Anisotropy of magnetic susceptibility (AMS) and anisotropy of remanent magnetization (ARM) data from Miocene ignimbrites, western Great Basin: A magnetic fabric study and comparison of magnetic fabric methods.

摘要

Magnetic fabric studies have become an integral part of any paleomagnetic investigation, and are especially pertinent to studies of ignimbrites, revealing inferred pyroclastic transport/source directions. Anisotropy of magnetic susceptibility (AMS) data were collected from regionally extensive ignimbrites in the southern Walker Lane area, including 226 sites in tuffs of the Timber Mountain Group, Tuff of Stonewall Flat, and Tuff of Mount Dunfee to infer local and regional transport/source directions based on imbrication fabrics. Anisotropy of remanent magnetization (ARM) data were obtained to refine the origin of AMS by isolating the ferro/ferrimagnetic minerals, and also to compare the fabric data for all anisotropy methods. Selected sites were analyzed to determine the effect of progressive alternating field (AF) demagnetization has on the magnetic fabric revealed by AMS on the ignimbrites.