Depositional processes and the inferred history of ice-margin retreat associated with the deglaciation of the Cordilleran Ice Sheet: The sedimentary record from Flathead Lake, northwest Montana, USA

abstract Since 1900, more than 290 earthquakes have been reported near Flathead Lake, Montana. Surprisingly, none has exceeded magnitude 5 to 512. Most recent earthquake swarms appear to result from east-west or northwest-southeast extension along short fault segments west and north of the lake. Major normal faults like the Swan and Mission faults east of the lake may pose higher risk, but they appear dormant today. Deformation of sediments in Flathead Lake may be caused by several large earthquakes more than 10,000 years ago but is more probably due to glacial processes accompanying the last retreat of the Cordilleran ice sheet.

Download Full-text

THE CORDILLERAN ICE SHEET OF THE NORTHERN ROCKY MOUNTAINS, AND RELATED QUATERNARY HISTORY OF THE COLUMBIA PLATEAU

The Quaternary of the U.S. ◽

10.1515/9781400876525-015 ◽

1965 ◽

pp. 231-242 ◽

Cited By ~ 7

Keyword(s):

Rocky Mountains ◽

Ice Sheet ◽

Northern Rocky Mountains ◽

Columbia Plateau ◽

History Of ◽

Quaternary History ◽

Cordilleran Ice Sheet

Download Full-text

Sequence stratigraphy and depositional history of the Baranof Fan: Insights for Cordilleran Ice Sheet outflow to the Gulf of Alaska

Geological Society of America Bulletin ◽

10.1130/b35164.1 ◽

2019 ◽

Vol 132 (1-2) ◽

pp. 353-372

Author(s):

Jiajia Zhang ◽

Sean P.S. Gulick

Keyword(s):

Deep Sea ◽

Ice Sheet ◽

Coupled System ◽

Gulf Of Alaska ◽

Coast Range ◽

Depositional History ◽

Sediment Distribution ◽

Sequence Correlation ◽

History Of ◽

Cordilleran Ice Sheet

AbstractThe Baranof Fan is one of three large Alaska deep-sea fans that preserve sedimentary records reflecting both tectonic and climatic processes. However, lack of drill sites in the Baranof Fan makes the depositional history across the southeastern Alaska margin still poorly understood. Sequence correlation from the adjacent Surveyor Fan to the Baranof Fan provides updated age constraints on the Baranof Fan evolution history. Results show that both the Baranof and Surveyor Fans are dominantly glacial and initiated ca. 2.8 Ma and expanded rapidly since ca. 1.2 Ma in response to the major glaciation events; these results place the deposition of the Baranof Fan younger than previously thought (ca. 7 Ma). The glacially influenced Baranof Fan contains two sub-fans that are laterally stacked with their depocenters migrating southeastward. Each sub-fan developed multiple channels that young southeastward as channel avulsion, coevolution, and tectonic beheading progressed over the past ∼2.8 m.y. Tectonic reconstruction suggests that the Baranof Fan is sourced from the Coast Range via shelf-crossing troughs near the Chatham Strait and Dixon Entrance and thus represents a major outflow for the Cordilleran Ice Sheet during glaciations; the Chatham Strait is the major conduit that has fed most of the Baranof Fan channels. Comparatively, the Surveyor Fan is sourced predominantly from the St. Elias Range where a confluence of orogenesis and glaciations are a coupled system and only partly from the Coast Range via the Icy Strait. It is concluded that the formation and expansion of the Cordilleran Ice Sheet has determined the timing of the Baranof Fan deposition, yet Pacific–North America strike-slip motion has influenced the Baranof Fan sediment distribution, as previously suggested, via a series of southeastward avulsing channels and resultant southeastward migration of deep-sea depocenters.

Download Full-text

Quaternary stratigraphy and history, Williams Lake, British Columbia

Canadian Journal of Earth Sciences ◽

10.1139/e87-012 ◽

1987 ◽

Vol 24 (1) ◽

pp. 147-158 ◽

Cited By ~ 24

Author(s):

John J. Clague

Keyword(s):

British Columbia ◽

Late Quaternary ◽

Ice Sheet ◽

Stream Channels ◽

Valley Fill ◽

Braided Streams ◽

History Of ◽

Late Wisconsinan ◽

Cordilleran Ice Sheet ◽

Sand And Gravel

Thick valley-fill sediments in the vicinity of Williams Lake, British Columbia, provide a detailed record of the late Quaternary history of an area near the centre of the former Cordilleran Ice Sheet. Stratigraphic units assigned to the late Wisconsinan Fraser Glaciation, the preceding (penultimate) glaciation, and the present interglaciation are described. Especially noteworthy are (1) thick units of sand and gravel deposited by braided streams, perhaps during periods of ice-sheet growth; and (2) complex glaciolacustrine sediments that accumulated in ice-dammed lakes during periods of deglaciation.Glaciers from the Coast and Cariboo mountains coalesced and flowed north over central British Columbia during late Wisconsinan time. Fraser Glaciation advance sediments and older Pleistocene deposits were partially removed by this ice sheet, and the eroded remnants were mantled with till. At the end of the Fraser Glaciation, the Cordilleran Ice Sheet downwasted and retreated southward along an irregular front across the study area. Parts of the ice sheet stagnated and disintegrated into tongues confined to valleys. Sediment carried by melt streams flowing from decaying ice masses was deposited in glacial lakes, in stream channels, and on floodplains.

Download Full-text

Tephrochronologic Constraints on the Late Pleistocene History of the Southern Margin of the Cordilleran Ice Sheet, Western Washington

Quaternary Research ◽

10.1006/qres.1996.1877 ◽

1997 ◽

Vol 47 (2) ◽

pp. 140-146 ◽

Cited By ~ 10

Author(s):

James E. Begét ◽

Mary J. Keskinen ◽

Kenneth P. Severin

Keyword(s):

Lake Sediments ◽

Late Pleistocene ◽

Ice Sheet ◽

Cascade Range ◽

Southern Margin ◽

Ash Layer ◽

History Of ◽

Western Washington ◽

Cordilleran Ice Sheet ◽

Eastern Washington

An ash layer that appears geochemically correlative with Mt. St. Helens tephra set S occurs in a sequence of Pleistocene lake sediments in the Ohop Valley of the southern Puget Lowland, below Vashon till deposited during the maximum late Pleistocene advance (Fraser Glaciation) of the Puget Lobe of the Cordilleran Ice Sheet. The Puget Lobe reached its maximum southern extent ca. 14,000–14,500 yr B.P., and at least part of set S is evidently somewhat older. Previous radiocarbon and thermoluminescence dates for set S have ranged from 13,000 to 16,000 yr B.P.Geochemically correlative deposits of set S tephra occur in slackwater sediments coeval with the Missoula Floods in eastern Washington, produced by jökulhlaups through the Purcell Trench Lobe of the Cordilleran Ice Sheet. These relationships suggest that advances of glacier lobes on the southern margin of the Cordilleran Ice Sheet were nonsynchronous, as the Pucell Trench lobe east of the Cascade Range advanced to its maximum southern extent prior to the time of the eruption of set S, before the Puget Lobe west of the Cascades reached its maximum southern extent.

Download Full-text

Advance of the Late Wisconsin Cordilleran Ice Sheet in Southern British Columbia Since 22,000 Yr B.P.

Quaternary Research ◽

10.1016/0033-5894(80)90060-5 ◽

1980 ◽

Vol 13 (3) ◽

pp. 322-326 ◽

Cited By ~ 62

Author(s):

J. J. Clague ◽

J. E. Armstrong ◽

W. H. Mathews

Keyword(s):

British Columbia ◽

Ice Sheet ◽

Laurentide Ice Sheet ◽

Major Advance ◽

Radiocarbon Dates ◽

Coast Mountains ◽

Growth History ◽

Glacier Ice ◽

History Of ◽

Cordilleran Ice Sheet

AbstractRadiocarbon dates from critical stratigraphic localities in southern British Columbia indicate that the growth history of the late Wisconsin Cordilleran Ice Sheet was different from that of most of the Laurentide Ice Sheet to the east. Much of southern British Columbia remained free of ice until after about 19,000 to 20,000 yr ago; only adjacent to the Coast Mountains is there a record of lowland glacier tongues in the interval 22,000 to 20,000 yr B.P. A major advance to the climax of late Wisconsin Cordilleran glacier ice in the northern States was not begun until after about 18,000 yr B.P. in the southwest of British Columbia and after about 17,500 yr B.P. in the southeast. The rate of glacier growth must have been very rapid in the two to three millennia prior to the climax, which has been dated in western Washington at shortly after 15,000 yr B.P.

Download Full-text