| Title | Linking Hudson Bay subglacial meltwater at the time of the Atlantic Heinrich 1 event with a meltwater flood event in the Gulf of Mexico about 13.5 ka (16.2 cal ka) |
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| Author | Lewis, M ; Todd,
B |
| Source | CANQUA 2015: conference program and abstracts; 2015 p. 57-58  Open Access |
| Links | Online - En ligne (complete volume - volume complet,
PDF, 2.08 MB)
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| Image |  |
| Year | 2015 |
| Alt Series | Earth Sciences Sector, Contribution Series 20150174 |
| Publisher | Canadian Quaternary Association |
| Meeting | CANQUA 2015: Canadian Quaternary Association (CANQUA) Meeting; St. John's, NL; CA; August 16-19, 2015 |
| Document | book |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf (Adobe® Reader®) |
| Program | GSC Atlantic Division |
| Released | 2015 08 01 |
| Abstract | The Heinrich 1 event about 14-13 ka (~17-15 cal ka) which discharged meltwater plumes with detrital carbonate from Hudson Strait to Labrador Sea and icebergs throughout the North Atlantic Ocean led to
instability in the Laurentide Ice Sheet with accelerated movements of ice and subglacial meltwater. Sediments deposited between 14.4 and 13.6 ka in the Finger Lakes area of New York State from meltwater moving southward from Hudson Bay beneath the
ice across the Lake Ontario basin have been related to this event by Mullins et al. (1996, Geological Society of America Special Paper 311: 1-35). N-S drumlins inferred to be associated with the southward flows are truncated along a WSW trend south
of Lake Ontario, suggesting diversion of the ice and meltwater flows WSW along the deep lake axis as the moving ice cover thinned. Lakebed relief in deep eastern Lake Ontario is dominated by WSW-trending ridges. Interpretation of multibeam sonar and
seismic reflection surveys showed that individual ridge features were drumlins. Incoherent internal reflections characterize the drumlin material, and a piston core which recovered stony, sandy diamicton (till) confirmed the glacial origin of the
relief-forming ridges, not faulted or glacially-scoured bedrock as in some previous interpretations. The till is absent in places between ridges, suggesting the drumlins were formed by erosion from a former till sheet. Erosion of drumlins by
horizontal vortices in turbulent meltwater flow is suggested by narrow furrows that wrap around their upstream (ENE) ends and sides.
South of central Lake Ontario, a land-based digital elevation model revealed drumlins in the same orientation,
suggesting the erosive ice and meltwater flows continued WSW into the northern part of the eastern Lake Erie basin where seismic profiles and a borehole at the tip of Long Point, Ontario revealed an absence of till, unusual for the region, except for
thin remnants, with glaciolacustrine sediments resting directly on bedrock. We suggest removal of the till by the WSW ice and meltwater flows. The till removal appears to extend to the cross-lake Norfolk Moraine between the base of Long Point and
Erie, Pennsylvania, the LIS margin at 13.5 ka (Dyke et al. 2003, GSC Open File 1574). Borehole sediment ages indicate the glaciolacustrine sedimentation following till removal began prior to 13 ka. An extensive cover of till remains atop a 45m-high
bedrock escarpment in the southern part of the eastern Erie basin, suggesting an ice cover was pinned there, protecting it from the erosive subglacial flows.
Excess meltwater would have continued westward from the ice margin into the Maumee or
Arkona glacial lakes which existed between approximately 13.8 and 13.4 ka in central and western Erie and southern Huron basins. These lakes with the excess meltwater discharged to the Mississippi drainage and the Gulf of Mexico where a meltwater
spike had been detected as 'MeltWater Flood 2' dated between 13.6 and 13.4 ka with a flux of 4600 km3.yr-1, nearly twice the Mississippi baseline discharge at the time (Aharon 2003, Paleoceanography 18: 1079). |
| Summary | (Plain Language Summary, not published)
About 16,200 years ago, meltwater moved southward beneath the ice sheet from Hudson Bay to upstate New York. The ice and meltwater flows were then
diverted west-southwest along the deep axis of the Lake Ontario basin, and overland to the northern part of the eastern Lake Erie basin where the flows removed pre-existing glacial deposits. Excess meltwater was delivered beyond the ice margin to
glacial lakes in the area of the present central and western Lake Erie and southern Lake Huron. These lakes and the meltwater drained westward to the Mississippi drainage and the Gulf of Mexico, explaining a meltwater spike of the same age which had
been previously identified. |
| GEOSCAN ID | 296869 |
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