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Research about Michigan, Wisconsin

Source-linked reports with geographic coverage including Michigan, Wisconsin.

At least 73 records · Page 4Linked to original sources
USGS1993

Distribution, abundance, and resting microhabitat of burbot on Julian's Reef, southwestern Lake Michigan

We used a remotely operated submersible vehicle equipped with a color video camera to videotape the lake bed and document the distribution and abundance of burbot Lota lota on a 156‐hectare portion of Julianˈs Reef in southwestern Lake Michigan. The substrates and bathymetry of the study area had been mapped recently by side‐scan sonar. Burbot density determined from videotapes covering 6,900 m 2 of lake bed at depths of 23–41 m averaged 139 individuals/ hectare (range, 0–571/hectare). This density was substantially higher than the highest burbot density (59–95/hectare) reported in the literature. Burbot were present on the lake bed at depths of 23–36 m, but were most abundant near the crest of the reef at 23–28 m, where the water temperature was 8–13°C, their preferred summer temperature range. Substrates in that temperature range on the reef were bedrock, bedrock ridges, and bedrock and rubble. Burbot were most abundant on the bedrock and rubble. Small fish and macroinvertebrates typically eaten by burbot elsewhere in western Lake Michigan were distributed on the reef according to their summer preferred temperatures and were not seen in abundance where burbot density was highest. We saw no lake trout Salvelinus namaycush on Julianˈs Reef, although large numbers of juvenile lake trout have been stocked there annually and temperatures on the reef were in the preferred summer temperature range for lake trout.

Michigan, Wisconsin↗
USGS1992

Climatic changes near the Great Lakes inferred from 141 year ice records

Freeze-up and break-up dates and duration of ice cover for lakes and rivers represent an integration of weather conditions prior to the specified event(s). Changes in mean ice conditions may be used as quantitative indicators of climatic changes if long homogenous ice records are accompanied by sufficiently homogenous air temperature records to calibrate the changes in mean ice cover in terms of climatic variables. Historical ice records dating back to 1855 are available for Lake Mendota, WI (located on the southwestern side of Lake Michigan) and back to 1851 for Grand Traverse Bay, MI (located on the northeastern side of Lake Michigan). Changes in the mean ice cover of these two systems were used to describe changes in fall, winter, and spring air temperatures in the area near the Great Lakes during the past 141 years.

Michigan, Wisconsin↗
USGS1991

National Water-Quality Assessment Program - Western Lake Michigan Drainage Basin

In 1991 , the U.S. Geological Survey (USGS) began to implement a full -scale National Water-Quality Assessment (NA WQA) program. The long-term goal of the NA WQA program are to desc ribe the tatus and trends in the quality of a large, representative part of the Nation's urface- and ground-water resources and to provide a sound , scientific understanding of the primary natural and human factor affecting the quality of these resources. In meeting these goal , the program will produce a wealth of water-quality information that will be useful to policy makers and managers at the nationa l, State , and local levels. A major design feature of the NA WQA program will enable water-quality information at di ffe rent areal scales to be integrated . A major component of the program is study-unit investigations, which comprise the princ ipal bui lding blocks of the program on which national-level asses ment activities a re based . The 60 study-unit in vestigations that make up the program are hydrologic systems that include parts of most major river bas ins and a qui fer systems. These study units cover areas of I ,200 to more than 65 ,000 square mi les and incorporate about 60 to 70 percent of the Nation's water use and popul ation e rved by public water supply. In 1991 , the Western Lake Michigan drainage basin was among the fir st 20 NA WQA study unit selected for study under the full -scale implementation plan.

Michigan, Wisconsin↗
USGS1985

The Dunbar Gneiss-granitoid dome: Implications for early Proterozoic tectonic evolution of northern Wisconsin

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. The granitoid rocks cut both the gneisses in the core and the supracrustal (cover) metavolcanic rocks and were emplaced essentially along the core-cover boundary. The Dunbar Gneiss is calc-alkaline and was derived from volcanic and intrusive rocks of intermediate composition. The various intrusive rocks have calcic, calc-alkaline, and alkali to alkali-calcic compositions, and they progress with time to more SiO 2 and K 2 -rich compositions. U-Pb zircon ages indicate that accumulation of the layered rocks in the core and cover, deformation and metamorphism, and intrusion of the granitoid rocks spanned a relatively short time, ∼1865–1835 Ma. We interpret the dome as being a large-scale, fold-interference structure resulting from polydeformation modified by diapirism. Northeast-oriented folds (F 3 ) and a related mylonitic foliation (S 3 ), nearly confined to the dome, are superposed on northwest-oriented folds (F 2 ) that developed during regional deformation. In the core-cover boundary, these structures are obliterated by a zone of intense deformation—a mylonitic foliation and a steeply plunging stretching lineation—as much as 500 m wide, which we interpret as resulting from diapirism. Metamorphic zoning is concentric: amphibolite facies in inner parts of the mantle and greenschist facies in the outer part of the mantle. The Wisconsin magmatic terrane, as represented by the rocks in the Dunbar dome, differs from the epicratonic, early Proterozoic sedimentary-volcanic sequence (Marquette Range Supergroup) in Michigan, to the north, in stratigraphy, structure, and volume and composition of igneous rocks. Whereas the basalts in northern Michigan are compositionally similar to continental rift basalts, the volcanic rocks in the Dunbar dome have over-all island-arc compositional affinities. The over-all calc-alkaline compositions of the intrusive rocks are similar to those in magmatic arcs formed at convergent plate-margin settings. Accordingly, we interpret the Wisconsin magmatic terrane as an oceanic-arc complex that was sutured to the North American continent during development of the Penokean orogen. Similar interpretations based on broad regional observations have been proposed previously.

Michigan, Wisconsin↗