Deep-dwelling foraminifera as thermocline temperature recorders

Caroline Cléroux (1, 2) , Elsa Cortijo (1, 2) , Jean-Claude Duplessy (1, 2) , Rainer Zahn (3)

1 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
2 PALEOCEAN - Paléocéanographie
3 ICREA - Institució Catalana de Recerca i Estudis Avançats = Catalan Institution for Research and Advanced Studies

[1] We measured the oxygen isotopic composition of the deep-dwelling foraminiferal species G. inflata, G. truncatulinoides dextral and sinistral, and P. obliquiloculata in 29 modern core tops raised from the North Atlantic Ocean. We compared calculated isotopic temperatures with atlas temperatures and defined ecological models for each species. G. inflata and G. truncatulinoides live preferentially at the base of the seasonal thermocline. Under temperature stress, i.e., when the base of the seasonal thermocline is warmer than 16°C, G. inflata and G. truncatulinoides live deeper in the main thermocline. P. obliquiloculata inhabits the seasonal thermocline in warm regions. We tested our model using 10 cores along the Mauritanian upwelling and show that the comparison of d 18 O variations registered by the surficial species G. ruber and G. bulloides and the deep-dwelling species G. inflata evidences significant glacial-interglacial shifts of the Mauritanian upwelling cells.

Mots clés: deep-dwelling foraminifera; depth habitat; isotopic temperature; thermocline; North Atlantic; Mauritanian upwelling

Domaines: Océan, Atmosphère; Interfaces continentales, environnement

Caroline Cléroux, Elsa Cortijo, Jean-Claude Duplessy, Rainer Zahn. Deep-dwelling foraminifera as thermocline temperature recorders. Geochemistry, Geophysics, Geosystems, 2007, 8 (4), pp.n/a-n/a. ⟨10.1029/2006GC001474⟩. ⟨hal-02958545⟩