HR: 0800h
AN: GP41F-03    [Abstracts]
TI: High-Resolution Magnetostratigraphic and Rock Magnetic Cyclo-stratigraphic Study of the Eocene Arguis Formation, Spanish Pyrenees
AU: * Kodama, K P
EM: kpk0@lehigh.edu
AF: Lehigh University, Dept of Earth and Environmental Sciences, Bethlehem, PA 18015, United States
AU: Anastasio, D J
EM: dja2@lehigh.edu
AF: Lehigh University, Dept of Earth and Environmental Sciences, Bethlehem, PA 18015, United States
AU: Pares, J
EM: jmpares@umich.edu
AF: University of Michigan, Department of Geological Sciences, Ann Arbor, MI 48109, United States
AU: Newton, M `
EM: mikeynewton@gmail.com
AF: Lehigh University, Dept of Earth and Environmental Sciences, Bethlehem, PA 18015, United States
AB: In order to provide a high-resolution chronostratigraphic record, an 800 meter section of the Arguis Formation, an Eocene marine flysch deposited in the Jaca Basin of the Spanish Pyrenees was sampled for magnetostratigraphy and rock magnetic cyclo-stratigraphy. Oriented cores were collected to refine a previously determined magnetostratigraphy. Their paleomagnetic analysis shows that the oldest 600 meters of the Arguis Formation spans chrons C18n.1n to C17n.2n or about two million years. For 300 m of the section 395 un- oriented hand samples were collected for rock magnetic cyclo-stratigraphy at a 75 cm sampling interval (about every 4 kyr) in order to resolve the precessional index. Anhysteretic remanent magnetization (ARM) was measured for each sample to construct a ferromagnetic mineral concentration time series. Spectral analysis of the ARM time series, calibrated by the magnetostratigraphically-determined chron boundaries, shows periodicities consistent with astronomical forcing at Milankovitch frequencies. Decompaction of the time series using a newly developed rock magnetic technique removed the effects of differential compaction and improved the resolution of Milankovitch power. The time series was bandpass filtered and tuned to the precessional index using the La2004 orbital model. The precessional tuning improves spectral power at all orbital frequencies. Primary detrital magnetite controls the ARM signal with minor contributions from secondary authigenic pyrrhotite. The ferromagnetic mineral concentrations are most likely caused by climate-driven source area, runoff or aridity variations. They provide a high resolution (precessional scale) chronostratigraphic record that allows a detailed deformation rate study of a nearby growth fold.
DE: 1512 Environmental magnetism
DE: 1525 Paleomagnetism applied to tectonics: regional, global
DE: 1527 Paleomagnetism applied to geologic processes
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2007 Joint Assembly