Reconnaissance Mapping of the southern Cape Breton Highlands - a Preliminary Report

Jamieson, Rebecca Anne; Craw, D.

doi:10.4095/111520

Cited by 8 publications

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“…However, transposed foliated but not gneissic mafic dykes in the Pleasant Bay complex chemically resemble mafic volcanic rocks of the Jumping Brook complex (Currie 1987). Jamieson and Craw (1983) also found that the amphibolitic component of the Pleasant Bay complex south of the mapped area appeared similar in composition to lower grade mafic schists in the Jumping Brook complex. The dykes of the Pleasant Bay complex could reasonably be interpreted as feeders to the volcanics of the Jumping Brook complex.…”

Section: Jumping Brook Complexmentioning

confidence: 88%

“…This paper describes a region near the town of Chtticamp where field mapping, analysis of mineral assemblages, and radiometric age determinations demonstrate that at least two diverse sequences of supracrustal rocks underwent metamorphism at significantly different times and P -T conditions. Comparison of this region with other parts of the highlands described by Wiebe (1972), Jamieson and Craw (1983), and Barr et al (1985) suggests that much of the highlands exhibits similar complex histories.…”

Section: Introductionmentioning

confidence: 83%

“…Two explanations have been offered for this anomaly. The high-grade of rocks of the highlands may represent metamorphosed equivalents of the supracrustal rocks typical of other Avalonian terranes (Jamieson and Craw 1983;MacDonald and Smith 1980), or the gneisses of the highlands may represent an older basement complex (Currie 1983).…”

Section: Discussionmentioning

confidence: 99%

“…Wiebe (1972), Neale and Kennedy (1975), Keppie (1979), andCume (1983) argued that two or more ages of metamorphosed supracrustal rocks could be recognized in the highlands, that basement-cover relationships could be worked out, at least locally, and that several periods of granite emplacement could be recognized. However, Macdonald and Smith (1980), Jamieson and Craw (1983), and Barr et al (1985) maintained that only a single, variably metamorphosed protolith and only two significant periods of granite generation could be recognized in the areas studied by them. Recent geochronological work revealed a complex magmatic history 'Geological Survey of Canada Contribution 44886.…”

Section: Introductionmentioning

confidence: 96%

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Contrasting metamorphic terranes near Chéticamp, Cape Breton Highlands, Nova Scotia

Currie¹

1987

Can. J. Earth Sci.

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Two contrasting metamorphic terranes can be recognized in northwestern Cape Breton Island. One terrane (Pleasant Bay complex) consists of biotite gneiss and quartzite with minor calc-silicate lenses that were metamorphosed in Late Precambrian time (about 550 Ma) and were subsequently intruded by Silurian salic and mafic plutons that were, in turn, deformed and intruded by granite in Devonian time. The other terrane (Jumping Brook complex) consists of volcanogenic and sedimentary schists of probable Silurian age that were metamorphosed in Devonian time. P-T estimates indicate that the older parts of the Pleasant Bay complex were metamorphosed at about 790°C and 7 kbar (1 kbar = 100 MPa) at low to moderate water fugacities during a major intrusive episode. The Jumping Brook complex exhibits a single progressive metamorphic sequence now disrupted by faulting. P-T conditions during this Devonian (370 -390 Ma) metamorphism varied from greenschist (300°C at < 3 kbar) to amphibolite (650°C at 4 kbar) facies. Metamorphism probably occurred in a thermal dome. The data suggest a moderately deformed basement-cover relation between the Pleasant Bay and Jumping Brook complexes. Deux terranes mCtamorphiques differents sont reconnus dans le nord-ouest de l'ile du Cap-Breton. Un terrane (complexe de Pleasant Bay) est form6 de gneiss i biotite et de quartzite accompagnCs d'une faible quantitC de lentilles calco-silicatCes qui furent mCtamorphisCes au temps du Pkcambrien tardif (environ 550 Ma) et subsCquemment recoupCes par des plutons mafiques et saliques siluriens qui i leur tour furent dCformCs et recoupCs par un granite au Dtvonien. L'autre terrane (complexe de Jumping Brook) inclut des schistes ~Cdimentaires et volcanogCniques, possiblement d'bge silurien, qui furent mCtamorphisCs au DCvonien. Les P-T estimCes indiquent que les zones les plus bgCes du complexe de Pleasant Bay furent mCtamorphisCes i environ 790°C et h 7 kbar (1 kbar = 100 MPa), dans des conditions de fugacitCs aqueuses faibles i modCrCes durant la plus grande pCriode de l'intrusion. Le complexe de Jumping Brook est form6 d'une unique stquence i mCtamorphisme progressif et maintenant disloquCe par des failles. Les conditions de P-Tdurant 1'CvCnement mktamorphique au DCvonien (370-380 Ma) variaient du facibs des schistes verts (300°C i < 3 kbar) au facibs des amphibolites (650°C et 4 kbar). Les transformations metamorphiques ont probablement en lieu dans un d6me thermique. Les rksultats indiquent une relation substratum-couverture modCrCment dCformCs entre les complexes de Pleasant Bay et de Jumping Brook.[Traduit par la revue]Can. J. Earth Sci. 24, 2422Sci. 24, -2435Sci. 24, (1987 Introduction Distinction between basement and cover rocks in high-grade polymetamorphic terranes can rarely be made according to unambiguous and noncontroversial criteria. Structural complexity and metamorphic overprinting obscure field criteria for distinguishing basement and cover, and thermal and hydrothermal events may partially or completely reset isotopic systems. The weste...

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Section: Jumping Brook Complexmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

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Contrasting metamorphic terranes near Chéticamp, Cape Breton Highlands, Nova Scotia

Currie¹

1987

Can. J. Earth Sci.

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“…This is not unreason able considering the recent proliferation of Devonian and Carboniferous ages in northern Cape Breton Island (French 1984, Jamieson andCraw 1983). Geochemistry Major and trace element data for nineteen samples from the Whycocomagh Mountain pluton are presented in Table 1.…”

Section: Pegmatite and Related Rocksmentioning

confidence: 99%

Granitoid rocks and associated coper skarn, Whycocomagh Mountain, Cape Breton Island, Nova Scotia

Barr

Choy

Colwell

et al. 1984

atgeol

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Mineralized (Fe-Cu-W-Mo) skarn in the Whycocomagh Mountain area is associated with a small pluton of Devonian (402+20 Ma) age, which intruded predominantly metasedimentary rocks of the Hadrynian George River Group. The pluton consists largely of granite porphyry with a marginal granodiorite to diorite zone, and minor porphyritic granodiorite to monzodiorite dykes and pegmatite. The suite is calc-alkalic with I-type characteristics. Although weakly mineralized, the Whycocomagh Mountain pluton has features typical of plutons associated with porphyry-type Cu-Mo deposits. Calc-silicate rocks derived from marbles of the George River Group are the chief hosts for magnetite+chalcopyrite+schee-lite±molybdenite±pyrite which occur in veinlets along fractures and as disseminated grains in adjacent alteration envelopes. Characteristics of the pluton and the skarn minerals suggest that the deposit is a copper skarn. Un skarn min6ralis6 (Fe-Cu-W-Mo), situ6 dans la region de la montagne Whycocomagh, est assocife a une petite intrusion ign6e d'Sge Dgvonien (402±20 m.a.) qui pGnetre des roches, principalement des m6tas6diments, du groupe George River (Hadrynien). Le pluton consiste surtout en un granite porphyrique accompagne d'une zone marginale (granodiorite a diorite), de dykes mineurs (granodiorite a monzodiorite porphyrique) et de pegmatite. L'ensemble est calco-alcalin et de "type I". Bien que faiblement mineralise, le pluton Whycocomagh Mountain possede les caractSristiques typiques des plutons associgs aux depots porphyriques de type Cu-Mo. Les calco-silicates derives des marbres du groupe George River sont les hStes principaux du cortege magn6tite±chalcopyrite±scheelite±molybdenite±pyrite que l'on retrouve dans des veinules le long des fractures et dissemings dans les enveloppes d'altgration voisines. Les caractferistiques du pluton ainsi que la minferalogie du skarn font croire qu'il s'agit d'un d6p6t de skarn cuprifere.[Traduit par le journal]

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Dual-Polarity Early Carboniferous Remagnetization of the Fisset Brook Formation, Cape Breton Island, Nova Scotia

Johnson

Voo

1989

Geophysical Journal International

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Red siltstones and volcanic flows of the Fisset Brook Formation of Cape Breton Island, Nova Scotia, were folded or tilted in two phases, one of Late Tournaisian and the other of Mid-Namurian age. Upon thermal demagnetization, both rock types yield three components of magnetization, herein denoted as L, I and H. The L component has low unblocking temperatures and a direction conforming to that of the present-day geomagnetic field. L is inferred to be of recent origin. The intermediate I component, carried by haematite, is of synfolding origin. Directions could be obtained through vector subtraction for the demagnetization interval of 300-550°C, and yield a mean of D / I = 160"/+38" (k = 90.8, ag5 = S.lo), after 39 per cent of the tilt correction is applied. The H component has even higher unblocking temperatures, which overlap to a large degree with those of the I component, but analysis of intersecting great circles appears to yield a best-fit direction for H which is nearly antipodal to that of the I component. H is also synfolding, and yields a mean direction of D / I = 342"/-38" (k = 120.9, ag5 = 6.9") after 60 per cent of tilt correction. Both components are interpreted as secondary chemical remanent magnetizations of Late Tournaisian to Early Namurian age. A comparison of all available Carboniferous results from the craton and the northern Appalachians indicates that palaeolatitudes for Nova Scotia changed from about 20"s to about 10"s in the interval between the Early and Late Namurian and that they changed again from about 10"s to 0" between the Late Namurian and the Stephanian. Declinations show good agreement between Newfoundland, Nova Scotia, New Brunswick and the craton, with the exception of the Meguma terrain, which underwent a counterclockwise rotation with respect to the mainland in the Late Carboniferous, as noted previously by Spariosu, Kent & Keppie (1984).

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Reconnaissance Mapping of the southern Cape Breton Highlands - a Preliminary Report

Cited by 8 publications

References 0 publications

Contrasting metamorphic terranes near Chéticamp, Cape Breton Highlands, Nova Scotia

Contrasting metamorphic terranes near Chéticamp, Cape Breton Highlands, Nova Scotia

Granitoid rocks and associated coper skarn, Whycocomagh Mountain, Cape Breton Island, Nova Scotia

Dual-Polarity Early Carboniferous Remagnetization of the Fisset Brook Formation, Cape Breton Island, Nova Scotia

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