Arc Explorer
Themes visible in this map are: STRUCTURE POINTS, LATITUDE/LONGITUDE,
COASTLINE and LAND.
|
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. |
|