MAGNETIC FABRICS AS INDICATORS OF MAGMA FLOW AND EMPLACEMENT MECHANISMS FOR THE SPANISH PEAKS IGNEOUS COMPLEX (SOUTH-CENTRAL COLORADO)

Dike exposure patterns of the late Eocene to mid-Miocene Spanish Peaks igneous complex, northernmost Raton Basin, correspond with temporal, spatial, chemical and thickness variations. The volcanic center includes a northern radial dike swarm (Silver Mountain), a set of N80E trending dikes, ten's of kilometers in length, radial dikes centered on the Spanish Peaks intrusions and a set of dikes, sills and stocks aligned with tilted strata along the eastern Sangre de Cristo Mountains. Magnetic fabric data (produced by, and used as a proxy for, the direction and sense of magma flow) have been obtained from 77 of 85 sites collected using anisotropy of magnetic susceptibility (AMS) methods. A total of 65 sites yield internally consistent and interpretable results. Of these, 43 sites were collected from the Spanish Peaks radial dike swarm, 13 from N80E trending dikes, 3 from Silver Mountain and the remaining 6 sites from dikes, sills and stocks parallel to the Sangre de Cristo Mountains. Dike emplacement studies using AMS data typically assume that K1 (maximum susceptibility for the AMS ellipsoid where K3