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The Dacites Of The Washakie Needles, Bunsen Peak, And The Birch Hills, Wyoming, And Their Relationship To The Absaroka-Gallatin Volcanic Province, Linda Lou Anderson Love

Earth and Planetary Sciences ETDs

ABSTRACT

TI1e Washakie Needles, Bunsen Peak, and Birch Hills dacites are three of many plugs which intrude the Eocene flows and volcaniclastic rocks of the Absaroka-Gallatin volcanic province. The dacites contain phenocrysts of plagioclase (oligoclase to andesine), biotite, and resorbed quartz. The dacites of the Washakie Needles and Bunsen Peak also contain phenocrysts of hornblende. The rocks of Bunsen Peak and the Birch Hills have two feldspar phases (oligoclase to andesine and sanidine) and quartz in the groundmass. The Washakie Needles dacite groundmass is composed of one feldspar (andesine to anorthoclase) and quartz. The fission track ages of the dacites …

Gravity Survey Of The Mogolion Plateau Volcanic Province, Southwestern New Mexico., Douglas Hugh Krohn

Earth and Planetary Sciences ETDs

A regional gravity survey has been conducted over the Mogollon Plateau, a mid-Tertiary volcano-tectonic complex 125 km in diameter located in southwestern New Mexico. The complete Bouguer gravity map (3 milligal contour interval) shows gravity values ranging form -167 milligals over an outcrop of Precambrian rocks near Silver City, on the southern rim of the Plateau to -251 milligals over an alluvium filled graben east of Reserve, in the northwestern part of the Plateau giving a maximum relief of 84 milligals. Gravity data show that in general the Mogollon Plateau is an area of low density rocks: gravity values within …

Geology And Ore Deposits Of The Southwest Nacimiento Range, Sandoval County, New Mexico, Otto L. Schumacher

Earth and Planetary Sciences ETDs

The mapped area is in Sandoval County, New Mexico, 4 miles east of La Ventana. Precambrian rocks in the core of the Nacimiento uplift in this area consist mainly of quartz monzonite gneiss which has been intruded by granite. Hornblende schist xenoliths, zones of sheared quartz-plagioclase schistose gneiss, and mafic and leucocratic dike rocks are less abundant. Strata totaling 6200 feet, ranging from the Pennsylvanian Madera Formation through the Cretaceous Mancos Formation, are exposed in the area. Overlying the marine Madera Formation is 3400 feet of continental, marginal marine, and evaporite deposits consisting in ascending order of the Permian Abo, …

A Geochemical Study Of Distribution Of Elements In Ores And Limestones From New Jersey Zinc Mines, Hanover, New Mexico, Dasharatham Sayala

Earth and Planetary Sciences ETDs

Limestone samples (424) from both surface and subsurface horizons in the New Jersey Zinc mines at Hanover have been analyzed by atomic absorption spectrophotometry for Ag, Cd, Mn, Pb, Zn, Cu and Sn. The lead­zinc ore bodies, occurring in Paleozoic limestones are a typical example of hydrothermal deposits; and are related to the Hanover intrusive. The distribution of trace elements in surface limestones was mainly due to primary dispersion, partly due to secondary dispersion. The depth of ore mineralization, concentration of element in ore solutions, porosity of limestones, diffusion coefficients of element, and the chemical nature of elements in the …

Structural Geology Of The Northern Part Of The East Helena Quadrangle, Lewis And Clark County, Montana., Jon A. Durham

Earth and Planetary Sciences ETDs

The map-area is located along the northwest flank of the Big Belt Mountains, Montana and includes the Eldorado thrust which marks the zone of frontal breakthrough where thrusts of the Cordilleran foldbelt are in contact with the Rocky Mountain foreland. Sedimentary rocks range in age from Precambrian to Cretaceous. Two formations of the Precambrian Belt Series, the Greyson Shale (Oldest) and Spokane Shale are present. Overlaying the Spokane Shale are five formations of the Cambrian; Flathead Quartzite (oldest), Wolsey Shale, Meagher Limestone, Park Shale, and Pilgrim Limestone. Their total aggregate thickness is about 1200 feet.