MARINE OXYGENATION PULSES DURING LATE DEVONIAN FRASNIAN-FAMENNIAN TRANSITION:EVIDENCE FROM CE ANOMALY RECORD FROM THE DONGCUN SECTION,SOUTH CHINA
The Frasnian/Famennian(F-F)extinction occurred in the Late Devonian is one of the five major extinction events in the Phanerozoic,the event is generally linked to global marine deoxygenation.In this study,a new redox proxy(sensitive rare element Ce anomaly)was used to reconstruct the paleo-redox conditions during the F-F transition in the Dongcun Section,South China.Results show that ocean oxygenation rather than anoxia as previously thought coincide with two positive carbon isotope excursions during the F-F interval.This observation combined with previous data from South China suggests that climate cooling may play a more important role in driving environmental fluctuations during the F-F transition.The cooler climate could increase the dissolved oxygen concentration in seawater,resulting in the enhancement of seawater temperature gradient between the equator and the polar regions.This process could accelerate ocean circulation and overturning enhancing regional upwelling,later promoting the transport of nutrients from deep-water to the ocean surface,stimulating the marine productivity in surface water and organic carbon burial fluxes,and consequently resulting in δ13Ccarb positive excursions.This study supported the idea that global cooling rather than ocean deoxygenation was the major cause for the F-F mass extinction event.
F-F mass extinctionglobal coolingmarine oxygenationcarbon isotopesrare earth elementsCe anomaly
NETL
NSTL
万方数据
维普
