| View Larger Image | Segregated-intrusive ice of subglacial meltwater origin in retrogressive thaw flow headwalls, Richardson Mountains, NWT, Canada [An article from: Quaternary Science Reviews] | Digitalby D. Lacelle (Author), J. Bjornson (Author), B. Lauriol (Author), I. Clark (Author), Tro (Author)
| List Price: | $5.95 | | | Available: | Available for download now |
| | Binding: | Digital | | Publisher: | Elsevier | | Publication Date: | March 01, 2004 |
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Product Description
This digital document is a journal article from Quaternary Science Reviews, published by Elsevier in 2004. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.Description: Extensive beds of icy sediments are exposed in the headwalls of active retrogressive thaw flows, which developed on the Aklavik Plateau, Richardson Mountains, NWT. Sedimentary and isotopic characteristics defined two units: debris-rich ice overlain by icy diamicton. These units originated from the same glacial sediment deposited during the Late Wisconsin westward expansion of the Laurentide Ice Sheet. The icy diamicton is a result of the development of thaw flows and mass movement processes during the early Holocene warm interval, which reworked the sediments. The ice in the diamicton is characterized by average @d^1^8O and @dD values of -22.6+/-1.8%% and -181 +/- 15%%, respectively, which are similar to the modern isotropic composition of precipitation for that area. The debris-rich ice is more depleted in ^1^8O and D, with @d^1^8O ranging from -30%% to -27%% and @dD ranging from -230%% to -210%%. Air bubbles enclosed in the ice have @d^1^3C values ranging between -24%% and -19%% and a CO"2 concentration nine times higher than the expected concentration of air entrapped in modern glacier ice but similar to that of soil CO"2. Both physical and isotopic properties of the debris-rich ice suggest that it is segregated-intrusive ice that formed after the retreat of the Laurentide ice sheet during permafrost aggradation as sediment-laden subglacial meltwater moved through a proglacial talik. This article discusses the mechanism involved in the formation of massive segregated-intrusive ice and how it differs from both buried glacier ice and Holocene massive intrasedimental ice. |
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