The geomorphic and paleoenvironmental record in the sediments of Atlin Lake, northern British Columbia

Gilbert, Robert G.; Desloges, Joseph R.; Lamoureux, Scott F.; Serink, Andrea; Hodder, Kyle R.

doi:10.1016/j.geomorph.2005.09.021

Cited by 11 publications

(6 citation statements)

References 26 publications

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“…After 8.4 14 C ka B.P., when the Laurentide Ice Sheet runoff no longer reached Christie Bay, the LSR dropped to ~0.2 mm yr -1 . A comparable drop in sedimentation rate was observed in recent times when glacial meltwater ceased to enter a lake near the Juneau Ice Field in Alaska (Gilbert et al, 2006). Our estimates are also in good quantitative agreement with those derived for lakes along the southern Laurentide Ice Sheet margin (Breckenridge et al, 2004;Dobson et al, 1995).…”

Section: Sediment and Meltwater Dynamicssupporting

confidence: 87%

Large subglacial lake beneath the Laurentide Ice Sheet inferred from sedimentary sequences

Christoffersen

Tulaczyk

Wattrus

et al. 2008

Geol

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Section: Sediment and Meltwater Dynamicssupporting

confidence: 87%

Large subglacial lake beneath the Laurentide Ice Sheet inferred from sedimentary sequences

Christoffersen

Tulaczyk

Wattrus

et al. 2008

Geol

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“…Within Bow Lake, Smith (1981) related reduced rates of deposition and altered spatial patterns of sedimentation after 1955 to a pond established at the terminus of Bow Glacier, Alberta. Gilbert et al (2006b) attributed reduced sediment accumulation by an order of magnitude in Llewellyn Inlet of Atlin Lake, British Columbia, to the formation of a lake at the toe of Llewellyn Glacier during the mid-20th century. Sedimentological studies were not conducted on these recently formed proglacial water bodies, but it is assumed that they represent a major variable factor on sediment delivery to downstream lakes, where varve proxy records are of interest.…”

mentioning

confidence: 99%

Proglacial sediment trapping in recently formed Silt Lake, upper Lillooet Valley, Coast Mountains, British Columbia

Schiefer

Gilbert

2008

Earth Surf Processes Landf

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The sedimentology of proglacial Silt Lake was assessed by lake sediment coring and monitoring of lacustrine processes during a late-summer period of high glacier melt to characterize sediment delivery from the heavily glacierized catchment and investigate the sediment trapping dynamics of this upland lake. A complete varve chronology was established for a distal basin of the lake which was exposed by Lillooet Glacier retreat between 1947 and 1962. The varve record showed decreasing sedimentation rates in the basin while the glacier retreated, and as the lake became free of ice contact in the early 1970s. Although recession has continued over recent decades, and glacier proximity to the lake has, therefore, continued decreasing, lacustrine sedimentation rates are now accelerating due to changing basin morphometry caused by delta progradation. Over shorter time scales, lake sedimentation patterns respond to changing runoff conditions, including late-summer glacier melt intensity, intra-annual flooding events, diumal runoff fluctuations, and within-lake turbidity currents. Turbidity currents included quasi-regular flows during high diurnal discharges and an episodic flushing of temporarily stored sediment from the sandur or delta at a time of low stage. Suspended sediment yield to Silt Lake is estimated to exceed 10 3 Mg km − − − − −2 a − − − − −1 , a magnitude that surpasses previous local and regional yield estimates for the glacierized headwaters of the Lillooet River valley. Since Silt Lake currently traps a significant prooportion of that upland sediment supply, and the trapping efficiency of the basin has been variable at decadal time scales, the formation and continued development of Lilt Lake has likely had a significant influence on downstream sediment delivery. Lacustrine sediment-based proxies of longterm hydroclimatic variability being developed in glacially distal settings should include provisions for dynamic sediment trapping effects in upstream water bodies that often form in the active proglacial environment.Recession of glaciers during the 20th century has resulted in the formation of proglacial lakes near the termini of many glaciers in the Canadian Cordillera. These include lakes occupying ice-scoured basins in bedrock and impoundments within or behind morainal deposits. The formation of these glacier-proximal water bodies may significantly alter sediment delivery to distal lakes, which are often targeted for sediment-based proxy studies. Within Bow Lake, Smith (1981) related reduced rates of deposition and altered spatial patterns of sedimentation after 1955 to a pond established at the terminus of Bow Glacier, Alberta. Gilbert et al. (2006b) attributed reduced sediment accumulation by an order of magnitude in Llewellyn Inlet of Atlin Lake, British Columbia, to the formation of a lake at the toe of Llewellyn Glacier during the mid-20th century. Sedimentological studies were not conducted on these recently formed proglacial water bodies, but it is assumed that they represent a major variable fact...

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“…Following deglaciation of coastal regions, some fjord basins were isolated from the sea to form fjord-lakes due to glacio-isostatic rebound (Batterson et al, 1993;Batterson and Catto, 2001;Lajeunesse, 2014;Dietrich et al, 2017b). Sharing similar limnogeological characteristics with coastal fjords, fjord-lakes have shown their potential for reconstructing past ice sheet dynamics, deglaciation, paleoenvironmental changes and natural hazards in studies using marine hydroacoustic, geophysical and sediment sampling analysis techniques, as Europe (Van Rensbergen et al, 1999;Beck et al, 2001;Fanetti et al, 2008;Hilbe et al, 2011;Heirman et al, 2012;Turner et al, 2012;Pinson et al, 2013;Vogel et al, 2013), British Columbia (Eyles et al, 1990(Eyles et al, , 1991Gilbert, 1995, 1998;Gilbert and Butler, 2004;Desloges, 2005, 2012;Gilbert et al, 2006a;Gilbert et al, 2006b;Tunnicliffe et al, 2012), New York State (Mullins and Hinchey, 1989;Mullins and Eyles, 1996;Mullins, 1998;Mullins and Halfman, 2001), Montana (Mullins et al, 1991), eastern Canada (Lajeunesse, 2016) and Patagonia (Kastner et al, 2010;Waldmann et al, 2010;Van Daele et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

Late-Quaternary glacial to postglacial sedimentation in three adjacent fjord-lakes of the Québec North Shore (eastern Canadian Shield)

Poiré

Lajeunesse

Normandeau

et al. 2018

Quaternary Science Reviews

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High-resolution swath bathymetry imagery allowed mapping in great detail the sublacustrine geomorphology of lakes Pentecôte, Walker and Pasteur, three deep adjacent fjord-lakes of the Québec North Shore (eastern Canada). These sedimentary basins have been glacio-isostatically uplifted to form deep steep-sided elongated lakes. Their key geographical position and limnogeological characteristics typical of fjords suggest exceptional potential for long-term high-resolution paleoenvironmental reconstitutions. Acoustic subbottom profiles acquired using a bi-frequency Chirp echosounder (3.5 & 12 kHz), together with cm-and m-long sediment core data, reveal the presence of four acoustic stratigraphic units. The acoustic basement (Unit 1) represents the structural bedrock and/or the ice-contact sediments of the Laurentide Ice Sheet and reveals V-shaped bedrock valleys at the bottom of the lakes occupied by ice-loaded sediments in a basin-fill geometry (Unit 2). Moraines observed at the bottom of lakes and in their structural valleys indicate a deglaciation punctuated by short-term ice margin stabilizations. Following ice retreat and their isolation, the fjord-lakes were filled by a thick draping sequence of rhythmically laminated silts and clays (Unit 3) deposited during glaciomarine and/or glaciolacustrine settings. These sediments were episodically disturbed by mass-movements during deglaciation due to glacial-isostatic rebound. AMS 14 C dating reveal that the transition between deglaciation of the lakes Pentecôte and Walker watersheds and the development of para-and post-glacial conditions occurred around 8000 cal BP. The development of the lake-head river delta plain during the Holocene provided a constant source of fluvial sediment supply to the lakes and the formation of turbidity current bedforms on the sublacustrine delta slopes. The upper sediment succession (i.e., ∼4-∼6.5 m) consists of a continuous para-to post-glacial sediment drape (Unit 4) that contains laminated and massive sediment and series of Rapidly Deposited Layers. These results allow establishing a conceptual model of how a glaciated coastal fjord develops during and after deglaciation in a context of rapid glacio-isostatically forced regression.

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The geomorphic and paleoenvironmental record in the sediments of Atlin Lake, northern British Columbia

Cited by 11 publications

References 26 publications

Large subglacial lake beneath the Laurentide Ice Sheet inferred from sedimentary sequences

Large subglacial lake beneath the Laurentide Ice Sheet inferred from sedimentary sequences

Proglacial sediment trapping in recently formed Silt Lake, upper Lillooet Valley, Coast Mountains, British Columbia

Late-Quaternary glacial to postglacial sedimentation in three adjacent fjord-lakes of the Québec North Shore (eastern Canadian Shield)

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