Paleomagnetism of the Front Range (Colorado) Morrison Formation and an alternative model of Late Jurassic North American apparent polar wander

Journal Article · Sun Mar 01 04:00:00 EST 1992 · Geology; (United States)

DOI:https://doi.org/10.1130/0091-7613(1992)020<0223:POTFRC>2.3.CO;2· OSTI ID:7202157

Fossen, M.C. Van; Kent, D V ^[1]

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1. Columbia Univ., Palisades, NY (United States)

A paleomagnetic study of the Upper Jurassic Morrison Formation in the Front Range of central Colorado yields high-unblocking-temperature, dual-polarity magnetizations. With respect to known paleohorizontal, the inclinations (absolute mean = 57.3{degree}, 95% confidence interval = 52.3{degree} to 63.1{degree}, N = 8 sites) pass tilt and reversal tests, whereas the dispersion in declinations can be attributed to apparent or real tectonic rotations and sedimentary processes. The site-centered colatitudinal locus of possible Front Range Morrison poles partially overlaps the 'upper' pole, but it excludes the 'lower' pole from the Morrison Formation on the Colorado Plateau as well as the 151 Ma Glance conglomerate pole from the Basin and Range province of southeastern Arizona. The authors offer various explanations for these disparities and suggest an alternative model of Late Jurassic North American apparent polar wander through {approximately}70{degree}N which is supported by Late Jurassic European poles (with positive stability tests) transferred to North American coordinates.

• OSTI ID: 7202157
• Journal Information: Geology; (United States), Journal Name: Geology; (United States) Vol. 20:3; ISSN GLGYB; ISSN 0091-7613
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
COLORADO
COORDINATES
DATA COVARIANCES
DEVELOPED COUNTRIES
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOMAGNETIC COORDINATES
GEOMAGNETIC FIELD
INCLINATION
JURASSIC PERIOD
MAGNETIC FIELDS
MAGNETISM
MESOZOIC ERA
NORTH AMERICA
PALEOMAGNETISM
ROCKS
SEDIMENTARY ROCKS
SHALES
USA