Chemistry, morphology, modal mineralogy, and photomicrographs of amphiboles and other minerals in the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin, USA
The Ironwood Iron-Formation, part of the Gogebic Iron Range in Wisconsin, is a Paleoproterozoic Superior-type banded iron formation (BIF) with substantial iron resource potential. The development of a Mesoproterozoic contact metamorphic aureole related to the emplacement of the Mellen Intrusive Complex resulted in the production of a variety of silicate minerals in the western portion of the Ironwood Iron-Formation, including amphibole, pyroxene, and olivine. The presence of amphibole minerals, some of which occur in a fibrous habit, has complicated development of this resource due to potential human health impacts. This data release provides information related to amphibole and other minerals in order that commercial,...
This is a report of geochemical data from various media collected on Isle Royale, a large island in northeastern Lake Superior. Isle Royale became a national park in 1940 and was designated as a wilderness area in 1976. USGS sampling began in 1996 as part of a larger project on the Midcontinent Rift in the Lake Superior region. Data are given in nine Microsoft Excel spreadsheets. All the data are newly acquired by the USGS.
This dataset comprises photomicrographs from drill core and outcrop samples from the Ironwood Iron-Formation.
Electron microprobe analyses of amphibole, pyroxene, and carbonate minerals from the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin, USA
These data comprise chemical analyses in weight percent of oxides, as well as chlorine and fluorine, conducted using a JEOL JXA-8900 electron microprobe analyzer (EPMA) on amphiboles, pyroxenes, and carbonates in the Ironwood Iron-Formation.
Energy-dispersive X-ray spectroscopy (EDS) analyses from the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin, USA
This dataset comprises various energy-dispersive spectroscopy (EDS) analyses from drill core and outcrop samples in the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin, USA.
Scanning electron microscope (SEM) images from the Ironwood Iron-Formation, Gogebic Iron Range, Wisconsin, USA
These data comprise various SEM images from drill cores and outcrops in the Ironwood Iron-Formation.
Exposed Precambrian Bedrock in Part of Dickinson County, Michigan, and Marinette and Florence Counties, Wisconsin
The U.S. Geological Survey conducted a program of bedrock geologic mapping in much of the central and western upper peninsula of Michigan and parts of Wisconsin from the 1940’s until the late 1990’s. Geologic studies in this region are hampered by a scarcity of bedrock exposures because of a nearly continuous blanket of unconsolidated sediments resulting from glaciation of the region during the Pleistocene ice ages. The USGS mapping, done largely at a scale of 1:24,000, routinely recorded the location and extent of exposed bedrock to provide both an indication of where direct observations were made, and as a guide for future investigations to expedite location of observable rock exposures. The locations of outcrops...