EFFECTS OF CHANGING SEA LEVEL ON THE QUALITY AND CHARACTER OF DEEP-WATER CLASTIC DEPOSITS, SANTA MONICA BASIN, CALIFORNIA

It is well known that sea level has a significant effect on the way in which clastic sediment is transported from land into the ocean. However, the impact of changing sea level on the provenance, mineralogy, and texture of deep-water deposits is less clear. The Santa Monica Basin, located in the southern California Borderland, is a closed system and is currently the region’s major sink for coarse-grained sediment. Pleistocene-Holocene sedimentation in the Santa Monica Basin provides an analog for older Cenozoic deep-water petroleum reservoirs in the region and in analogous tectonic settings globally. We aim to determine the influence of glacio-eustatic sea level rise and fall on sediment properties by characterizing the provenance, bulk mineralogy, and sediment texture of sediment deposited within the Santa Monica Basin and from sediment transported to the ocean via fluvial processes. To date, 22 samples have been collected: 11 from a core drilled by the Ocean Drilling Program (Leg 167, Site 1015) within the Santa Monica Basin and 11 from associated fluvial systems draining the Western Transverse Ranges. Preliminary portable X-ray fluorescence (XRF) data collected from all 22 samples reveal relative homogeneity for the deep-water samples compared to much more geochemically diverse fluvial inputs. Efforts are currently ongoing to collect data associated with the provenance and texture of the sediment through zircon U-Pb geochronologic analysis, heavy mineral analysis, further petrographic analysis, and grain size and shape measurements. Results of this study are expected to clarify sediment sources to the Santa Monica Basin over time and improve understanding of how fluvial transport versus littoral transport influences the quality and character of deep-water clastic deposits and associated petroleum reservoirs.