Studies of sedimentary organic matter to infer rapid climatic changes at the barents and iberian continental margins on centennial time resolution over the past four climate cycles of the quaternary (ca.420,000 years)

• Autores: Belen Martrat Sotil
• Directores de la Tesis: Joan Grimalt Obrador (dir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2007
• Idioma: español
• Tribunal Calificador de la Tesis: Francesc Xavier de las Heras Cisa (presid.), Romà Tauler Ferré (secret.), Polychronis Constantinos Tzedakis (voc.), María Ángeles Bárcena Pernía (voc.), Jordi Agustí i Ballester (voc.)
• Materias:
  • Ciencias de la tierra y del espacio
    • Climatología
      • Paleoclimatología
    • Geoquímica
      • Geoquímica orgánica
    • Geología
      • Estratigrafía
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• Resumen

  • A number of essential elements closely related to each other are involved in the Earth's climatic system. The temporal and spatial distribution of insolation determines wind patterns and the ocean's thermohaline pump. In turn, these last two are directly linked to the extension and retreat of marine and continental ice and to the chemistry of the atmosphere and the ocean. The variability of these elements may trigger, amplify, sustain or globalize rapid climatic changes. Paleoclimatic oscillations have been identified in this thesis by using fossil organic compounds synthesized by marine and terrestrial flora. High sedimentation rate deposits at the Barents and the Iberian peninsula continental margins were chosen in order to estimate the climatic changes on centennial time resolution. At the Barents margin, the sediment recovered was up to 15,000 years old (a) (M23258; west of the Bjørnøya island). At the Iberian margin, the sediment cores studied covered a wide range of time spans: up to 115,000 a (MD99-2343; north of the Minorca island), up to 250,000 a (ODP-977A; Alboran basin) and up to 420,000 a (MD01-2442, MD01-2443, MD01-2444, MD01-2445; close to the Tagus abyssal plain). At the northern site, inputs containing marine, continental and ancient reworked organic matter provided a detailed reconstruction of climate history at the time of the final retreat of the Barents ice sheet. At the western Barents continental slope, warm climatic conditions were observed during the early Holocene (~from 8,650 a to 5,240 a ago); in contrast, an apparent long-term cooling trend occurred in the late Holocene (~from 5,240 a to 760 a ago), in consistence with other paleoarchives from northern and southern European latitudes. The Iberian margin sites, which were never covered with large ice sheets, preserved exceptionally complete sequences of rapid events during ice ages hitherto not studied in such great detail: during the last glacial (~from 70,900 a to 11,800 a ago), the