Geology topics
G.A. Nowlan
Publications and source records attributed to G.A. Nowlan.
Significance of gold and silver in drainage samples from the vicinity of the Baboquivari Peak Wilderness Study Area, Pima County, Arizona
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Analytical results and sample locality map of stream-sediment and panned-concentrate samples from the Baboquivari Peak Wilderness Study Area, Pima County, Arizona
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Maps showing water geochemistry of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee Counties, Colorado
This report presents results of geochemical studies carried out in June and July of 1982 in the Buffalo Peaks Wilderness Study Area, Colo. (see index map). Samples of water were collected from 84 streams and 18 springs draining the study area. Tabulations of the analyses and a sample locality map are in Ficklin and others (1984). The geochemistry of stream sediments and panned concentrates of the study area is in Nowlan and Gerstel (1985). The geology of the study area and vicinity is in Hedlund (1985). The mineral resource potential of the study area is described in Hedlund and others (1983). This report (1) assists in the assessment of the mineral resource potential of the Buffalo Peaks Wilderness Study Area; and (2) compares analyses of water samples with analyses of stream-sediment and panned-concentrate samples (Nowlan and Gerstel, 1985).
Analytical results and sample locality maps for stream-sediment samples collected in the Sherbrooke 1° x 2° quadrangle, Maine, New Hampshire, and Vermont
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Analytical results and sample-locality map for stream-sediment samples from streams draining the Attean Quartz Monzonite and vicinity, Somerset and Franklin Counties, Maine
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Analytical results and sample locality map for stream-sediment and panned-concentrate samples from The Pinnacles Addition to the River of No Return Wilderness, Valley County, Idaho
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Origin of concretionary Mn-Fe-oxides in stream sediments of Maine, U.S.A.
Studies of stream and sediment-pore waters largely explain the genesis of concretionary Mn-Fe-oxides in Maine. Waters of two small streams near Jackman, Maine, were studied in terms of pH, Eh, dissolved oxygen, dissolved organic carbon, dissolved Mn, total dissolved Fe, and ferrous and ferric Fe. Pyrite Creek has profuse concretions and coatings of Mn-Fe-oxides, whereas West Pyrite Creek has only sparse Mn-Fe-oxide stains. Pyrite Creek drains boggy terrain and West Pyrite Creek drains well-drained terrain. In West Pyrite Creek, stream and subjacent pore waters have chemical characteristics that do not differ greatly. However, dissolved Mn, ferrous Fe, dissolved oxygen, and in situ Eh measurements show that a steep Eh gradient exists between stream and subjacent pore waters of Pyrite Creek. The steep Eh gradient is manifested by the common zonation of coatings and stains on rocks in stream sediment. The bottom zone has no deposition of oxides, the middle zone is red and consists mostly of Fe-oxides, and the upper zone is black or dark-brown and consists of Mn-oxides with varying amounts of Fe-oxides. The zonation agrees with theoretical predictions of oxide stability as one moves from a reducing to an oxidizing environment. At locations where concretionary Mn-Fe-oxides form, pore waters are depleted of oxygen because of abundant decaying organic material in the stream sediment. The pore waters are charged with dissolved Mn and Fe because mechanically deposited Mn-Fe-oxides are remobilized due to the low-Eh conditions. Groundwaters also contribute dissolved Mn and Fe. Stream waters, on the other hand, are oxygenated and the high-Eh conditions result in low concentrations of dissolved Mn and Fe in stream waters because of the insolubility of Mn-Fe-oxides in high-Eh environments. Therefore, concretionary Mn-Fe-oxides form at the interface between pore and stream waters because Mn- and Fe-rich pore waters, which are undersaturated with respect to Mn-Fe-oxides, mix with oxygen-rich stream waters, which are saturated with respect to Mn-Fe-oxides. ?? 1983.
Mineral resource potential map of the Buffalo Peaks Wilderness Study Area, Lake, Park, and Chaffee Counties, Colorado
Under the provisions of the Wilderness Act (Public Law 88-577, September 3, 1964) and the Joint Conference Report on Senate Bill 4, 88th Congress, the U.S. Geological Survey and the U.S. Bureau of Mines have been conducting mineral surveys of wilderness and primitive areas. Areas officially designated as "wilderness," "wild," or "canoe" when the act was passed were incorporated into the National Wilderness Preservation System, and some of them are presently being studied. The act provided that areas under consideration for wilderness designation should be studied for suitability for incorporation into the Wilderness System. The mineral surveys constitute one aspect of the suitability studies. The act directs that the results of such surveys are to be made available to the public and be submitted to the President and the Congress. This report discusses the results of a mineral survey of the Buffalo Peaks Wilderness Study Area, Pike and San Isabel National Forests, Lake, Park, and Chaffee Counties, Colo. The area was established as a wilderness study area by Public Law 96-560, December 22, 1980.
Analyses of heavy-mineral-concentrate samples, east half of the Lewiston 1° x 2° quadrangle, Maine and New Hampshire
No abstract available.
Analytical results for 544 water samples collected in the Attean Quartz Monzonite in the vicinity of Jackman, Maine
Water samples were collected in the vicinity of Jackman, Maine as a part of the study of the relationship of dissolved constituents in water to the sediments subjacent to the water. Each sample was analyzed for specific conductance, alkalinity, acidity, pH, fluoride, chloride, sulfate, phosphate, nitrate, sodium, potassium, calcium, magnesium, and silica. Trace elements determined were copper, zinc, molybdenum, lead, iron, manganese, arsenic, cobalt, nickel, and strontium. The longitude and latitude of each sample location and a sample site map are included in the report as well as a table of the analytical results.
Guidelines for finding concretionary Mn-Fe oxides in streams
Concretionary Mn-Fe oxides in streams form at interfaces between oxidizing and reducing environments. A reducing environment produces waters high in dissolved Mn and Fe, and an oxidizing environment causes precipitation. Mineralogical, microprobe, and optical studies of concretionary Mn-Fe oxides may further our understanding of the role of Mn-Fe oxides in determining the trace-element geochemistry of stream sediments.