TSIVAT BASIN CONDUIT SYSTEM PERSISTS THROUGH 2 SURGES, BERING PIEDMONT GLACIER, ALASKA

Citation
Pj. Fleisher et al., TSIVAT BASIN CONDUIT SYSTEM PERSISTS THROUGH 2 SURGES, BERING PIEDMONT GLACIER, ALASKA, Geological Society of America bulletin, 110(7), 1998, pp. 877-887
Citations number
24
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Geosciences, Interdisciplinary
ISSN journal
0016-7606
Volume
110
Issue
7
Year of publication
1998
Pages
877 - 887
Database
ISI
SICI code
0016-7606(1998)110:7<877:TBCSPT>2.0.ZU;2-L
Abstract
The 1993-1995 surge of Bering Glacier, Alaska, occurred in two distinc t phases. Phase 1 of the surge began on the eastern sector in July, 19 93 and ended in July, 1994 after a powerful outburst of subglacial mel twater into Tsivat Lake basin on the north side of Weeping Feat Island . Within days, jokulhlaup discharge built a 1.5 km(2) delta of ice blo cks (25-30 m) buried in outwash, By late October 1994, discharge tempo rarily shifted to a vent on Weeping Feat island, where a second smalle r outburst dissected the island and built two new sandar, During phase 2, which began in spring 1995 and ended within five months, continuou s discharge issued from several vents along the ice front on Weeping F eat Island before returning to the Tsivat Basin. Surge-related changes include a five- to six-fold increase in meltwater turbidity; the redi rection of supercooled water in two ice contact lakes; and an increase in the rate of glaciolacustrine sedimentation. U.S. Geological Survey aerial photos by Austin Post show Large ice blocks in braided channel s indicating excessive subglacial discharge in a similar position adja cent to Weeping Feat Island during the 1966-1967 surge. During the sub sequent three decades of retreat, the location of ice-marginal, subgla cial discharge vents remained aligned on a linear trend that describes the position of a persistent subglacial conduit system, The presence of a major conduit system, possibly stabilized by subglacial bedrock t opography; is suggested by (1) high-level subglacial meltwater venting along the northern side of Weeping Feat Island during the 1966-1967 s urge, (2) persistent low-level discharge between surges, and (3) the r ecurrence of localizing meltwater outbursts associated with both phase s of the 1993-1995 surge.