HR: 1340h
AN: U33A-0021    [Abstracts]
TI: Corrected Paleolatitudes for Pangea in the Early Mesozoic
AU: * Kent, D
EM: dvk@rci.rutgers.edu
AF: Rutgers University, Department of Geological Sciences, Piscataway, NJ 08854 United States
AU: * Kent, D
EM: dvk@rci.rutgers.edu
AF: Lamont-Doherty Earth Observatory, Paleomagnetics Lab, Palisades, NY 10964 United States
AU: Tauxe, L
EM: ltauxe@ucsd.edu
AF: Scripps Institution of Oceanography, Mailcode 0220, La Jolla, CA 92093-0220 United States
AB: A series of continental basins that developed during rifting of the Pangea supercontinent in the early Mesozoic are now distributed along the margins of the North Atlantic and their preserved contents (mainly redbeds and CAMP basalts) have often been targets of paleomagnetic studies. A continuous record of paleolatitudinal drift and a geomagnetic polarity time scale for ~35 Myr of the Late Triassic and earliest Jurassic have been derived from several of the basins in eastern North America and provide a precise spatio-temporal framework for detailed paleogeographic analysis. However, reported paleomagnetic directions from Jameson Land in East Greenland are anomalously shallow with respect to coeval sections in North America, a discrepancy that is too large to be explained by uncertainties in the reconstruction of Greenland to North America. Therefore, either the magnetizations of the Jameson Land (and perhaps other early Mesozoic rift basin) sediments are biased by inclination error or the Late Triassic time-averaged field included significant nondipole (axial octupole) contributions. According to a new statistical geomagnetic field model (Tauxe and Kent, 2004) constrained by paleomagnetic data from young lava flows, these two phenomena result in very different distributions of paleomagnetic directions, providing a basis to diagnose and correct for inclination error in sufficiently large paleomagnetic datasets. The resulting congruence of independent data from sedimentary and igneous rocks ranging over thousands of kilometers and 10s of millions of years can be taken as strong support that a geocentric axial dipole field similar to the last 5 Myr was operative more than 200 Myr ago. The corrected paleolatitudes indicate a faster rate of poleward motion of this sector of Pangea and broader continental climate belts in the Late Triassic and earliest Jurassic.
DE: 1520 Magnetostratigraphy
DE: 1522 Paleomagnetic secular variation
DE: 1527 Paleomagnetism applied to geologic processes
SC: Union [U]
MN: 2004 AGU Fall Meeting