Southern-ocean and glaciogenic nutrients control diatom export production on the Chile margin

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doi: 10.1016/j.quascirev.2014.06.015
Author(s): Chase, Zanna; McManus, James; Mix, Alan C.; Muratli, Jesse
Author Affiliation(s): Primary:
University of Tasmania, Institute for Marine and Antarctic Studies, Hobart, Tasmania, Australia
Oregon State University, United States
Volume Title: Quaternary Science Reviews
Source: Quaternary Science Reviews, Vol.99, p.135-145. Publisher: Elsevier, International. ISSN: 0277-3791
Note: In English. 70 refs.; illus., incl. 1 table, sketch map
Summary: Biogenic particle flux was reconstructed using 230-Thorium normalization at two sites on the southern Chile margin. ODP Site 1233 at 41°S, 838 m depth, is at the southern limit of the Peru-Chile upwelling system, where the northern extent of the Antarctic Circumpolar Current impinges on the South American continental margin. ODP Site 1234, at 36°S, 1014 m depth, is located within the core of the coastal upwelling system near the mouths of the Bio Bio and Itata Rivers. At 41°S, opal, lithogenic and carbonate fluxes are greatest during the Last Glacial interval (26-20 ka), carbonate has a secondary peak during the mid Holocene (∼8 ka) and organic carbon fluxes increase slightly from 17 ka to the present. At 36°S, large lithogenic fluxes are observed both during the Last Glacial interval and the Holocene, and a maximum in organic carbon flux is observed during the late Holocene (∼5 ka) without an accompanying peak in opal flux. These reconstructed fluxes at 36°S and 41°S fit within a larger latitudinal pattern of a poleward increase in the magnitude of opal flux during the glacial period. The pattern of normalized opal flux, opal mass accumulation rate and opal:carbonate ratios is consistent with either i) enhanced supply of Si from the Southern Ocean, as proposed by the Silicic Acid Leakage Hypothesis or ii) enhanced Si and Fe delivery from land, driven by glacial erosion. The pattern of reconstructed export production supports our view that the appearance of more reducing conditions in the sediments upon deglaciation was most likely driven by decreased ventilation, rather than increased local productivity. Abstract Copyright (2014) Elsevier, B.V.
Year of Publication: 2014
Research Program: ODP Ocean Drilling Program
Key Words: 24 Surficial Geology, Quaternary Geology; Actinides; Carbonates; Cenozoic; Chemostratigraphy; Chile; Cores; East Pacific; Framework silicates; Holocene; Isotope ratios; Isotopes; Leg 202; Lithostratigraphy; Marine sedimentation; Marine sediments; Metals; ODP Site 1233; ODP Site 1234; Ocean Drilling Program; Opal; Pacific Ocean; Paleo-oceanography; Pleistocene; Productivity; Quaternary; Radioactive isotopes; Reconstruction; Sedimentation; Sediments; Silica minerals; Silicates; South America; South Pacific; Southeast Pacific; Terrigenous materials; Th-230; Thorium; U-238/U-234; Upper Pleistocene; Uranium
Coordinates: S410000 S410000 W0742700 W0742700
S361300 S361300 W0734100 W0734100
Record ID: 2015009328
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from CAPCAS, Elsevier Scientific Publishers, Amsterdam, Netherlands