A new genus of ichthyosaur from the Late Triassic Pardonet Formation of British Columbia: bridging the Triassic-Jurassic gap

Application of bandpass and directional filtering to potential-field data i n northwestern Canada allows separation of anomalies due to northwest-orien ted upper crustal sources that are associated with Cordilleran structures f rom anomalies due to northeast-oriented lower crustal sources that are prim arily associated with Precambrian Shield rocks. In northeastern British Col umbia, northeast-trending lower crustal structures of the Canadian Shield a s represented in the gravity patterns appear to project west of the Tintina fault - Northern Rocky Mountain Trench at about 56 degreesN. About 400-500 km farther north, the Tintina fault may penetrate into the lithospheric ma ntle. 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.