Deformation associated with gypsum karst in the Salt River Escarpment, northeastern Alberta

1984 ◽  
Vol 21 (8) ◽  
pp. 949-959 ◽  
Author(s):  
Po C. Tsui ◽  
David M. Cruden
Keyword(s):  
Groundwater Flow ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Normal Faults ◽  
Gypsum Karst ◽  
Salt River ◽  
Fort Smith ◽  
Devonian Age ◽  
Northeastern Alberta ◽  
Subsurface Cavities

An escarpment formed by the carbonate Keg River and evaporitic Chinchaga formations of Middle Devonian age extends southwards from the Slave River 30 km west of Fort Smith, Northwest Territories. Newly described folds in the bedrock are due to hydration of the anhydrite to gypsum in the Chinchaga Formation underlying the escarpment. Local groundwater flow has also dissolved subsurface cavities in the Chinchaga Formation. As these openings grew, the carbonates of the Keg River Formation subsided along stepped normal faults. Depressions within the fault blocks occurred where subsidence was concentrated along joints.

DISCOVERY CASE HISTORY OF THE PYRAMID ORE BODIES PINE POINT, NORTHWEST TERRITORIES, CANADA

Geophysics ◽  
1968 ◽  
Vol 33 (4) ◽  
pp. 645-656 ◽  
Author(s):  
H. O. Seigel ◽  
H. L. Hill ◽  
J. G. Baird
Keyword(s):  
Northwest Territories ◽  
Time Domain ◽  
Case History ◽  
Middle Devonian ◽  
Electromagnetic Induction ◽  
Ore Bodies ◽  
Lead And Zinc ◽  
History Of ◽  
Pine Point ◽  
Devonian Age

In the fall of 1965 a geophysical exploration program, in the Pine Point area, Northwest Territories, Canada, revealed indications which led to the discovery of 11.2 million tons of ore grading 11.7 percent combined lead and zinc in two separate ore bodies. The ore bodies are relatively flat‐lying although irregular in plan and section. They lie in limestones and dolomites, some reefoidal, of Middle Devonian age and are generally conformable to these sea sediments. The basic discoveries were effected by a time‐domain, induced‐polarization survey. A subsequent gravity survey proved to be of considerable value in guiding the extensive drilling program which followed and in predicting the amount of ore to be expected in each body. Despite a high marcasite content, the ore bodies did not respond appreciably to electromagnetic induction methods. This is attributed to the mode of distribution of the various sulfide minerals in the deposits.

Fort Smith, Northwest Territories

2011 ◽  
Vol 18 ◽  
pp. 49-50
Author(s):  
James Croft ◽  
Keyword(s):  
Northwest Territories ◽  
Fort Smith

An enigmatic blastozoan echinoderm fauna from central kentucky

2009 ◽  
Vol 83 (5) ◽  
pp. 739-749 ◽  
Author(s):  
Colin D. Sumrall ◽  
Carlton E. Brett ◽  
Troy A. Dexter ◽  
Alexander Bartholomew
Keyword(s):  
North America ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Fossil Record ◽  
Foreland Basin ◽  
Late Ordovician ◽  
Upper Devonian ◽  
Range Extension ◽  
First Report ◽  
Appalachian Foreland

A series of small road cuts of lower Boyle Formation (Middle Devonian: Givetian) near Waco, Kentucky, has produced numerous specimens of three blastozoan clades, including both “anachronistic” diploporan and rhombiferan “cystoids” and relatively advanced Granatocrinid blastoids. This unusual assemblage occurs within a basal grainstone unit of the Boyle Limestone, apparently recording a local shoal deposit. Diploporans, the most abundant articulated echinoderms, are represented by a new protocrinitid species, Tristomiocystis globosus n. gen. and sp. Glyptocystitoid rhombiferans are represented by isolated thecal plates assignable to Callocystitidae. Three species of blastoids, all previously undescribed, include numerous thecae of the schizoblastid Hydroblastus hendyi n. gen. and sp., the rare nucleocrinid Nucleocrinus bosei n. sp., and an enigmatic troosticrinid radial. The blastoid Nucleocrinus is typical for the age; however, the callocystitid, schizoblastid, and protocrinitid are not. Hydroblastus is the oldest known schizoblastid. Middle and Upper Devonian callocystitids have been previously reported only from Iowa and Michigan USA with unpublished reports from Missouri USA and the Northwest Territories, Canada. This occurrence is thus the first report of a Middle Devonian rhombiferan from the Appalachian foreland basin. Tristomiocystis is the first known protocrinitid in North America and the only protocrinitid younger than Late Ordovician. This occurrence thus represents a range extension of nearly 50 million years for protocrinids. This extraordinary sample of echinoderms in a Middle Devonian limestone from a well-studied area of North America highlights the incompleteness of the known fossil record, at least in fragile organisms such as echinoderms.

The otarionine trilobites Harpidella and Maurotarion, with species from northwestern Canada, the United States, and Australia

1995 ◽  
Vol 69 (2) ◽  
pp. 307-326 ◽  
Author(s):  
Jonathan M. Adrain ◽  
Brian D. E. Chatterton
Keyword(s):  
United States ◽  
New Species ◽  
Northwest Territories ◽  
Middle Devonian ◽  
The United States ◽  
Upper Ordovician ◽  
Mackenzie Mountains ◽  
New Diagnosis

Maurotarion Alberti, 1969, is a diverse otarionine clade that can be readily distinguished from Harpidella M'Coy, 1849. Both genera appear in the Upper Ordovician and range until the Middle Devonian. A new diagnosis for each taxon is given. New species of the genera from the Ordovician and Silurian of the central Mackenzie Mountains, Northwest Territories, Canada, include Harpidella kurrii (Ashgill), H. tikkaneni (Llandovery), H. greggi (Wenlock), and Maurotarion messieri (Llandovery). Harpidella megalops (M'Coy, 1846), H. triloba (Hu, 1975), H. spinafrons (Williams in Cooper and Williams, 1935), Maurotarion struszi (Chatterton, 1971), and M. instita (Whittington and Campbell, 1967) are revised.

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