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Phasing of deglacial warming and Laurentide ice sheet meltwater in the Gulf of Mexico

Benjamin P. Flower, David W. Hastings, Heather W. Hill and Terrence M. Quinn
Phasing of deglacial warming and Laurentide ice sheet meltwater in the Gulf of Mexico
Geology (Boulder) (July 2004) 32 (7): 597-600


Evidence is emerging that the tropical climate system played a major role in global climate change during the last deglaciation. However, existing studies show that deglacial warming was asynchronous across the tropical band, complicating the identification of causal mechanisms. The Orca Basin in the northern Gulf of Mexico is ideally located to record subtropical Atlantic sea-surface temperature (SST) warming in relation to meltwater input from the Laurentide Ice Sheet. Paired delta (super 18) O and Mg/Ca data on the planktonic foraminifer Globigerinoides ruber from core EN32-PC6 are used to separate deglacial changes in SST and delta (super 18) O of seawater. SST as calculated from Mg/Ca data increased by >3 degrees C from ca. 17.2 to 15.5 ka in association with Heinrich event 1 and was not in phase with Greenland air temperature. Subtracting temperature effects from delta (super 18) O values in G. ruber reveals two excursions representing Laurentide meltwater input to the Gulf of Mexico, one of >1.5 ppm from ca. 16.1 to 15.6 ka and a second major spike of >2.5 ppm from ca. 15.2 to 13.0 ka that encompassed meltwater pulse 1A and peaked ca. 13.8 ka during the Bolling-Allerod. Conversion to salinity through the use of a Laurentide meltwater end member of -25 ppm indicates that near-surface salinity decreased by 2 ppm-4 ppm during these spikes. These results suggest that Gulf of Mexico SST warming preceded peak Laurentide Ice Sheet decay and the Bolling-Allerod interval by >2 k.y. and that heat was retained in the subtropical Atlantic during Heinrich event 1, consistent with modulation of deglacial climate by thermohaline circulation.

ISSN: 0091-7613
EISSN: 1943-2682
Serial Title: Geology (Boulder)
Serial Volume: 32
Serial Issue: 7
Title: Phasing of deglacial warming and Laurentide ice sheet meltwater in the Gulf of Mexico
Affiliation: University of South Florida, College of Marine Science, Saint Petersburg, FL, United States
Pages: 597-600
Published: 200407
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 34
Accession Number: 2004-056730
Categories: Quaternary geologyIsotope geochemistry
Document Type: Serial
Bibliographic Level: Analytic
Annotation: With GSA Data Repository Item 2004095
Illustration Description: illus. incl. sketch map
N26°55'60" - N26°56'60", W91°19'60" - W91°19'60"
Secondary Affiliation: Eckerd College, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200416
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