Accession Number : AD0690608

Title :   MAGNETO-TELLURIC DEEP EARTH RESISTIVITY AT EIGHT U. S. TYPE-LOCATIONS.

Descriptive Note : Final rept.,

Corporate Author : GEOSCIENCE INC CAMBRIDGE MASS

Personal Author(s) : Vozoff,K. ; Orange,A. S. ; Lahman,H. S.

Report Date : JAN 1969

Pagination or Media Count : 73

Abstract : Magneto-Telluric measurements were carried out in eight 'type-areas' of the U. S., to see whether systematic differences exist in their deep crustal and upper mantle electrical resistivities. Digital recording, electrode spacings of tens of kilometers, and a frequency range of five decades were used at most locations. Results varied between those of the Adirondacks, where a resistive crust overlies a moderately conductive, strongly anisotropic mantle, to the thin resistive crust north of Spokane overlying a very thick, resistive intermediate layer. Where they can be compared with subsurface geological and electrical data our results agree with those data. In general, the Moho does not appear to be associated with a pronounced conductivity transition. Although an upper mantle conductivity increase is usual it is typically deeper than the Moho. (Author)

Descriptors :   (*EARTH(PLANET), ELECTRICAL RESISTANCE), ALTERNATING CURRENT, GEOMAGNETISM, EXPERIMENTAL DATA, MOHOROVICIC DISCONTINUITY, UNITED STATES

Subject Categories : Geomagnetism
      Geology, Geochemistry and Mineralogy

Distribution Statement : APPROVED FOR PUBLIC RELEASE