Windsor Group (Late Mississippian) stratigraphy, Magdalen Islands, Quebec: a rare eastern Canadian record of late Visean basaltic volcanism

Giles, P. S.

doi:10.4138/5932

Cited by 19 publications

(7 citation statements)

References 21 publications

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“…b). The islands are built on Carboniferous–Visean volcanic and sedimentary substrata (Brisebois ; Giles ). The geomorphology of the islands is dominated by basaltic conical hills surrounded by sandstone and shale platforms slightly inclined towards the sea, which are interpreted as cryopediment surfaces (Laverdière & Guimont ; Paquet ).…”

Section: Geological and Geomorphological Settingsmentioning

confidence: 99%

Chronology and stratigraphy of the Magdalen Islands archipelago from the last glaciation to the early Holocene: new insights into the glacial and sea‐level history of eastern Canada

Rémillard

St‐Onge

Bernatchez

et al. 2016

Boreas

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The Magdalen Islands (Québec, Canada) are a key location for unravelling the glacial and sea‐level history of the Maritime Provinces of eastern Canada. Although many sedimentary sequences have been described in the literature, absolute ages are lacking, impeding an accurate interpretation of the deposits and the establishment of a precise chronological framework. This study provides a detailed description of 21 stratigraphical sequences located throughout the archipelago, as well as the first comprehensive luminescence chronology from the Last Glacial Maximum (LGM) to c. 10 ka. In addition to the five samples collected for age control purposes, 34 luminescence samples were taken from 17 different sites in glacial, periglacial and coastal deposits. The stratigraphical and chronological data reveal that the islands were at the crossroads of two icecaps during the LGM; the southern islands were glaciated by the Escuminac icecap located in the western Gulf of St. Lawrence whereas the northern archipelago was glaciated at the end of the LGM by an ice flow from Newfoundland. The glacial deposit covering the northern Magdalen Islands was associated with the Newfoundland icecap; here it is named the Grande‐Entrée till and is dated to c. 20 ka. OSL ages between c. 23 and 17 ka acquired from cryopediment and coastal deposits on the southern islands indicate that this part of the archipelago was deglaciated shortly after the LGM and was affected by a high sea level and periglacial processes. Around 15 ka, the entire archipelago was deglaciated and partially submerged until c. 10 ka. This data set is the first major contribution to a detailed chronology of the Magdalen Islands and constitutes the first step towards interpreting the glacial and sea‐level history of the central area of the Gulf of St. Lawrence; this new understanding will provide input to regional marine and glacial modelling.

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Section: Geological and Geomorphological Settingsmentioning

confidence: 99%

Chronology and stratigraphy of the Magdalen Islands archipelago from the last glaciation to the early Holocene: new insights into the glacial and sea‐level history of eastern Canada

Rémillard

St‐Onge

Bernatchez

et al. 2016

Boreas

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show abstract

“…B). Both islands are composed of Carboniferous−Visean volcanic and sedimentary substrata (Brisebois ; Giles ). The geomorphology of the islands is dominated by basaltic conical hills surrounded by sandstone and shale platforms slightly inclined towards the sea, which are interpreted as cryopediment surfaces (Laverdière & Guimond ; Paquet ).…”

Section: Geological and Geomorphological Settingmentioning

confidence: 99%

Chronology and palaeoenvironmental implications of the ice‐wedge pseudomorphs and composite‐wedge casts on the Magdalen Islands (eastern Canada)

Rémillard

Hétu

Bernatchez

et al. 2015

Boreas

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The Magdalen Islands are a valuable terrestrial record, evidencing the complex glacial and periglacial history of the Gulf of St. Lawrence. Thirteen structures interpreted as ice‐wedge pseudomorphs or composite‐wedge casts were observed at four sites on the southern Magdalen Islands and testify to the former presence of permafrost under periglacial conditions. These features truncate Carboniferous sandstone or Last Glacial Maximum (LGM) glacial and glaciomarine diamicts, both overlain by subtidal or coastal units. Six optically stimulated luminescence (OSL) and four radiocarbon ages were obtained from both host and infilled sedimentary units. These ages provide the first absolute chronological data on these structures, shedding new light on the relationships between glacial and periglacial phases. Our chronostratigraphic data suggest that, after the deglaciation and the emersion of the archipelago, thermal contraction cracks grew during the cold period of the Younger Dryas (11–10 ka; 12.9–11.5 cal. ka BP). The Younger Dryas, which is well documented in the Maritime Provinces of Canada, occurred after a pedogenesis phase associated with the Allerød warm period evidenced by the well‐developed palaeopodzol ubiquitous on the Magdalen Islands.

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“…The methods are largely sensitive to the average of the crustal structure, and thus are insufficient to constrain the details of the evolution, geometry, and structure of the GSL region [ Jackson , ]. Petrological investigations revealed that extensive bodies of Mississippian age volcanic rocks cover the thick column of Paleozoic sedimentary rocks [ Barr et al , ; Keen and Williams , ; Giles , ]. The capping volcanic rocks are associated with local salt tectonism at depth [ Barr et al , ], and they conceal the deeper sedimentary and crustal structures from active seismic profiling such as the reflection and refraction surveys conducted by the oil and gas industry and the Lithoprobe project [e.g., Keen et al ., , ; Voogd and Keen , ; Marillier and Verhoef , ; Marillier et al , ; Hall et al ., , ].…”

Section: Introductionmentioning

confidence: 99%

Upper crustal investigation of the Gulf of Saint Lawrence region, eastern Canada using ambient noise tomography

et al. 2017

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We studied the 3‐D shear wave velocity (Vs) structure in the Gulf of St. Lawrence (GSL) and adjacent onshore areas to 20 km depth by inverting Rayleigh wave dispersion extracted from the vertical components of continuous ambient seismic noise waveforms. The region is divided into three broad zones based on their Vs characteristics. In the northwest, the Grenville Province (i.e., the exposed edge of predominantly Middle‐Proterozoic Laurentian crust) is dominated by high Vs, except for well‐known anorthosite sites, which are characterized by relatively lower Vs. In contrast, the central segment of the GSL region corresponds to a belt with generally low Vs at upper crustal levels. In the southeastern part of the GSL, prominent low Vs in the uppermost crust are found to coincide with locations of subsidiary basins of the Canadian Maritime Basin, while higher Vs characterize the accreted Appalachian terranes where they are exposed on land. The Grenville Province is wedged out at depth by the Red Indian Line, which is the suture between composite Laurentia and peri‐Godwanan Ganderia in the Canadian Appalachians. The geometry and Vs characteristics of the south‐easternmost peri‐Gondwanan terranes of Avalonia and Meguma suggest that they may be fully or partially structurally overlying a basement with distinct seismic characteristics, which could be a vestige of the West African craton that was underthrust beneath composite Laurentia during the terminal Alleghenian continent‐continent collision. In the middle of the GSL, the 3‐D geometry of the Canadian Maritimes sedimentary basins overlying the Appalachian terranes shows that the depth to the top of basement is in excess of 8 km.

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Windsor Group (Late Mississippian) stratigraphy, Magdalen Islands, Quebec: a rare eastern Canadian record of late Visean basaltic volcanism

Abstract: The

Cited by 19 publications

References 21 publications

Chronology and stratigraphy of the Magdalen Islands archipelago from the last glaciation to the early Holocene: new insights into the glacial and sea‐level history of eastern Canada

Chronology and stratigraphy of the Magdalen Islands archipelago from the last glaciation to the early Holocene: new insights into the glacial and sea‐level history of eastern Canada

Chronology and palaeoenvironmental implications of the ice‐wedge pseudomorphs and composite‐wedge casts on the Magdalen Islands (eastern Canada)

Upper crustal investigation of the Gulf of Saint Lawrence region, eastern Canada using ambient noise tomography

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