Anisotropy of magnetic susceptibility in relation to source vents of ignimbrites: empirical observations

The anisotropy of magnetic susceptibility (AMS) of young undeformed ashflow deposits (e.g., Bishop Tuff, California; Bandlier Tuff, New Mexico) show a lignment of the maximum axis of magnetic susceptibility (K-max) with inferr ed flow lines. The sense of flow is deduced from the predominant plunge bia s of K-max axes. These principles are discussed in relation to four deforme d settings of ashflow deposits in the Great Basin of the western United Sta tes. The magnetic susceptibility data provide valuable, but not always unam biguous, insight into probable source areas. Various complications arise in interpreting the AMS data in terms of flow directions but these can be red uced by integration with geologic observations. (C) 1999 Elsevier Science B .V. All rights reserved.