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Reconstruction of past climates from sedimentary biomarkers. Ancient molecules for past climate reconstructions: a large field of application for spectroscopic methods.

Abstract : Although we have now a better picture of past climates, there are still numerous questions that remain unsolved. These uncertainties primarily arise from the possible human impact on climate dynamics, the need to assess feedbacks from the biosphere and to better understand and anticipate natural variability of climate (forcing mechanisms, time lags...). In order to record past climatic and environmental changes, numerous tools have been applied to multiple records. The direct interpretation of these data in terms of climatic parameters is sometimes questionable and strengthens the necessity for more accurate paleodata from sedimentary archives. Sedimentary organic matter is a renewing target for paleoclimate information because it derives from living organisms that are sensible to environmental changes and its complexity promises a virtually infinite source of information. In order to access this information at a molecular or isotopic level, the organic geochemist must now use a large panel of spectroscopic tools (GC-MS, HPLC-MS and GC-IRMS). I will here present some recent advances in the field of molecular and compound-specific isotopes applications to paleoclimate reconstructions. So as to estimate the impact of climatic changes on the ecosystems, paleoflora can be deciphered from the occurrence, in the sediments, of taxon-specific molecules. Similarly, the physico-chemical conditions that prevailed at time of deposition of the sediment are accessible by the study of diagenetic by-products, derived from the alteration of biomolecules. Other molecules are produced by organisms as a response to the variations of environmental/climatic parameters. Their identification and quantitation in sediments can be used as a proxy of these parameters. Finally, the recent development of compound-specific isotope techniques allows measuring the isotopic composition (ΔD, Δ13C, 15N...) of single molecules, therefore affording a better constrain on the significance of isotopic signatures.
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Conference papers
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Submitted on : Tuesday, May 2, 2006 - 1:55:54 PM
Last modification on : Monday, October 19, 2020 - 2:34:03 PM

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  • HAL Id : hal-00023602, version 1

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Jérémy Jacob, Jean-Robert Disnar, Yongsong Huang, Mohammed Boussafir, Abdelfettah Sifeddine, et al.. Reconstruction of past climates from sedimentary biomarkers. Ancient molecules for past climate reconstructions: a large field of application for spectroscopic methods.. 21e Congrès de la Société Française de Spectrométrie de Masse, 2004, Strasbourg, France. ⟨hal-00023602⟩

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