An oxygen-isotope climatic record from the Devon Island ice cap, arctic Canada

Paterson, W. S. B.; Koerner, R. M.; Fisher, David; Johnsen, S. J.; Clausen, Henrik; Dansgaard, W.; Bucher, P. J. M.; Oeschger, H.

doi:10.1038/266508a0

Cited by 211 publications

(111 citation statements)

References 15 publications

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“…Sections A and C are texturally similar. Section B has been identified as Wisconsin (Paterson and others, 1977) and section D has been thought to represent ice formed in the superimposed ice zone on t\1e ice cap when it was considerably smaller; we show later that this may not be the case.…”

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confidence: 81%

“…A second process, which causes a variable vertical strain-ra te to exist in the basal layers, is due to the effect on the flow dynamics of the different properties of the fine-a nd coarsegrained ice. Paterson (1977) found tertia ry creep-ra tes four times those of th e ice immedia tely a bove a nd below the 2.6-4 .25 m fine-grained section . V ery recent measurements in a bore hole on Agassiz I ce Cap in n orthern ElIesmere I sla nd confirm P a terson 's ( 19 77 ) work.…”

Section: Flow Processesmentioning

confidence: 89%

“…Below that, where we enter ice of Wisconsin (B) and pre-Wisconsin age (C and D) (Paterson and others, 1977), there are major variations. As the micro-particle profile can only be altered by non-Iaminar flow of the ice rather than by molecular diffusion (8 18 0) or grainboundary migration (crystals), it serves as an additional datum signature for comparing D72 and D73 in terms of ice dynamics.…”

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confidence: 99%

“…PREVIOUS WORK Fisher (unpublished [a] ) and Paterson and others ( 1977) , in a study of the 8 18 0 profiles in D72 and D73, concluded that 25-30 % of each core record was missing from the lowermost 6 m with an additional 6-9% missing from both cores. Using a sliding correlation technique on the 8 profiles, Fisher (unpublished [a] ) identified sections of each core which correlated highly enough to assume them to be identical temporally.…”

Section: * = 24(pip*)-o'78mentioning

confidence: 99%

“…Using a sliding correlation technique on the 8 profiles, Fisher (unpublished [a] ) identified sections of each core which correlated highly enough to assume them to be identical temporally. Fisher (unpublished [a] ) then reconstructed a Devon Island ice-cap 8 record using both cores and ignoring the possible 6-9 % combined loss; a similar reconstruction is in Paterson and others ( 1977 ) . Fisher (unpublished [b]), using the same correlation technique for the crystal-size data ( Fig.…”

Section: * = 24(pip*)-o'78mentioning

confidence: 99%

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Discontinuous Flow, Ice Texture, and Dirt Content in the Basal Layers of the Devon Island Ice Cap

Koerner

Fisher

1979

J. Glaciol.

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ABSTRACT. Surface-to-bedrock cores obtained with a CRREL thermal drill we re taken in 1972 and 1973 from the top of the Devon Island ice cap. There are very pronounced variations in oxygen isotope, microparticle concentration, and ice texture in the lowermost 5 m of the core. There is a section of isotopically cold, very fin e bubbly ice with high mic ro-particle concentrations between 2.6 and 4 .4 m above the bed, considered to represe nt the Last l ee Age. There is coarse, isotopically warm, clean ice above and below this. F o r 1. 2 m a bove the bed, the ice is finer again with high micro-particle concentrations but it shows very low bubble concentration and is isotopically the warmest in the core. While the broad variations are common to both cores, in detail there are signifi ca nt variations despite the fa ct that the cores were taken only 27 m apart. The variations, when analysed statisticall y, show that at least 25-30 % of the originally continuous profile is missing from each core. Faulting within the near-bedrock ice may be responsible for some of the effect but bubble fabric also gives evid e nce for irregular non-Iaminar flow. Because of the strong relationship between crystal size and micro-particle co ncentrations in the Devon Isla nd cores, it is suggested that the fine-grained nature of dirty layers in the Antarctic and Greenland ice sheets is due to the effect of the dirt inclusions a nd not of shearing. Steep isotopic gradients in the Devon Isla nd cores are shown to be evidence for possible shearing, which does not effect any change in the crystal texture. C lear ice near the bed is consid ered a tectonic feature, but the lack of effect on its bed by the ice cap confirms the non-erosional nature of an ice cap froz en to its bed .In terms of paleoclimatic history, it m eans that, because of bedrock effects, ice caps of intermediate d epth (i.e. < 400 m ) ca n give continuous informatio n only over the last approximate 5000 years. Between 5000 a nd 10000 B.P. the time seri es becomes sli ghtly discontinuous and beyond 10000 B.P. so discontinuous as to allow only broad climatic inferences to b e drawn. RES UME. Ecoulemellts discOlltillllS, texture de la glace et teneur en debris dall s les niveaux de base de la calotte glaciairede l'lle D evon. On a preleve avec une sonde thermique CRREL des carottes continues surface-bedrock en 1972 et 1973 depuis le sommet de la calotte glaciaire de l'Ile Devon. Il y a des variations tres prononcees en isotopes de l' oxygene, en concentration e n micro-particul es e t en texture de la glace dans les cinq derniers m etres a u bas de la carotte. II y a un e section d'une glace isotopiquement fro ide, tres finement bulleuse, rich e en mi cro-pa rticules e ntre 2,6 et 4,4 m au d ess us du lit, que l'o n considere comme representant le Dernier Age G lac iaire. Au d ess us et en dessous, on trouve une glace propre, a gros grains, isotopiquement chaud e. Sur 1,2 m au dessus du lit, la glace est d e nouvea u a grains plus fin s avec un e forte concentration en bulles ...

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Section: ~--'---R--'----'i----'---'i----'----'i---'----rl---'----'mentioning

confidence: 81%

Section: Flow Processesmentioning

confidence: 89%

Section: ~--'---R--'----'i----'---'i----'----'i---'----rl---'----'mentioning

confidence: 99%

Section: * = 24(pip*)-o'78mentioning

confidence: 99%

Section: * = 24(pip*)-o'78mentioning

confidence: 99%

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