Siberian Trap volcanism, global warming and the Permian-Triassic mass extinction: New insights from Armenian Permian-Triassic sections

Abstract

Permian-Triassic boundary sections from Armenia were studied for carbon isotopes of carbonates as well as oxygen isotopes of conodont apatite in order to constrain the global significance of earlier reported variations in the isotope proxies and elaborate the temporal relationship between carbon cycle changes, global warming and Siberian Trap volcanism. Carbon isotope records of the Chanakhchi and Vedi II sections show a 3–5‰ negative excursion that start in the Clarkina nodosa (C. yini) conodont Zone (latest Permian) with minimum values recorded in Hindeodus parvus to Isarcicella isarcica conodont zones (earliest Triassic). Sea surface temperatures (SST) reconstructed from oxygen isotopes of conodont apatite increase by 8–10 °C over an extrapolated time interval of ∼39 ka with the onset of global warming occurring in the C. iranica (C. meishanensis) Zone of the latest Permian. Climate warming documented in the Armenian sections is comparable to published time-equivalent shifts in SST in Iran and South China suggesting that this temperature change represents a true global signature. By correlating the Armenian and Iranian section with the radiometrically well-dated Meishan GSSP (Global Stratotype Section and Point) section (South China), the negative shift in δ13C is estimated to have occurred 12–128 ka prior to the onset of global warming. This temporal offset is unexpected given the synchrony in changes in atmospheric CO2 and global temperature as seen in Pleistocene ice core records. The negative δ13C excursion is explained by the addition of emission of isotopically light CO2 and CH4 from thermogenic heating of organic carbon-rich sediments by Siberian Trap sill intrusions. However, the observed time lag in the δ13C and δ18O shifts questions the generally assumed cause-effect relationship between emission of thermogenically produced greenhouse gases and global warming. The onset of temperature rise coincides with a significant enrichment in Hg/TOC (total organic carbon) ratios arguing for a major volcanic event at the base of the extinction interval. Whether global warming was a major factor for the Late Permian mass extinction depends on the duration of the extinction interval. Warming only starts at the base of the extinction interval, but with the extinction encompassing a time interval of 60 ± 48 ka, global climate warming in conjunction with temperature-related stressors as hypoxia and reduced nutrient availability may have been one of the major triggers of the most devastating biotic crisis in Earth history.

Temperature-driven nutrient recycling and euxinia as a marine mass extinction mechanism

“…Given the relatively prolonged interval of warming in the lead up to the P/Tr boundary (∼39 kyr 6 ), our analysis favors a conceptual model in which higher metabolic rates drive a pronounced vertical partitioning in ocean redox. This biogeochemically driven partitioning occurs within an ocean that remains not only well ventilated at depth, but consistent with previous modelling work 13,36 , increases in overturning strength for warmer states (Figure 3j-l).…”

“…Because the time-scale of warming leading up to the P/Tr boundary is slow relative to the adjustment time-scale of large-scale ocean circulation (i.e. warming likely occurred over ∼39 kyr or more, starting in the C. meishanensis biostratigraphic zone 6,11 ), a series of (10 kyr) steady-state simulations is appropriate for simulating the biogeochemical response to warming. In these, we prescribe a range of atmospheric pCO 2 (1 -30 × pre-industrial pCO 2 , i.e.…”

“…Although the extinction event itself has been intensely studied and is relatively well characterized, the specific physical and/or biogeochemical environmental changes that drove biodiversity loss in the ocean are uncertain 3 . Proxy evidence reveals a 7-10 • C increase in sea surface temperature occurring in as little as ∼39 kyr [4][5][6] ( Fig. 1a+d), the development of (photic-zone) euxinia (waters containing sulphide 7 ), an expansion in the extent of seafloor anoxia 8,9 , and a decrease in the carbon isotopic signature recorded in carbonates 10 (δ 13 C carb , Fig.…”

Size variations in foraminifers from the early Permian to the Late Triassic: implications for the Guadalupian–Lopingian and the Permian–Triassic mass extinctions

“…In addition, our data reveal that the decline of foraminiferal size is significantly greater during the PTB interval than during the GLB interval, consistent with the wider extent and intensity of anoxia during the PTB interval. Global warming, triggered by volcanogenic and thermogenic greenhouse gases from Siberian Traps volcanism and contemporaneous volcanic activity around the Paleotethys Ocean (Renne et al 1995; Svensen et al 2004, 2009; Brand et al 2012; Joachimski et al 2012; Yin and Song 2013; Majorowicz et al 2014). Oxygen isotope data from conodont apatite represent tropical sea-surface temperature warming of ~10°C during the PTB interval (Joachimski et al 2012, 2020). This hot climate lasted for much of the Early Triassic (Sun et al 2012; Romano et al 2013), and therefore temporally coincided with the Lilliput effect experienced by foraminifers (Fig.…”

Digitalized Earth's most severe sea-level regression and extinction

“…Despite half a century has passed, what caused the catastrophe remains unexplained. Geological events, e.g., global warming [4][5][6][7][8] , negative excursions of δ 13 C and δ 18 O, Siberian Traps volcanism [8][9][10] , anoxia [6,11] , ocean acidification [10,12] , etc. are proposed mechanisms to interpret EPME.…”