Changes in precipitation regimes over North America during the Holocene as recorded by mineralogy and geochemistry of Gulf of Mexico sediments

Jean Carlos Montero-Serrano (1) , Viviane Bout‑roumazeilles (2) , Thomas Sionneau (1, 3) , Nicolas Tribovillard , Aloys Bory (1) , Benjamin P Flower (4) , Armelle Riboulleau (1) , Philippe Martinez (5) , Isabelle Billy (1)

1 Géosystèmes - UMR 8157
2 LOG - Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187
3 IUEM - Institut Universitaire Européen de la Mer
4 College of Marine Science [St Petersburg, FL]
5 EPOC - Environnements et Paléoenvironnements OCéaniques

Changes in terrigenous-transfer patterns from North America toward the Gulf of Mexico via the Mississippi River during the Holocene were investigated using mineralogical and geochemical records from the northern Gulf of Mexico (Pigmy Basin). Clay mineralogy (smectite/illite + chlorite) and geochemical signatures (K and Ti intensities) indicate fluctuations in the detrital sedimentation during the Holocene in the Pigmy Basin. They likely reflect alternations between at least two dominant terrigenous sources: the smectite-rich NW Mississippi watershed, and the illite-and chlorite-rich Great Lakes province and NE Mississippi watershed. These recurring and rapid modifications of erosional processes over this period suggest changes in the hydrological regime via rainfall patterns. Such a modification during the Holocene is likely linked with the rapid atmospheric reorganization following the final collapse of the Laurentide Ice Sheet. Indeed, mineralogical and geochemical proxies indicate east-to-west migrations of the main detrital source (from the Great Lakes and northeastern province toward the northwestern province) associated with Mississippi River megaflood episodes. These modifications of the main detrital sources likely record migrations of the precipitation belt, which are constrained by atmospheric configuration (Jet Stream, Bermuda High and Intertropical Convergence Zone position) and subtropical oceanic hydrological properties (meridional extension of the Atlantic Warm Pool). In the frame of previously published rainfall patterns over the Caribbean and North America, our results highlight some marked modifications of moisture transfer throughout the Holocene. These changes are interpreted as resulting from two atmospheric configurations that have driven alternately the precipitation distribution over North America for the last 10 ka with an apparent cyclicity of~2.5 ka. The coherent common cyclicity between the Gulf of Mexico detrital parameters and Greenland atmospheric proxies over the Holocene suggests that the initial external forcing was rapidly transferred latitudinally through atmospheric processes.

Mots clés: Pigmy Basin; Mississippi River; Holocene; atmospheric configuration; clay mineralogy; geochemistry; Pigmy Basin

Domaines: Géochimie; Minéralogie; Climatologie

Jean Carlos Montero-Serrano, Viviane Bout‑roumazeilles, Thomas Sionneau, Nicolas Tribovillard, Aloys Bory, et al.. Changes in precipitation regimes over North America during the Holocene as recorded by mineralogy and geochemistry of Gulf of Mexico sediments. Global and Planetary Change, 2010, 74 (3-4), pp.132 - 143. ⟨10.1016/j.gloplacha.2010.09.004⟩. ⟨hal-03280609⟩