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- catalog abstract "Proterozoic quartzite is exposed at several isolated localities within an area of nearly 13,000 square kilometers in Wisconsin. Although early workers proposed that the quartzite is of two different ages, more recent workers have suggested that the various quartzite bodies are correlative, and that their protoliths were deposited between 1,760 and 1,630 Ma. Structural and stratigraphic studies of the quartzite deposits together with new age data indicate that the quartzite is at least of two distinct ages. Quartzite at McCaslin and Thunder Mountains, in northeastern Wisconsin, is older than 1,812 Ma, as indicated indirectly by a dated intrusion, and quartzite boulders in conglomerates in central Wisconsin are at least as old as the rhyolite country rock (=1,840 Ma). Deformed quartzite at Hamilton Mounds, in south-central Wisconsin, is intruded by undeformed granite that is 1,764 Ma. The ages of many other quartzite bodies, however, cannot be tightly constrained at present. Quartzite exposed in central and southern Wisconsin, south of the Eau Pleine shear zone, is interpreted as remnants of a passive margin sequence that was deposited on an Archean microcontinent (Marshfield terrane) and subsequently deformed in a major south-verging fold-thrust system during collision between the microcontinent and oceanic-arc rocks of the Pembine-Wausau terrane. The occurrence of quartzite-bearing conglomerates in the 1,860 Ma volcanic rocks of the Marshfield terrane suggests that the allochthonous quartzite bodies are 1,860 Ma or older. Collision occurred at about 1,840 Ma, and marked the end of the Penokean orogeny.".
- catalog contributor b7594554.
- catalog contributor b7594555.
- catalog contributor b7594556.
- catalog created "1991.".
- catalog date "1991".
- catalog date "1991.".
- catalog dateCopyrighted "1991.".
- catalog description "Includes bibliographical references (p. 16-18).".
- catalog description "Proterozoic quartzite is exposed at several isolated localities within an area of nearly 13,000 square kilometers in Wisconsin. Although early workers proposed that the quartzite is of two different ages, more recent workers have suggested that the various quartzite bodies are correlative, and that their protoliths were deposited between 1,760 and 1,630 Ma. Structural and stratigraphic studies of the quartzite deposits together with new age data indicate that the quartzite is at least of two distinct ages. Quartzite at McCaslin and Thunder Mountains, in northeastern Wisconsin, is older than 1,812 Ma, as indicated indirectly by a dated intrusion, and quartzite boulders in conglomerates in central Wisconsin are at least as old as the rhyolite country rock (=1,840 Ma). Deformed quartzite at Hamilton Mounds, in south-central Wisconsin, is intruded by undeformed granite that is 1,764 Ma. The ages of many other quartzite bodies, however, cannot be tightly constrained at present. Quartzite exposed in central and southern Wisconsin, south of the Eau Pleine shear zone, is interpreted as remnants of a passive margin sequence that was deposited on an Archean microcontinent (Marshfield terrane) and subsequently deformed in a major south-verging fold-thrust system during collision between the microcontinent and oceanic-arc rocks of the Pembine-Wausau terrane. The occurrence of quartzite-bearing conglomerates in the 1,860 Ma volcanic rocks of the Marshfield terrane suggests that the allochthonous quartzite bodies are 1,860 Ma or older. Collision occurred at about 1,840 Ma, and marked the end of the Penokean orogeny.".
- catalog extent "iii, 18 p. :".
- catalog isPartOf "Contributions to Precambrian geology of Lake Superior region ; ch. B".
- catalog isPartOf "U.S. Geological Survey bulletin ; 1904-B".
- catalog issued "1991".
- catalog issued "1991.".
- catalog language "eng".
- catalog publisher "Washington : U.S. G.P.O. ; Denver, CO : For sale by the Books and Open-File Reports Section, U.S. Geological Survey,".
- catalog spatial "Wisconsin.".
- catalog subject "557.3 s 552/.4 20".
- catalog subject "Geology, Stratigraphic Proterozoic.".
- catalog subject "Geology, Structural Wisconsin.".
- catalog subject "QE75 .B9 no. 1904-B QE475.Q3".
- catalog subject "Quartzite Wisconsin.".
- catalog title "New observations on the age and structure of Proterozoic quartzites in Wisconsin / by Gene L. Laberge, J.S. Klasner, and Paul E. Myers.".
- catalog type "text".