Geophysical Surveys near Chino Valley, Arizona

Abstract

Four different geophysical methods were used near Chino Valley, Arizona in order to map a suspected andesite intrusive, identified as plug 15, which had originally been found using aeromagnetic data already acquired over the area. Magnetic, transient electromagnetic, seismic, and gravity measurements were collected between 3/1/2003-3/2/2003 and 3/22/2003-3/23/2003. The surveys were located near the center of section 35, township 17 North, Range 2 West, just north of Chino Valley, AZ. The magnetic and TEM surveys provided the best indication of the location and depth of the plug. The north-south spatial extent of the plug was estimated to be approximately 600 meters. The depth to the top of the plug was found from the TEM survey to be approximately 300 meters at the center of the survey. The seismic survey did not reach deep enough to find the andesite anomaly and the gravity survey did not appear to be affected by the plug. Magnetic, TEM, and seismic surveys were also performed at another site located approximately 1.25 km northeast of plug 15. The seismic survey did not reach deep enough and the magnetic survey was too short to provide a depth interpretation. The single TEM sounding measured a very high resistivity (approximately 900 ohm-m) at this site.