| Summary: | The northwestern Bowser Basin overlies Mesozoic units of Stikine Terrane and
encompasses deformation of the western Skeena Fold Belt. The region includes a portion of
Lithoprobe SNORCLE Line 2A seismic reflection transect. The research has allowed detailed
observation of the surface geology to be combined with high quality subsurface information.
Folds within the western Skeena Fold Belt are separated into three groups, based on fold
trend. Northeast-trending folds are located in select areas through the region and exhibit
transected cleavage that is northwest-striking. North- and northwest-trending folds comprise
separate fold groups in the area. North-trending folds are observed in the central area of the
region and are spatially associated with north- or northwest-striking cleavage. In the majority of
cases northwest-trending folds are spatially associated with relatively axial-planar cleavage. The
transected nature of folds in this region is interpreted to be the result of a temporal sequence of
rotating fold orientation, with initial northeast-trending folds overprinted by north- then
northwest-trending folds. This temporal sequence supports the work of Evenchick [2001] within
the western Skeena Fold Belt.
Seismic reflection data for the area were post-stack migrated to produce a data set
highlighting near surface structures. Near surface velocity variations were examined using
forward modelling and 2-D tomographic inversion of first-break arrival data. The near surface
velocities were used to produce a laterally varying velocity sequence for post-stack migration.
Reflection data for the upper eight seconds contains the boundary between the Bowser Basin and
Stikine Terrane. The Bowser Basin is observed to have a variable thickness, with the thickest
sections caused by the structural stacking of units. The data set also indicates that below the
Bowser Basin Stikine Terrane is involved in Skeena Fold Belt deformation, with faulting and
overthrusting of Stikine Terrane on Bowser Basin units observable.
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