THE BC87 DATASET - TECTONIC SETTING, PREVIOUS EM RESULTS, AND RECORDED MT DATA

As part of project LITHOPROBE, magnetotelluric data were acquired at twenty-seven sites along a 150 km east-west profile in southeastern British Columbia straddling the complex tectonic boundary between ancestral North American rocks and those of the easternmost accreted terranes. These data, named the BC87 dataset, display complex effects due to both three-dimensional induction and galvanic scattering at virtually all scale sizes, from that of the electrode array (<50 m) to that of the large plutonic Nelson batholith (150 x 50 km surface extent). The dataset was distributed widely in order to compare and contrast different schemes for extracting the underlying predominant two-dimensional structure, and to test differing interpretational algorithms on data from a complex crystalline terrane. The MT data are shown, and the tectonic setting described. Also, seismic and previous EM studies of the region are described.