Magnetic Properties of the Taiguati Formation, Bolivia

Measurements have been made of the magnetic properties of samples of red sandstone of the Taiguati formation from near Santa Cruz, Bolivia; the rocks possess a stable remanent magnetization with normal and reversed polarities. With the exception of intensity of natural magnetization, the magnetic properties correlate well with the content of ferric oxide in the samples, both the red pigment and black iron oxide particles contributing to these properties. Chemical demagnetization provides evidence that the natural remanence is carried by the red pigment; the pigment is also the dominant form of iron oxide in the samples. Estimates are made of the magnitude of the magnetic properties of the black and red forms of ferric oxide in the rocks, using both chemical and ultrasonic separation of the constituents. The bearing of the experimental results on the geological and magnetic history of the formation is discussed.