Crustal origin of the West Florida Terrane, and detrital zircon provenance and development of accommodation during initial rifting of the southeastern Gulf of Mexico and western Bahamas

Published on 2020-06-01T16:01:15Z (GMT) by
Well and seismic data were combined with existing radiometric data and 1328 new LA-ICP-MS U-Pb zircon ages from igneous, sedimentary, and volcaniclastic rocks in three wells to determine the origin and evolution of key crustal terranes, and the timing of initial rifting and syn-rift deposition in the southeastern Gulf of Mexico and western Bahamas. These data reveal that several southeastern Gulf of Mexico crustal terranes, distinguished by their zircon age distributions and geochemistries, were amalgamated into a single terrane of mixed Pan-African and Amazonian crustal affinity (the newly named West Florida Terrane) during the formation of Pangea. Sinistral offset along the Florida Transfer Zone (FTZ) during the Late Triassic to Middle Jurassic was likely facilitated by crustal heterogeneity at the boundary between the West Florida and Suwannee Terranes, a prime area for reactivation during the breakup of Pangea. Initial extension, igneous activity, and syn-rift deposition in the region began during the Middle Triassic in the western Bahamas and offshore North Florida and rapidly expanded into the South Florida Basin by the Early Jurassic. Peak igneous activity and accommodation in the region was diachronous from north to south, beginning in the north during the Early Jurassic (Sinemurian-Pliensbachian) before ending in the south in the Early to Middle Jurassic (Sinemurian to Aalenian-early Bajocian). Detrital zircons in sedimentary and volcaniclastic rocks were primarily derived from local erosion of pre-existing crustal terranes. Long-distance transport was likely for pre-Neoproterozoic and post-Cambrian Palaeozoic zircons. Middle Jurassic detrital zircons in volcaniclastic rocks of the western Bahamas may have been deposited during ash fall events from hotspot activity in the southeastern Bahamas.

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Erlich, R. N.; Pindell, J. (2020): Crustal origin of the West Florida Terrane, and detrital zircon provenance and development of accommodation during initial rifting of the southeastern Gulf of Mexico and western Bahamas. Geological Society of London. Collection. https://doi.org/10.6084/m9.figshare.c.5001527.v1