@article {2044,
	title = {Radiocarbon and stable isotope constraints on Last Glacial Maximum and Younger Dryas ventilation in the western North Atlantic},
	journal = {Paleoceanography},
	volume = {19},
	year = {2004},
	note = {870dfTimes Cited:72
Cited References Count:60
},
	month = {Nov 3},
	abstract = {[1] Foraminiferal abundance, C-14 ventilation ages, and stable isotope ratios in cores from high deposition rate locations in the western subtropical North Atlantic are used to infer changes in ocean and climate during the Younger Dryas (YD) and Last Glacial Maximum (LGM). The delta(18)O of the surface dwelling planktonic foram Globigerinoides ruber records the present-day decrease in surface temperature (SST) of similar to 4 degreesC from Gulf Stream waters to the northeastern Bermuda Rise. If during the LGM the modern delta(18)O/salinity relationship was maintained, this SST contrast was reduced to 2 degreesC. With LGM to interglacial delta(18)O changes of at least 2.2parts per thousand, SSTs in the western subtropical gyre may have been as much as 5 degreesC colder. Above similar to 2.3 km, glacial delta(13)C was higher than today, consistent with nutrient-depleted ( younger) bottom waters, as identified previously. Below that, delta(13)C decreased continually to - 0.5parts per thousand, about equal to the lowest LGM delta(13)C in the North Pacific Ocean. Seven pairs of benthic and planktonic foraminiferal C-14 dates from cores > 2.5 km deep differ by 1100 +/- 340 years, with a maximum apparent ventilation age of similar to 1500 years at 4250 m and at similar to 4700 m. Apparent ventilation ages are presently unavailable for the LGM < 2.5 km because of problems with reworking on the continental slope when sea level was low. Because LGM \&delta;C-13 is about the same in the deep North Atlantic and the deep North Pacific, and because the oldest apparent ventilation ages in the LGM North Atlantic are the same as the North Pacific today, it is possible that the same water mass, probably of southern origin, flowed deep within each basin during the LGM. Very early in the YD, dated here at 11.25 +/- 0.25 ( n = 10) conventional C-14 kyr BP ( equal to 12.9 calendar kyr BP), apparent ventilation ages < 2.3 km water depth were about the same as North Atlantic Deep Water today. Below similar to 2.3 km, four YD pairs average 1030 +/- 400 years. The oldest apparent ventilation age for the YD is 1600 years at 4250 m. This strong contrast in ventilation, which indicates a front between water masses of very different origin, is similar to glacial profiles of nutrient-like proxies. This suggests that the LGM and YD modes of ocean circulation were the same.},
	keywords = {benthic foraminifera, deep-sea sediments, ice-age, Ocean circulation, ocean ventilation, pacific-ocean, radiocarbon, SARGASSO SEA, southern-ocean, Thermohaline circulation, united-states, water circulation, western north atlantic},
	isbn = {0883-8305},
	doi = {10.1029/2004PA001029},
	url = {http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2\&amp;SrcAuth=Alerting\&amp;SrcApp=Alerting\&amp;DestApp=WOS\&amp;DestLinkType=FullRecord;UT=WOS:000225033500003},
	author = {Keigwin, L. D.}
}
@article {2117,
	title = {Ocean ventilation and sedimentation since the glacial maximum at 3 km in the western North Atlantic},
	journal = {Geochemistry Geophysics Geosystems},
	volume = {3},
	year = {2002},
	note = {565rlTimes Cited:26
Cited References Count:43
},
	month = {Jun 22},
	abstract = {[1] Stable isotope, sedimentological, and radiocarbon data from cores at similar to 3 km water depth on the Blake Ridge, western subtropical North Atlantic, reveal the history of deep water ventilation since the last glacial maximum (LGM). Bulk sediment accumulation rates varied locally by a factor of 2 under the influence of bottom currents in this sediment drift environment, but the sand flux, mostly foraminifera, was nearly identical at a given time. This suggests that the rain rate of foraminifera (mostly planktonic) was constant, that transport of foraminifera was negligible, and that current-controlled differences in clay and silt transport drive bulk accumulation. In two of the cores, flux peaks in the benthic foraminifera Cibicidoides and Uvigerina peregrina occurred during the Younger Dryas (YD) cold event, and at 18.2, 19.6, 21.1, 25.0, and 28.1 ka. Radiocarbon measurements on those benthic foraminifera show the ventilation age of bottom waters was similar to 1000 years during the YD, and for older events it was as great as 2000 years. These results contrast with Holocene ventilation, which was similar to 500 years and 700 years at 1500 years and similar to 7100 years before present, respectively.},
	keywords = {abyssal circulation, benthic foraminifera, c-14 ages, Calibration, climate-change, deep-water, Holocene, Last glacial maximum, ocean ventilation, radiocarbon, radiocarbon age, sea, sediment drifts, Younger Dryas},
	isbn = {1525-2027},
	doi = {10.1029/2001GC000283},
	author = {Keigwin, L. D. and Schlegel, M. A.}
}
@article {2383,
	title = {Lake-Level History of Lake-Michigan for the Past 12,000 Years - the Record from Deep Lacustrine Sediments},
	journal = {Journal of Great Lakes Research},
	volume = {20},
	year = {1994},
	note = {Nl348Times Cited:47
Cited References Count:29
},
	month = {1994},
	pages = {73-92},
	abstract = {Collection and analysis of an extensive set of seismic-reflection profiles and cores from southern Lake Michigan have provided new data that document the history of the lake basin for the past 12,000 years. Analyses of the seismic data, together with radiocarbon dating, magnetic, sedimentologic, isotopic, and paleontologic studies of core samples, have allowed us to reconstruct lake-level changes during this recent part of the lake{\textquoteright}s history.The post-glacial history of lake-level changes in the Lake Michigan basin begins about 11.2 ka with the fall from the high Calumet level, caused by the retreat of the Two Rivers glacier, which had blocked the northern outlet of the lake. This lake-level fall was temporarily reversed by a major influx of water from glacial Lake Agassiz (about 10.6 ka), during which deposition of the distinctive gray Wilmette Bed of the Lake Michigan Formation interrupted deposition of red glaciolacustrine sediment. Lake level then continued to fall, culminating in the opening of the North Bay outlet at about 10.3 ka. During the resulting Chippewa low phase, lake level was about 80 m lower than it is today in the southern basin of Lake Michigan.
The rise of the early Holocene lake level, controlled primarily by isostatic rebound of the North Bay outlet, resulted in a prominent, planar, transgressive unconformity that eroded most of the shoreline features below present lake level. Superimposed on this overall rise in lake level, a second influx of water from Lake Agassiz temporarily raised lake levels an unknown amount about 9.1 ka. At about 7 ka, lake level may have fallen below the level of the outlet because of sharply drier climate. Sometime between 6 and 5 ka, the character of the lake changed dramatically, probably due mostly to climatic causes, becoming highly undersaturated with respect to calcium carbonate and returning primary control of lake level to the isostatically rising North Bay outlet. Post-Nipissing (about 5 ka) lake level has fallen about 6 m due to erosion of the Port Huron outlet, a trend around which occurred relatively small (+/- approximately 2 m), short-term fluctuations controlled mainly by climatic changes. These cyclic fluctuations are reflected in the sedimentological and sediment-magnetic properties of the sediments.
},
	keywords = {lake michigan, ostracodes, radiocarbon, sedimentology, sediments, southern},
	isbn = {0380-1330},
	author = {Colman, S. M. and Forester, R. M. and Reynolds, R. L. and Sweetkind, D. S. and King, J. W. and Gangemi, P. and Jones, G. A. and Keigwin, L. D. and Foster, D. S.}
}
