HR: 1400h
AN: PP43C-14    [Abstracts]
TI: Paleoclimatic changes between ca.2 and 27 ka cal BP derived from lacustrine sediments of Laguna San Felipe, Sonoran Desert, NW Mexico
AU: * Roy, P D
EM: p_debajyotiroy@yahoo.com, pdroy@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autónoma de Mexico, Ciudad Universitaria, Mexico City, 04510, Mexico
AU: * Roy, P D
EM: p_debajyotiroy@yahoo.com, pdroy@geofisica.unam.mx
AF: Centro de Investigaciones en Ciencias de la Tierra, Universidad Autónoma del Estado de Hidalgo, Cuidad Universitaria, Pachuca, 42184, Mexico
AU: Ortega, B
EM: bortega@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autónoma de Mexico, Ciudad Universitaria, Mexico City, 04510, Mexico
AU: Caballero, M
EM: maga@geofisica.unam.mx
AF: Instituto de Geofisica, Universidad Nacional Autónoma de Mexico, Ciudad Universitaria, Mexico City, 04510, Mexico
AU: Lozano, R
EM: tpuig@geologia.unam.mx
AF: Instituto de Geologia, Universidad Nacional Autónome de Mexico, Mexico City, 04510, Mexico
AU: Pi, T
EM: tpuig@geologia.unam.mx
AF: Instituto de Geologia, Universidad Nacional Autónome de Mexico, Mexico City, 04510, Mexico
AB: Laguna San Felipe (115° 15' W, 31° 08' N) is located in the western part of the Sonoran Desert (rainfall 100-200 mm/yr), NW Mexico. Multi-proxy analysis in the upper 5.6 m sediments from a 9.5 m core of the laguna, including sedimentology, mineralogy, multiple element geochemistry, C_org, diatoms and mineral magnetism, were performed to document the late Quaternary climatic changes of the Sonoran Desert. AMS ¹⁴C ages constrained the sediment profile between ca.2 ka cal BP and ca.27 ka cal BP. The distribution of mineralogy, major and trace elements and magnetic susceptibility along the sedimentary sequence document the varying terrigenous influx, chemical weathering, precipitation/evaporation and hence climatic changes during last glacial-post glacial transition. The phases of higher evaporation in the basin and lower chemical weathering in the catchments indicate dry conditions during ca.27-14.5 ka cal BP, ca.13-12 ka cal BP and ca.7 ka cal BP. During these arid phases, the higher influx of both quartz and zircon into the basin could be due to the increased aeolian activity in the surroundings of the laguna. The phases of higher chemical weathering suggest that the laguna received higher inflow during ca.14-13 ka cal BP, ca.12-8.5 ka cal BP and ca.6-3 ka cal BP. During these phases, the preservation of C_org indicates anoxic condition and hence relatively high lake stand for part of the year.
DE: 1051 Sedimentary geochemistry
DE: 1105 Quaternary geochronology
DE: 4914 Continental climate records
DE: 9350 North America
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Joint Assembly