Late Silurian – Early Devonian rifting during dextral transpression in the southern Gaspé Peninsula (Quebec): petrogenesis of volcanic rocks

1993 ◽  
Vol 30 (12) ◽  
pp. 2283-2294 ◽  
Author(s):  
J. Dostal ◽  
R. Laurent ◽  
J. D. Keppie
Keyword(s):  
Rift Zone ◽  
Volcanic Rocks ◽  
Significant Proportion ◽  
Spinel Peridotite ◽  
Initial Surface ◽  
Crustal Material ◽  
Early Devonian ◽  
Ree Patterns ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

The Upper Silurian – Lower Devonian volcanic rocks in the southern Gaspé Peninsula of the Quebec Appalachians crop out at the northeast end of the Connecticut Valley – Gaspé Synclinorium. These shallow marine and subaerial sequences reach a thickness of up to at least 2000 m and comprise two groups: (1) the Late Silurian volcanic rocks, which are mainly transitional alkalic–tholeiitic basalts with steeply sloping REE patterns; (2) the Early Devonian volcanic rocks, which include a significant proportion of intermediate rocks in addition to tholeiitic basalts. Compared with the Silurian rocks, the Devonian basalts have lower abundances of strongly incompatible trace elements such as Ba, Th, Ta, Nb, and light REE and relatively flat heavy REE patterns. Basalts of both groups display negative Nb and Ta anomalies (relative to Th and La).Although the basalts of both sequences were derived from lithospheric mantle, the Silurian basalts were generated from garnet peridotite at ~ 80 km depth while the Devonian basalts appear to have resulted from a larger degree of melting of spinel peridotite at a shallower depth (~ 60 km). Devonian intermediate rocks are probably the result of mixing of the basaltic magma with upper crustal material through assimilation – fractional crystallization processes. The basalts are interpreted to have formed in a northwest-trending rift zone located in the Quebec Reentrant during dextral transpression along the Appalachian Orogen. Rotation during and after the volcanism reoriented the rift zone to a northeast trend. The high density layer at the base of the crust under the Magdalen Basin may be the former magma chamber for the Silurian–Devonian volcanism. The change from transitional to tholeiitic volcanism at the Silurian–Devonian boundary suggests that the stretching value (ratio of final to initial surface area) increased from < 2 to > 2 at that time. This boundary is also coincident with the Salinic disturbance that is inferred to have been produced by erosion of the thermally uplifted block associated with rifting.

Geochemistry of Sainte-Marguerite volcanic rocks: implications for the evolution of Silurian–Devonian volcanism in the Gaspé Peninsula

2008 ◽  
Vol 45 (1) ◽  
pp. 15-29 ◽  
Author(s):  
Alan D’hulst ◽  
Georges Beaudoin ◽  
Michel Malo ◽  
Marc Constantin ◽  
Pierre Pilote
Keyword(s):  
Lower Devonian ◽  
Volcanic Rocks ◽  
Magma Source ◽  
Volcanic Arc ◽  
Lower Silurian ◽  
Trace Element Signature ◽  
Arc Setting ◽  
Back Arc ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

The Lower Devonian Sainte-Marguerite volcanic rocks are part of a Silurian–Devonian volcanic sequence deposited between the Taconian and Acadian orogenies in the Gaspé Peninsula, Quebec, Canada. The Sainte-Marguerite unit includes basaltic and dacitic lava flows with calc-alkaline and volcanic-arc affinities. Such affinities are also recorded by the trace-element signature in Lower Silurian and most Lower Devonian volcanic units of the Gaspé Peninsula. However, most of the other Silurian–Devonian volcanic rocks occurring in the Gaspé Peninsula have been previously interpreted to have erupted in an intracontinental setting. A back-arc setting for the Gaspé Peninsula between the Taconian and Acadian orogenies could account for these subduction volcanic-arc signatures, though a metasomatized lithospheric mantle magma source, unrelated to subduction, cannot be excluded. Lower Silurian and Lower Devonian volcanic rocks in the central part of the Gaspé Peninsula show an arc affinity, whereas Upper Silurian and Lower to Middle Devonian volcanic rocks, located in the south and north of the Gaspé Peninsula, respectively, show a within-plate affinity. The Lower Devonian Archibald Settlement and Boutet volcanic rocks of the southern and northern Gaspé Peninsula, respectively, show a trend toward a within-plate affinity. This suggests that within-plate volcanism migrated from south to north through time in an evolving back-arc environment and that the subduction signature of Lower Silurian and Lower Devonian rocks results from a source that melted only under the central part of the Gaspé Peninsula.

A new stratigraphic framework for the Gaspé Belt in southern Quebec: implications for the pre-Acadian Appalachians of eastern Canada

2004 ◽  
Vol 41 (5) ◽  
pp. 507-525 ◽  
Author(s):  
Denis Lavoie ◽  
Esther Asselin
Keyword(s):  
New Brunswick ◽  
Sea Level Rise ◽  
Sea Level ◽  
Eastern Canada ◽  
Early Devonian ◽  
Stratigraphic Framework ◽  
Marine Facies ◽  
Saint Francis ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

The post-Taconian units in the Quebec and northern New Brunswick Appalachians constitute the Gaspé Belt and geological studies have mostly focussed on its eastern Quebec segment. Biostratigraphic data indicate that the succession in southern Quebec is no older than Late Silurian and extends into the Early Devonian. Two distinct stratigraphic assemblages are present. The first assemblage (Saint-Luc, Cranbourne, and Lac Aylmer formations, and Glenbrooke Group) unconformably overlies the Humber and Dunnage zones. The units show a basal alluvial conglomerate that passes progressively to deeper marine facies upsection, which have recorded a post-Late Silurian transgressive event. The second assemblage (Saint-Francis Group and Frontenac Formation) is faulted against either Dunnage units or autochthonous post-Taconian units. It locally unconformably overlies units of the Dunnage Zone; the succession shows progressively deeper marine conditions upsection and also has recorded a post-Late Silurian transgressive event. The biostratigraphic framework suggests that some of the units that were assumed to be vertically stacked are rather laterally equivalent. Independant evidence supports the hypothesis that the Gaspé Belt in southern Quebec formed after the collapse of the Taconian orogen in Late Silurian time. This event is ascribed to the Salinian Orogeny. The framework from southern Quebec is incorporated in a regional scenario. The Gaspé Belt experienced a Pridolian–Lochkovian sea-level rise. In Pragian time, shallower marine conditions were established in southern Quebec, whereas in the Gaspé Peninsula, the shallower conditions only occurred in early Emsian time.

scholarly journals VIII. On the spines, sporangia, and spores of Psilophyton princeps , Dawson, shown in specimens from Gaspé

1931 ◽  
Vol 219 (462-467) ◽  
pp. 421-442 ◽  
Keyword(s):  
Geological History ◽  
Early Devonian ◽  
History Of ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

Psilophyton princeps , though still incompletely known, is one of the most important Early Devonian plants, both on account of its morphology and of the place it occupies in the history of investigation of Pre-carboniferous vegetation. It was originally distinguished and described by Dawson from specimens collected in the Gaspé peninsula, Canada. As shown in the restoration, published in the ‘Geological History of Plants’ (DAWSON, 1882), he regarded the plant as consisting of horizontally growing rhizomes, from which sprang erect branch-systems; the branching was dichotomous and the fine distal ramifications terminated in large ovoid sporangia. From the description (DAWSON, 1871) it is clear that the lower portions of the sub-aerial branch-systems were markedly spiny, while the spines, though present, became less numerous and more distant in the distal, fertile regions. The distribution of the spines according to Dawson is not shown in his restoration; it is well illustrated in a modification of Dawson’s restoration by PIA (1926, fig. 109).

Halysitid corals from Silurian and Devonian rocks of Québec

1980 ◽  
Vol 17 (6) ◽  
pp. 788-796 ◽  
Author(s):  
A. J. Wright ◽  
P.-A. Bourque
Keyword(s):  
West Point ◽  
The West ◽  
Early Devonian ◽  
Gaspe Peninsula ◽  
Different Levels ◽  
Tabulate Corals ◽  
Gaspé Peninsula

Halysitid tabulate corals occur in the Silurian and Devonian rocks of northeastern Gaspé Peninsula, Québec. Silurian specimens from the Dartmouth River and Madeleine River areas are referred to Cystihalysites. A specimen from a possibly Early Devonian level in the Gascons Formation in the Dartmouth River area is assigned to Cystihalysites. Two specimens from different levels in the Early Devonian part of the West Point Formation in the Madeleine River area are assigned questionably to Quepora. The latter occurrences in the West Point Formation demonstrate that this group of tabulate corals lingered into the Devonian.

scholarly journals Silurian and Devonian Volcanic Rocks of the Gaspe Peninsula

1990 ◽  
Author(s):  
M Doyon ◽  
C Dalpe ◽  
G Valiquette
Keyword(s):  
Volcanic Rocks ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

Weather and Outbreaks of the Spruce Budworm in the Province of Quebec from 1939 to 1956

1961 ◽  
Vol 93 (2) ◽  
pp. 118-123 ◽  
Author(s):  
J. G. Pilon ◽  
J. R. Blais
Keyword(s):  
Choristoneura Fumiferana ◽  
Abies Balsamea ◽  
Spruce Budworm ◽  
Balsam Fir ◽  
The Past ◽  
Forest Regions ◽  
Tree Component ◽  
Gaspe Peninsula ◽  
Gaspé Peninsula

Nearly all forest regions in the Province of Quebec where balsam fir (Abies balsamea (L.) Mill.) is an important tree component have been subjected to severe defoliation by the spruce budworm, Choristoneura fumiferana (Clem.), during the past 20 years. These outbreaks have followed an easterly direction beginning near the Ontario-Quebec border in 1939 and ending in the Gaspé Peninsula in 1958.

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