Abstract
Research on the Permian-Triassic boundary (PTB) along the northern margins of Pangaea (exposed today in the Arctic region) has been heavily reliant on field observations, where data resolution was consequently determined by outcrop condition and accessibility. Core drilling in central Spitsbergen allowed for a near-complete recovery of two ~90 m cores through the PTB. Analyses of the core and nearby outcrops include stratigraphic logging and sampling, XRF scanning, petrography, biostratigraphy, isotope geochemistry, and geochronology. The First Appearance Datum (FAD) of H. parvus in Svalbard places the base of the Triassic ca. 4 m above the base of the Vikinghøgda Formation, and ca. 2.50 m above the End-Permian Mass Extinction (EPME) and its associated sharp negative δ13C. The PTB therefore falls within the Reduviasporonites chalastus Assemblage Zone in Svalbard. Precise U-Pb TIMS dating of two zircon crystals in a tephra layer just above the first documented Hindeodus parvus in Svalbard gives an age of 252.13 ± 0.62 Ma. High-resolution palaeoenvironmental proxies, including Si/kcps (kilo counts per second), Zr/Rb, K/Ti, Fe/K, and V/Cr, indicate a transition towards a more arid climate in the earliest Triassic, contemporaneous with prolonged bottom-water dysoxic/anoxic conditions, following an increase in volcanic activity in the Late Permian. Statistical analysis of Zr/Rb, K/Ti and V/Cr elemental ratios suggests that the system was impacted by long-eccentricity (400 kyr) cyclicity. The δ13C excursion in organic carbon (δ13Corg) record signals a large negative carbon isotope excursion (CIE) associated with the mass extinction event, but also records a second, smaller negative CIE ca. 22 m above this interval. This younger δ13Corg excursion correlates to similar CIEs in the Dienerian (late Induan) records of other sections, notably in the Tethys Ocean, which have been interpreted as recording a small biotic crisis during the post-extinction recovery. Evidence of this negative CIE in Spitsbergen suggests that the Dienerian crisis may have been global in extent. The negative δ13Corg values are associated with evidence for dysoxia or anoxia in the core, and the occurrence of tephra layers in the same interval suggests a possible connection between the Dienerian crisis and a discrete episode of volcanic activity.
Highlights
The Permian-Triassic boundary (PTB) has been the focus of intense scientific study since the end of the nineteenth century (Baud, 2014) as life on Earth nearly disappeared during what is known today as the End-Permian Mass Extinction (EPME; Wignall and Twitchett, 1996) ca. 252 Ma (Burgess et al, 2014)
These eight facies have been grouped in two facies associations (FAs) separated by a transition zone represented by
Fine- to medium-grained sandstone (Facies H1–3, Table 1) which belongs to the Stensiöfjellet Member of the Kapp Starostin Formation
Summary
The PTB has been the focus of intense scientific study since the end of the nineteenth century (Baud, 2014) as life on Earth nearly disappeared during what is known today as the End-Permian Mass Extinction (EPME; Wignall and Twitchett, 1996) ca. 252 Ma (Burgess et al, 2014). Environmental disruptions included global warming, sea surface temperature increase, ocean acidification, increased nutrient and sediment fluxes to the oceans, atmospheric ozone destruction, and widespread pulses of marine euxinia and anoxia (Wignall and Twitchett, 1996; Kidder and Worsley, 2004; Svensen et al, 2009; Joachimski et al, 2012; Clarkson et al, 2015; Dustira et al, 2013; Grasby et al, 2013; Wignall et al, 2016; Bond and Grasby, 2017; Stordal et al, 2017; Burger et al, 2019; Schobben et al, in press) These dramatic changes were contemporaneous with a sharp yet sustained negative carbon isotope excursion (CIE; Korte and Kozur, 2010)
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