Seismic stratigraphy and late Quaternary shelf history, south-central Monterey Bay, California

摘要: Abstract The south-central Monterey Bay shelf is a high-energy, wave-dominated, tectonically active coastal region on the central California continental margin. A prominent feature of this sediment lobe off mouth Salinas River that has surface expression. High-resolution seismic-reflection profiles reveal an angular unconformity (Quaternary?) underlies entire and separates undeformed strata above it from deformed below it. convex bulge covering area approximately 72 km 2 in water depths 10 to 90 m. It reaches maximum thickness 35 m about 2.5 seaward river thins all directions away point. Adjacent areas are characterized by only thin (2 5 thick) uniform veneer sediment. Acoustic stratigraphy complex at least three unconformity-bounded depositional sequences. Acoustically, these sequences relatively well bedded. foresets occur within intermediate sequence dip 0.7° 2.0°. Comparison with sedimentary uplifted onshore Pleistocene marine-terrace deposits area, which were presumably formed similar setting under processes, suggests general interpretation can be formulated for seismic stratigraphic patterns. Depositional interpreted represent shallowing-upwards progradational marine nonmarine during interglacial highstands and/or early stages falling sea level. evidence progradation. unconformities separate as having largely shoreface planation may record intervening transgressions. internal thus several late Quaternary regressions transgressions recorded present shelf. This last major eustatic cycle level, interval not observed terraces.