HR: 16:00h
AN: GP14A-01 INVITED     [Abstracts]
TI: The use of 3D Magnetotelluric Inversion for Exploration in Complex Geologic Environments: Potential Pitfalls and Real World Examples
AU: * Mackie, R L
EM: randy@gsy-usa.com
AF: GSY-USA, Inc., 2261 Market St., PMB 643, San Francisco, CA 94114-1600 United States
AU: Watts, M D
EM: dwatts@geosystem.net
AF: Geosystem srl, V.le Abruzzi, 17, Milano, 20131 Italy
AB: The interpretation of magnetotelluric data collected in complex geological environments requires not only that the data themselves are reliable, but that the interpretation schemes are reliable. Unfortunately, since magnetotellurics is a diffusion phenomenon rather than wave propagation, it is difficult (if not impossible) to present MT data in an intermediate form corresponding to a seismic time-section. This also has implications for imaging schemes due to the inherent inability to resolve sharp boundaries. This does not mean that you can not find a sharp boundary model consistent with the data, but rather that they are NOT required by the data. The interpretation process, including inversion, is clearly subjective (for example, what exactly does 'smooth' mean?). In this short talk, we will examine several issues inextricably linked to interpretation of magnetotelluric data in complex geological environments including: (1) how the assumptions inherent in the inversion process restrict or distort the results, (2) what are the physical limits of our interpretations, and, (3) what are the sensitivity of the data to the geology. These issues will be addressed using both synthetic and real field data from a variety of complex exploration targets including oil exploration in over-thrust and sub-volcanic regions.
DE: 3260 Inverse theory
DE: 1515 Geomagnetic induction
DE: 0629 Inverse scattering
DE: 0925 Magnetic and electrical methods
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2004 AGU Fall Meeting