Abstract

New geophysical and geochronological data are presented for a lower Paleozoic subsurface (794–827 m depth) sedimentary core recovered from Alachua County, northern Florida. Paleomagnetic data from samples taken at various depths along the core indicate that a high unblocking temperature component is isolated during thermal demagnetization between 400 and 600 °C. The mean inclination of this component is 65°, yielding a paleolatitude of 49°. Previous paleogeographic reconstructions for the early Paleozoic of North America place Florida at a significantly lower paleolatitude (∼28°), whereas our data are consistent with a Gondwanian fit (∼50°–60°). U/Pb isotopic systematics of zircons separated from core samples yield five dates ranging from ca. 1650 to 1800 Ma. Because there are no known source rocks of this antiquity in southeastern North America, the most probable provenance for these detrital zircons is either Africa or South America. These two new lines of geologic data provide strong evidence confirming previous suggestions that Florida was part of Gondwana during the early Paleozoic and that its current configuration is that of an exotic terrane sutured to North America during the fragmentation of Pangea.

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