Near-surface Geophysical Imaging of Complex Structures: Meteor Crater, AZ and Jemez Pueblo, NM

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2013-05

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Abstract

This work is the culmination of two independent but related projects regarding the near-surface. The first involves a geophysical examination of Barringer Meteorite Crater (a.k.a. Meteor Crater) in northern Arizona. The objective, to obtain ground-truth data to better characterize the subsurface, was accomplished via a 660 m 2-D seismic line and several potential field surveys. The reflection seismic results, although lacking in vertical resolution, indicate several prominent horizons and possible faults. A tomographic inversion of the refraction data reveals a complex near-surface velocity structure that is in agreement with a faulted subsurface. Forward models based on the gravity and magnetic surveys were created and complement the seismic findings—they too indicate a possible fault at 250 m along the seismic survey and suggest the top of the Moenkopi to be at a depth of 20-30 m below the surface, similar to results obtained by Roddy et al. (1975). The purpose of the 2nd study was to characterize the near surface at Pueblo of Jemez, New Mexico, to assess the geothermal potential of the geologically active rift zone via a 475 m 2-D seismic reflection line and a 1.44 km gravity survey. Specifically, imaging faults in the subsurface may indicate possible hydrothermal migration pathways. The results show beds dipping to the south at 5°, cross-cut by the large Indian Springs fault zone, consistent with previous geologic work in the area.

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Keywords

Near-surface, Meteor Crater, Seismic, Jemez Pueblo, Gravity

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