Research Interests

Uranium-series isotope and trace element studies of ocean sediments and their application to the fields of paleoclimatology, low-temperature geochemistry, and tectonics.

Current Research Projects:

Paleoclimatology

I recently returned to Barbados to continue research using fossil corals to determine the timing of sea level changes associated with the ice ages. Earlier results indicated that sea level was as high 200,000 years ago as it is today and that the timing of high sea level events during the last 200,000 years coincide with the predictions of the Milankovitch Theory of the ice ages. This theory argues that the glacial cycles are driven by changes in the Earth's orbit around the sun. More recent results from Barbados fossil corals show that the timing of the deglaciation prior to the last time sea level was as high as it is today is earlier than would be predicted by the Milankovitch Theory (Gallup et al., 2002). This suggests that the Milankovitch Theory may be too simple or that something other than orbital changes, such as climate/ocean dynamics, may be as important as orbital changes.

In 2001, I participated in a collection trip for fossil corals that are currently on the ocean floor off the coast of New Guinea, up to 2,000 meters below sea level. My collaborators, Drs. Eli Silver and Donald Potts at UC Santa Cruz, and I used Jason, a remotely operated submersible, to collect the corals. These fossil corals should provide information about 1) the timing of the transitions between major glaciations and the following major interglacial periods, which occur roughly every 100,000 years, and 2) the rate of subsidence of the sea floor in this area.

Precambrian Geochronology/Tectonics

The Precambrian rocks of Minnesota have an incredibly intricate story to tell about the building of the North American Craton. Unfortunately, there is insufficient age control to give the story a detailed timeline. I am interested in constraining the history of the Vermillion District in NE Minnesota high-precision uranium-lead dating of zircon crystals.

Publications

Webster J. M., Wallace L., Silver E., Applegate., B., Potts D., Braga J. C., Riker-Coleman K and Gallup C (In press) Drowned carbonate platforms in the Huon Gulf, Papua New Guinea, Geochemistry, Geophysics, Geosystems - G-Cubed.

Webster, J.M., Clague D.A., Riker-Coleman K., Gallup C. D., Braga J.-C., Burr G., Potts D., Moore J.G., Winterer E.L., Paull C.K. (2004) Drowning of the -150 m reef off Hawaii: A casualty of global meltwater pulse 1A? Geology 32, 249-252.

Webster, J.M., Wallace L., Silver E. Potts D., Braga J.-C., Renema W., Riker-Coleman K, Gallup C.D. (2004). Coralgal composition of drowned carbonate platforms in the Huon Gulf, Papua New Guinea; implications for lowstand reef development and drowning, Marine Geology 204, 59-89.

Edwards, R.L., Gallup, C.D., K.B. Cutler, Cheng, H., (2004). Geochemical Evidence for Quaternary Sea Level, in Treatise on Geochemistry, Eds. H.D. Holland, K.K. Turekian, Elsevier. Volume 6, Oceans and Marine Geochemistry, Ed. H. Elderfield, 343-364.

Edwards, R.L., Gallup, C.D., Cheng, H., (2003). Uranium-series Dating of Marine and Lacustrine Carbonates. Reviews in Mineralogy and Geochemistry, Vol 52, 363-405.

Cutler K.B., Edwards R.L., Taylor F.W., Cheng H., Adkins J., Gallup C.D., Cutler P.M., Burr G.S., Chappell J., and Bloom A.L. (2003). Rapid sea-level fall and deep-ocean temperature change since the last interglacial. Earth and Planetary Science Letters, 206, 253-271.

Gallup, C.D., Cheng, H., Edwards, R.L. (2002). Direct determination of the timing of sea level change during Termination II. Science, 295, 310-313.

Cheng, H., Edwards, R.L., Hoff, J.A., Gallup, C.D., Richards, D.A., Asmerom, Y. (2000). The half-lives of uranium-234 and thorium-230. Chemical Geology, 169, 17-33.

Gallup, C.D. 1997. High-precision uranium-series analyses of fossil corals and Nicaragua Rise sediments: The timing of high sea levels and the marine 234U value during the past 200,000 years. Ph.D. Thesis, University of Minnesota.

Galewsky, J., Silver, E.A., Gallup, C.D., Edwards, R.L., and Potts, D. 1996. Carbonate platform dynamics in the Huon Gulf, Papua New Guinea, Geology, 24, 819-822.

Min, G.R., Edwards, R.L., Taylor, F.W., Gallup, C.D., and Beck, J.W. 1995. Annual cycles of U/Ca in coral skeletons and U/Ca thermometry. Geochim. Cosmochim. Acta. v. 59, no. 10, pp. 2025-2042.

Gallup, C.D., Edwards, R.L., and Johnson, R.G. 1994. The timing of high sea levels over the past 200,000 years. Science 263, 796-800.

Taylor, F.W., Quinn, T., Gallup, C.D., and Edwards, R.L. 1994. Quaternary plate convergence rates at the New Hebrides Arc from the chronostratigraphy of Bougainville Guyot (Site 831). Proceedings of the Ocean Drilling Program, Scientific Results, v. 134, 47-57.

Edwards, R.L. and Gallup, C.D. 1993. Dating of the Devils Hole calcite vein. Science 259, 1626-1627.

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