Distribution and provenance of wind-blown SE Pacific surface sediments

Cornelia Saukel*, Frank Lamy, Jan Berend W. Stuut, Ralf Tiedemann, Christoph Vogt

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The reconstruction of low-latitude ocean-atmosphere interactions is one of the major issues of (paleo-)environmental studies. The trade winds, extending over 20° to 30° of latitude in both hemispheres, between the subtropical highs and the intertropical convergence zone, are major components of the atmospheric circulation and little is known about their long-term variability on geological time-scales, in particular in the Pacific sector. We present the modern spatial pattern of eolian-derived marine sediments in the eastern equatorial and subtropical Pacific (10°N to 25°S) as a reference data set for the interpretation of SE Pacific paleo-dust records. The terrigenous silt and clay fractions of 75 surface sediment samples have been investigated for their grain-size distribution and clay-mineral compositions, respectively, to identify their provenances and transport agents. Dust delivered to the southeast Pacific from the semi- to hyper-arid areas of Peru and Chile is rather fine-grained (4-8 Μm) due to low-level transport within the southeast trade winds. Nevertheless, wind is the dominant transport agent and eolian material is the dominant terrigenous component west of the Peru-Chile Trench south of ~. 5°S. Grain-size distributions alone are insufficient to identify the eolian signal in marine sediments due to authigenic particle formation on the sub-oceanic ridges and abundant volcanic glass around the Galapagos Islands. Together with the clay-mineral compositions of the clay fraction, we have identified the dust lobe extending from the coasts of Peru and Chile onto Galapagos Rise as well as across the equator into the doldrums. Illite is a very useful parameter to identify source areas of dust in this smectite-dominated study area.

Original languageEnglish
Pages (from-to)130-142
Number of pages13
JournalMarine Geology
Volume280
Issue number1-4
DOIs
Publication statusPublished - 15 Feb 2011

Funding

We thank R. Fröhlking and S. Wiebe (AWI) for technical support in the lab and Hannes Schmidt for the clay-mineral sample preparation. We also thank D. Heslop (University of Bremen) for analytical support. Thomas Laepple kindly provided his expertise plotting the NCEP data. Core-top samples were provided by the Marine Geology Repository at the Oregon State University. We thank Bobbi Conrad and Alan Mix for support during sampling. Gert-Jan Weltje is acknowledged for providing the end-member modeling algorithm. The German Science Foundation financed this study within the project Ti 240/17 (DFG) . Appendix A

Keywords

  • Clay-mineral assemblages
  • Eolian dust
  • Grain-size distribution
  • SE Pacific
  • Trade winds

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