High-resolution stratigraphy of the Mediterranean outflow contourite system in the Gulf o Cadiz during the Late Pleistocene: the impact of Henrich events

Llave, E., Schönfeld, Joachim, Hernández-Molina, F.J., Mulder, T., Somoza, L., Díaz del Río, V. and Sánchez-Almazo, I. (2006) High-resolution stratigraphy of the Mediterranean outflow contourite system in the Gulf o Cadiz during the Late Pleistocene: the impact of Henrich events Marine Geology, 227 . pp. 241-262. DOI 10.1016/j.margeo.2005.11.015.

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Abstract

A detailed, high-resolution stratigraphic analysis of the Mediterranean Outflow contourite system at the continental slope of the
Gulf of Cadiz has been carried out through the correlation between a dense network of seismic reflection profiles (sparker, airgun,
3.75 kHz and parametric echosounder — TOPAS), Calypso giant piston and standard gravity cores. From such correlation we
determine a stacking pattern constituted by four main seismic units (a–d) that are internally structured into ten subunits. Each
subunit shows a single sequence formed by transparent seismic facies at the base to smooth, parallel reflectors of moderate to high
amplitude facies at the top, being well correlated in the cores with a coarsening-upward sequence. The latest Pleistocene–Holocene
deposits form glacial/interglacial depositional sequences related to cycles with a frequency range below the Milankovitch band that
corresponds to millennial timescale climatic changes such as Dansgaard–Oeschger (1.5 ka) and Bond Cycles (10–15 ka). Oxygen
isotope records of planktonic foraminifera and the occurrence of ice-rafted debris (IRD) in the most recent contourite subunits show
clear evidence of the influence of the North Atlantic climatic conditions, especially the climatic Heinrich events (H) in the slope
sedimentation of the Gulf of Cadiz and then in the circulation of the Mediterranean Outflow Water (MOW). The coarser contourite
deposits are mostly associated with the Last Glacial Maximum, Younger Dryas and Heinrich events on the central area of the
middle slope. During globally cooler conditions, the MOW was denser so that it was more active in deeper areas than today. On the
other hand, during warm periods the MOW became less dense favoring an increased intensity of the MOWon the distal area of the
upper slope. Therefore, spatial and vertical fluctuations of the MOW contourite system are strongly affected by global climate and
oceanographic changes, being clearly influenced by iceberg discharges and probably also, by the resumption of thermohaline
circulation in the North Atlantic Ocean during ice melting periods.

Document Type: Article
Keywords: Gulf of Cadiz; contourite deposits; Late Pleistocene; paleoclimate changes; Heinrich events; Mediterranean Outflow Water; paleoceanography
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
DOI etc.: 10.1016/j.margeo.2005.11.015
ISSN: 0025-3227
Projects: FADO, TASYO, GADES, MVSEIS, MOUNDFORCE
Date Deposited: 03 Dec 2008 16:52
Last Modified: 04 Aug 2017 07:47
URI: http://eprints.uni-kiel.de/id/eprint/4575

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