Early Holocene sea-level record from submerged fossil reefs on the southeast Florida margin

• Main Authors: Toscano, M.A. (Marguerite A.), Lundberg, J. (Joyce)
• Format: Article in Journal/Newspaper
• Language: English
• Published: 1998
• Subjects: Antarctic; West Antarctic Ice Sheet; Antarc*; Ice Sheet; North Atlantic
• Online Access: https://ir.library.carleton.ca/pub/6703; https://doi.org/10.1130/0091-7613(1998)026%3C0255:EHSLRF%3E2.3.CO;2

Massive fossil (outlier) reefs are preserved seaward of the modern shelf and reef tract along the southeast Florida margin. Thermal ionization mass-spectrometric (TIMS) U-Th dating of 16 pristine Acropora palmata and head corals cored from two transects document early Holocene reef growth from 8.9 to 5.0 ka, from approximately -13.5 to -7 m MSL (mean sea level). These samples fill a gap in the Florida Keys sea-level database and clarify the timing of a significant decrease in the rate of sea-level rise. A portion of this interval, represented by a gap in the Caribbean record of A. palmata reefs, has been interpreted as reef drowning during an inferred catastrophic sea-level rise event of >45 mm/yr, or a 6.5 m rise between 7.6 and 7.2 ka, attributed to West Antarctic Ice Sheet instability and changes in marine ice extent between 8 and 7 ka. Continuous in situ shallow-water reef growth in Florida during this interval precludes the occurrence of exceedingly rapid rates of sea-level rise and is consistent with the North Atlantic record of deglaciation from 9 to 7 ka. Gaps in the early Holocene sea-level records for Florida and the Caribbean are thus more likely to be artifacts of limited sampling and/or core coverage, and not necessarily a result of drowning.