PALEOMAGNETISM OF LATE MESOZOIC ROCKS IN NORTHERN CALIFORNIA: STRUCTURAL SIGNIFICANCE.
Final rept., pt. 3, Jul 63-Dec 64,
CALIFORNIA UNIV BERKELEY DEPT OF GEOLOGY AND GEOPHYSICS
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Directions of natural remanent magnetization have been determined at ten sites in the late Jurassic Guadalupe igneous complex and Bucks Lake batholith in the western Sierra Nevada, California. Paleomagnetic pole positions from these two plutons agree with one another and with other late Jurassic and Cretaceous poles from North America. These plutons, which are located 150 miles apart, have therefore been little affected by later tectonic events. The pole positions are preliminary only, and may be subject to slight modification after removal of secondary components of NRM by a.c. demagnetization of all specimens. One or more geomagnetic field reversals appear to be recorded in the Bucks Lake batholith, but possibly the NRM in titanohematite in both the plutons has been self-reversed. Igneous rocks of the Franciscan Formation in Marin County have provided a pole position which is greatly discordant to those mentioned this discordance may be due to tectonic deformation or possibly to anomalous geomagnetic variation. Author
- Geology, Geochemistry and Mineralogy