Abstract


CORAL REEF RESPONSE TO RAPID SEA-LEVEL RISE DURING THE LAST DEGLACIATION: NEW EVIDENCE FROM THE DROWNED REEF TERRACES OF WESTERN HAWAII

Fossil reefs are valuable recorders of glacio-eustatic sea-level changes, providing key constraints on last deglacial meltwater pulses (MWP). Determining the timing, magnitude, rate and meltwater source of these rapid sea-level rise events has important implications for understanding ice sheet dynamics and abrupt climatic change. Several global records span MWP-1A, but no consensus has been reached on the precise details or its impact on reef growth. The Barbados reef record initially suggested MWP-1A occurred between 14.2-13.8 ka but subsequent studies from Hawaii and Tahiti suggest it occurred ~500 years earlier at ~14.7 ka. To further investigate MWP-1A and the drowned reef terraces of Hawaii, a SCUBA diving field campaign was conducted off Kawaihae to recover samples down to -150 m. We report eight new radiocarbon ages and corresponding laser ablation inductively coupled plasma mass spectrometry U-Th ages, which are interpreted within the context of all available published dates, to better constrain the timing of reef drowning around Hawaii. Detailed sedimentological analysis and sample vetting were employed to identify key indicators of paleo-sea level, and standardized paleoenvironmental interpretations of coralgal assemblages and drowning signatures were made. These data are integrated with dive observations and mapping data, revealing that the backstepping terraces are multi-generational features with sea level acting as a primary control on their complex evolution. We conclude that the age of Hawaiian reef drowning is consistent with a ~14.75 ka onset of MWP-1A.

Authors

Sanborn, K. L., University of Sydney, Australia, ksan2228@uni.sydney.edu.au

Webster, J. M., University of Sydney, Australia, jody.webster@sydney.edu.au

Yokoyama, Y., University of Tokyo, Japan, yokoyama@aori.u-tokyo.ac.jp

Dutton, A., University of Florida, USA, adutton@ufl.edu

Braga, J. C., University of Granada, Spain, jbraga@ugr.es

Eggins, S. M., Australian National University, Australia, Stephen.Eggins@anu.edu.au

Clague, D. A., Monterey Bay Aquarium Research Institute, USA, clague@mbari.org

Paduan, J. B., Monterey Bay Aquarium Research Institute, USA, paje@mbari.org

Rooney, J. J., University of Hawaii, USA, john.rooney@noaa.gov

Hansen, J. R., Association for Marine Exploration, USA, Rydeaway@yahoo.com

Wagner, D., NOAA Papahanaumokuakea Marine National Monument, USA, wagndani@gmail.com

Details

Oral presentation

Session #:34
Date: 06/23/2016
Time: 14:30
Location: 311

Presentation is given by student: Yes