Print this pageFormation of the Fish Creek-Vallecito basin, Salton Trough, California
Catherine Shirvell,
UCLA Department of Earth & Space Sciences,
The Fish Creek-Vallecito
(FCV) basin is one of the oldest rift-related basins in the Salton Trough. The Salton Trough is the northern-most
portion of the North American-Pacific oblique-rift system. The purpose of this study is to understand
the structural development of the FCV basin by recording the interplay between
sedimentation and tectonics. Documenting
the formation of the FCV basin will provide insight into the earliest stages of
oblique-continental rifting as well as the structures on which oblique
extension is accommodated in the continental crust.
Understanding the development of the
FCV basin will be accomplished by field work, specifically: 1) detailed
geologic mapping (1:12,000), especially where the oldest syn-rift sediments are
exposed, 2) sedimentological and stratigraphic analysis of these sediments,
including description of lithofacies variations, paleocurrent analysis, and
correlation based on clast composition, and 3) kinematic analysis of
faults. One 2-month field season
(January-February 2005) has already been completed. Approximately half of the map area was
covered during this time. In addition to
geologic mapping, over 100 fault planes and ~50 paleocurrent indicators were
measured in this area. Furthermore, the
previously described stratigraphy was altered to reflect new observations.
During the upcoming 2006 field
season (January-March 2006) I will finish mapping the remaining northern
portion of the FCV basin, gather additional fault and paleocurrent
measurements, and continue to revise and add to the existing stratigraphy of
the oldest sedimentary deposits in the FCV basin.