Short-lived U- and Th-series isotopes: Tracers and chronometers of Earth surface processes though Anthropocene to global change time frames

• Autores: Claude Hillaire-Marcel
• Localización: Mudanças em Sistemas Ambientais e sua Expressão Temporal: Livro de Resumos da IX Reunião do Quaternário Ibérico / Ana Gomes (ed. lit.), Célia Gonçalves (ed. lit.), Lino André (ed. lit.), Nuno Bicho (ed. lit.), T. Boski (ed. lit.), 2017, págs. 14-15
• Idioma: inglés
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• Resumen

  • A large array of short-lived natural U and Th-series isotopes are useful tools for the documenting of recent to on-going geochemical and sedimentological processes as well as for the calculation of geochemical fluxes between reservoirs (e.g., 226Ra, 210Pb, 210Po, 228Ra, 228Th, 234Th, with time scales ranging from ~ 103 to days). In combination with longer-lived U-series isotopes (238U, 234U, 230Th, 231Pa) and nuclear fallout isotopes (e.g.,137Cs, 241Pu...), they may be used for estimating the behavior and fluxes of aerosols, soil evolution and weathering processes (106 Ma to the above time scales), particulate and coloidal transport in continental and marine waters, as well as for the documenting of extreme events (floods, storminess, etc.) and more generally, the fate of sediments in rivers, lakes and the marine realm (from accumulation rates to ongoing sedimentological processes). Applications in the domains of hydrothermal systems and of volcanology are also of importance. Examples illustrating the use of a few of the above isotopes for the documenting of Earth Surface processes from the Anthropocene (sensu lato) including the present global change context, will be discussed, with a focus on short-lived isotopes of the U and Th-series. They include (i) dowscaling through time-dependent processes in soils, (ii) the monitoring of geochemical properties of recent lava flows, (iii) evolution of hydrothermal systems, (iv) the recording of extreme events in estuarine and costal areas.