Terrestrial record of Laurentide Ice Sheet reorganization during Heinrich events: Comments and Reply

Baas, Jaco H.; Schönfeld, Joachim; Meyer, G.N.; Patterson, Carrie J.; Hobbs, H.C.; Johnson, Mark D.; Cotter, James Finn; Mooers, Howard D.; Lehr, J. D.

doi:10.1130/0091-7613(1998)026<0666:trolis>2.3.co;2

Cited by 3 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In spite of the strong research focus on Heinrich Stadials, the southern limit of iceberg penetration across the North Atlantic remains incompletely constrained [ Thouveny et al , 2000; Watkins et al , 2007]. Intervals containing significant amounts of Ice Rafted Debris have been found in marine sediment cores from the Portuguese Margin [ Baas et al , 1998; Cayre et al , 1999; Eynaud et al , 2009; Grousset et al , 2000; Lebreiro et al , 1996; Schönfeld and Zahn , 2000; Thomson et al , 1995; Thouveny et al , 2000], but IRD is rare in the Gulf of Cadiz, between Iberia and Morocco [ Cacho et al , 2001; Llave et al , 2006; Voelker et al , 2006]. The southern‐most record of Ice Rafted Debris is at 33.5°N off the Moroccan margin [ Kudrass , 1973].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Mediterranean‐Atlantic exchange during Atlantic freshening phases

Rogerson

Colmenero-Hidalgo

Levine

et al. 2010

Geochem Geophys Geosyst

102

View full text Add to dashboard Cite

The Atlantic‐Mediterranean exchange of water at Gibraltar represents a significant heat and freshwater sink for the North Atlantic and is a major control on the heat, salt and freshwater budgets of the Mediterranean Sea. Consequently, an understanding of the response of the exchange system to external changes is vital to a full comprehension of the hydrographic responses in both ocean basins. Here, we use a synthesis of empirical (oxygen isotope, planktonic foraminiferal assemblage) and modeling (analytical and general circulation) approaches to investigate the response of the Gibraltar Exchange system to Atlantic freshening during Heinrich Stadials (HSs). HSs display relatively flat W–E surface hydrographic gradients more comparable to the Late Holocene than the Last Glacial Maximum. This is significant, as it implies a similar state of surface circulation during these periods and a different state during the Last Glacial Maximum. During HS1, the gradient may have collapsed altogether, implying very strong water column stratification and a single thermal and δ18Owater condition in surface water extending from southern Portugal to the eastern Alboran Sea. Together, these observations imply that inflow of Atlantic water into the Mediterranean was significantly increased during HS periods compared to background glacial conditions. Modeling efforts confirm that this is a predictable consequence of freshening North Atlantic surface water with iceberg meltwater and indicate that the enhanced exchange condition would last until the cessation of anomalous freshwater supply into to the northern North Atlantic. The close coupling of dynamics at Gibraltar Exchange with the Atlantic freshwater system provides an explanation for observations of increased Mediterranean Outflow activity during HS periods and also during the last deglaciation. This coupling is also significant to global ocean dynamics, as it causes density enhancement of the Atlantic water column via the Gibraltar Exchange to be inversely related to North Atlantic surface salinity. Consequently, Mediterranean enhancement of the Atlantic Meridional Overturning Circulation will be greatest when the overturning itself is at its weakest, a potentially critical negative feedback to Atlantic buoyancy change during times of ice sheet collapse.

show abstract

Section: Introductionmentioning

confidence: 99%

Enhanced Mediterranean‐Atlantic exchange during Atlantic freshening phases

Rogerson

Colmenero-Hidalgo

Levine

et al. 2010

Geochem Geophys Geosyst

102

View full text Add to dashboard Cite

show abstract

Geology, Vegetation, and Hydrology of the S2 Bog at the MEF: 12,000 Years in Northern Minnesota

Verry¹

2011

Peatland Biogeochemistry and Watershed Hydrology at the Marcell Experimental Forest

View full text Add to dashboard Cite

The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America

Prest¹,

Donaldson²,

Mooers³

2002

gpq

Self Cite

View full text Add to dashboard Cite

The direction of Wisconsinan glacial dispersion of distinctive Proterozoic erratics derived from the Belcher Group in southeastern Hudson Bay is shown to have been northwestward, westward and southward for hundreds of kilometres across Hudson Bay, Northern Ontario, western Canada, and several adjoining northern States. The most distinctive of these erratics, termed "omars", are composed of massive siliceous wacke characterized by buff-weathering calcareous concretions; these erratics were derived from the Omarolluk Formation of the Belcher Group, exposed in the Belcher Islands of eastern Hudson Bay, and probably underlying much of the southern part of this inland sea. Far less common but equally distinctive are erratics of red oolitic jasper that were derived from the Kipalu Formation of the Belcher Group. In parallel with the now widely accepted field term "omar", we introduce the term "kipalu" for such erratics of oolitic jasper. A map showing the distribution of the distinctive erratics, in relation to indicators of Wisconsinan glacier movement, provides the basis for inferring at least two discrete glaciations that produced several major ice lobes. This paper summarizes the field observations of numerous Canadian and American earth scientists, traces the evolution of thought on provenance of the distinctive erratics, and outlines the criteria for distinguishing "true" omars from erratics derived from other bedrock sources of concretion-bearing wackes.Des erratiques de roches protérozoïques du Groupe de Belcher du sud-est de la baie d'Hudson, montrant certaines caractéristiques particulières, ont été transportés vers le nord-ouest, l'ouest et le sud, sur des centaines de kilomètres au cours du Wisconsinien, à travers la baie d'Hudson, le nord de l'Ontario, jusque dans l'Ouest canadien et dans plusieurs états voisins du nord des États-Unis. Le plus abondant de ces erratiques, l'« omar », est un grauwacke silicieux et massif contenant, dans les cas d'altération, des concrétions calcaires de couleur chamois. Ces erratiques proviennent de la Formation d'Omarolluk du Groupe de Belcher, qui affleure dans l'archipel des Belcher et qui occupe probablement une grande partie du fond marin du sud-est de la baie d'Hudson. Des erratiques de jaspe oolitique rouge, beau- coup moins abondants que les omars, mais tout aussi distinctifs, proviennent de la Formation de Kipalu du Groupe de Belcher. Nous proposons donc le terme « kipalus » pour désigner ces jaspes. La répartition de ces deux types d'erratiques, en conjonction avec les indicateurs d'écoulement glaciaire du Wisconsinien, résulte probablement de deux glaciations distinctes qui ont engendré plusieurs lobes glaciaires majeurs. Cet article, qui résume les observations de terrain de nombreux géoscientifiques canadiens et américains, retrace l'évolution de notre interprétation sur la provenance des erratiques et décrit les critères permettant d'isoler les « vrais » omars d'autres erratiques de grauwacke à concrétions provenant d'autres parties du soubassement rocheux.Erra...

show abstract

Terrestrial record of Laurentide Ice Sheet reorganization during Heinrich events: Comments and Reply

Cited by 3 publications

References 0 publications

Enhanced Mediterranean‐Atlantic exchange during Atlantic freshening phases

Enhanced Mediterranean‐Atlantic exchange during Atlantic freshening phases

Geology, Vegetation, and Hydrology of the S2 Bog at the MEF: 12,000 Years in Northern Minnesota

The Omar Story: The Role of Omars in Assessing Glacial History of West-Central North America

Contact Info

Product

Resources

About