HR: 14:45h
AN: PP53A-04    [Abstracts]
TI: The 8.2 ka event in Southwestern Mexico, what did really happen?
AU: * Bernal, J
EM: jpbernal@geologia.unam.mx
AF: Departamento de Geoquímica, Instituto de Geología, UNAM, Ciudad Universitaria, Coyoacan, Mexico City, DF 04510, Mexico
AU: Lachniet, M
EM: matthew.lachniet@unlv.edu
AF: Department of Geoscience, University of Nevada, Las Vegas, 4505 Maryland Parkway, Box 4010, Las Vegas, NV 89154, United States
AU: McCulloch, M
EM: malcolm.mcculloch@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Acton, Canberra, ACT 0200, Australia
AU: Mortimer, G
EM: graham.mortimer@anu.edu.au
AF: Research School of Earth Sciences, The Australian National University, Acton, Canberra, ACT 0200, Australia
AU: Morales, P
EM: pmorales@geologia.unam.mx
AF: Departamento de Geoquímica, Instituto de Geología, UNAM, Ciudad Universitaria, Coyoacan, Mexico City, DF 04510, Mexico
AU: Cienfuegos, E
EM: cienfuegos@servidor.unam.mx
AF: Departamento de Geoquímica, Instituto de Geología, UNAM, Ciudad Universitaria, Coyoacan, Mexico City, DF 04510, Mexico
AB: The 8.2 ka cooling event is the most important climate anomaly occurring during the Holocene. First detected in Greenland ice-cores and lasting approximately 160 years, its expression has been detected mostly in the Atlantic Ocean and the Caribbean Sea. However, there is little evidence of the effects that the climate anomaly may have had elsewhere. Here we present a U/Th dated stalagmite from "Cueva del Diablo", Guerrero State (southwestern Mexico) that grew between 11.11 ± 0.32 and 4.5 ± 0.18 ka B.P., has been analyzed for variations in trace elements, Sr/Ca, Mg/Ca, Ba/Ca, U/Ca ratios, δ¹⁸O and δ¹³C with decadal to semi-decadal age resolution depending on the growth rate. A peak in the Sr/Ca and δ¹³C at the onset of the 8.2 ka event, followed by a hiatus indicates that massive outflow of freshwater to the North Atlantic, resulted in arid conditions for Soutwestern Mexico. These were most likely the result from a southward migration of the ITCZ, and a temporal reorganization of the major features of atmospheric circulation in the area.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1635 Oceans (1616, 3305, 4215, 4513)
DE: 3309 Climatology (1616, 1620, 3305, 4215, 8408)
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly