Quantifying the seasonal variations in fluvial and eolian sources of terrigenous material to Cariaco Basin,Venezuela |
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| Authors: | Aurora C Elmore Robert C Thunell Richard Styles David Black Richard W Murray Nahysa Martinez Yrene Astor |
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| Institution: | 1. School of Environmental Sciences, University of Liverpool, Liverpool, L69 7ZT, UK;2. Division of Polar Climate Research, Korea Polar Research Institute, Get-pearl Tower, South Korea;3. School of Ocean Sciences, University of Wales, Bangor, UK;1. CERAFRI — Center of Research and Advanced Education for Hydrogeological Risk Prevention, Retignano di Stazzema (Lu), Italy;2. Department of Civil and Environmental Engineering, University of Florence, Italy;3. Department of Earth Sciences, University of Florence, Italy;1. Department of Oceanography and Coastal Sciences, Louisiana State University, 1002-Y Energy, Coast & Environment Building, Baton Rouge, LA 70803, USA;2. Center for Computation and Technology, Louisiana State University, 340 E Parker Blvd, Baton Rouge, LA 70803, USA;3. Department of Earth and Environment, Boston University, 675 Commonwealth Avenue, Boston, MA 02215, USA;1. Department of Earth and Environmental Studies, Montclair State University, NJ 07043, USA;2. Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA 70803, USA;3. Center for Computation and Technology, Louisiana State University, Baton Rouge, LA 70803, USA |
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| Abstract: | The varved sediments that accumulate in the Cariaco Basin provide a detailed archive of the region’s climatic history, including a record of the quantity of fluvial and wind-transported material. In this study, we examine the sedimentological characteristics (clay mineralogy and grain size) of both surface sediments and sinking lithogenic material collected from sediment trap samples over a three-year period from 1997 to 2000. Data from biweekly sediment trap samples show a tri-modal particle size distribution, with prominent peaks at 2, 22 and 80 μm, indicating sediment contributions from both eolian and fluvial sources. The clay mineralogy of the water column samples collected from 1997 to 1999 also shows distinctive characteristics of eolian and fluvial material. An examination of surface sediment samples from the Cariaco Basin indicates that the Unare River is the main source of riverine sediments to the eastern sub-basin. By combining these sedimentological proxies, we estimate that ～10% of the terrigenous material delivered to the Cariaco Basin is eolian, while ～90% is fluvial. This represents an annual dust accumulation rate of ～0.59 mg/cm2/yr. Since aerosols are closely linked to climate variability, the ability to quantify paleo-dust fluxes using sedimentological characteristics will be a useful tool for future paleoclimate studies looking at sub-Saharan aridity and latitudinal migration of the Intertropical Convergence Zone. |
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