High-frequency fluctuations in redox conditions during the latest Permian mass extinction

• Published in: Palaeogeography, Palaeoclimatology, Palaeoecology
• Main Authors: Mettam, C., Zerkle, A. L., Claire, M. W., Izon, G., Junium, C. J., Twitchett, R. J.
• Other Authors: NERC, University of St Andrews. Earth and Environmental Sciences, University of St Andrews. St Andrews Centre for Exoplanet Science, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Ferruginous sea; Fe speciation; East Greenland; Stable isotopes; Palaeoenvironment; GE Environmental Sciences; DAS; SDG 14 - Life Below Water; GE; Greenland
• Online Access: http://hdl.handle.net/10023/11831; https://doi.org/10.1016/j.palaeo.2017.06.014; http://www.sciencedirect.com/science/article/pii/S0031018217302109#appd001

This study was supported financially by NERC Fellowship NE/H016805/2 (to AZ), NERC Standard Grant NE/J023485/2 (to AZ and MC), NSFEAR-1455258 (to CJK). Samples were collected by RJT, who thanks G. Cuny and the Danish National Research Foundation for logistics and financial support. New high-resolution geochemical and sedimentological data from Fiskegrav, East Greenland, reveal fluctuations in marine redox conditions associated with the final disappearance of bioturbating organisms during the latest Permian mass extinction (LPME). Sedimentological observations imply a transgressive episode, and associated geochemical evidence for decreasing oxygen availability and the establishment of persistently ferruginous (Fe2 +-rich) conditions implies the shoreward migration of oxygen deficient waters. The long-term decline in dissolved oxygen (DO) availability could have been exacerbated by increasing water temperatures, reducing the solubility of oxygen and promoting thermal stratification. Mixing of the water column could have been further inhibited by freshwater influxes that could have generated salinity contrasts that reinforced thermal stratification. Enhanced runoff could also have increased the delivery of nutrients to the marine shelf, stimulating biological oxygen demand (BOD). During the transition to persistently ferruginous conditions we identify intervals of intermittent benthic meiofaunal recolonization, events that we attribute to small transient increases in DO availability. The mechanism controlling these fluctuations remains speculative, but given the possible centennial- to millennial-scale frequency of these changes, we hypothesise that the mid-latitude setting of Fiskegrav during the Late Permian was sensitive to changes in atmospheric circulation patterns, which may have influenced local precipitation and intermittently modulated some of the processes promoting anoxia. Publisher PDF Peer reviewed