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The end-Permian mass extinction (EPME) is associated with the loss of approximately 80–90 % marine species and 70 % terrestrial taxa. Massive greenhouse gas emissions from activities of the Siberian Traps Large Igneous Province (ST-LIP) and arc volcanisms are thought to be the trigger of the EPME. Global temperatures rose significantly following the EPME, and such extreme warmth persisted into the Early Triassic, which may have led to enhanced silicate weathering, and increased river runoff and sediment accumulation rate. However, ecosystem recovery was delayed by at least five million years after the EPME. One leading hypothesis attributes this protracted recovery to sustained atmospheric CO₂ accumulation, resulting from volcanic emissions from the ST-LIP that overwhelmed the normal Earth surface carbon cycle. To evaluate this, we synthesize geochemical and sedimentological records of continental weathering across the Permian–Triassic (PT) transition, drawing on a suite of proxies including major elements-based proxies, strontium (87/86Sr and δ88/86Sr), osmium (187Os/188Os), lithium (δ7Li), magnesium (δ26Mg) and calcium (δ44Ca) isotopes. We highlight the strengths and limitations of each proxy and assess how chemical and physical weathering may have responded to the environmental perturbations across the PT transition. Collectively, these records can help test the hypothesis that the silicate weathering feedback were insufficient to counteract elevated CO2 levels, thereby failing to stabilize Earth’s climate during the prolonged Early Triassic warmth. 

Abstract Geologic records support a short-lived carbon release, known as the pre-onset excursion (POE), shortly before the Paleocene-Eocene Thermal Maximum (PETM; ~ 56 Ma). However, the source and pace of the POE carbon release and its relationship to the PETM remain unresolved. Here we show a high-temporal-resolution stratigraphic record spanning the POE and PETM from the eastern Tethys Ocean that documents the evolution of surface ocean carbon cycle, redox and eutrophication, confirming the global nature of the POE. Biomarkers extracted from the sedimentary record indicate a smaller environmental perturbation during the POE than that during the PETM in the eastern Tethys Ocean. Earth system modeling constrained by observed δ¹³C and pH data indicates that the POE was driven by a largely thermogenic CO₂source, likely associated with sill intrusions prior to the main eruption phase of the North Atlantic Igneous Province and possibly biogeochemical feedbacks involving the release of biogenic methane. 

Abstract The Paleocene‐Eocene Thermal Maximum (PETM; 56 Ma) is considered to be one of the best analogs for future climate change. The carbon isotope composition (δ¹³C) ofn‐alkanes derived from leaf waxes of terrestrial plants and marine algae can provide important insights into the carbon cycle perturbation during the PETM. Here, we present new organic geochemical data and compound‐specific δ¹³C data from sediments recovered from an early Cenozoic basin‐margin succession from Spitsbergen. These samples represent one of the most expanded PETM sites and provide new insights into the high Arctic response to the PETM. Our results reveal a synchronous ∼−6.5‰ carbon isotope excursion (CIE) in short‐chainn‐alkanes (nC₁₉; marine algae/bacteria) with a ∼−5‰ CIE in long‐chainn‐alkanes (nC₂₉andnC₃₁; plant waxes) during the peak of the PETM. Although δ¹³C_n‐alkanesvalues were potentially affected via a modest thermal effect (1‰–2‰), the relative changes in the δ¹³C_n‐alkanesremain robust. A simple carbon cycle modeling suggests peak carbon emission rate could be ∼3 times faster than previously suggested using δ¹³C_TOCrecords. The CIE magnitude of both δ¹³C_n‐C19and δ¹³C_n‐C29can be explained by the elevated influence of¹³C‐depleted respired CO₂in the water column and increased water availability on land, elevatedpCO₂in the atmosphere, and changes in vegetation type during the PETM. The synchronous decline in δ¹³C of both leaf waxes and marine algae/bacteria argues against a significant contribution to the sedimentary organic carbon pool from the weathering delivery of fossiln‐alkanes in the Arctic region.