HR: 09:20h
AN: GP41B-04    [Abstracts]
TI: Environmental Magnetism Study in Zirahuen Lake, Michoacan, Central Mexico
AU: * Ortega, B
EM: bortega@geofisica.unam.mx
AF: Universidad Nacional A. de Mexico Instituto de Geofisica, Cd. Universitaria, Mexico, DF 04510 Mexico
AU: Peralta, R
EM: ivxa@yahoo.com.mx
AF: UNAM Posgrado de Ciencias del Mar y Limnologia, Cd. Universitaria, Mexico, DF 04510 Mexico
AU: Israde, I
EM: aisrade@zeus.umich.mx
AF: Universidad Michoacana SNH Dept. Geologia, Cd. Universitaria, Morelia, Mic 58000 Mexico
AB: In Michoacan area major civilizations developed in a time of climatic shifts and volcanic activity, as the historically emplaced Jorullo (1759 AD) and Paricutin (1942 AD) volcanoes. Research in the central-western Mexico, has pointed several uncertainties and difficulties in paleoclimatic reconstructions for periods between the late glacial and the mid Holocene. Rock-magnetism data and non magnetic parameters are combined in order to provide insights in the environmental history for the last ca. 14 kyr in Zirahuen basin, Michoacan, Mexico (19.4° N, 101.7° W). A core 6.5 m long was collected in the shallow NE part of Zirahuen lake. Three main zones reflect major changes in environmental conditions. Sediments older than 10.3 kyr, have low concentration of ferrimagnetic minerals. Between 10.3 to 4 kyr, a hiatus occurred. For the mid and late Holocene sediments, the data suggests higher catchment erosion. A period of relative catchment stability is recorded in 630-1200 AD, followed by a return to previous conditions.
DE: 1512 Environmental magnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2005 Joint Assembly