49 Current Research in Coastal and Marine Processes

Tuesday, 20 March 2018
8:00 AM - 12:00 PM
Emerald Ballroom I

MEASURING THE MOST COMPLICATED POST-GLACIAL SEA-LEVEL CHANGES IN THE WORLD: NORTHERN IRELAND

Paper number: 49-1
Program: Theme Sessions
Time: 8:00 AM – 8:20 AM

Authors

Abstract

It has long been noted that Maine, with two post-glacial sea-level transgressions and one regression to lowstand, has a very complicated sea-level history. Recent work in Belfast Lough, Northern Ireland has demonstrated a much more complex record. possibly the most complex in the world. Located less than 50 km from Scotland, Belfast was alternately glaciated by ice originating from both Scotland and Ireland. The recent Brit-Chron project showed that the last glaciation was not simply one of ice advance/retreat, but complicated by several retreats and readvances over more than 10 ka and ending in Belfast by 16 ka. Sea-level changes here were driven by “eustatic” rise due to global ice melt, along with time-varying episodes of isostatic depression and rebound and gravitational attraction. Continental levering as the sea filled the Irish Sea and forebulge collapse likely remain ongoing processes. Complete multibeam mapping of Belfast Lough with more than 50 km of seismic reflection profiles and 42 vibracores with 18 C-14 dates provided data to reconstruct the sea-level history. A highstand at +20m at ~15 ka was followed by a rapid fall to a lowstand at -35 m by 13.5 ka. A rapid rise to + 17 m at 12.3 ka was followed again by a lowstand at – 35 m around 11.5ka. Sea level then rose to -15m at 11ka, remained at this level for ca. 2000 years, and then rose to a highstand at + 3 m at 6.3ka followed by a fall to present sea level. Glacial isostatic adjustment models provide a fair but not perfect fit to this scenario. This work provides a template for similar efforts ranging from Cape Cod to Newfoundland.

Geological Society of America Abstracts with Programs. Vol. 50, No. 2

doi: 10.1130/abs/2018NE-311085

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