HR: 1330h
AN: PP23B-06    [Abstracts]
TI: Mid-Late Holocene Climate and Ocean Variability Recorded in Laminated Sediments of the Bay of La Paz, Gulf of California.
AU: * Perez-Cruz, L
EM: perezcruz@geofisica.unam.mx
AF: National University of Mexico, Instituto de Geofisica, UNAM D. Coyoacan, Mexico, DF 04510 Mexico
AB: Alfonso Basin in the Bay of La Paz contains a sedimentary record ideal for paleoclimate studies because regional -and global- scale climate signals are preserved in its laminated sediments. A sequence of these sediments is analysed in order to reconstruct the climatic and oceanographic variability in the southern part of the Gulf of California, and to provide a climate scenario that would reproduce global paleoclimate patterns in the mid-late Holocene. 14C AMS dating performed on three core intervals determine the chronstratigraphic framework for the last 8000 cal yrs BP. The assemblages of radiolarians are examined in order to supply a tool for deciphering paleoceanographic and paleoclimatic conditions. The records suggest that in the period from 7,800 to 2,700 cal yr BP, dry climatic conditions prevailed with high evaporation that promoted the formation of the Gulf of California Water (GCW). In the interval between 2,700 to 450 cal yr BP the environment of the Bay was warm, dominated by the Equatorial Surface Water (ESW). Several significant millenary-scale cooling events were recognized at 6100, 3600, 3000 and 1400 cal yr BP. In addition, magnetic susceptibility measurements reveal significant terrigeneous input at 7900, 5700, 1700 and 1400 cal yr BP. A 2000 year climatic change cycle was identified, associated to changes in solar activity.
DE: 2162 Solar cycle variations (7536)
DE: 3022 Marine sediments--processes and transport
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2005 Joint Assembly