Mediterranean outflow and surface water variability off southern Portugal during the early Pleistocene; a snapshot at Marine Isotope stages 29 to 34 (1020-1135 ka)

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doi: 10.1016/j.gloplacha.2015.08.015
Author(s): Voelker, Antje H. L.; Salgueiro, Emilia; Rodrigues, Teresa; Jiménez-Espejo, Francisco J.; Bahr, André; Alberto, Ana; Loureiro, Isabel; Padilha, Maria; Rebotim, Andreia; Röhl, Ursula
Author Affiliation(s): Primary:
Instituto Portugues do Mar e da Atmosfera, Divisao de Geologia e Georecursos Marinhos, Lisbon, Portugal
Other:
Japan Agency for Marine-Earth Science and Technology, Japan
Goethe University, Germany
University of Bremen, Germany
Volume Title: Global and Planetary Change
Source: Global and Planetary Change, Vol.133, p.223-237. Publisher: Elsevier, Amsterdam, Netherlands. ISSN: 0921-8181
Note: In English. 145 refs.; illus., incl. 2 tables
Summary: Centennial-to-millennial scale records from IODP Site U1387, drilled during IODP Expedition 339 into the Faro Drift at 558 m water depth, now allow evaluating the climatic history of the upper core of the Mediterranean Outflow (MOW) and of the surface waters in the northern Gulf of Cadiz during the early Pleistocene. This study focuses on the period from Marine Isotope Stages (MIS) 29 to 34, i.e. the interval surrounding extreme interglacial MIS 31. Conditions in the upper MOW reflect obliquity, precession and millennial-scale variations. The benthic δ18O signal follows obliquity with the exception of an additional, smaller δ18O peak that marks the MIS 32/31 transition. Insolation maxima (precession minima) led to poor ventilation and a sluggish upper MOW core, whereas insolation minima were associated with enhanced ventilation and often also increased bottom current velocity. Millennial-scale periods of colder sea-surface temperatures (SST) were associated with short-term maxima in flow velocity and better ventilation, reminiscent of conditions known from MIS 3. A prominent contourite layer, coinciding with insolation cycle 100, was formed during MIS 31 and represents one of the few contourites developing within an interglacial period. MIS 31 surface water conditions were characterized by an extended period (1065-1091 ka) of warm SST, but SST were not much warmer than during MIS 33. Interglacial to glacial transitions experienced 2 to 3 stadial/interstadial cycles, just like their mid-to-late Pleistocene counterparts. Glacial MIS 30 and 32 recorded periods of extremely cold (< 12 °C) SST that in their climatic impact were comparable with the Heinrich events of the mid and late Pleistocene. Glacial MIS 34, on the other hand, was a relative warm glacial period off southern Portugal. Overall, surface water and MOW conditions at Site U1387 show a strong congruence with Mediterranean climate, whereas millennial-scale variations are closely linked to North Atlantic circulation changes. Abstract Copyright (2015) Elsevier, B.V.
Year of Publication: 2015
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Assemblages; Atlantic Ocean; Cenozoic; Currents; Expedition 339; Foraminifera; Gulf of Cadiz; IODP Site U1387; Integrated Ocean Drilling Program; Invertebrata; Isotope ratios; Isotopes; Lower Pleistocene; Marine sediments; Mediterranean Outflow; Mediterranean Sea; Microfossils; North Atlantic; Northeast Atlantic; O-18/O-16; Ocean currents; Organic compounds; Oxygen; Paleoclimatology; Paleotemperature; Pleistocene; Protista; Quaternary; Sea-surface temperature; Sediments; Stable isotopes; West Mediterranean
Coordinates: N364819 N364820 W0074308 W0074308
Record ID: 2016037565
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands