Abstract of paper presented at American Geophysical Union 1985 Fall Meeting, San Francisco, California.
Trans. American Geophysical Union (Eos), v. 66, p. 876.

Paleomagnetism of upper Precambrian through Middle Cambrian sedimentary rocks from the Nopah Range, SE California

S. L. Gillett, Woodinville, WA
J. L. Kirschvink, California Institute of Technology, Pasadena, CA
D. R. Van Alstine, Z-Axis Exploration, Pleasant Hill, CA
R. E. Lewis, Shell Oil Co., Houston, TX
E. M. Shoemaker, U. S. Geological Survey, Flagstaff, AZ

Miogeoclinal sedimentary rocks spanning the Cambrian-Precambrian boundary yield diverse, multicomponent magnetizations that mostly appear to reflect remagnetization. A steep, northwesterly secondary magnetization present in most units was probably imposed on slightly dipping beds in the mid-Tertiary during early Basin and Range uplift. The Middle Cambrian Jangle Limestone Member of the Carrara Fm. yields a southerly, low-inclination magnetization that probably resides in magnetite and represents a viscous partial thermoremanent magnetization imposed on nearly flat-lying rocks during Permian or Triassic uplift. A poorly defined, directionally similar magnetization residing in hematite, present in the Lower Cambrian Wood Canyon Fm., probably also reflects Permo-Triassic remagnetization, in this case resulting from later recrystallization of the hematite. A similar hematite-borne magnetization also seems to be present in red siltstones of the upper Precambrian Stirling Quartzite, which underlies the Wood Canyon.

The carbonate-rich middle part of the Rainstorm Member of the upper Precambrian Johnnie Fm. yields a diffuse, two-polarity, roughly east-west characteristic magnetization probably residing in specular hematite. This magnetization may be a penecontemporaneous detrital remanent magnetization; if so, little tectonic rotation with respect to the Desert Range of southern Nevada, where the Rainstorm Member had previously been sampled, has occurred. With the Desert Range results, the Rainstorm yields a late Precambrian paleomagnetic north pole at 11° S, 163° E, in general agreement with other reported poles of this age from North America.