Lithospheric geometry revealed by deep-probing magnetotelluric surveying, Melville Peninsula, Nunavut
Spratt, J. A.G. Jones, D. Corrigan, and C. Hogg
As part of a multidisciplinary geoscience project, the conductivity structure of the lithosphere beneath the Melville Peninsula, Nunavut, has been imaged using lithosphere-probing magnetotelluric methods.
Two-dimensional resistivity models demonstrate a strong correlation between the resistivity structure and features mapped at the surface.
An analysis of distortion effects and structural dimensionality show that, toward the north at crustal depths, the geoelectric strike angle is 099° azimuth, consistent with abundant east-trending faults; however toward the south and at mantle depths the geoelectric strike direction is 034°, similar to the regional structural trend.
The data reveal near-vertical, less resistive features that extend through the highly resistive Archean-age Prince Albert crustal block to the base of the crust and correlate with surface fault traces.
Paleoproterozoic metasedimentary rocks of the Penrhyn Group are characteristic of extremely low resistivities associated with graphite-bearing metapelites.
A near-vertical low resistivity zone is interpreted to represent a shear zone that marks the northern extent of the Archean Repulse Bay Block. Variations in the resistivity structure of the mantle lithosphere suggest changes in structure or composition between the Repulse Bay Block to the south and the Prince Albert Block to the north.
Geological Survey of Canada Current Research, 2013-12, doi: 10.4095/292482, 18 p.. [PDF]
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Alan G Jones / 13 July 2013 /