High porosity of basal till at Burroughs Glacier, southeastern Alaska

Debris-rich basal ice at Burroughs glacier, southeastern Alaska, has 60 vol% to 70 vol% debris. Recently deposited basal till exceeds 60 vol% sediment with 30% to almost 40% porosity. Where basal ice is very rich in debris, basal till is deposited through melt out with only slight compaction of the...

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Bibliographic Details
Published in:Geology (Boulder) 1992-09, Vol.20 (9), p.849-852
Main Authors: Ronnert, Lars, Mickelson, David M
Format: Article
Language:English
Subjects:
Alaska
basal till
Burroughs Glacier
clastic sediments
debris
Geology
geomorphology
glacial geology
glacial sedimentation
glacial transport
Glacier Bay National Park
Glaciers
porosity
processes
Quaternary geology
sedimentation
sediments
Southeastern Alaska
till
United States
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Summary:Debris-rich basal ice at Burroughs glacier, southeastern Alaska, has 60 vol% to 70 vol% debris. Recently deposited basal till exceeds 60 vol% sediment with 30% to almost 40% porosity. Where basal ice is very rich in debris, basal till is deposited through melt out with only slight compaction of the debris. Porosity this high in till is commonly associated with subglacially deforming and dilated sediment. However, the recently deposited basal melt-out till at Burroughs glacier has not been deformed after deposition, but has porosity values similar to tills elsewhere interpreted to be subglacially deforming and dilated in an unfrozen state. High porosity can occur in basal melt-out till deposited directly by basal melt out.
ISSN:0091-7613
1943-2682
DOI:10.1130/0091-7613(1992)020<0849:HPOBTA>2.3.CO;2