Late Guadalupian–early Lopingian marine geochemical records from the Upper Yangtze, South China: Implications for climate-biocrisis events

Abstract

Major paleoenvironmental changes occurred during the Guadalupian-Lopingian boundary (GLB) transition, but the causative linkages among the Emeishan Large Igneous Province (LIP), end-Guadalupian crisis and climatic fluctuations are still in dispute. Variation of geochemical proxies preserved in the sedimentary records is important evidence in examining potential links between volcanisms and environmental changes. Herein, we carried out a comprehensive study of carbon/strontium isotope and trace element geochemistry at the Dukou section, northern margin of the Upper Yangtze. During the Late Guadalupian, the carbon isotope showed a negative drift, the marine primary productivity declined simultaneously, and redox proxies indicate the enhancement of ocean oxidation. It is worth noting that the δ13Ccarb turns into a rapid negative drift from a slow decline at approximately 260.55 Ma, which was almost synchronized with the latest reported eruption ages of Emeishan Large Igneous Province. This coincidence suggests that global volcanic-tectonic activity during the Late Guadalupian might have been the important factor in carbon-cycle perturbation. Subsequently, the δ13Ccarb presents a rapid positive shift at approximately 259.4 Ma, and climate transformed from interglacial to P4 glacial, indicating that the climate rapidly cooled before the Emeishan LIP completely ended, which may be due to carbon sinks caused by weathering of mafic rocks, and may also be associated with a significant reduction in global volcanic activity. Accompanied by sudden weathering attenuation, the 87Sr/86Sr ratios show a significant increase instead from the previous long-time low value, which only can be explained reasonably by the rapid decline in mantle-derived Sr flux associated with the weakening of volcanic activity and mafic weathering. Intergrated geochemical indices in this interval shows that there is a rapid climate perturbation associated with a significant δ13Ccarb negative shift at approximately 260.55 Ma ∼ 259.10 Ma, which may be related to the eruption surge of the Emeishan LIP, active volcanic arcs, and triggered the end-Guadalupian biocrisis.

Carbon Cycle Perturbations and Environmental Change of the Middle Permian and Late Triassic paleo-Antarctic Circle

“…The Guadalupian (Middle Permian, ~262 Mya) mass extinction event is associated with a signi cant negative CIE of >-5 ‰ disrupting the otherwise positive carbon isotope trend in Mid-Permian sediments (cf. Wang et al, 2004;Isozaki et al, 2007aIsozaki et al, , 2007bLai et al, 2008;Wignall et al, 2009;Bond et al, 2010a;Detian et al, 2013;Shen et al, 2013;Zhang et al, 2020;Li et al, 2023). This event is typically interpreted to be associated with an overall climatic cooling, a drop in biological productivity both on land and in the oceans, and the demise of many photosynthetic marine taxa (Wang et al, 2004;Isozaki et al, 2007aIsozaki et al, , 2007bDetian et al, 2013;Nishikane et al, 2014), formation of ocean strati cation and anoxia (Saitoh et al, 2013;Zhang et al, 2015), sea-level change (Wang et al, 2004;Lai et al, 2008;Wei et al, 2018), and methane release (Retallack and Jahren, 2008;Bond et al, 2010b).…”