Radiometric dating of the Coldbrook Group of southern New Brunswick, Canada

1969 ◽  
Vol 6 (3) ◽  
pp. 393-398 ◽  
Author(s):  
R. F. Cormier
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Volcanic Rocks ◽  
The Other ◽  
Radiometric Dating ◽  
Late Devonian ◽  
Initial Ratio ◽  
Initial Value ◽  
Saint John ◽  
Probable Presence

The Coldbrook Group of southern New Brunswick is composed almost entirely of volcanic rocks and has been assigned a Precambrian age on the basis of field relationships. Rocks of the group are overlain by fossiliferous Lower Cambrian beds of the Saint John Group.Rubidium-strontium total-rock analyses of 46 samples of Coldbrook Group volcanic rocks have been carried out. Analysis of the data indicates the probable presence of two different isochron ages. One of these is apparently defined by those rocks in which the ratio 87Rb/86Sr is low, with values less than about 1.0. This isochron yields an age of 750 ± 80 million years, with an initial ratio 87Sr/86Sr of 0.7054 ± 0.0010. The other isochron is defined by rocks in which the value of the ratio 87Rb/86Sr is higher, with values greater than about 1.0. The age calculated from the second isochron is 370 ± 38 million years, with an indicated initial value for the ratio 87Sr/86Sr of 0.7135 ± 0.0010.The 750 million year age is interpreted to represent the time of extrusion of the Coldbrook volcanics. The 370 million year age appears to be secondary and related to metamorphism of the Coldbrook Group. This age is correlated with the Acadian orogeny, which strongly deformed this part of the northern Appalachians in Middle to Late Devonian time.

Autochthonous and allochthonous rocks in the Pistolet Bay area in northernmost Newfoundland

1968 ◽  
Vol 5 (3) ◽  
pp. 501-513 ◽  
Author(s):  
M. F. Tuke
Keyword(s):  
Lower Cambrian ◽  
Volcanic Rocks ◽  
The Other ◽  
North Central ◽  
Middle Ordovician ◽  
Early Ordovician ◽  
Bay Area

Rocks outcropping in the northernmost part of the island of Newfoundland belong to two sequences, which are partly contemporaneous and very different in lithology. One sequence consists of Lower Cambrian sandstones and Lower and Middle Ordovician carbonates and shales. The other sequence consists of graywackes, volcanic rocks, and ultrabasic intrusions, which are, in part, early Ordovician. This latter sequence is interpreted as allochthonous because it is underlain by major low-angle faults and because of its strong facies contrast with the first sequence. The allochthonous rocks occur in three separate klippen.The trend of slickensides, attitude of folds, and deflection of beds at fault surfaces all indicate that movement along the low-angle faults that underlie the klippen was to the northwest. The klippen probably originated from an area 60 km to the southeast, which is on strike with similar rocks in north-central Newfoundland.It is suggested that the klippen moved by gravity sliding in late Middle Ordovician time.

Implications of spore evidence for Late Devonian age of the Piskahegan Group, southwestern New Brunswick

1988 ◽  
Vol 25 (9) ◽  
pp. 1349-1364 ◽  
Author(s):  
D. C. McGregor ◽  
S. R. McCutcheon
Keyword(s):  
New Brunswick ◽  
Eastern Europe ◽  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Surface Expression ◽  
Alluvial Fan ◽  
Late Devonian ◽  
Red Sandstone ◽  
Stratigraphic Position ◽  
Devonian Age

The predominantly volcanic Piskahegan Group has commonly been considered Early Carboniferous, based on its stratigraphic position. However, spores recently discovered in the Carrow Formation, an alluvial fan deposit in the exocaldera facies, indicate that most, if not all, of the group is of Late Devonian (late Famennian) age. The spore assemblage includes several species reported previously from Ireland, Belgium, and eastern Europe, some of them apparently restricted to the southern parts of the Old Red Sandstone Continent in Late Devonian time. Comparison of records of earliest occurrences suggests that the incoming of some species was diachronous. Volcanic rocks of the Piskahegan Group are coeval with post-Acadian, tin–tungsten-bearing granites elsewhere in New Brunswick and are considered the surface expression of plutonism that resulted from Acadian continental collison.

Structural setting and age of the Partridge Island block, southern New Brunswick, Canada: a link to the Cobequid Highlands of northern mainland Nova Scotia

2014 ◽  
Vol 51 (1) ◽  
pp. 1-24 ◽  
Author(s):  
Adrian F. Park ◽  
Robert L. Treat ◽  
Sandra M. Barr ◽  
Chris E. White ◽  
Brent V. Miller ◽  
...  
Keyword(s):  
Nova Scotia ◽  
New Brunswick ◽  
Tectonic Setting ◽  
Sedimentary Rocks ◽  
Alkali Feldspar ◽  
Early Carboniferous ◽  
Late Devonian ◽  
Island Formation ◽  
Lake Formation ◽  
Saint John

The Partridge Island block is a newly identified tectonic element in the Saint John area of southern New Brunswick, located south of and in faulted contact with Proterozoic and Cambrian rocks of the Ganderian Brookville and Avalonian Caledonia terranes. It includes the Lorneville Group and Tiner Point complex. The Lorneville Group consists of interbedded volcanic and sedimentary rocks, subdivided into the Taylors Island Formation west of Saint John Harbour and West Beach Formation east of Saint John Harbour. A sample from thin rhyolite layers interbedded with basaltic flows of the Taylors Island Formation at Sheldon Point yielded a Late Devonian – Early Carboniferous U–Pb (zircon) age of 358.9 +6/–5 Ma. Petrological similarities indicate that all of the basaltic rocks of the Taylors Island and West Beach formations are of similar age and formed in a continental within-plate tectonic setting. West of Saint John Harbour, basaltic and sedimentary rocks of the Taylors Island Formation are increasingly deformed and mylonitic to the south, and in part tectonically interlayered with mylonitic granitoid rocks and minor metasedimentary rocks of the Tiner Point complex. Based on magnetic signatures, the deformed rocks of the Tiner Point complex can be traced through Partridge Island to the eastern side of Saint John Harbour, where together with the West Beach Formation, they occupy a thrust sheet above a redbed sequence of the mid-Carboniferous Balls Lake Formation. The Tiner Point complex includes leucotonalite and aegirine-bearing alkali-feldspar granite with A-type chemical affinity and Early Carboniferous U–Pb (zircon) ages of 353.6 ± 5.7 and 346.4 ± 0.7 Ma, respectively. Based on similarities in age, petrological characteristics, alteration, iron oxide – copper – gold (IOCG)-type mineralization, and deformation style, the Partridge Island block is correlated with Late Devonian – Early Carboniferous volcanic–sedimentary–plutonic rocks of the Cobequid Highlands in northern mainland Nova Scotia. Deformation was likely a result of dextral transpression along the Cobequid–Chedabucto fault zone during juxtaposition of the Meguma terrane.

Reconstructing the Avalon continent: marginal to inner platform transition in the Cambrian of southern New Brunswick

1996 ◽  
Vol 33 (8) ◽  
pp. 1185-1192 ◽  
Author(s):  
Ed Landing
Keyword(s):  
North America ◽  
New Brunswick ◽  
Lower Cambrian ◽  
Saint John ◽  
Eastern Massachusetts

A west to east, marginal to inner Avalonian platform transition, comparable to that in southeast Newfoundland and southern Britain, is present in the Cambrian of southern New Brunswick. The Saint John–Caton's Island–Hanford Brook area lay on the marginal platform, and its thick, uppermost Precambrian–lower Lower Cambrian is unconformably overlain by trilobite-bearing, upper Lower Cambrian. An inner platform remnant is preserved in the Cradle Brook outlier 60 km northeast of Saint John. In contrast to the marginal platform sequences, the Cradle Brook outlier has a very thin lower Lower Cambrian and has middle Lower Cambrian strata (Bonavista Group) not present on the marginal platform. The Cradle Brook Lower Cambrian closely resembles inner platform successions in eastern Massachusetts and Trinity and Placentia bays, southeast Newfoundland. A limestone with Camenella baltica Zone fossils on Cradle Brook seems to be the peritidal limestone cap of the subtrilobitic Lower Cambrian known in Avalonian North America (Fosters Point Formation) and England (Home Farm Member).

The significance of radiometric ages from the Gulquac Lake area of New Brunswick

1979 ◽  
Vol 16 (10) ◽  
pp. 2046-2052 ◽  
Author(s):  
L. R. Fyffe ◽  
R. F. Cormier
Keyword(s):  
New Brunswick ◽  
Volcanic Rocks ◽  
Radiometric Dating ◽  
Lake Area ◽  
Structural Relationships ◽  
Minimum Age ◽  
Radiometric Ages ◽  
Intrusive Activity ◽  
Rhyolitic Volcanism ◽  
Radiometric Data

Radiometric dating of igneous rocks in the Gulquac Lake area of west-central New Brunswick confirms that rhyolitic volcanism and shallow granitic intrusive activity were closely associated in time. Rb–Sr whole rock isochrons yield an age of 409 ± 35 Ma for the volcanic rocks and 409 ± 25 Ma from the intrusive rocks (λ = 1.42 × 10−11 year−1). Structural relationships in the area show that emplacement of the granite coincided with an episode of intense faulting and uplift of sillimanite-grade Cambro–Ordovician terrain.The combined radiometric data indicate a minimum age for the Silurian–Devonian boundary of 409 ± 20 Ma.

Upper Lower Cambrian depositional sequence in Avalonian New Brunswick

1996 ◽  
Vol 33 (3) ◽  
pp. 404-417 ◽  
Author(s):  
Ed Landing ◽  
Stephen R. Westrop
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Long Island ◽  
High Energy ◽  
Depositional Sequence ◽  
Middle Cambrian ◽  
Fine Grained ◽  
Volcanic Ashes ◽  
Saint John

The Hanford Brook Formation (emended) is a thin (up to 42+ m), upper Lower Cambrian depositional sequence that is unconformably bounded by the lower Lower Cambrian (Random Formation) and the middle Middle Cambrian (Fossil Brook Member of the Chamberlain's Brook Formation). These stratigraphic relationships of the trilobite-bearing Hanford Brook Formation indicate deposition on the Avalonian marginal platform in the Saint John, New Brunswick, region and provide more evidence for a uniform, latest Precambrian–Cambrian epeirogenic history and cover sequence in Avalon. The Hanford Brook Formation is a deepening–shoaling sequence with (i) lower, transgressive sandstone deposited in episodically high-energy environments (St. Martins Member, new); (ii) highstand–regressive, dysaerobic mudstone – fine-grained sandstone with volcanic ashes (Somerset Street Member, new); and (iii) upper, regressive, planar and hummocky cross-stratified sandstone (Long Island Member, new). Trilobites are common in the distal Somerset Street Member, and ostracodes and brachiopods dominate the St. Martins and Long Island members. Condensation of the St. Martins Member and absence of the Long Island Member where the Random Formation and Fossil Brook Member are thinnest suggest onlap of the Hanford Brook and pronounced, sub-Middle Cambrian erosion across epeirogenically active blocks in southern New Brunswick.

A newly recognized sequence of possible Early Cambrian age in southern New Brunswick: evidence for major southward-directed thrusting

1981 ◽  
Vol 18 (6) ◽  
pp. 1012-1017 ◽  
Author(s):  
M. J. McLeod ◽  
S. R. McCutcheon
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Volcanic Belt ◽  
Basal Part ◽  
Early Cambrian ◽  
Iapetus Ocean ◽  
Saint John

Several previously unidentified occurrences of possible Lower Cambrian strata have been discovered recently in the Eastern Volcanic Belt (Avalon zone) of southern New Brunswick. The basal part of the sequence is lithologically similar to the Lower Cambrian parastratotype on Hanford Brook near Saint John, New Brunswick. Some of the newly recognized Cambrian rocks crop out beneath major northeast-trending and north-dipping thrusts, and rest unconformably on subaqueous Upper Precambrian equivalents of the Coldbrook Group. The presence of these Cambrian rocks in the Eastern Volcanic Belt indicates that the Cambrian–Ordovician Iapetus Ocean transgressed across the entire Avalon zone of southern New Brunswick.

Revised stratigraphy of the Long Reach area, southern New Brunswick: evidence for major, northwestward-directed Acadian thrusting

1981 ◽  
Vol 18 (3) ◽  
pp. 646-656 ◽  
Author(s):  
S. R. McCutcheon
Keyword(s):  
New Brunswick ◽  
Lower Cambrian ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Thrust Fault ◽  
Northern Boundary ◽  
Granitoid Rocks ◽  
Felsic Volcanic ◽  
Stratigraphic Succession ◽  
Felsic Volcanic Rocks

In the Long Reach area of southern New Brunswick, a new stratigraphic succession has been delineated; it consists of Precambrian (?) volcanic rocks, Cambrian sedimentary, volcanic and hypabyssal rocks, Silurian sedimentary rocks, and Devonian plus Precambrian (?) heterogeneous, granitoid rocks. The northern boundary of this succession is postulated to be a northwestward-directed thrust fault of Acadian age. Other Acadian thrust faults are interpreted in the area and major reverse movement of the same age occurred along the Belleisle Fault.Mafic and felsic volcanic rocks that were previously thought to be either Precambrian or Silurian are demonstrably part of the Lower Cambrian section. Some of the granitoid rocks intrude Silurian strata and therefore cannot be basement to the Cambrian succession. Other granitoid rocks appear to be older and may be Precambrian in age.

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