Deep crustal collisional processes through time revealed by
magnetotelluric studies

JONES, Alan G., Geological Survey of Canada, 615 Booth St., Room 214,
Ottawa, Ontario, Canada,  K1A 0E9

Processes during orogenesis emplace fluids, both saline water and
partial melt, and conducting metasediments, such as graphite, iron oxides
and sulphides, in the deep crust. These fluids and metasediments cause
anomalous enhancements of electrical conductivity, in the otherwise highly
resistive crust, and can be imaged from the surface using the deep-probing
magnetotelluric technique. This paper will review MT results from active and
ancient orogenic zones, from the Phanerozoic to Archean times, and highlight
the similarities and differences between them.