Five thousand years of sediment transfer in a high arctic watershed recorded in annually laminated sediments from Lower Murray Lake, Ellesmere Island, Nunavut, Canada

Cook, Timothy L.; Bradley, Raymond S.; Stoner, J. S.; Francus, Pierre

doi:10.1007/s10933-008-9252-0

Cited by 69 publications

(37 citation statements)

References 43 publications

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“…Slabs were then embedded in epoxy resin under vacuum and cured afterwards. For more details on the method see Cook et al (2009) and Francus and Asikainen (2001). To obtain thin sections, the dried epoxyimpregnated sediment slabs were cut, ground and polished to a thickness of only a few millimetres.…”

Section: Methodsmentioning

confidence: 99%

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

et al. 2014

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Abstract. The Weddell Sea and the associated FilchnerRønne Ice Shelf constitute key regions for global bottomwater production today. However, little is known about bottom-water production under different climate and icesheet conditions. Therefore, we studied core PS1795, which consists primarily of fine-grained siliciclastic varves that were deposited on contourite ridges in the southeastern Weddell Sea during the Last Glacial Maximum (LGM). We conducted high-resolution X-ray fluorescence (XRF) analysis and grain-size measurements with the RADIUS tool (Seelos and Sirocko, 2005) using thin sections to characterize the two seasonal components of the varves at sub-mm resolution to distinguish the seasonal components of the varves.Bright layers contain coarser grains that can mainly be identified as quartz in the medium-to-coarse silt grain size. They also contain higher amounts of Si, Zr, Ca, and Sr, as well as more ice-rafted debris (IRD). Dark layers, on the other hand, contain finer particles such as mica and clay minerals from the chlorite and illite groups. In addition, Fe, Ti, Rb, and K are elevated. Based on these findings as well as on previous analyses on neighbouring cores, we propose a model of enhanced thermohaline convection in front of a grounded ice sheet that is supported by seasonally variable coastal polynya activity during the LGM. Accordingly, katabatic (i.e. offshore blowing) winds removed sea ice from the ice edge, leading to coastal polynya formation. We suggest that glacial processes were similar to today with stronger katabatic winds and enhanced coastal polynya activity during the winter season. Under these conditions, lighter coarser-grained layers are likely glacial winter deposits, when brine rejection was increased, leading to enhanced bottom-water formation and increased sediment transport. Vice versa, darker finer-grained layers were then deposited during less windier season, mainly during summer, when coastal polynya activity was likely reduced.

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Section: Methodsmentioning

confidence: 99%

Seasonal changes in glacial polynya activity inferred from Weddell Sea varves

et al. 2014

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“…Relative paleointensity (RPI) was determined by following the methods of Barletta et al (44), correlated to nearby records from a varved lake from Ellesmere Island and geomagnetic field model output (45,46), and then validated and augmented with seven radiocarbon ages. Samples submitted for accelerator mass spectrometry (AMS) radiocarbon dating were prepared at the Université Laval Radiocarbon Laboratory and analyzed at the Keck Carbon Cycle AMS Facility (Irvine, CA) or Beta Analytic (Miami, FL) ( Table S1).…”

Section: Methodsmentioning

confidence: 99%

“…The age-depth model (Fig. 2) was constructed by using Markov chain Monte Carlo Bayesian methods based on seven AMS dates of hand-picked foraminiferal 14 C and four unambiguous inflection points where our RPI record was tied to published paleomagnetic curves (45,46) (SI Materials and Methods and Table S2). All dates presented are calibrated with the Marine09 dataset (47), with a local ΔR of 335 ± 85 years applied to all samples (48) and an additional variable carbon reservoir within epishelf stages assuming a fixed carbon pool because of isolation by the strong perennial ice cover (49, 50) (SI Materials and Methods and Table S1).…”

Section: Methodsmentioning

confidence: 99%

Holocene dynamics of the Arctic's largest ice shelf

Antoniades

Francus

Pienitz

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Ice shelves in the Arctic lost more than 90% of their total surface area during the 20th century and are continuing to disintegrate rapidly. The significance of these changes, however, is obscured by the poorly constrained ontogeny of Arctic ice shelves. Here we use the sedimentary record behind the largest remaining ice shelf in the Arctic, the Ward Hunt Ice Shelf (Ellesmere Island, Canada), to establish a long-term context in which to evaluate recent ice-shelf deterioration. Multiproxy analysis of sediment cores revealed pronounced biological and geochemical changes in Disraeli Fiord in response to the formation of the Ward Hunt Ice Shelf and its fluctuations through time. Our results show that the ice shelf was absent during the early Holocene and formed 4,000 years ago in response to climate cooling. Paleoecological data then indicate that the Ward Hunt Ice Shelf remained stable for almost three millennia before a major fracturing event that occurred ∼1,400 years ago. After reformation ∼800 years ago, freshwater was a constant feature of Disraeli Fiord until the catastrophic drainage of its epishelf lake in the early 21st century.climate change | glaciology | paleoceanography | geochemistry

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“…Kalnay et al, 1996;Rayback and Henry, 2006) and likely the warmest of the past several hundred years (e.g. Overpeck et al, 1997;Cook et al, 2009). Projections of future temperature change in the High Arctic indicate the potential for continued warming in excess of 5 uC by the end of the 21st century (Christensen et al, 2007).…”

Section: Introductionmentioning

confidence: 99%