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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2018-396
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2018-396
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 11 Sep 2018

Submitted as: research article | 11 Sep 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Reconstructing past variations in environmental conditions and paleoproductivity over the last ~ 8000 years off Central Chile (30° S)

Práxedes Muñoz1,2, Lorena Rebolledo3,4, Laurent Dezileau5, Antonio Maldonado2, Christoph Mayr6,7, Paola Cárdenas4,8, Carina B. Lange4,9,10, Katherine Lalangui9, Gloria Sanchez11, Marco Salamanca9, Karen Araya1,5, Ignacio Jara2, Gabriel Vargas12, and Marcel Ramos1,2 Práxedes Muñoz et al.
  • 1Departamento de Biología Marina, Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile
  • 2Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo-La Serena, Chile
  • 3Departamento Científico, Instituto Antártico Chileno, Punta Arenas, Chile
  • 4Centro FONDAP de Investigación Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Campus Isla Teja, Valdivia, Chile
  • 5Laboratoire Géosciences Montpellier (GM), Université de Montpellier, 34095 Montpellier Cedex 05, France
  • 6Institut für Geographie, FAU Erlangen-Nürnberg, 91058 Erlangen, Germany
  • 7Department of Earth and Environmental Sciences & GeoBio-Center, LMU Munich, 80333 Munich
  • 8Programa Magister en Oceanografía, Universidad de Concepción, casilla 160C, Concepción, Chile
  • 9Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Casilla 160C, Concepción, Chile
  • 10Centro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Casilla 160C, Concepción, Chile
  • 11Universidad de Magallanes, Punta Arenas, Chile
  • 12Departamento de Geología, Universidad de Chile, Santiago, Chile

Abstract. This study aims at establishing past variations of the main oceanographic and climatic features in the Central Chilean coast, using recent sedimentary records of a transitional semi-arid ecosystem susceptible to environmental forcing conditions. Coquimbo (30° S) region is characterized by dry summers and short rainfall periods during winter. The relatively wet-winter climate results from the interactions between the southern westerly winds and the South Pacific Anticyclone (SPA); in summer, the SPA moves southwards while in winter it returns to the north, allowing the passage of storm fronts. This semi-arid zone is strongly affected by variations associated with El Niño-Southern Oscillation (ENSO), caused by seasonal latitudinal changes in the SPA that produce high variability and precipitation in Chilean mid-latitudes. Sediment cores were retrieved in two bays, Guanaqueros and Tongoy, for geochemical analyses including: sensitive redox trace elements, biogenic opal, total organic carbon (TOC), diatoms, stable isotopes of organic carbon and nitrogen. The results suggest a main dry phase of high primary productivity concomitant with high fluxes of organic compounds to the bottom and suboxic-anoxic conditions in the sediments. This period reached a maximum at cal BC ~ 4500, followed by a continuous increase in wet conditions, low primary productivity and a more oxygenated environment towards the present, being remarkably stronger in the last 2000 years. We suggest that this might be associated with greater El Niño frequencies or similar conditions that increase precipitation, concomitantly with the introduction of oxygenated waters to coastal zones by the propagation of equatorial origin waves.

Práxedes Muñoz et al.
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Status: final response (author comments only)
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Práxedes Muñoz et al.
Práxedes Muñoz et al.
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