Stratigraphy and correlation of the precambrian belt supergroup of the southern Lewis and Clark Range, Montana

Geological Society of America Bulletin
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Abstract

Several well-exposed and little-deformed Belt Supergroup sections have been studied in the southern Lewis and Clark Range. In the area studied, the Belt thins eastward or northeastward due both to primary sedimentation and to pre-Middle Cambrian erosion. These rocks can now be more precisely correlated with the well-known sections near Bonner, Helena, and Glacier National Park. In the western part of the area, the Missoula Group is thickest and lithologically intermediate between the sections at Bonner and Marias Pass. Formation names from these two sections are applied in the southern Lewis and Clark Range. The thin Belt sequence in the eastern part of the area includes the lower part of the Missoula Group and older formations that may be traced southward into the Helena, Empire, and Spokane Formations of the Helena area. Consequently, the Helena Dolomite of the Helena area, the Siyeh Formation of the Marias Pass area, and the "Newland Limestone" of the Bonner area are probably lateral equivalents.

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Publication type Article
Publication Subtype Journal Article
Title Stratigraphy and correlation of the precambrian belt supergroup of the southern Lewis and Clark Range, Montana
Series title Geological Society of America Bulletin
DOI 10.1130/0016-7606(1967)78[343:SACOTP]2.0.CO;2
Volume 78
Issue 3
Year Published 1967
Language English
Publisher Geological Society of America
Description 10
First page 343
Last page 352
Country United States
State Montana
Other Geospatial Lewis and Clark range
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