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Eugene L. Boudette

Publications and source records attributed to Eugene L. Boudette.

9 recordsLinked to original sources
USGS1967

Geology and petrology of the Greenville quadrangle, Piscataquis and Somerset Counties, Maine

In the Greenville quadrangle, west-central Maine, slate, siltstone, and sandstone (calcareous and noncalcareous) of probable Silurian to Early Devonian age are intruded by a large mafic pluton and two granitic stocks of probable Early Devonian age. Ages of the sedimentary rocks are based upon tentative correlations with fossiliferous beds in adjacent quadrangles because the few fossils in the Greenville quadrangle are nondiagnostic; ages of the intrusive rocks are based upon radiometric age determinations. The sedimentary rocks are tightly folded about northeast-trending axes and have strong slaty cleavage. Widespread graded bedding is very useful in determining the tops of beds and thus the location of fold axes. The sedimentary rocks are in the chlorite zone of metamorphism except in the contact aureoles where the metamorphism ranges from the biotite zone, through the andalusiite-amphibole zone, to the sillimanite-cordierite zone adjacent to the intrusions; retrograde metamorphism is a minor local feature. The mafic rocks are part of the Moxie pluton, which extends southwest and northeast of the Greenville quadrangle for a total distance of about 45 miles. Troctolite and norite are the principal rock types; gabbro is less common. Plagioclase is the dominant mineral; it usually makes up 50-75 percent of the rock. Olivine and orthopyroxene are widespread, clinopyroxene is uncommon and biotite and hornblende are generally present in small amounts. The rocks can be separated into magnesium-rich and iron-rich varieties; magnesium-rich olivine and orthopyroxene are usually accompanied by plagioclase containing from 57 to 77 percent anorthite, and iron-rich olivine and orthopyroxene are associated with plagioclase containing about 50-62 percent anorithite. Compositional layering is rare, but flow structure is very common. Flow structure generally dips northward to eastward, whereas geophysical data indicate that the contacts of the pluton dip southeastward. The granitic stocks are discordant pipelike bodies that range from granodiorite to quartz monzonite in composition. Both the mafic and the felsic intrusions are undeformed and unmetamorphosed. Slate quarrying was once an important industry in the region, but in 1965 only one quarry was active at Monson just east of the report area. Slate is a potential source of raw material for lightweight concrete aggregate. There are several possible sites for stone quarries in the intrusive masses. Sand and gravel resources seem to be limited. Small amounts of sulfides that have low copper and nickel values are known at a few places in the mafic pluton.

Maine↗
USGS1956

Geology of the Midnite Mine area, Spokane Indian Reservation, Stevens County, Washington

The Midnite mine is on the Spokane Indian Reservation, Stevens County, Wash. Geologic mapping and reconnaissance in the vicinity of the mine indicate metasedimentary rocks of probable Precambrian age have been intruded by two varieties of quartz monzonite of probable Cretaceous age. Porphyritic quartz monzonite underlies about three-fourths of the mapped area, and equigranular quartz monzonite underlies about one-thirtieth of the area. Metasedimentary rocks have been thermally metamorphosed in the vicinity of the intrusives. Uranium minerals are restricted to the vicinity of the contact between porphyritic quartz monzonite and schistose or spotted phyllite. The largest and richest uranium deposits are where the contact is relatively steeply dipping and highly irregular in detail. Uranium minerals are most abundant in brecciated and fractured or jointed schist but are also present along joints and grain boundaries in the adjacent quartz monzonite. Secondary uranium minerals comprise all known ore deposits; uraninite was found only in one diamond-drill core from the Midnite property. The origin of the deposits is not known, but several features suggest a hydrothermal origin.

Washington↗