Budgeting postglacial sedimentation history on the Santa Cruz, California mid-continental shelf
Dataset Identification:
Resource Abstract:
High-resolution seismic reflection profiling and surface texture mapping of the central California continental shelf, reveal
a prominent subsurface reflector interpreted as a low stand erosion surface and an overlying mudbelt that covers 421 km2 of
the mid-shelf in depths of 40-90 m. Radiometric and sedimentologic analyses of samples from vibracores taken along the seaward
edge of the mudbelt show that initial deposition above the pre-Holocene erosion surface began ca. 14.5 ka. These data and
model results of sea-level history, tectonics, and the Monterey Bay littoral sediment budget support the notion that the entire
midshelf deposit was formed during the postglacial transgression. An alternative explanation, that <30% of the deposit
is Holocene, requires that (1) sediment input is overestimated and/or loss is greatly underestimated, and (2) preservation
on the shelf was significant despite deep and active wave scour observed in the form of rapid cliff and bedrock cutting early
and late in the transgression. The difference between a basal age of ???14.5 ka and residence time of midshelf sediment (3,273
years), derived from dividing mudbelt volume by modern accumulation rate, implies: (1) significant sediment loss occurred
since the mudbelt formed and/or (2) sediment accumulation has varied greatly over time. Although modern sediment budgets are
relatively well constrained, it remains uncertain how well we can apply them to the past. An evolving model of sedimentation
history explores the likelihood of changes in sediment supply, accumulation patterns, and depositional patterns owing to postglacial
sea-level history and human land-use activities while providing important boundary conditions for modeling shoreface evolution.
Citation
Title Budgeting postglacial sedimentation history on the Santa Cruz, California mid-continental shelf