Fold Geometry
Model of Coyote Hills Segment of Puente Hills Blind-Thrust System Applied to
Interpretation of Long-Term Water Level Data
Cranham, Greg T.1, Christopher
G.A. Ross1, Steven P. Netto1 (1) Hargis + Associates,
Inc,
Recent work by others along the Coyote
Hills segment of the Puente Hills blind-thrust system has imaged the
near-surface structural features generated by activity of that intrabasin
fault. Published shallow seismic profiles near the south flank of the Coyote
Hills indicate the blind-thrust system is expressed by south-facing folding of
Quaternary terrestrial sediments underlying the hills. Monitoring wells
installed at a former aerospace facility on the south flank of the Coyote Hills
between 1997 and 2004 were completed in highly interbedded sediments of the
regional aquifer to various depths, ranging from approximately 165 feet to 500
feet. Correlation of strata based on drill cuttings and core samples was
attempted, but was of limited confidence due to pervasive interbedding.
Stratigraphic continuity and geometry were evaluated using long-term water
level monitoring of wells completed to various depths. Selected wells were
fitted with pressure transducers / dataloggers, recording water levels nearly
continuously over periods of months to years. A conceptual site model (CSM) was
developed based on differential water level responses as well as on subsurface
soil sampling, published surface geologic mapping and hydrogeologic cross
sections of the
AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California