Bedrock geological mapping and basin studies in the Hudson Bay region

Grant, A C; Sanford, B. V.

doi:10.4095/122445

Cited by 6 publications

(3 citation statements)

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“…Hudson Bay bedrock west of the Belcher and Ottawa Islands consists of Paleozic carbonate rocks (Shilt, 1986;Grant and Sanford, 1988) while east of those islands, where the study area is located, Precambrian formations constitute the bedrock (Shilts, 1986). The Precambrian rocks consist of Proterozoic metavolcanic and metasedimentary formations which lie unconformably on an Archean metamorphosed crystalline terrain that forms much of the Hudson Bay coastline (Shilts, 1986).…”

Section: Regional Geology and Physiographymentioning

confidence: 99%

Seismo-Stratigraphy and Sedimentology of Holocene Sediments off Grande Rivière de la Baleine, Southeastern Hudson Bay, Québec

Gonthier¹,

d'Anglejan²,

Josenhans³

2007

gpq

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The regional distribution of Holocene sediments of eastern Hudson Bay off the Grande Rivière de la Baleine mouth was mapped using a grid of reflection seismic lines (approximately 300 km long and covering an area of approximately 800 km2) and data from 7 piston cores. Based on the seismic records and piston cores, 4 stratigraphic units overlying the Proterozoic bedrock (unit 1) were defined and interpreted: (unit 2) glacial till deposited by a westward flowing ice sheet, (unit 3) rhythmically bedded clays and silts presumably deposited in glacial Lake Ojibway, (unit 4) postglacial marine muds deposited in the Tyrrell Sea overlain by undifferentiated modern marine muds, and (unit 5) distal fluviodeltaic sediments from Grande Rivière de la Baleine. Similar stratigraphie units have been described onshore. Textural and geochemical analyses suggest that unit 3 rhythmites are true varves; dark "summer" laminae were deposited mainly by underflows during the open water season, and light "winter" laminae were deposited by overflows-interflows along thermal stratifications under a seasonal ice cover. Unit 5 covers approximately 400 km2 and occurs as a deltaic constructional wedge protruding as far as 11 km offshore of the Grande Rivière de la Baleine entrance with thicknesses reaching 30 m along the coast. It was deposited between 3500 BP and the present from remobilization of glacial sediments farther upstream due to river downcutting during emergence.La répartition régionale des sédiments holocènes de l'est de la baie d'Hudson, face à l'embouchure de la Grande rivière de la Baleine, a été cartographiée à l'aide d'un grille de profils de sismique réflexion (d'environ 300 km de long et d'une superficie de 800 km2) et de données provenant de sept forages par carottier à piston. Quatre unités stratigraphiques reposant sur le socle protérozoïque (unité 1) ont été définies et interprétées : un till (unité 2) déposé par un glacier progressant vers l'ouest, des argiles et silts stratifiés (unité 3) probablement déposés dans le Lac glaciaire Ojibway, des boues marines postglaciaires (unité 4) déposés dans la Mer de Tyrrell auxquelles se superposent des boues marines récentes indifférenciées et des sédiments fluvio-deltaiques distaux (unité 5) provenant de la Grande rivière de la Baleine. Les mêmes unités stratigraphiques ont été décrites sur la côte. Les analyses granulométriques et géochimiques laissent croire que les rythmites de l'unité 3 sont des varves; les couches foncées d'été ont surtout été déposées par des courants de densité s'écoulant sur le fond pendant la période libre de glace et les couches pâles d'hiver ont été transportés en suspension le long de stratifications thermiques sous un couvert de glace saisonnier. L'unité 5 couvre environ 400 km2 et forme un prisme s'étendant jusqu'à 11 km de l'embouchure de la Grande rivière de la Baleine avec des épaisseurs atteignant 30 m le long de la côte. La mise en place de l'unité 5 s'est faite entre 3500 BP et aujourd'hui et résulte de l'érosion et de l'apport de sédiments d...

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Section: Regional Geology and Physiographymentioning

confidence: 99%

Seismo-Stratigraphy and Sedimentology of Holocene Sediments off Grande Rivière de la Baleine, Southeastern Hudson Bay, Québec

Gonthier¹,

d'Anglejan²,

Josenhans³

2007

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“…). Palaeozoic carbonate rocks also crop out beneath the waters of Hudson Bay (Grant & Sanford ). Transported Dubawnt Supergroup lithologies (Fig.…”

Section: Regional Settingmentioning

confidence: 99%

Inherited clast dispersal patterns: Implications for palaeoglaciology of the SE Keewatin Sector of the Laurentide Ice Sheet

Trommelen¹,

Ross

Campbell

2012

Boreas

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The net effect of ice-flow shifts resulting in the dilution or reworking of clasts on a single preserved till sheet is often unknown yet has major implications for palaeoglaciology and mineral exploration. Herein, we analyse variations in till clast lithologies from a single till sheet, within palimpsest-type Glacial Terrain Zones in NE Manitoba, Canada, to better understand sediment-landform relationships in this area of high landform inheritance. This near-ice-divide area is known to consist of a highly fragmented subglacial landscape, resulting from spatio-temporal variations in intensity of reworking and inheritance throughout multiple glacial events (subglacial bed mosaic). We show that a seemingly homogenous 'Keewatin' till sheet is composed of local (>15 km) and continental-scale (~100-km-long carbonate train and 350-600 km long Dubawnt red erratic train) fan, irregular (amoeboid) or lobate palimpsest dispersal patterns. Local dispersal is more complex than the preserved local landform flowset(s) record, but appears consistent with the overall glacial history reconstructed from regional flowset and striation analyses. The resultant surface till is a spatial mosaic interpreted to reflect variable intensities in modification (overprinting) and preservation (inheritance) of a predominately pre-existing till sheet. A multifaceted approach integrating till composition, regional landforms, ice-flow indicators, and stratigraphic knowledge is used to map relative spatio-temporal erosion/reworking intensity. Michelle S. Trommelen (michelle.trommelen@gov.mb.The subglacial geomorphic record of palaeo-ice sheets is often a detailed series of 'snapshots' that provide a window into palaeosubglacial conditions and basal processes. Previous research envisioned largely 'steady-state' subglacial processes, assuming relatively uniform conditions beneath an ice sheet, where at a large scale changes in erosion and deposition rate varied with distance from an ice divide and the external climatic regime (Boulton 1996). It is now recognized that the subglacial environment was one of significant spatio-temporal variability and evolution throughout the Quaternary (

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“…At Ungava Bay this fracture zone truncates a northwestsoutheast-trending fault system in Hudson Strait. Localized extensional deformation associated with these fault systems is the likely cause of the topographic depression that makes Ungava Bay (Adams and Basham, 1989;Grant and Sanford, 1988). Postglacial isostatic rebound has resulted in an emergent coast (Gray et al, 1980).…”

Section: Ungava Bay Area (3)mentioning

confidence: 99%