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TitleCambrian wave-dominated tidal-flat deposits, central Wisconsin, USA
AuthorMacNaughton, R BORCID logo; Hagadorn, J W; Dott, R H, Jr.
SourceSedimentology 2018 p. 1-30,
Alt SeriesEarth Sciences Sector, Contribution Series 20090316
Mediapaper; on-line; digital
File formatpdf; html; tif
AreaWisconsin; United States of America
Lat/Long WENS -93.0000 -87.0000 47.0000 42.5000
Subjectsregional geology; sedimentology; paleontology; stratigraphy; depositional environment; coastal environment; tidal flats; channels; mud flats; tides; bedrock geology; lithology; sedimentary rocks; arenites; sandstones; mudstones; siltstones; sedimentary structures; facies; ichnofacies; fossils; ichnofossils; lithofacies; Elk Mound Group; Wonewoc Formation; Eau Claire Formation; Mount Simon Formation; Cruziana; Molluscs; Furongian; Miaolingian; Trends; Phanerozoic; Paleozoic; Cambrian
Illustrationslocation maps; cross-sections; lithologic sections; rose diagrams; photographs; sketches; geoscientific sketch maps; tables; plots; block diagrams
ProgramPeople Support
Released2018 10 18
AbstractIn central Wisconsin, Cambrian strata of the Elk Mound Group record deposition on open-coast, wave-dominated tidal flats. Mature, medium-grained quartz arenite is dominated by parallel-bedding with upper-flow regime parallel-lamination, deposited during high-energy storms that also produced three-dimensional bedforms on the flats. Abundant wave ripples were produced as storms waned or during fair weather, in water depths <=2 m. Indicators of variably shallow water (washout structures and stranded cnidarian medusae) and subaerial exposure (adhesion marks, rain-drop impressions and desiccation cracks, including cracked medusae) are abundant. Parallel-bedded facies preserve a Cruziana ichnofacies, similar to other Cambrian tidal-flat deposits. Flats were dissected by small, mainly straight channels, the floors of which were grazed intensely by molluscs. Most channels were ephemeral but some developed low levées, point bars and cut-banks, probably reflecting stabilization by abundant microbial mats and biofilms. Channels were filled with trough cross-bedding that is interpreted to have been produced mainly during storm runoff. The strata resemble deposits of open-coast, wave-dominated tidal flats on the east coast of India and west coast of Korea. Ancient wave-dominated and open-coast tidal flats documented to date appear to have been limited to mud-rich strata with 'classic' tidal indicators such as flaser bedding and tidal bundles. The Cambrian (Miaolingian to early Furongian) Elk Mound Group demonstrates that sandy, wave-dominated tidal flats also can be recognized in the stratigraphic record.

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