Correlation of Montana Algonkian Formations

Clapp, Charles H.; Deiss, Charles

doi:10.1130/gsab-42-673

Cited by 11 publications

(21 citation statements)

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“…distribution, but he interpreted it as representing four units: his Newland limestone, Spokane shale, Helena limestone, and Miller Peak argillite. Clapp and Deiss (1931) correlated the Spokane shale and Helena limestone of the Helena vicinity with the upper part of the Wallace limestone (Wallace limestone equals Newland limestone) of the Missoula area; but neither their correlation chart nor their stratigraphic descriptions show the Spokane shale and Helena limestone this far west.…”

Section: Correlationmentioning

confidence: 89%

“…C. M. Langton (1935) used "Newland limestone" in this area, and Calkins and Emmons (1915) used it in the Philipsburg quadrangle, which is about 22 miles southeast of the Bonner quadrangle. Clapp and Deiss (1931) used the term "Wallace limestone" within this area, but its present use is restricted to areas farther west. Wallace and Hosterman (1956) used the term "Wallace" in the vicinity of St. Regis, Mont., which is about 60 miles northwest of the Bonner quadrangle.…”

Section: Namementioning

confidence: 99%

“…The Missoula group is the uppermost part of the Belt series. It is well exposed in the mountains east of Missoula, Mont., where Clapp and Deiss (1931) originally named and described it and its component formations. The type localities of all but one of their formations are within the Bonner quadrangle; the type locality of the McNamara argillite is about 4 miles east of the quadrangle, where it is well exposed.…”

Section: Missoula Groupmentioning

confidence: 99%

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Geology of the Bonner quadrangle, Montana

Nelson¹,

Dobell²

1961

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The geology of the Bonner quadrangle in western Montana was mapped principally to study the Missoula group of the Belt series, and the structure of the area. The type localities of the formations comprising this group are all in or near the Bonner quadrangle. These formations are here redefined and in part renamed. Like the rest of the Belt series, the Missoula group has been regarded heretofore as of late Precambrian age but in our opinion the results of the present study suggest that its upper part may be of Cambrian age. The oldest rocks exposed in the quadrangle belong to the Newland limestone, the local representative of the Piegan group. That group is characterized by the prevalence of calcite-rich rocks and is near the middle of the Belt series. Here clayey and sandy tan to gray limestone is the major component of the Newland limestone. Thin layers of very dark gray argillite are intercalated with the limestone; and noncarbonatic shale, sandy shale, and quartzite occur locally in units as much as 100 feet thick. The thickness is at least 4,000 feet. The Piegan group is succeeded upward by the Missoula group, which occupies most of the Bonner quadrangle. The Missoula group has an aggregate thickness of about 14,300 feet, and as subdivided here includes, from the base upward, the Miller Peak quartzite (including the Hellgate quartzite member), Bonner quartzite, McNamara argillite, Garnet Range quartzite, and Pilcher quartzite. All components of the Belt series within the quadrangle appear to have gradational contacts. Shallow-water features, such as mud cracks and ripple marks, are plentiful in argillite beds in both the Piegan and Missoula groups. The Miller Peak argillite is composed of red and green silty argillite and argillaceous quartzite, and locally a little pale-red and tan quartzite, and light-gray impure limestone. Some argillite units several hundred feet thick are of uniform color, but in others the colors alternate every few feet. Few argillite beds are free from clastic quartz which locally is sufficiently abundant to warrant naming the rocks clayey quartzite, or even quartzite. The quartzite forms isolated lenticular beds and lenses with some intercalated argillite. The Hellgate quartzite member, high in the formation, is one of the thickest of these lenses. It is about 1,200 feet thick, and has about 3,800 feet of argillite below it and 1,000 feet of argillite above. The Bonner quartzite (here newly named) corresponds to the middle member of the McNamara formation as previously defined. The formation is charac-189 190 CONTRIBUTIONS TO GENERAL GEOLOGY terized by its tendency to break into blocks speckled with grains of white, translucent, weathered feldspar. Pink vitreous quartzite predominates; the quartzite is commonly crossbedded and intercalated with minor amounts of green and red argillite. The formation is about 1,500 feet thick. The McNamara argillite, as here restricted, is composed largely of red and green metamorphosed clayey siltstone and minor amounts of argillite and quartzite. T...

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Section: Correlationmentioning

confidence: 89%

Section: Namementioning

confidence: 99%

Section: Missoula Groupmentioning

confidence: 99%

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Geology of the Bonner quadrangle, Montana

Nelson¹,

Dobell²

1961

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“…Borings have not been found, and remains of animals are lacking, as are those of planktonic plants. The Belt series has been described by many authors whose work is reviewed, with correlations, by Schofield (1914), Clapp and Deiss (1931), Fenton and Fenton (1937), and Ross (1949). Traditionally regarded as Proterozoic, it has been placed in the Paleozoic by Hinds (1936, p. 129;1940a;1940b), who assigns it to a restricted Algonkian system which also includes the Grand Canyon, Apache, and Keweenawan series, as well as unnamed Beltian equivalents in the Death Valley region.…”

Section: General Statementmentioning

confidence: 99%

Chapter 7: Paleoecology of the Precambrian of Northwestern North America

Fenton¹,

Fenton²

1957

Geological Society of America Memoirs

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Precambrian formations of Northwestern North America contain no fossil assemblages suitable for ecologic analysis. The closest approximations to associations are found in stromatolite biostromes and reefs of the Snowy Range and Belt series, in which stony algae were the dominant life forms. Snowy Range stromatolites were produced in quiet, shallow marine waters by algae intolerant of clastic sediment. Builders of Belt stromatolites were tolerant and very hardy, since they thrived in shallows subject to disturbance by storms, floods, lava flows, and periodic desiccation. Reef stromatolites show great variation, apparently in response to varied conditions of light and water.

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“…Walcott (1906Walcott ( , 1908Walcott ( , 1910 made the earliest known geological studies of the Precambrian and Cambrian rocks in and adjacent to the Scapegoat additions. Clapp and Deiss (1931) studied the Belt rocks in and adjacent to the area. Clapp (1932Clapp ( , 1934 published the first geologic map of the area and briefly discussed the stratigraphy and structure.…”

Section: Introductionmentioning

confidence: 99%