Patterns of Coastal Sedimentation: Carbonate Muds of Florida Bay: ABSTRACT

Abstract

Muddy carbonate sediments of Florida Bay have accumulated in response to hydraulic processes characteristic of coastal environments. These processes are reflected in faunal distribution as well as physiography of the accumulations. The frequently encountered coastal sedimentary pattern of lakes, and mainland veneer is expanded laterally in Florida Bay because of topography of the underlying Pleistocene rock surface. In Florida Bay the dominant physiographic pattern consists of circular lakes of deeper water surrounded by curvilinear banks and islands. The banks, composed predominantly of mud sediment, reach within a foot or so of mean sea level and are largest in the western bay nearest the open Gulf of Mexico. The northeastern (interior) segment of the bay is characterized by narrower banks, in many places exposed subaerially as islands. Spitlike accretion is apparent from growth lines on islands and some banks. This indicates locally directed currents; however, overall randomness of orientation and circular patterns of sediment distribution suggest that significant currents develop in all directions. The larger submerged banks of the outer bay display prominent accretion lines and are in addition elaborately channeled. The channeling follows a distinctive cycle of establishment and decline that seems closely related to bank growth. Current control of deposition of muddy sediments is reflected also in the ancient sedimentary record, notably the Pennsylvanian Virgil mounds near Alamogordo, New Mexico, and Pennsylvanian Lansing mounds in southeastern Kansas. Sediment-baffle processes previously proposed for the construction of mound-topography appear unneeded inasmuch as current processes may achieve similar results. End_of_Article - Last_Page 632------------