Basal Mississippian volcanic rocks in Cape Breton Island, Nova Scotia

Kelley, D G; Mackasey, W. O.

doi:10.4095/101005

Cited by 10 publications

(3 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Volcanic and sedimentary rocks generally assigned to the Devonian-Carboniferous Fissett Brook Formation (Kelley and Mackasey, 1965;Blanchard, 1982) form the southwestern margin of the Creignish Hills Pluton (Fig. 1).…”

Section: Geological Settingmentioning

confidence: 99%

Petrology of the Creignish Hills Pluton, Cape Breton Island, Nova Stotia

White

Barr

Campbell

1990

atgeol

View full text Add to dashboard Cite

Mapping and petrologic studies of the Creignish Hills Pluton in the Bras d'Or Terrane of central Cape Breton Island have shown that the pluton consists mainly of tonalite-diorite and coarse-grained monzogranite units, with smaller areas of granodiorite-tonalite, granodiorite-monzogranite, and fine-grained monzogranite. Petrographic and chemical characteristics of the tonalite-diorite suggest that hornblende fractionation (± biotite accumulation) may have produced much of the observed variation in the unit, whereas feldspar fractionation was the dominant process producing variation within each of the other units. The tonalite-diorite unit is interpreted to be late Precambrian (ca. 560 Ma) in age like most other dioritic and tonalitic plutons in the Bras d'Or Terrane. It is probably not co-genetic with the intermediate and felsic units of the pluton. The latter may be of Early Ordovician age (ca. 495 Ma) on the basis of penological similarities of the coarse-gTained monzogranite unit to the Cape Smoky and Kellys Mountain monzogranites. Like other Bras d'Or Terrane plutons, the Creignish Hills Pluton probably formed in a continental margin volcanic arc setting during and after late Precambrian to Early Cambrian subduction. RÉSUMÉ Des travaux de cartographie et de pétrologie ont permis d'établir que le pluton de Creignish Hills (Lanière de Bras d'Or, centre de l'ile du Cap Breton) se compose surtout de tonalite-diorite et d'unités de monzogranite à grain grossier, avec des llots de granodiorite-tonalite, granodiorite-monzogranite et monzogranite à grain fin. Les caractéres de sa pérographie et de son chimisme suggèrent que le variation prisente au sein de la tonalite-diorite émane pour une grande part du fractionnement de la hornblende (± accumulation de biotite). En revanche, la variation observée dans chacune des autres unités provient surtout du fractionnement du feldspath. On interprète l'âge de l'unité de tonalite-diorite comme étant précambrien lardif (env. 560 Ma), âge qu'ont en commun la plupart des plutons dioritiques et tonalitiques au sein de la Lanière de Bras d'Or. Cette unitl n'est probablement pas cogenéique avec les unités intermédiaires et felsiques du pluton. Ces dernières pourraient remonter au début de l'Ordovicien (env. 495 Ma) si l’on se fie aux similitudes pétrologiques entre l'unité de monzogranite à grain grossier et les monzogranites de Cape Smoky et de Kellys Mountain. A l'instar des autres plutons de la Lanière de Bras d'Or, le pluton de Creignish Hills s'est probablement formé en contexte d'arc insulaire sur une marge continentale pendant et après la subduction tardiprécambrienne à éocambrienne. [Traduit par le journal]

show abstract

Section: Geological Settingmentioning

confidence: 99%

Petrology of the Creignish Hills Pluton, Cape Breton Island, Nova Stotia

White

Barr

Campbell

1990

atgeol

View full text Add to dashboard Cite

show abstract

“…In the Atlantic Canada region, these basins have been collectively referred to as the Fundy Epieugeosyncline (Howie and Barss 1975). They were the main sites of upper Paleozoic sedimentation, but volcanism was also typically part of their evolution, for example, in the Magdalen Islands (Sanschagrin 1964;Brisebois 198 l), Newfoundland (Chorlton 1980), Cape Breton Island (Kelley and MacKasey 1963;Blanchard et al 1984), northern mainland Nova Scotia (Keppie and Dostal 1980;Donohoe andWallace 1982), New Brunswick (MacKenzie 1964;Ruitenberg and McCutcheon 1980), and Maine (Schluger 1963). Most of these volcanic rock suites are bimodal, and the basaltic components are generally tholeiitic or tholeiitic transitional to alkalic (e.g., Keppie and Dostal 1980;Blanchard et al 1984).…”

Section: Introductionmentioning

confidence: 99%

Carboniferous volcanic rocks of the Magdalen Islands, Gulf of St. Lawrence

Barr¹,

Brisebois²,

Macdonald³

1985

Can. J. Earth Sci.

View full text Add to dashboard Cite

Volcanic rocks of Mississippian age occur on the Magdalen Islands as cap rocks and within collapse breccias above salt diapirs that have formed the islands. They consist of coarse volcaniclastic deposits and basaltic flows, intruded by minor mafic dykes and plugs. Petrologic studies of the basaltic rocks show that they are extensively altered. Original plagioclase, clinopyroxene, olivine, and interstitial glass are partially to entirely replaced by mixtures of chlorite, sericite, smectite, sphene, carbonate, epidote, albite, potassium feldspar, and iron oxides, and the samples display a relatively wide range in chemical compositions. Especially mobile were K, Na, and Ca, and most samples are classified as potash spilites (poenites). Using standard discriminant diagrams for mafic igneous rocks, it can be seen that the basalts appear to range from continental tholeiitic to continental alkalic. However, relict clinopyroxene compositions and the presence of kaersutitic amphibole and titaniferous biotite in some samples imply that the suite may originally have been more alkalic than tholeiitic.Les volcanites mississippiennes des iles de la Madeleine sont prksentes dans le "caprock et dans les brkches d'effondrement qui recouvrent les diapirs de sel qui sont ii I'origine des iles. Ces volcanites sont constituees de pyroclastites grossikres et de coul&s basaltiques recoup6es par quelques dykes et plutons mafiques. Les ttudes p6trologiques effectuees sur les basaltes indiquent que ces roches ont t t t profondtment alttrees. Les minkraux primaires tels les plagioclase, clinopyroxkne et olivine, ainsi que le verre interstitiel, ont kt6 remplaces, en totalit6 ou en partie, par un assemblage de chlorite, skricite, smectite, spkne, carbonate, kpidote, albite feldspath potassique et oxydes de fer. La compositon chimique des tchantillons est trks variable. Na, K et Ca Ctaient particulikrement mobiles, et la majorit6 des tchantillons sont classifits comme des spillites potassiques (poenites). En les comparant aux diagrammes discriminants usuels des roches igntes mafiques, les tchantillons analysks ont une affinitt continentale qui varie de tholtitique h alcaline. Toutefois, la composition des reliques des clinopyroxknes rksiduels, ainsi que la presence dans certains Cchantillons d'amphibole kaersutitique et de biotite titanifkre, indiquent que la suite volcanique Ctait ii I'origine plus alcaline que tholkiitique.

show abstract

“…Sample The Price Point Formation occurs in the southeastern Cape Breton Highlands and consists of mainly intermediate lithic and lithic-crystal tuff with minor andesitic and dacitic flows (Macdonald and Barr 1985). The volcanic rocks were interpreted initially to be of Devonian-Carboniferous age because of inferred correlation with the Fisset Brook Formation (Kelley and Mackasey 1965). However, Macdonald and Barr (1985) suggested a Neoproterozoic age based on interpreted intrusive contacts with plutonic rocks in the area, in particular the Indian Brook granodiorite which yielded a U-Pb (titanite) age of 564 ± 4 Ma interpreted to be the approximate crystallization age of the granodiorite (Dunning et al 1990).…”

Section: New Ages From the Bras D'or Terrane (Appendix A)mentioning

confidence: 99%

Granitoid plutons in peri-Gondwanaan terranes of Cape Breton Island, Nova Scotia, Canada: new U-Pb (zircon) age constraints

Barr

Rooyen

White

2018

atgeol

View full text Add to dashboard Cite

Granitoid plutons are a major component of pre-Carboniferous rocks in Cape Breton Island and knowledge of the time and tectonic setting of their emplacement is crucial for understanding the geological history of the island, guiding exploration for granite-related economic mineralization, and making along-orogen correlations. The distribution of these plutons and their petrological characteristics have been used in the past for recognizing both Laurentian and peri-Gondwanan components in Cape Breton Island, and for subdividing the peri-Gondwanan components into Ganderian and Avalonian terranes. However, ages of many plutons were assumed on the basis of field relations and petrological features compared to those of the relatively few reliably dated plutons. Seventeen new U–Pb (zircon) ages from igneous units reported here provide enhanced understanding of the distribution of pluton ages. Arc-related plutons in the Aspy terrane with ages of ca. 490 to 475 Ma likely record the Penobscottian tectonomagmatic event recognized in the Exploits subzone of central Newfoundland and New Brunswick but not previously recognized in Cape Breton Island. Arc-related Devonian plutonic activity in the same terrane is more widespread, continuous, and protracted (445 Ma to 395 Ma) than previously known. Late Devonian magmatism in the Ganderian Aspy terrane is similar in age to that in the Avalonian Mira terrane (380 to 360 Ma) but the tectonic settings are different. In contrast, magmatic activity in the Bras d’Or terrane is almost exclusively arc-related in the Late Ediacaran (580 to 540 Ma) and rift-related in the Late Cambrian (520 to 490 Ma). The new data support the terrane distinctions previously documented.

show abstract

Basal Mississippian volcanic rocks in Cape Breton Island, Nova Scotia

Cited by 10 publications

References 0 publications

Petrology of the Creignish Hills Pluton, Cape Breton Island, Nova Stotia

Petrology of the Creignish Hills Pluton, Cape Breton Island, Nova Stotia

Carboniferous volcanic rocks of the Magdalen Islands, Gulf of St. Lawrence

Granitoid plutons in peri-Gondwanaan terranes of Cape Breton Island, Nova Scotia, Canada: new U-Pb (zircon) age constraints

Contact Info

Product

Resources

About