2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 3
Presentation Time: 8:30 AM

DROWNING OF THE -150 M REEF OFF HAWAII: A CASUALTY OF GLOBAL MELTWATER PULSE 1A?


WEBSTER, Jody M.1, CLAGUE, David A.2, RIKER-COLEMAN, Kristin3, GALLUP, Christina3, BRAGA, Juan Carlos4, POTTS, Donald5, BURR, George6, MOORE, James G.7, WINTERER, Edward L. and PAULL, Charles K.1, (1)Monterey Bay Aquarium Rsch Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, (2)Monterey Bay Aquarium Research Institute, 7700 Sandholdt Road, Moss Landing, CA 95039, (3)Department of Geological Sciences, Univ of Minnesota (Duluth), Duluth, MN, (4)Departamento de Estratigrafia y Paleontologia, Universidad de Granada, (5)Department of Ecology and Evolutionary Biology, Univ of California, Santa Cruz, (6)NSF-Arizona AMS Laboratory, Univ of Arizona, PAS Building 81, Tuscon, AZ 85721, (7)USGS (Menlo Park), jwebster@mbari.org

Based on new submersible dives off NW Hawaii, we present evidence that the drowning of the –150 m reef around Hawaii may have been caused by rapid sea-level rise associated with meltwater pulse 1A (MWP-1A) during the last deglaciation. A re-interpretation of existing coral conventional 14C dates, U/Th dates and new 14C AMS dates constrain the drowning time of the coral reef to ~14.3-13.4 cal kyr BP (mean 13.9 cal kyr BP). This date appears to be roughly synchronous with meltwater pulse 1A (MWP-1A, ~14.2-13.8 cal kyr BP). Dates measured from overlying coralline algal material gave a mean age of 11.6 ka, ~ 2.3 kyr younger than the mean coral age. A paleoenvironmental reconstruction incorporating all available radiometric dates, high-resolution bathymetry, dive observations and coralgal paleobathymetry data, indicate a dramatic rise in sea-level occurred around Hawaii ~13.4-14.3 cal kyr BP. This caused paleowater depths over the –150 m reef crest to increase rapidly above a critical depth (~30-40 m), drowning the shallow reef building Porites corals. Deepwater coralline algae growth, preserved as a crust/pavement and associated mobile substrates (rhodoliths and smaller cemented nodules) dominated as sea-level rise and subsidence continued to present. Additional paired 14C AMS and U/Th dates will more precisely constrain the timing of coral reef drowning and subsequent deep water coralline algal accretion.