Salvatteci R. auteur aut IRD Field D. auteur aut IRD Sifeddine Abdelfettah auteur aut IRD Ortlieb Luc auteur aut IRD Ferreira V. auteur aut IRD Baumgartner T. auteur aut IRD Caquineau Sandrine auteur aut IRD Velazco F. auteur aut IRD Reyss J. L. auteur aut IRD Sanchez-Cabeza J. A. auteur aut IRD Gutierrez D. auteur aut IRD text journalArticle eng text/pdf born digital access Marine laminated sediments in dysoxic areas of the ocean floor are an excellent archive for high-resolution climate reconstructions. While the existence of discontinuities produced by natural events, such as underwater landslides (slumps), strong bottom currents, and/or bioturbation is usually acknowledged for long records, the extent of their influence on high-resolution sequences is usually not considered. In the present work we show strong evidence for multiple stratigraphic discontinuities in different gravity and box-cores retrieved off Pisco (Peru) covering the last 600 years. Chronostratigraphies are largely based on cross-correlation of distinct sedimentary structures (determined by X-ray image analysis) and validated using Pb-210, Am-241, and C-14 profiles, as well as proxy records. The cross-correlation of distinct stratigraphic layers allows for chronostratigraphic tie points and clearly shows that some sedimentary sequences are continuous across scales of tens of kilometers, indicating that regional processes often determine laminae formation. Some differences in laminae thickness were found among cores, which could be explained by different sedimentation rates, spatially variable deposition of diatom blooms, changes in silica dissolution and partial deposition/erosion caused by bottom currents. Using multiple stratigraphic tie points provides clear evidence for laminated sequences present in some cores to be missing in other cores. Moreover, instantaneous depositions from upslope were identified in all the cores disrupting the continuity of the sediment records. These discontinuities (instantaneous deposits and missing sequences) may be due to slumps, possibly triggered by earthquakes and/or erosion by strong bottom currents. In spite of the missing sequences in some cores, a continuous composite record of the last six centuries was reconstructed from spliced sequences of the different cores, which provides a well-constrained temporal framework to develop further high-resolution proxies in this region. The present work shows that paleoreconstructions developed from single cores, particularly in areas with strong seismic activity and/or strong bottom currents, are subject to both temporal gaps and instantaneous depositions from upslope, both of which could be misinterpreted as abrupt climate changes or anomalous climate events. We stress the need for multiple cores to determine the stratigraphic continuity and chronologies for high-resolution records. specialized high-resolution records laminated sediments hiatus slumps cross-correlation composite record PEROU 064 357 72-89 2014 0025-3227 https://www.documentation.ird.fr/hor/fdi:010063607 10.1016/j.margeo.2014.07.008 0025-3227 [F B010063607] https://www.documentation.ird.fr/hor/fdi:010063607 https://www.documentation.ird.fr/intranet/publi/2015/01/010063607.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2015-02-02 2017-08-23 fdi:010063607 fre