Title
Latitudinal variability of preserved sedimentary organic matter along the Peruvian continental margin as inferred from petrographic and geochemical properties
Date Issued
20 September 2021
Access level
open access
Resource Type
journal article
Author(s)
Igarza M.
Boussafir M.
Valdés J.
Publisher(s)
Elsevier B.V.
Abstract
Processes controlling preservation and accumulation of organic matter (OM) in marine sediments are highly sensitive towards both natural and anthropogenic impacts. Thus, the sedimentary OM is considered a key proxy for the characterization of recent and past sedimentary environments. Along the Peruvian continental margin (PCM), high primary production and an intense oxygen minimum zone (OMZ) favor the accumulation and preservation of OM in sediments. Spatial variations in oceanographic conditions impact on both productivity and the redox conditions, in particular the OMZ intensity. These factors in turn lead to spatial differences in depositional conditions and OM accumulation and preservation. Therefore, this study aims at characterizing nature and types of recent sedimentary OM along the PCM covering a wide latitudinal and bathymetric range. With this purpose, a total of 29 surface sediment samples were collected from Tumbes (3°S) to San Juan (15°S) and analyzed by means of organic petrography (palynofacies analysis) and Rock-Eval pyrolysis. Results allowed characterizing the OM from recent sediments. Along the PCM, the sedimentary OM is predominantly amorphous, revealing its overwhelming marine origin. The highest abundances of gelified amorphous OM, total organic carbon, S1 and S2 Rock-Eval fractions occurred towards the southern part of the study area, especially off Callao (12°S) and Pisco (14°S), considered important upwelling and primary productivity centers. A principal component analysis performed allowed the description of main OM depositional environments. In the outer continental shelf of Callao (12°S) and OMZ of Pisco (14°S), accumulation of well-preserved OM occurs whereas in the inner shelf of Callao redox oscillations lead to less OM accumulation and pyrite formation in sediments. North of Callao, from Tumbes (3°S) to Huacho (11°S), a mixed signal of OM accumulation was observed. Finally, along the slope, transportation processes seem to play a key role in OM accumulation. This study also allowed the evaluation of certain proxies (e.g. Rock-Eval hydrogen index and oxygen index) routinely used in palaeoceanographic studies.
Volume
235
Language
English
OCDE Knowledge area
Ecología
Subjects
Scopus EID
2-s2.0-85110138716
Source
Marine Chemistry
ISSN of the container
03044203
Sponsor(s)
This work was supported by the Peruvian National Council of Science and Technology (Contrato No. 223-2010-CONCYTEC-OAJ) through a fellowship awarded to M. Igarza to perform her master studies in Marine Science at Universidad Peruana Cayetano Heredia (UPCH).We would like to thank the Institut de Recherche pour le Développement (IRD) and the Institut de Sciences de la Terre d'Orléans (ISTO) that made possible, through its projects LMI PALEOTRACES and PROSUR, the four months internship of M. Igarza to perform all geochemical analyses. J. Valdés was supported by MINEDUC-UA grant, ANT 1855. We also thank the Laboratory of Marine Benthos from the Instituto del Mar del Perú (IMARPE) for providing background data of bottom water oxygenation. We would also like to thank the crew of the RV Meteor, RV Galathea and RV José Olaya Balandra for their help in sample collection. Finally, we would like to thank the two anonymous reviewers whose comments greatly helped to improve the quality of the present research article.
This work was supported by the Peruvian National Council of Science and Technology (Contrato No. 223-2010-CONCYTEC-OAJ ) through a fellowship awarded to M. Igarza to perform her master studies in Marine Science at Universidad Peruana Cayetano Heredia (UPCH).
We would like to thank the Institut de Recherche pour le Développement (IRD) and the Institut de Sciences de la Terre d'Orléans (ISTO) that made possible, through its projects LMI PALEOTRACES and PROSUR, the four months internship of M. Igarza to perform all geochemical analyses. J. Valdés was supported by MINEDUC-UA grant, ANT 1855 .
Sources of information:
Directorio de Producción Científica
Scopus