scholarly journals Lithofacies and basinal development of the type 'Etcheminian Series' (Lower Cambrian Ratcliffe Brook Formation), Saint John area, southern New Brunswick

10.4138/1693 ◽  
1990 ◽  
Vol 26 (1) ◽  
Author(s):  
S. K. Tanoli ◽  
R. K. Pickerill
1969 ◽  
Vol 6 (3) ◽  
pp. 393-398 ◽  
Author(s):  
R. F. Cormier

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.


1996 ◽  
Vol 33 (8) ◽  
pp. 1185-1192 ◽  
Author(s):  
Ed Landing

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).


1996 ◽  
Vol 33 (3) ◽  
pp. 404-417 ◽  
Author(s):  
Ed Landing ◽  
Stephen R. Westrop

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.


1981 ◽  
Vol 18 (6) ◽  
pp. 1012-1017 ◽  
Author(s):  
M. J. McLeod ◽  
S. R. McCutcheon

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.


1988 ◽  
Vol 25 (5) ◽  
pp. 669-690 ◽  
Author(s):  
Saifullah K. Tanoli ◽  
Ron K. Pickerill

The Cambrian – Lower Ordovician Saint John Group of the Saint John area, southern New Brunswick, has historically been subdivided into 11 formations. The existing scheme is inappropriate, however, as many of the supposed formations, particularly those of Middle Cambrian–Early Ordovician age, were distinguished on a biostratigraphic rather than lithostratigraphic basis. We suggest the sequence can be more appropriately subdivided into seven formations, each of which can be clearly and easily identified by the field geologist. Lower Cambrian formations comprise, from base to top, the Ratcliffe Brook, Glen Falls, and Hanford Brook formations, all of which are retained from the previous nomenclature. Middle Cambrian strata comprise the Forest Hills Formation (to replace the Fossil Brook and Porter Road formations) and Upper Cambrian strata the King Square Formation (to replace the Hastings Cove and Agnostus Cove formations) and Silver Falls Formation (to replace the Black Shale Brook and Narrows formations). Lower Ordovician strata are referred to as the Reversing Falls Formation (to replace the Navy Island and Suspension Bridge formations). Descriptions of each formation are given, major sections of each are included, and stratigraphic correlation of the sequence in different geographic areas is demonstrated.


2013 ◽  
Vol 142 (3) ◽  
pp. 717-730 ◽  
Author(s):  
Sima Usvyatsov ◽  
Jeffrey Picka ◽  
Andrew Taylor ◽  
James Watmough ◽  
Matthew Kenneth Litvak

Sign in / Sign up

Export Citation Format

Share Document