Tertiary and Quaternary
structures of the eastern Juan de Fuca Strait:
point map
Samuel Y. Johnson, David C. Mosher, Shawn V. Dadisman, Jon R.
Childs and Susan B. Rhea, 2000.
The scatter points on this map sheet show locations where Quaternary
and pre-Quaternary faulting and folding were interpreted from
seismic reflection profiles, the tracks and many examples of which
are presented in this atlas
(follow the hotspot links on Figure
2 and the various tracks pages).
Faults are recognized on the
basis of truncated reflections and (or) abrupt changes in reflection
dip or seismic facies, such as amplitude, frequency, continuity,
and geometry. Fault identification was greatly facilitated by
the availability of diverse and complementary seismic-reflection
data sets with variable depth imaging and resolution. There are
a significant number of relatively high-angle contacts bounding
reflections or sets of reflections within the Quaternary section
(see depth to base of Quaternary Map) in
the upper ~ 1 s TWT that could be interpreted either as faults
(e.g., Figures 3, 6,
9, and 13)
or as steep depositional contacts associated with glaciofluvial
erosion and deposition (Figure 1).
Differentiating between tectonic and nontectonic origins is possible
with the benefit of deeper seismic data such as from the SHIPS
program or the INDUSTRY lines that
reveal whether potential structures are "rooted" within the basement
and are faults or, in contrast, are confined to the Quaternary
section and are sedimentary features.
Reference citation:
Johnson, S.Y., Mosher, D.C., Dadisman, S.V., Childs, J.R., and
Rhea, S.B., 2000. Tertiary and Quaternary structures of the eastern
Juan de Fuca Strait: point map, in: Mosher, D.C. and Johnson,
S.Y. (Eds.), Rathwell, G.J., Kung, R.B., and Rhea, S.B. (Compilers),
Neotectonics of the eastern Juan de Fuca Strait; a digital geological
and geophysical atlas. Geological Survey of Canada Open File Report
3931
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