Stratigraphic evidence for rate of sedimentation in an ice-contact, proglacial lake, Bering Glacier, Alaska

Conference · Mon Mar 01 04:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5878901

Fleisher, P J ^[1]; Bailey, P K ^[2]

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1. Univ. of New York, Oneonta, NY (United States). Dept. of Earth Sciences
2. Army Cold Regions Research and Engineering Lab., Hanover, NH (United States)

A semi-continuous aerial photo record documents retreat positions of the eastern Bering Glacier and the development of a shallow embayment of ice-contact Tsiu Lake during the summer of 1986. An observed break out in August, 1989, abruptly dropped lake level 17 m and exposed lake sediments containing three annual couplets 54 cm thick. This continuous record of accumulation during a documented 3-year period yields an average annual accumulation rate of 18 cm/year. The lower portion of each annual couplet averages 11.5 cm in thickness and consists of fine, gray silt laminae, each approximately 0.7 mm thick. These grade upward into interlaminated light and dark gray silt and tan, very fine sand beds, each about 0.5 cm thick, with an average cumulative thickness of 6.5 cm. The sand is commonly cross bedded and contains subtle graded bedding. Because the uppermost interlaminated unit was the last to be deposited prior to the break out, it must represent summer-season sediments. This interpretation is consistent with intermittent higher summer discharge and associated currents that periodically introduce sand and hold silt in suspension. Lower energy conditions beneath frozen lakes during winter months favor quieter water and yield a thicker accumulation of uniform silt. Measurements of contemporary summer accumulation were made using cylinder sediment traps. Resulting data indicate that rates of sediment accumulation are directly related to length of collection column, trap depth, duration of sample period and turbidity, and may be an order of magnitude greater than that represented by the measured stratigraphic record. These field studies shed light on specific conditions of deposition and the glaciolacustrine environment during Laurentide retreat from central New York State.

• OSTI ID: 5878901
• Report Number(s): CONF-9303211--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 25:2
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
580000* -- Geosciences
AERIAL MONITORING
AERIAL SURVEYING
ALASKA
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC DEPOSITS
GEOLOGY
GLACIERS
LAKES
MONITORING
NORTH AMERICA
SEDIMENTATION
STRATIGRAPHY
SURFACE WATERS
USA