Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for EducatorsMindat Articles
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
Mining CompaniesStatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Watersmeet dome, Gogebic Co., Michigan, USA

This page is currently not sponsored. Click here to sponsor this page.
Latitude & Longitude (WGS84): 46° 19' 30'' North , 89° 11' 10'' West
Latitude & Longitude (decimal): 46.32500,-89.18611

The Watersmeet dome is composed of an Archean core about 25 km long in an E-W direction and about 8 km wide in a N-S direction. The dome is considered to be a mantled gneiss dome. Early Proterozoic rocks in the core are infolded with the Archean. Deformation of the Archean and adjacent Early Proterozoic rocks occurred during the Penokean orogeny. The rocks in the core were metamorphosed to the amphibolite facies, with a 15 km-wide zone of epidote amphibolite facies surrounding the core, and this in turn passes outward into greenschist facies. The Early Proterozoic rocks to the north of the dome have been overturned toward the northwest.

The gray rock of the dome is a tonalitic augen gneiss about 3560 Ma old (zircon data). It is a medium-gray, medium- to coarse-grained, biotiterich, irregularly layered rock with plagioclase augen. The alternating layers are feldspar-quartz-rich and biotite-rich. A modal analysis showed 48% plagioclase, 30% quartz, 8% K-feldspar, and 13% biotite. A possible protolith was dacitic volcanic rock. In places, biotite leucogranite veins 2590 Ma old (Rb/Sr and U-Pb methods) cut the gneiss. Secondary whole-rock and mineral isochrons give ages of 1750 to 1800 Ma and are thought to approximate the timespan of the Penokean event in this area. Parts of the ancient gneiss terrane are separated from the granite-greenstone terrane to the north by the Great Lakes Tectonic Zone. Whereas the Archean gneisses of the area may have been folded three times, the cross-cutting Late Archean leucogranite shows only a single foliation, that of the Penokean event. The gneiss is comparable in age to those of the Minnesota River Valley, about 3500 Ma old.

Mineral List

6 valid minerals.

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Neoarchean - Paleoarchean
2500 - 3600 Ma
Migmatitic gneiss and amphibolite (Late to Early Archean)

Age: Archean (2500 - 3600 Ma)

Description: Varied gneisses of mostly unknown age in cores of gneiss domes and fault-bounded uplifts (Archean gneiss terranes). Except for the Watersmeet dome (Late to Early Archean), all dated rocks are Late Archean. Includes granite of Late Archean age that transgresses gneisses and amphibolite.

Comments: continental margin assemblage (north of Niagara Fault)

Lithology: Major:{gneiss,amphibolite,migmatite}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.


LaBerge, G.L., Ojakangas, R.W., and Licht, K.J., 1992, Archean and Early Proterozoic Geology of the Gogebic District, Northern Michigan and Wisconsin, in 38th Annual Meeting of the Institute on Lake Superior Geology, Part 2: Field Trip Guidebook, v. 38.

Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Public Relations by Blytheweigh.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2019, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: February 17, 2019 18:44:42 Page generated: October 13, 2017 01:30:14
Go to top of page