12. STRONTIUM-ISOTOPIC CORRELATION OF OLIGOCENE TO MIOCENE SEQUENCES,NEW JERSEY AND FLORIDA1Peter J. Sugarman,2,3 Lucy McCartan,4 Kenneth G. Miller,3,5 Mark D. Feigenson,3 Stephen Pekar,3 Ronald W. Kistler,6 and A.G. Robinson6 |
ABSTRACTWe use Sr-isotopic age estimates to date siliciclastic, carbonate, and mixed siliciclastic-carbonate Oligocene and Miocene sequences for the New Jersey Coastal Plain and Florida Peninsula and to correlate sequence boundaries with the deep-sea delta18O record and the inferred eustatic record of Exxon. The New Jersey onshore Oligocene to lower Miocene sequences correlate reasonably well with the Florida Miocene sequences. However, the majority of middle Miocene sequences mapped in New Jersey are missing from central Florida. The age of Oligocene to Miocene sequence boundaries determined in continuous boreholes from New Jersey, Alabama, and Florida show excellent correlation with deep-sea delta18O increases, which are inferred glacio-eustatic lowerings. This is strong confirmation that global sea-level change is a primary control on the timing of Oligocene to Miocene sequence boundaries for the coastal plain sections studied here. Whereas global sea level has a significant influence on coastal plain sequences, there are major differences in the preservation of sequences within the same depositional basin (e.g., Salisbury Embayment) and between basins (e.g., Florida basins vs. Salisbury Embayment). These intra- and interbasinal differences must be ascribed to noneustatic processes such as tectonics or differential erosion. Tectonic mechanisms include faulting of crustal blocks, mobile basins with evolving arches and depocenters, local flexural subsidence, or differential subsidence caused by sediment loading. |
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