The early proterozoic Richmond Gulf Graben, east coast of Hudson Bay, Quebec

Chandler, F W

doi:10.4095/126313

Cited by 14 publications

(14 citation statements)

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“…1). According to Chandler (1982Chandler ( , 1988, the basin corresponds to a complexly faulted east-west-oriented Precambrian graben. The regional bedrock geology comprises two Late Proterozoic sedimentary-volcanic sequences over the regional bedrock of Precambrian granite-gneiss (Stevenson 1968;Avramtchev 1982;Ciesielski 1998).…”

Section: Settingmentioning

confidence: 99%

High-resolution seismo-stratigraphy and sedimentological properties of late- and postglacial sediments in Lac Guillaume-Delisle Estuary and Nastapoka Sound, eastern Hudson Bay

et al. 2008

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Lac Guillaume-Delisle Estuary and Nastapoka Sound are two sedimentary basins that recorded the late Quaternary deglaciation on the eastern coast of Hudson Bay. Acoustic profiles reveal an average sediments thickness of 15 m in the estuary and 6 m in the sound. These sediments reach 70 m thick in deep glacial troughs. Within the studied basins, four seismo-stratigraphic units overlying the acoustic basement were recognized. Unit 1 (subaqueous ice-contact and draped glaciomarine deposits associated with the Quebec-Labrador Ice Sector (QLIS) of the Laurentide Ice Sheet (LIS) and the Tyrrell Sea) records the presence of a short ice-marginal stillstand during glacial retreat. Unit 2 (paraglacial and postglacial fluvial-deltaic deposits) and unit 3 (postglacial silty deposits) result from erosion of emerged sediments and redeposition in response to changes in relative sea level (RSL). Finally, unit 4 is composed of deformed deposits associated with a mass wasting event. The stratigraphic sequence and the spatial distribution patterns of deposits show that Lac Guillaume-Delisle is a good model to explain the dynamics of the QLIS margin during and after successive ice stillstands, continuous RSL fall, river discharge (ablation on land), and its final ablation inland. Additionally, seven cores were sampled in the southeast part of the estuary. Geochemical (organic carbon and total nitrogen) and carbon isotopic contents, used as alternative proxy, indicate that the sampled sediments correspond to the postglacial estuarine deposits of unit 3. Allochthonous sources of carbon dominate the supply to the sediments where the environment is regularly flushed by fresh and marine waters.Résumé : L'estuaire Lac Guillaume-Delisle et le chenal Nastapoka sont deux bassins sédimentaires où l'on retrouve des évi-dences de la déglaciation, au Quaternaire tarif, sur la côte Est de la baie d'Hudson. Des profils acoustiques indiquent une épaisseur moyenne de sédiments de 15 m dans l'estuaire et de 6 m dans le chenal. Ces sédiments atteignent une épaisseur de 70 m dans des fosses glaciaires profondes. Dans les bassins à l'étude, on reconnaît quatre unités sismostratigraphiques audessus du socle acoustique. L'unité 1 (des dépôts de contact glaciaire sous l'eau et des dépôts glaciomarins drapés associés au secteur glaciaire Québec-Labrador de la calotte glaciaire laurentidienne et à la mer de Tyrrell) enregistre la présence d'une brève pause de stabilization de la bordure glaciaire durant le retrait de la glace. L'unité 2 (des dépôts para-glaciaires et post-glaciaires fluvio-deltaïques) et l'unité 3 (des dépôts postglaciaires silteux) proviennent de l'érosion et de la redéposition de sédiments émergés en réponse aux changements du niveau relatif de la mer. Finalement, l'unité 4 est composée de dépôts déformés associés à un événement de mouvement de masse. La séquence lithologique et les patrons de répartition spatiale des dépôts montrent que le Lac Guillaume-Delisle est un bon modèle pour expliquer la dynamique de la bordure du secteur Québec-L...

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Section: Settingmentioning

confidence: 99%

High-resolution seismo-stratigraphy and sedimentological properties of late- and postglacial sediments in Lac Guillaume-Delisle Estuary and Nastapoka Sound, eastern Hudson Bay

et al. 2008

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“…On the basis of reconnaissance mapping it has been subdivided into a northern metasediment-rich Minto Subprovince and a southern granitoid-rich Bienville Subprovince [Card and Ciesielski, 1986] along an ENE trending boundary that passes just north of Richmond Gulf in the middle of the arc. In and around Richmond Gulf there are shallow-water sediments and pillowed basalts of the Richmond Gulf Group (Figure 1), that unconformably overlie the Archean basement [Chandler, 1988]. Rocks of this group are now preserved only near Richmond Gulf, due to the formation of an east trending graben there after their deposition; they may formerly have had a wider distribution [Chandler, 1988].…”

Section: Geology Of the Nastapoka Arcmentioning

confidence: 99%

“…The almost perfectly circular coastline of eastern Hudson Bay has been the subject of discussion for several decades. The circularity led Beals [1968] to suggest a meteoritic origin for it, although Wilson [1968] pointed out that many intercontinental suture zones also have essentially circular forms, and there are now many proponents of a mid-Proterozoic suture in eastern Hudson Bay [e.g., Ricketts and Donaldson, 1981;Gibb, 1983;Chandler, 1984Chandler, , 1988Hoffman, 1988Hoffman, , 1989. Although a meteoritic origin retains popular appeal, no conclusive evidence for it has been forthcoming; the only supporting evidence is the circularity of the structure, which is due in large part to the uniformly seaward dipping attitudes of Nastapoka Group supracrustal rocks exposed at the coast.…”

Section: Introductionmentioning

confidence: 99%

The gravity field of eastern Hudson Bay: Evidence for a flextural origin for the Hudson Bay (Nastapoka) Arc?

Hynes¹

1991

Tectonics

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The Nastapoka Arc, on the east coast of Hudson Bay, is almost perfectly circular and closely follows the unconformable contact between Archean Superior province gneisses and shallowly seaward dipping early Proterozoic Nastapoka Group supracrustals. Its form may be explained by flexing of the lithosphere due to loading by thrust sheets from the Trans‐Hudson orogen to the west. Such flexing produces a peripheral bulge east of the coast which should be reflected in a positive gravity anomaly there. Gravity data averaged around the arc show such a positive anomaly, although its precise amplitude is uncertain because of local variation in the gravity field. Lithospheric flexure of the arc due to loading can be modeled by superposition of discshaped loads centered on the arc. For a lithospheric Young's modulus of 1.0 × 1011 N m−2 and Poisson's ratio 0.25, the present geometry of the arc can be reproduced only by reducing the elastic thickness to 20±2 km. The peripheral bulge predicted for the model yields a gravity anomaly very similar to that observed if it is fully imaged at the Moho. The absence of a regional negative gravity anomaly over the arc, despite a great thickness of transported rocks present at its center, requires that the crust in the region was unusually thin before thrust emplacement. The unusually low elastic thickness required for the model may reflect highly fractured crust. Both features are consistent with the former presence of a rifted continental margin in the region, as predicted for many models of the Trans‐Hudson orogen.

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“…Proterozoic sandstone basins contain a wide variety of authigenic clay minerals that indicate their diagenetic histories are similar to those of Phanerozoic basins (Aldahan and Morad 1986). In addition to authigenic clay and chlorite, phosphate minerals such as apatite are common cements in Proterozoic fluvial sandstones (Chandler 1988;Ross 19836). Although apatite has long been recognized as a suitable mineral for uranium-lead geochronology in igneous rocks (Oosthuyzen and Burger 1973), the full potential of apatite ages in constraining the diagentic history and age of sedimentary basins has yet to be realized.…”

Section: Introductionmentioning

confidence: 97%

U–Pb, Pb–Pb, and K–Ar isotopic study and petrography of uraniferous phosphate-bearing rocks in the Thelon Formation, Dubawnt Group, Northwest Territories, Canada

Miller¹,

Cumming²,

Krstić³

1989

Can. J. Earth Sci.

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The Thelon Formation, uppermost unit of the Dubawnt Group, overlies a regionally extensive paleoweathered zone developed on a wide range of lithochronological units including formations in the lower Dubawnt Group. Authigenic uraniferous phosphate minerals, fluorapatite and goyazite, cementing Thelon conglomerate–sandstone and filling fractures in the underlying paleoweathered zone, were dated in an attempt to better constrain the age of Thelon sedimentation and diagenesis. The oldest age, 1720 ± 6 Ma, derived from phosphate-cemented sediments, is interpreted as a minimum age for diagenesis and therefore brackets initial Thelon sedimentation between emplacement of fluorite-bearing granites at 1753 Ma and authigenic phosphate cementation at 1720 Ma. Additional ages of 1685 ± 4 and 1647 Ma are interpreted as remobilization or subsequent cementation events. K–Ar ages on illite, 1386 ± 37 and 1266 ± 31 Ma, from the paleoweathered zone and basal conglomerate, respectively, are significantly younger than ages derived from coexisting phosphate. These K–Ar ages record hydrothermal events that may be related to processes associated with unconformity-type uranium mineralization at approximately 1400–1300 Ma.Ages from the Thelon Basin permit geochronologic correlations with the Athabasca and Hornby basins, long correlated on the basis of similarities in sedimentation, stratigraphy, and tectonic setting.

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The early proterozoic Richmond Gulf Graben, east coast of Hudson Bay, Quebec

Cited by 14 publications

References 0 publications

High-resolution seismo-stratigraphy and sedimentological properties of late- and postglacial sediments in Lac Guillaume-Delisle Estuary and Nastapoka Sound, eastern Hudson Bay

High-resolution seismo-stratigraphy and sedimentological properties of late- and postglacial sediments in Lac Guillaume-Delisle Estuary and Nastapoka Sound, eastern Hudson Bay

The gravity field of eastern Hudson Bay: Evidence for a flextural origin for the Hudson Bay (Nastapoka) Arc?

U–Pb, Pb–Pb, and K–Ar isotopic study and petrography of uraniferous phosphate-bearing rocks in the Thelon Formation, Dubawnt Group, Northwest Territories, Canada

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