Connection between North America and the Gulf of Mexico during the last climatic cycle: Evidence from terrigenous sediments of the northern Gulf of Mexico

• Main Author: Sionneau, Thomas
• Other Authors: Géosystèmes - UMR 8157, Université de Lille, Sciences et Technologies-Centre National de la Recherche Scientifique (CNRS), Université des Sciences et Technologie de Lille - Lille I, Viviane Bout-Roumazeilles([e-mail])
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2008
• Subjects: last climatic cycle; meltwater pulse; Laurentide Ice Sheet; clay minerals; Orca Basin; Mississippi River; Basin 4; dernier cycle climatique; décharge d'eau de fonte; calotte glaciaire Laurentide; minéralogie des argiles; Bassin d'Orca; Mississippi; Bassin 4; [SDU.STU.MI]Sciences of the Universe [physics]/Earth Sciences/Mineralogy; Ice Sheet; Orca; Planktonic foraminifera
• Online Access: https://theses.hal.science/tel-00366377; https://theses.hal.science/tel-00366377/document; https://theses.hal.science/tel-00366377/file/These_TSionneau.pdf

The Gulf of Mexico (GOM) is a key area for the global thermohaline circulation (THC) and for the global climatic system, since its hydrological characteristics (high salinity and temperature) partly control Gulf Stream physical properties. During the last climatic cycle, GOM hydrology was impacted by episodic freshwater inputs via the Mississippi River resulting from intermittent melting of the Laurentide Ice Sheet (LIS). The resulting salinity changes affected the THC, global heat exchange and worldwide climatic conditions. Direct effects of these freshwater supplies on the GOM paleoceanography have been documented studying the planktonic foraminifera d18O evolution. By contrast, terrigenous inputs associated with these meltwater pulses are poorly understood. These detrital fractions are, however, likely to provide information on the link between continental and marine records during the last climatic cycle. An overview of the main continental detrital source areas, of the dominant factors controlling clay mineral transport patterns (by drawing clay mineral distribution maps in the US and northern GOM) and of thin terrigenous particle sedimentation in the GOM (by analogical modelling), lays the groundwork for the use of clay-mineral assemblages for understanding the connection between North America and the GOM. The downcore investigations of sedimentary (clay mineralogy, grain-size.) and isotopic (d18O) records in two mini-basins of the GOM (Orca Basin and Basin 4) allow us to explain the fluvial inputs variations, during the last climatic cycle, by paleoenvironmental (ice meltback) and paleoclimatic (atmospheric circulation) fluctuations that affected North America. Les eaux du Golfe du Mexique (GOM) jouent un rôle important dans le système climatique global car elles influencent les propriétés hydrologiques du Gulf Stream (GS), courant océanique chaud de surface faisant partie intégrante de la circulation thermohaline (THC). Or, au cours du dernier cycle climatique, d'importantes arrivées d'eau douce en ...