Paleomagnetic results from the Upper Cretaceous Maudlow and Livingston Formations, southwest Montana

Journal Article · Sat Jul 01 00:00:00 EDT 1989 · Geophysical Research Letters (American Geophysical Union); (USA)

DOI:https://doi.org/10.1029/GL016i007p00669· OSTI ID:5599175

Swenson, P; McWilliams, M ^[1]

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1. Stanford Univ., CA (USA)

A paleomagnetic investigation of welded tuff units was undertaken to refine the Late Cretaceous to Paleocene apparent polar wander path (APWP) for cratonic North America. The Maudlow Formation yields a paleomagnetic pole at 70{degree}N, 208{degree}E. Tectonic correction improves the directional grouping. Two normal polarity intervals bounding a single reversed polarity interval are present. The authors interpret the reversed interval to be Chron 33r, on the basis of: (1) stratigraphic correlation of the Maudlow Formation with the Campanian Sedan Formation located 40 km to the east, and (2) K-Ar dates of 83 {plus minus} 2 Ma at the middle of the sampled section and 74.9 {plus minus} 1 Ma near the top of the sampled section. The Livingston Formation yields a high H{sub c} magnetization with a negative fold test, suggesting a post-folding secondary magnetization. The Livingston mean direction yields a paleomagnetic pole at 72{degree}N, 218{degree}E. Neither the Maudlow Formation pole nor the pole derived from the Livingston Formation agree with previously published poles for either the Late Cretaceous or Tertiary but they do lie on a simple continuation of the APWP between Late Cretaceous and Paleocene mean poles. Secondary magnetizations found in the Franciscan Complex of California also yield poles which lie on a proposed extension of the APWP. If the Franciscan secondary poles represent an overprint event associated with early Tertiary accretion, and if the Livingston secondary pole represents a deformational event related to Laramide uplift of the nearby Beartooth Range, then together these poles suggest that the North American APWP may continue farther to the east and south to define a Cretaceous-Tertiary cusp.

• OSTI ID: 5599175
• Journal Information: Geophysical Research Letters (American Geophysical Union); (USA), Vol. 16:7; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
GEOLOGIC FORMATIONS
PALEOMAGNETISM
MONTANA
AGE ESTIMATION
ARGON ISOTOPES
CRETACEOUS PERIOD
GEOLOGIC MODELS
GEOMAGNETIC COORDINATES
GEOMAGNETIC FIELD
ISOTOPE DATING
MAGNETIZATION
POTASSIUM ISOTOPES
STRATIGRAPHY
TECTONICS
TERTIARY PERIOD
TUFF
ALKALI METAL ISOTOPES
CENOZOIC ERA
COORDINATES
DEVELOPED COUNTRIES
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGY
ISOTOPES
MAGNETIC FIELDS
MAGNETISM
MESOZOIC ERA
NORTH AMERICA
USA
580000* - Geosciences