Climate changes in south western Iberia and Mediterranean Outflow variations during two contrasting cycles of the last 1 myrs; MIS 31-MIS 30 and MIS 12-MIS 11

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doi: 10.1016/j.gloplacha.2015.11.006
Author(s): Sánchez Goñi, Maria Fernanda; Llave, E.; Oliveira, Dulce; Naughton, F.; Desprat, Stéphanie; Ducassou, E.; Hodell, D. A.; Hernández Molina, F. J.
Author Affiliation(s): Primary:
Université de Bordeaux, Ecole Pratique des Hautes Etudes, Pessac, France
Other:
Instituto Geológico y Minero de España, Spain
Instituto Portugues do Mar e da Atmosfera, Portugal
Center of Marine Sciences, Portugal
University of Cambridge, United Kingdom
University of London, United Kingdom
Volume Title: Global and Planetary Change
Source: Global and Planetary Change, Vol.136, p.18-29. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0921-8181
Note: In English. 70 refs.; illus., incl. 1 table, sketch map
Summary: Grain size analysis and physical properties of Sites U1388, U1389 and U1390 collected in the Contourite Depositional System of the Gulf of Cadiz during the Integrated Ocean Drilling Program (IODP) Expedition 339 "Mediterranean Outflow" reveal relative changes in bottom current strength, a tracer of the dynamics of the Mediterranean Outflow Water (MOW), before and after the Middle Pleistocene Transition (MPT). The comparison of MOW behavior with climate changes identified by the pollen analysis and δ18O benthic foraminifera measurements of Site U1385, the Shackleton Site, collected in the south western Iberian margin shows that the interval MIS 31-MIS 30, ∼ 1.1-1.05 million years ago (Ma), before the MPT, was marked by wetter climate and weaker bottom current than the interval MIS 12-MIS 11 (0.47-0.39 Ma), after the MPT. Similarly, the increase in fine particles from these glacials to interglacials and in coarse fraction from interglacials to glacials was coeval with forest and semi-desert expansions, respectively, indicating the lowering/enhancement of MOW strength during periods of regional increase/decrease of moisture. While these findings may not necessarily apply to all glacial/interglacial cycles, they nonetheless serve as excellent supporting examples of the hypothesis that aridification can serve as a good tracer for MOW intensity. The strongest regional aridity during MIS 12 coincides with a remarkable increase of coarse grain size deposition and distribution that we interpret as a maximum in MOW strength. This MOW intensification may have pre-conditioned the North Atlantic by increasing salinity, thereby triggering the strong resumption of the Meridional Overturning Circulation that could contribute to the great warmth that characterizes the MIS 11c super-interglacial. Abstract Copyright (2016) Elsevier, B.V.
Year of Publication: 2016
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Assemblages; Atlantic Ocean; Cenozoic; Climate change; Cyclic processes; Europe; Expedition 339; Granulometry; Gulf of Cadiz; IODP Site U1388; IODP Site U1389; IODP Site U1390; Iberian Peninsula; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; MIS 11; MIS 12; MIS 30; MIS 31; Marine sediments; Mediterranean Outflow; Mediterranean Sea; Microfossils; Miospores; North Atlantic; Northeast Atlantic; O-18/O-16; Oxygen; Paleo-oceanography; Paleoclimatology; Palynomorphs; Plantae; Pleistocene; Pollen; Quaternary; Sedimentology; Sediments; Southern Europe; Spectra; Stable isotopes; Strait of Gibraltar; West Mediterranean; X-ray fluorescence spectra
Coordinates: N361902 N361909 W0074304 W0092405
N353000 N370000 W0060000 W0090000
Record ID: 2016089143
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands