RT Journal Article
T1 Rapid warming and ostracods mass extinction at the Lower Toarcian (Jurassic) ofcentral Spain
A1 Gómez Fernández, Juan José
A1 Arias Fernández, María Del Carmen
AB Here we present the results of the study of two Lower Toarcian carbonate sections located in the IberianRange of central Spain. Analyses of stable isotope on belemnite calcite allowed calculation of seawaterpalaeotemperature variations, which were compared with the stratigraphical distribution of ostracods. Theseorganisms are particularly sensitive to ratios of temperature and salinity variations and hence are goodindicators of climate changes. From a cooling interval, with seawater temperatures of 13.2 °C recorded at thePliensbachian−Toarcian transition, seawater temperature began to rise in the lowermost ToarcianTenuicostatum Zone, reaching average temperatures between 14.6 °C and 16.3 °C during the time ofdeposition of this Zone. Coinciding with this seawater warming, up to 85% of the ostracods speciesprogressively disappeared during a period of approximately 300 kyr, marking the extinction interval. Theextinction boundary, located around the Tenuicostatum−Serpentinum zonal boundary, coincides with amarked increase in temperature in the Serpentinum Zone, on which average seawater temperatures of 22 °Chave been calculated. Warming continued through part of the Middle Toarcian Bifrons Zone, reachingaverage temperatures of 24.7 °C. Readjustment of the ostracod population allowed recovery of these faunasin the upper Serpentinum Zone, although the extinction of a major ostracod group, the healdioids, was alsorecorded. The correlation between mass extinction and warming infers a causal relationship. Comparison ofthe results with the records of stable isotopes in belemnites and in bulk carbonates, as well as TOC and faciesanalysis suggests that the anoxia linked to the Early Toarcian oceanic anoxic event was not the mainresponsible for the ostracod mass extinction.
PB Elsevier Science B.V., Amsterdam.
SN 0377-8398
YR 2010
FD 2010
LK https://hdl.handle.net/20.500.14352/44363
UL https://hdl.handle.net/20.500.14352/44363
LA eng
DS Docta Complutense
RD 10 abr 2025