Foraminifera Zonations In Southern California Salt Marshes
Salt marsh foraminiferal species live in distinct elevation zones relative to tidal and sea level datums. Their strict vertical zonation can be used as a tool in recognizing rates of sea-level rise as well as tectonic activity along the coast. Although foraminifera have been used worldwide to reconstruct past sea levels, no such elevation zonations have been produced for southern California salt marsh foraminifera. We sampled foraminifera from three southern California estuaries: Carpenteria Slough, Mugu Lagoon, and Sweetwater Marsh, for the purpose of establishing a foraminifera zonation for southern California marshes. The results from Carpenteria Slough display a distinct zonation in foraminifera species based on their elevation in relation to tidal datums. The high marsh foraminifera consist primarily of Trochomina inflata and show a small assemblage of Milammina fusca. The low (subtidal) marsh is dominated by textularids and rotalids, while also showing an abundance of palnktonic foraminifera and several deep-sea benthic species. These results will allow for the construction of a better-defined paleo sea level curve for southern California, as well as providing insights into tectonic activity along the southern California coast.
AAPG Datapages/Search and Discovery Article #90215 © 2015 Pacific Section AAPG Convention, Oxnard, California, May 3-6, 2015