Siliciclastic Facies Belt Formation and the Late Oligocene to Middle Miocene Partial Drowning of the Southern Florida Platform

Abstract

ABSTRACT A series of siliciclastic shoreline deposits began to prograde onto the southern Florida Platform during deposition of the early Oligocene-age Suwannee Limestone. These sediments were fine to very fine quartz sands deposited in belts parallel to the margin of the platform. The influx and mixing of these siliciclastic sediments did not affect the continued deposition of carbonate sediments on the platform because the sediments did not contain significant quantities of mud. Major siliciclastic sediment influxes occurred during minor regressive, eustatic sea level events affecting primarily the platform margins. Beginning in late Oligocene time, the frequency and volume of siliciclastic sediment influx onto the southern Florida Platform began to cause the drowning of the eastern margin of the platform. The eastern margin of the platform receded from the current geographic margin position westward a distance of about 65 miles. In the central part of the platform about 600 ft of mixed carbonate and siliciclastic sediment was deposited from the late Oligocene to the middle Miocene (Chattian to Serravallian) compared to a maximum of about 65 ft on the eastern margin. Subsequent influx of predominantly siliciclastic sediment with some carbonates in the late Miocene and early Pliocene terminated the growth of the platform and infilled the drowned part of the platform to produce the approximate geometry observed today.