Imaging Sedimentary Structures of Monterey Bay Dune Complex in California Using Ground Penetrating Radar
Abstract
Numerous coastal dune studies have successfully used ground penetrating radar (GPR) to image sedimentary structures and correlate them with climatic variations and depositional history during the late Holocene. The Monterey Bay dune complex spans approximately 18 km of the Central California coastline and is the largest coastal dune complex in Central and Northern California. A 100 m2 survey grid consisting of 14 GPR profile lines was recorded at Ford Ord Dunes State Park in Monterey Bay, California, using 50 MHz antennas. Topography along the profiles was surveyed using differential GPS and used to apply elevation corrections to the GPR profiles. GPR data were bandpass filtered, spatially filtered, and migrated. Vertical resolution of the data is approximately 0.5 m. All profiles show four distinct units separated by erosional or depositional surfaces. The uppermost 5 - 6 m of dune sediments primarily exhibit horizontal layering, with some layers gently dipping in the windward direction. A deeper zone of dune sediments shows reflections dipping in both the leeward and windward directions. Some profiles exhibit foreset laminations that appear to correspond to relict slipfaces. Based on the orientation of both relict and active dunes, the dominant wind direction during the Holocene has consistently been from the northwest. The variations in sedimentary structures suggest alternating wind velocity. Parallel beds that are gently dipping in the windward direction are interpreted as accretionary strata that formed during periods of relatively low wind velocity, while a transverse ridge and foreset laminations indicate periods of higher wind velocity.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFMNS51A1824C
- Keywords:
-
- 0999 EXPLORATION GEOPHYSICS / General or miscellaneous;
- 4217 OCEANOGRAPHY: GENERAL / Coastal processes;
- 4546 OCEANOGRAPHY: PHYSICAL / Nearshore processes;
- 4558 OCEANOGRAPHY: PHYSICAL / Sediment transport