New constraints on Meltwater Pulse 1A from U-series dating of Tahitian fossil corals
Abstract
Glacial terminations are marked by periods of rapid ice sheet loss and sea-level rise, providing important constraints on the rates and timing of dynamic ice sheet retreat. Paleo sea-level reconstructions from the Termination I deglaciation (~21 - 11.7 ka), which separates the last ice age from the Holocene interglacial, have shown that sea-level rise during this event included accelerations in sea-level rise derived from pulses of meltwater. The largest such event, known as Meltwater Pulse 1A (MWP-1A), resulted in as much as 20 m of global mean sea-level rise in less than 500 years. It is evident that a considerable amount of ice volume was lost from the continental ice sheets at this time. The source(s) of this meltwater, however, remains intensely debated as well as the exact climatic mechanism that drove such rapid ice sheet retreat. Identifying the origins of MWP-1A is further complicated by discrepancies in the precise timing and magnitude of the meltwater pulse, in particular, between paleo reconstructions from submerged fossil reefs at Barbados and Tahiti. This is largely because of uncertainty regarding the depth these fossil corals were growing at, or paleowater depth. Here, we present new fossil-coral U-series ages from the IODP 310 Tahiti core record to further refine the rate and timing of sea-level rise leading up to and encompassing MWP-1A. We targeted a thin reef unit at the base of each drill core that contains the first corals to colonize the Pleistocene substrate at each hole during Termination I and attempt to narrow the vertical uncertainty in the existing sea-level reconstructions. These new constraints on the relative sea-level budget for MWP-1A at Tahiti can be used to optimize meltwater partitioning between the major continental ice sheets at that time, which is essential for modeling the dynamic processes that can lead to rapid ice sheet retreat on centennial timescales.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMPP014..07C
- Keywords:
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- 0726 Ice sheets;
- CRYOSPHERE;
- 4556 Sea level: variations and mean;
- OCEANOGRAPHY: PHYSICAL;
- 4926 Glacial;
- PALEOCEANOGRAPHY;
- 4936 Interglacial;
- PALEOCEANOGRAPHY