Evolution of the Galicia Interior Basin over the last 60 ka: sedimentary processes and palaeoceanographic implications

• Published in: Journal of quaternary science Vol. 33; no. 5; pp. 536 - 549
• Main Authors: Mena, Anxo, Francés, Guillermo, Pérez‐Arlucea, Marta, Hanebuth, Till J. J., Bender, Vera B., Nombela, Miguel A.
• Format: Journal Article
• Language: English
• Published: Chichester Wiley Subscription Services, Inc 01.07.2018
• Subjects: Bottom currents; Climate change; Cores; Deep sea sediments; Dislocation; Dislocations; Evolution; Galicia Interior Basin; Glacial periods; Gravity; Gyres; Heinrich events; Holocene; late Pleistocene; Ocean currents; Ocean floor; Pleistocene; Sea currents; Sea level changes; sedimentary processes; Sedimentation; Sedimentation & deposition; Sedimentation rates; Sediments; Stratigraphy; Surface currents; Surface water; Variation
• ISSN: 0267-8179; 1099-1417
• DOI: 10.1002/jqs.3032

ABSTRACT The Galicia Interior Basin (GIB; NW Iberian Peninsula) is located near a critical transition between the subtropical (temperate) and subpolar (cold) gyres of the North Atlantic. It therefore witnesses oceanographic changes driven by global climatic events. This study reports on the recent (latest Pleistocene) sedimentary, palaeoceanographic and palaeoclimatic history of the basin. We integrated analysis of deep‐sea sediment cores retrieved from an E–W transect across the GIB. The analysis indicated three types of sedimentary processes recording glacial (Marine Isotope Stage 2–4) and deglacial events: along‐slope bottom currents (forming contourite deposits), pelagic and hemipelagic sedimentation, and gravitational dislocation. Variation in depositional patterns and sedimentation rates indicate distinctive transport (along‐slope and down‐slope) and depositional processes. These in turn reflect climatic and oceanographic drivers. We interpret changes in sea level from core evidence showing changes in sediment supply. The cores exhibited conspicuous sedimentary evidence of Heinrich events (HEs). The stratigraphic intervals associated with HEs showed significant lateral variation. We suggest that the lateral variation may result from the development of an oceanographic boundary between surface water masses with different temperature and salinity parameters or changes in surface currents which may have introduced relatively warmer water into the GIB during the last glacial period.