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Communication Dans Un Congrès Année : 2011

On the need for using multiple cores for developing a robust chronostratigraphy in a seismically active mud lens off Peru

Résumé

Marine laminated sediments that accumulate over time on the ocean floor are an excellent tool to study past climate variability at high temporal resolution. While the existence of discontinuities produced by natural events such as strong bottom currents, bioturbation or lateral depositions are acknowledged, particularly for long records, the extent of their influence on high-resolution sequences has not been well documented. In the present work we show widespread evidence for stratigraphic discontinuities from multiple gravity and box-cores retrieved off Pisco (Peru). Chronostratigraphies are largely based on cross-correlation of distinct sedimentary structures (determined by x-ray image analysis). The visual cross-correlations were validated using 210-Pb, 241-Am, and 14-C profiles, as well as proxy records. The cross-correlation of distinct stratigraphic layers clearly shows that some sedimentary sequences are continuous across scales of tens of kilometers, indicating regional processes determine laminae formation. However, there are often notable absences of laminated sequences in some cores that are present in other cores. The lack of some laminae is likely due to erosion caused by a slump. Despite the losses of sedimentary structures a continuous composite record of the last several centuries was assembled from spliced sequences of different cores. This composite record provides a well constrained temporal framework to develop further high resolution proxies in this highly productive region. However, proxy records developed from single cores will be subject to temporal gaps.
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Dates et versions

hal-00909854 , version 1 (27-11-2013)

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Renato Salvatteci, David Field, Dimitri Gutiérrez, Abdel Sifeddine, Tim R. Baumgartner, et al.. On the need for using multiple cores for developing a robust chronostratigraphy in a seismically active mud lens off Peru. American Geophysical Union, Fall Meeting 2011, Dec 2011, San Francisco, United States. pp.1804. ⟨hal-00909854⟩
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