Geology Reports⌕ Search

Geology topics

E. R. Force

Publications and source records attributed to E. R. Force.

35 records · Page 2Linked to original sources
USGS1980

The provenance of rutile.

Most coarse detrital rutile is derived from high-grade metamorphic rocks. Contrary to a conventional assumption, independent rutile grains are particularly rare in igneous rocks except alkalic rocks. The use of rutile in the ZTR (zircon-tourmaline-rutile) index of mineralogic maturity is only partially valid, owing to its restricted provenance.

Journal of Sedimentary Petrology↗
USGS1979

Mineral resources of the Citico Creek Wilderness Study Area, Monroe County, Tennessee

The proposed Citico Creek Wilderness comprises about 5,670 hectares (56.7 km2) in the Cherokee National Forest south of the Little Tennessee River in easternmost Monroe County, Tennessee. Principal drainages are Citico Creek and Doublecamp Creek. Rocks of the study area include greenschist-facies arkosic metasandstone, metagraywacke, slate, and metaconglomerate of the Great Smoky Group of late Precambrian age. Minor deposits of unconsolidated Quaternary alluvium locally mantle the bedrock. Deformation is shown by asymmetric and overturned folds and by several major faults. More than 500 sample s of soil, rock, and stream sediment were collected and analyzed for 31 major, minor, and trace elements by semiquantitative spectrographic, atomic absorption, and fire assay methods No significant metal anomalies were detected. Concentrations of Cu, Co, As, Pb, and Zn slightly higher than background are found within sulfidic parts of a distinctive stratigraphic unit composed of graphitic slate and metagraywacke. Pyrite and pyrrhotite are the chief sulfide minerals, with traces o f accessory sphalerite, chalcopyrite, galena, and arsenopyrite occurring as microscopic intergrowths. A reconnaissance ground radiometric survey and subsequent neutron activation analyses of selected radioactive rock samples show that the sulfidic parts of the graphitic slate unit have a relatively high content of Th and U, but are not potentially economic. No metallic mineral resources appear to exist within the Citico Creek Wilderness Study Area. Resources of slate, silica, and stone are present, but they display no special qualities to differentiate them from other such material throughout the region. Ceramic evaluation tests on selected samples of slate indicate that the slate would have only marginal use for structural clay products such as brick and tile. Minor sand and gravel deposits occur along a few streams but are present in larger quantities and are more easily recovered in other areas.

Tennessee↗
USGS1978

Distribution of rutile in metamorphic rocks and implications for placer deposits

Pelitic units in the eastern Great Smoky Mountains of the North Carolina Blue Ridge contain rutile grains only in kyanite and higher zones. Adjacent non-pelitic rocks do not contain rutile at kyanite grade but commonly contain sphene. Detrital rutile breaks down at metamorphic grades lower than those at which metamorphic rutile forms. Similarly, pelitic rocks in southeastern Connecticut contain rutile grains above, but not below, the sillimanite isograd. Most non-pelitic rocks there contain rutile only in the hypersthene zone. The slight difference in behavior of rutile in the two terranes is attributed primarily to a slight difference in calcium content of the pelites. In both areas, rutile commonly appears first as inclusions in garnet. Geologic maps showing metamorphic and stratigraphic or compositional information should be useful as prospecting tools for placer deposits. A variety of rocks at granulite facies and pelitic rocks of the upper amphibolite facies contain rutile and these could provide an extensive source for rutile in rutile placer deposits. ?? 1978 Springer-Verlag.

Mineralium Deposita↗
USGS1974

Geologic map of the Gbanka Quadrangle, Liberia

As part of a program undertaken cooperatively by the Liberian Geological Survey (LGS) and the U. S. Geological Survey (USGS), under the sponsorship of the Government of Liberia and the Agency for International Development, U. S. Department of State, Liberia was mapped by geologic and geophysical methods during the period 1965 to 1972. The resulting geologic and geophysical maps are published in ten folios, each covering one quadrangle (see index map).

Gbanka Quadrangle↗