Title
Laminated sediments from the central Peruvian continental slope: A 500 year record of upwelling system productivity, terrestrial runoff and redox conditions
Date Issued
01 October 2008
Access level
open access
Resource Type
journal article
Author(s)
Ortlieb L.
Boucher H.
Field D.
Vargas G.
Boussafir M.
Salvatteci R.
Ferreira V.
García M.
Valdés J.
Caquineau S.
Mandeng Yogo M.
Cetin F.
Solis J.
Soler P.
Baumgartner T.
Abstract
Sedimentological studies including X-ray digital analyses, mineralogy, inorganic contents, and organic geochemistry on cores of laminated sediments accumulated in the oxygen minimum zone of the central Peruvian margin reveal variable oceanographic and climate conditions during the last 500 yr. Coherent upcore variations in sedimentological and geochemical markers in box cores taken off Pisco (B0405-6) and Callao (B0405-13) indicate that variability in the climate proxies examined has regional significance. Most noteworthy is a large shift in proxies at ∼1820 AD, as determined by 210Pb and 14C radiometric dating. This shift is characterized by an increase in total organic carbon (TOC) in parallel with an abrupt increase in the enrichment factor for molybdenum Mo indicating a regional intensification of redox conditions, at least at the sediment water interface. In addition there was lower terrestrial input of quartz, feldspar and clays to the margin. Based on these results, we interpret that during several centuries prior to 1820, which corresponds to the little ice age (LIA), the northern Humboldt current region was less productive and experienced higher terrestrial input related to more humid conditions on the continent. These conditions were probably caused by a southward displacement of the inter-tropical convergence zone and the subtropical high pressure cell during the LIA. Since 1870, increases in TOC and terrigenous mineral fluxes suggest an increase of wind-driven upwelling and higher productivity. These conditions continued to intensify during the late 20th century, as shown by instrumental records of wind forcing. © 2008 Elsevier Ltd. All rights reserved.
Start page
190
End page
197
Volume
79
Issue
April 2
Language
English
OCDE Knowledge area
Ecología
Scopus EID
2-s2.0-54749147224
Source
Progress in Oceanography
ISSN of the container
00796611
Sponsor(s)
This study was supported by the IRD PALEOTROPIQUE research unit (UR 055) and the IMARPE PALEOMAP research program, as well as by the PALEOPECES project (IMARPE-IRD), the Inter-American Institute for Global Change Research - IAI small grant project SGP 211-222 (PI: D. Gutiérrez), the Humboldt current system program (ATI-IRD) and finally the PCCC project (French national research agency ANR, P.I. B. Dewitte). We thank the Instituto del Mar del Peru (IMARPE) for full support of this research and acknowledge the crew of the RV José Olaya Balandra and other scientific participants in the box-coring survey. Agence Nationale de la Recherche - ANR
Sources of information: Directorio de Producción Científica Scopus