Abstract

Application of bandpass and directional filtering to potential-field data in northwestern Canada allows separation of anomalies due to northwest-oriented upper crustal sources that are associated with Cordilleran structures from anomalies due to northeast-oriented lower crustal sources that are primarily associated with Precambrian Shield rocks. In northeastern British Columbia, northeast-trending lower crustal structures of the Canadian Shield as represented in the gravity patterns appear to project west of the Tintina fault – Northern Rocky Mountain Trench at about 56°N. About 400–500 km farther north, the Tintina fault may penetrate into the lithospheric mantle. It is, thus, likely that the depth extent of the Tintina fault rises southward into the crust, as dextral strike-slip motion is transformed into contractional structures of the southern Cordillera.

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