Geology of Wisconsin - Wikipedia
网页The oldest Precambrian rocks in Wisconsin are late Archean quartzofeldspathic gneiss, migmatite and amphibolite up to three billion years old and igneous rock such as the granite of the Puritan Quartz Monzonite. Mafic and intermediate metavolcanic rocks together with metasedimentary rocks are found in the Ramsey Formation in Iron County and ...
The Dunbar Gneiss-granitoid dome: Implications for early …
网页The Dunbar dome in northeastern Wisconsin is a critical structural feature in the early Proterozoic Penokean orogen. It provides exposures of gneisses (Dunbar Gneiss) that structurally underlie the voluminous metavolcanic rocks of northeastern Wisconsin, and exposures of abundant granitoid rocks ranging from tonalite to granite.
USGS Mineral Resources On-Line Spatial Data
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网页INTRODUCTION. The bedrock geologic record in Wisconsin is divided into two major divisions of time: the Pre-cambrian, older than 600 million years, and the Paleozoic, younger than 600 million years. The Precambrian rocks are at the bottom and consist predominantly of crystalline rocks.
Archean (WI only) | Silurian Reef | The Field Museum
网页Gneiss is the oldest type of rock in Wisconsin. It is a metamorphic rock that has been so altered that it is difficult to determine the nature of the original rock. Gneiss can be derived from volcanic rock, sedimentary rock, or granite.
Petrology and Structure of Precambrian Gneisses at Big Falls, Eau ...
网页Precambrian amphibolite gneisses and schists at Big Falls County Park in Eau Claire County, Wisconsin, include four main lithologic units: banded amphibolite gneiss, amphibolite schist, transition gneisses and feldspathic gneiss. Structural and petrologic investigation indicate three deformational phases accompanied by recrystallization.
Boundary between Archean greenstone and gneiss terranes in …
网页The boundary between the greenstone and gneiss terranes is covered by younger supracrustal rocks, but is interpreted to trend approximately eastward across northern Wisconsin to the vicinity of Marquette, Michigan, and beyond.
Penokean deformation in central Wisconsin - GeoScienceWorld
网页An Archean, early Proterozoic, and middle Proterozoic sequence of metamorphic and plutonic rocks is exposed along and near the Wisconsin River in central Wisconsin, between Stevens Point and Wisconsin Rapids. Major lithologic units, from oldest to youngest, consist of (1) banded tonalitic gneiss with inter-layered amphibolite, (2) …
Gneiss - Wikipedia
网页Gneiss (/ naɪs / nice) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. This rock is formed under pressures anywhere from 2 to 15 kbar, sometimes even more, and temperatures over 300°C (572°F).
Kyanite – WGNHS – UW–Madison
网页Description: Kyanite schist outcrop near Powell in Iron County, Wisconsin. (Photo courtesy Tod Roush.) Kyanite is formed by the metamorphism of alumium-rich rocks, and is often associated with biotite, muscovite, almandine, staurolite, and sillimanite. It is indicative of relatively high pressures during metamorphism.