Odom, J. Edgar||Morris, Robert C. (Robert Clarence), 1928-||Weiss, Malcolm P. (Malcolm Pickett), 1921-
M.S. (Master of Science)
Department of Earth Science
Petrology--Wisconsin--Monroe County; Sandstone--Wisconsin; Petrology--Wisconsin--Adams County
The stratigraphy and petrology of the Woodhill, Birkmose, Tomah, Reno, and Mazomanie Members of the Franconia Formation (Upper Cambrian) were studied from samples of these units from an area of several hundred square miles in parts of Adams, Juneau, and Monroe Counties, Wisconsin. Grain-size data indicate that all the members are well sorted except for the Woodhill, which is poorly sorted. The mean grain size of each member is different, with the Wood- hill being the coarsest and the Tomah the finest. Each member of the Franconia can be distinguished by textural parameters, but the Woodhill cannot always be distinguished from the underlying Galesville Member of the Dresbach Formation. The mineral composition of each member is also distinctive. The Woodhill, as well as the Galesville, is composed mainly of quartz with a trace of feldspar. The Birkmose, Tomah, and Reno Members are composed of quartz, glauconite, potassium feldspar, muscovite, and dolomite. The Tomah generally contains more feldspar than the other units (about 40 percent) whereas the Reno contains the most glauconite (about 12 percent). The Mazomanie sandstone interfingers with the Reno and is composed of quartz with about ten percent feldspar. The quartz, feldspar, muscovite, heavy minerals, and the clay are primarily of detrital origin. Calcite and glauconite formed in the environment but the latter was often redeposited by wave action. After deposition of these constituents, parts of the formation were dolomitized. The dolomite has completely replaced the original calcite and partially replaced some quartz and feldspar. Before dolomitization occurred, abundant authigenic overgrowths developed on feldspars and on some quartz grains. The amount of feldspar in a particular unit is dependent on the low energy (i.e., lack of disturbance) of the environment and not on changing sources. The textural and mineralogical data support the conclusions advanced by other workers that the Franconia was deposited on a flat, shallow, marine shelf over which the sea was advancing to the north. This history is recorded in the study area by the different textures and compositions of the various members.
Hiatt, John Ludlow, "The petrology of the Franconia formation, Monroe to Adams counties, Wisconsin" (1969). Graduate Research Theses & Dissertations. 6069.
ix, 96 pages
Northern Illinois University
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