MAGNETIC STRATIGRAPHY AND TECTONIC ROTATION OF THE MIDDLE EOCENE MATILIJA SANDSTONE AND COZY DELL SHALE, VENTURA COUNTY, CALIFORNIA - IMPLICATIONS FOR SEQUENCE STRATIGRAPHIC CORRELATIONS
Dr. Prothero et Jr. Britt, MAGNETIC STRATIGRAPHY AND TECTONIC ROTATION OF THE MIDDLE EOCENE MATILIJA SANDSTONE AND COZY DELL SHALE, VENTURA COUNTY, CALIFORNIA - IMPLICATIONS FOR SEQUENCE STRATIGRAPHIC CORRELATIONS, Earth and planetary science letters, 163(1-4), 1998, pp. 261-273
The Matilija Sandstone and Cozy Dell Shale in the western Transverse R
anges of California record a long history of Eocene regression from de
ep marine turbidites to non-marine red shales and then transgression t
o deep marine shales in a rapidly subsiding tectonic basin. In its typ
e area along the Ventura River north of Ojai, the Matilija Sandstone c
onsists of over 800 m of deep marine to non-marine sandstones, and the
Cozy Dell Shale contains over 760 m of deep marine shales and turbidi
te sandstones. Paleomagnetic sampling of these rocks yielded a stable
magnetic remanence which passed both a fold test and a reversal test;
some samples were reversed at NRM after dip correction. Based on calib
ration from planktonic microfossils, the Matilija Sandstone spans the
interval from Chron C21r to early Chron C20r (46.0-48.5 Ma), and the C
ozy Dell from late Chron C20r to C19r (46.0-42.0 Ma). The samples show
a tectonic rotation of approximately 85 +/- 18 degrees clockwise, con
sistent with previous results reported for this tectonic block. Previo
us sequence stratigraphic correlations of these rocks are inconsistent
with this chronostratigraphy. None of the sequence boundaries predict
ed from these sections matches the global sequence chart. (C) 1998 Els
evier Science B.V. All rights reserved.