Sequence stratigraphy of a South Florida carbonate ramp and bounding siliciclastics (late Miocene-Pliocene)

Abstract

In southern peninsular Florida, a late-early to early-late Pliocene carbonate ramp (Ochopee Limestone Member of the Tamiami Formation) is sandwiched between underlying marine siliciclastics of the late Miocene to early Pliocene Peace River Formation and an overlying late Pliocene unnamed sand. At least three depositional sequences (DS1, DS2, and DS3), of which two contain condensed sections, are recognized in the Peace River Formation; an additional depositional sequence (DS4) is proposed to include the Ochopee Limestone. Established chronologies and new biostratigraphic results indicate that the Tortonian and Zanclean ages bracket the Peace River Formation. Depositional sequence 1 (DS1) prograded across the present-day peninsular portion of the Florida Platform during the Tortonian age and laps out near the southern margin of the peninsula. During the latest Tortonian and Messinian ages, progradation of DS2 overstepped the southern lap out of DS1 and extended at least as far as the Florida Keys. Deposition of DS2 ended, at the latest, near the Miocene-Pliocene boundary. Siliciclastic supply was reduced during early Pliocene deposition of DS3, which is absent in southernmost peninsular Florida. This reduction in supply of siliciclastics was followed by aggradational accumulation of heterozoan temperate carbonate sediments on a widespread carbonate ramp that includes the Ochopee Limestone. The Ochopee Limestone was deposited during eustatic cycle TB3.6 and ended in the late Pliocene with basinward lap out near the southern margin of the Florida peninsula. The Ochopee Limestone ramp was buried with a late Pliocene resumption of southward influx of siliciclastics (unnamed sand and Long Key Formation) that extended south beyond the middle and upper Florida Keys.