GRAVITY AND MAGNETIC ANALYSIS OF THE MOUNT TAYLOR VOLCANIC FIELD, NEW MEXICO

The Mount Taylor volcanic field (MTVF) is one of several Cenozoic-aged volcanic fields that lie on the southern boundary of the Colorado Plateau. The 1.5 to 3.0 m.y. old MTVF covers approximately 1000 sq. km. near Grants, New Mexico and contains the composite volcano Mount Taylor and approximately 100 cinder cones and maars. Geochemical analyses indicate that the lavas are mostly mildly alkaline and were erupted from small, short-lived magma chambers. Even though the lavas have been characterized geochemically, no detailed study has been conducted on determining the number and volume of the magma chambers, and the role of regional structural trends on their location. To aid in determining these parameters, we conducted a detailed gravity and aeromagnetic analysis of the MTVF.

Available aeromagnetic and gravity data along with 119 newly collected gravity data points were merged into coherent data sets, gridded and contoured to produce complete Bouguer and residual magnetic intensity anomaly maps. These maps show that the most prominent anomalies are associated with latites erupted from Mount Taylor in the south-central portion of MTVF. These latites produce a large amplitude gravity minimum and magnetic maximum. The latites may extend up to 4 to 5 km based on 2-D forward modeling and may cover an larger area than is presently mapped. Smaller amplitude gravity and magnetic maxima and minima enhanced by wavelength filtering and edge-enhancement techniques indicate the possible existence of two to five additional magma chambers. 2-D modeling and map analyzes do not indicate the presence of a single large buried magma chamber that has been associated with nearby Cenozoic volcanic fields (e.g., Zuni, Springerville, San Francisco) but confirms geochemical studies that the lavas were erupted from multiple small magma chambers.