingian and PTB strata are from Meishan section whereas those in the Lower and Middle Triassic are from Nanpanjiang Basin. Age data are from Figure S1. Abbreviation: G. = Griesbachian, D. = Dienerian, S. = Smithian, OMZ = oxygen minimum zone, LPE = latest Permian extinction, ETE = earliest Triassic extinction, and SSE = Smithian-Spathian extinction.

Mentions: The refuge zone concept can also be used to evaluate the subsequent Early Triassic radiation and recovery. The evolution of this zone is based on seawater temperature, redox proxy data, carbon and sulphur isotope data (Fig. 4), which reveals that, as well as the two phases of shrinkage on either side of the PTB there was also a contraction around the Smithian-Spathian boundary during a peak of warmth (Fig. 4). As with the earlier phases, the Smithian-Spathian refuge zone contraction also coincides with an extinction event32. The refuge zone expanded during the Dienerian-Smithian boundary during a cooling trend (Fig. 4) that coincided with evidence for recovery in several groups, e.g. conodonts33, ammonoids3334 and foraminifers35. This is interpreted here to reflect radiation into expanding habitats. That the radiation is best seen in deeper waters35 further suggests the recovery was driven more by the retreat of anoxic waters into deeper depths rather than the opening up of shallower waters by cooling.


Anoxia/high temperature double whammy during the Permian-Triassic marine crisis and its aftermath.

Song H, Wignall PB, Chu D, Tong J, Sun Y, Song H, He W, Tian L - Sci Rep (2014)

The evolution of the mid-water refuge zone during the Early Triassic.Carbon isotope data3729, sulfur isotope data3031, temperature data35, and conodont ΩCe data showing redox conditions22 are all from South China. Environmental data in the Changhsingian and PTB strata are from Meishan section whereas those in the Lower and Middle Triassic are from Nanpanjiang Basin. Age data are from Figure S1. Abbreviation: G. = Griesbachian, D. = Dienerian, S. = Smithian, OMZ = oxygen minimum zone, LPE = latest Permian extinction, ETE = earliest Triassic extinction, and SSE = Smithian-Spathian extinction.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928575&req=5

f4: The evolution of the mid-water refuge zone during the Early Triassic.Carbon isotope data3729, sulfur isotope data3031, temperature data35, and conodont ΩCe data showing redox conditions22 are all from South China. Environmental data in the Changhsingian and PTB strata are from Meishan section whereas those in the Lower and Middle Triassic are from Nanpanjiang Basin. Age data are from Figure S1. Abbreviation: G. = Griesbachian, D. = Dienerian, S. = Smithian, OMZ = oxygen minimum zone, LPE = latest Permian extinction, ETE = earliest Triassic extinction, and SSE = Smithian-Spathian extinction.
Mentions: The refuge zone concept can also be used to evaluate the subsequent Early Triassic radiation and recovery. The evolution of this zone is based on seawater temperature, redox proxy data, carbon and sulphur isotope data (Fig. 4), which reveals that, as well as the two phases of shrinkage on either side of the PTB there was also a contraction around the Smithian-Spathian boundary during a peak of warmth (Fig. 4). As with the earlier phases, the Smithian-Spathian refuge zone contraction also coincides with an extinction event32. The refuge zone expanded during the Dienerian-Smithian boundary during a cooling trend (Fig. 4) that coincided with evidence for recovery in several groups, e.g. conodonts33, ammonoids3334 and foraminifers35. This is interpreted here to reflect radiation into expanding habitats. That the radiation is best seen in deeper waters35 further suggests the recovery was driven more by the retreat of anoxic waters into deeper depths rather than the opening up of shallower waters by cooling.

Bottom Line: The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery.Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters.Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.

ABSTRACT
The Permian-Triassic mass extinction was the most severe biotic crisis in the past 500 million years. Many hypotheses have been proposed to explain the crisis, but few account for the spectrum of extinction selectivity and subsequent recovery. Here we show that selective losses are best accounted for by a combination of lethally warm, shallow waters and anoxic deep waters that acted to severely restrict the habitable area to a narrow mid-water refuge zone. The relative tolerance of groups to this double whammy provides the first clear explanation for the selective extinction losses during this double-pulsed crisis and also the fitful recovery. Thus, high temperature intolerant shallow-water dwellers, such as corals, large foraminifers and radiolarians were eliminated first whilst high temperature tolerant ostracods thrived except in anoxic deeper-waters. In contrast, hypoxia tolerant but temperature intolerant small foraminifers were driven from shallow-waters but thrived on dysoxic slopes margins. Only those mollusc groups, which are tolerant of both hypoxia and high temperatures, were able to thrive in the immediate aftermath of the extinction. Limited Early Triassic benthic recovery was restricted to mid-water depths and coincided with intervals of cooling and deepening of water column anoxia that expanded the habitable mid-water refuge zone.

Show MeSH
Related in: MedlinePlus