Rapid bottom-water circulation changes during the last glacial cycle in the coastal low-latitude NE Atlantic

Autor: Francisca Martínez-Ruiz, Barbara Donner, David Gallego-Torres, Oscar E Romero, Jung-Hyun Kim, Miguel Ortega-Huertas
Rok vydání: 2014
Předmět:
Zdroj: Quaternary Research. 81:330-338
ISSN: 1096-0287
0033-5894
DOI: 10.1016/j.yqres.2013.11.004
Popis: Previous paleoceanographic studies along the NW African margin focused on the dynamics of surface and intermediate waters, whereas little attention has been devoted to deep-water masses. Currently, these deep waters consist mainly of North Atlantic Deep Waters as part of the Atlantic Meridional Overturning Circulation (AMOC). However, this configuration was altered during periods of AMOC collapse. We present a high-resolution reconstruction of bottom-water ventilation and current evolution off Mauritania from the last glacial maximum into the early Holocene. Applying redox proxies (Mo, U and Mn) measured on sediments from off Mauritania, we describe changes in deep-water oxygenation and we infer the evolution of deep-water conditions during millennial-scale climate/oceanographic events in the area. The second half of Heinrich Event 1 and the Younger Dryas were recognized as periods of reduced ventilation, coinciding with events of AMOC reduction. We propose that these weakening circulation events induced deficient deep-water oxygenation in the Mauritanian upwelling region, which together with increased productivity promoted reducing conditions and enhanced organic-matter preservation. This is the first time the effect of AMOC collapse in the area is described at high resolution, broadening the knowledge on basin-wide oceanographic changes associated with rapid climate variability during the last deglaciation.
Databáze: OpenAIRE
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