2011 GSA Annual Meeting in Minneapolis (912 October 2011)
Paper No. 224-11
Presentation Time: 10:45 AM-11:00 AM


FLANNERY, Jennifer A., United States Geological Survey, 600 4th St. South, St. Petersburg, FL 33701, jflannery@usgs.gov and POORE, Richard Z., U.S. Geol Survey, 600 Fourth St, South, St. Petersburg, FL 33701

This study examined the variations in the ratio of strontium to calcium (Sr/Ca) from modern and fossil Montastraea faveolata coral cores from the Dry Tortugas National Park (DTNP, centered on 24.7°N, 82.8°W) in the Gulf of Mexico. A modern coral core (collected in 2008) was micro-sampled with a computer-driven milling device, obtaining at least 15 samples per year. Sr/Ca variations were calibrated (r = -0.97) with a 12-year local sea-surface temperature (SST) record from NOAA National Data Buoy Center (C-MAN) stations PLSF1 and DRYF1 using maximum and minimum temperatures (Sr/Ca = -0.0385 SST + 10.188). This resulting calibration was used to generate a 47-year modern (1961-2008) Sr/Ca proxy record of SST variability. Modern annual Sr/Ca cycles range in amplitude between ~0.4 and 0.6 mmol/mol, equating to an ~10-15°C seasonal amplitude, which is consistent with available local instrumental records. Winter months demonstrate the highest variability, with a cool interval in the early 1970s. Summer maxima tend to be more stable: most summer SST maxima were 29 +/- 1°C.

To test the potential of Sr/Ca from Montastraea faveolata as a SST proxy in paleoclimate studies, we sampled a Holocene (~6Ka) M. faveolata specimen recovered from a wire-line rotary core from DTNP, using the same high-resolution sampling methods utilized on the modern coral. The Holocene coral Sr/Ca displayed distinct annual cycles with amplitudes ranging from ~0.3 to 0.6 mmol/mol. Absolute Sr/Ca values and the resulting temperature estimates were similar to those of the modern record. Thus, Sr/Ca variations in M. faveolata have high potential as a reliable proxy for modern and Holocene SST reconstructions.

2011 GSA Annual Meeting in Minneapolis (912 October 2011)
General Information for this Meeting
Session No. 224
Minneapolis Convention Center: Room 200FG
8:00 AM-12:00 PM, Wednesday, 12 October 2011

Geological Society of America Abstracts with Programs, Vol. 43, No. 5, p. 540

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