EGU2020-11702
https://doi.org/10.5194/egusphere-egu2020-11702
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

How well is the deep Tore seamount basin ventilated?

Laura Antón1, Susana Lebreiro1, Silvia Nave2, Luke Skinner3, Elizabeth Michel4, Claire Waelbroeck4, and Francisco Sierro5
Laura Antón et al.
  • 1Instituto Geológico y Minero de España, Madrid, Spain (l.anton@igme.es)
  • 2Laboratorio Nacional Energia e Geologia, Alfragide, Portugal
  • 3Godwin Laboratory, University of Cambridge, Cambridge, United Kingdom
  • 4Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France
  • 5Department of Geology, University of Salamanca, Salamanca, Spain

The Last Glacial Maximum (LGM) was characterized by increased carbon storage in the deep ocean, as well as extremely poorly ventilated southern-sourced deep water (AABW) compared to northern-sourced deep water (NADW).

Here we analyse benthic (Cibicidoides wellerstorfi) d13C, and compare 3 sites sitting on the deep floor at 5 km water depth: MD13-3473 in the Tore inside basin; MD03-2698 in the Iberian margin; and TN057-21 in the South Atlantic. The Tore Seamount is a geological structure 300 km off the West Iberian margin at 40°N latitude. It has a crater-like morphology with a 5500 m deep basin in its middle, where calypso core MD13-3473 was collected, confined from the open ocean by a summit rim at 2200 m water depth (wd). The only connection between the deepest Tore Seamount basin and the Atlantic circulation is a NE gateway down to 4300 mwd.

The results for the LGM show similar values around -1.0 ‰ for the South Atlantic and the Iberian margin, in other words these sites were both bathed by AABW. However, the Tore basin record exhibits values around 0 ‰, similarly to open sites in the Iberian margin at 3.5 km depth. This seems to indicate a remarkable isolation of the Tore inside basin from the Atlantic deep bottom waters influence.

Among other things, we plan to examine the residence time of the Tore basin bottom water by measuring the radiocarbon age difference between benthic and planktonic foraminifera. 

Our results confer to this enclosed environment the status of an in-situ deep ocean laboratory where to test hypotheses of past ocean circulation changes like the role of deep waters in sequestering glacial CO2. Core MD13-3473 covers 430 thousands of years, therefore 5 deglacial cycles (Spanish project “TORE5deglaciations”, CTM2017-84113-R, 2018-2020).

How to cite: Antón, L., Lebreiro, S., Nave, S., Skinner, L., Michel, E., Waelbroeck, C., and Sierro, F.: How well is the deep Tore seamount basin ventilated?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11702, https://doi.org/10.5194/egusphere-egu2020-11702, 2020

This abstract will not be presented.