Atmosphere-ocean linkages in the eastern Equatorial Pacific over the early Pleistocene

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doi: 10.1002/2015PA002883
Author(s): Povea, Patricia; Cacho, Isabel; Moreno, Ana; Pena, Leopoldo D.; Menéndez, Melisa; Calvo, Eva; Canals, Miquel; Robinson, Rebecca S.; Méndez, Fernando J.; Flores, Jose-Abel
Author Affiliation(s): Primary:
Universitat de Barcelona, Departament de Dinamica de la Terra i de l'Ocea, Barcelona, Spain
Other:
Pyrenean Institute of Ecology, Spain
Universidad de Cantabria, Spain
Consejo Superior de Investigaciones Cientificas, Spain
University of Rhode Island, United States
University of Salamanca, Spain
Volume Title: Paleoceanography
Source: Paleoceanography, 31(5), p.522-538. Publisher: American Geophysical Union, Washington, DC, United States. ISSN: 0883-8305 CODEN: POCGEP
Note: In English. 99 refs.; illus., incl. 1 table, sketch map
Summary: Here we present a new set of high-resolution early Pleistocene records from the eastern equatorial Pacific (EEP). Sediment composition from Ocean Drilling Program Sites 1240 and 1238 is used to reconstruct past changes in the atmosphere-ocean system. Particularly remarkable is the presence of laminated diatom oozes (LDOs) during glacial periods between 1.85 and 2.25 Ma coinciding with high fluxes of opal and total organic carbon. Relatively low lithic particles (coarse and poorly sorted) and iron fluxes during these glacial periods indicate that the increased diatom productivity did not result from dust-stimulated fertilization events. We argue that glacial fertilization occurred through the advection of nutrient-rich waters from the Southern Ocean. In contrast, glacial periods after 1.85 Ma are characterized by enhanced dust transport of finer lithic particles acting as a new source of nutrients in the EEP. The benthic ecosystem shows dissimilar responses to the high productivity recorded during glacial periods before and after 1.85 Ma, which suggests that the transport processes delivering organic matter to the deep sea also changed. Different depositional processes are interpreted to be the result of two distinct glacial positions of the Intertropical Convergence Zone (ITCZ). Before 1.85 Ma, the ITCZ was above the equator, with weak local winds and enhanced wet deposition of dust. After 1.85 Ma, the glacial ITCZ was displaced northward, thus bringing stronger winds and stimulating upwelling in the EEP. The glacial period at 1.65 Ma with the most intense LDOs supports a rapid southward migration of the ITCZ comparable to those glacial periods before 1.85 Ma. Abstract Copyright (2016), . American Geophysical Union. All Rights Reserved.
Year of Publication: 2016
Research Program: ODP Ocean Drilling Program
Key Words: 02 Geochemistry; 24 Surficial Geology, Quaternary Geology; Algae; Atmosphere; Atmospheric transport; Buliminacea; Carnegie Ridge; Cenozoic; Chemostratigraphy; Clastic sediments; Diatoms; East Pacific; Equatorial Pacific; Foraminifera; Framework silicates; Grain size; Invertebrata; Iron; Isotope ratios; Isotopes; Leg 202; Lower Pleistocene; Marine environment; Marine sediments; Metals; Microfossils; Mineral composition; Nitrogen; O-18/O-16; ODP Site 1238; ODP Site 1240; Ocean Drilling Program; Ooze; Opal; Organic compounds; Oxygen; Pacific Ocean; Paleo-oceanography; Paleoecology; Paleoenvironment; Panama Basin; Plantae; Pleistocene; Productivity; Protista; Quaternary; Rotaliina; Sediments; Silica minerals; Silicates; South Pacific; Southeast Pacific; Spectra; Stable isotopes; Total organic carbon; Transport; Uvigerina; Uvigerinidae; X-ray fluorescence spectra
Coordinates: N000100 N000100 W0822800 W0822800
S015200 S015200 W0824700 W0824700
Record ID: 2016063081
Copyright Information: GeoRef, Copyright 2017 American Geosciences Institute. Reference includes data from John Wiley & Sons, Chichester, United Kingdom