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Geology topics

W. R. Miller

Publications and source records attributed to W. R. Miller.

At least 19 recordsLinked to original sources
USGS1997

Geochemical processes controlling uranium mobility in mine drainages

Comprehensive models of ore genesis incorporate metal sources, transport and concentration mechanisms, and preservation mechanisms. Analogous concepts apply to the problem of metal migration from mines, mine wastes, and mine tailings, including: the concentrations, mineralogical occurrence, and availability of metals in mineral deposits, host rocks, mine wastes, and tailings (the source); the mechanisms for metal mobilization and transport during weathering; the mechanisms for metal fixation and the permanence of the fixation. Similarly, undisturbed mineral deposits or alteration zones that are exposed at the Earth's surface may be natural sources from which metals can be solubilized during weathering. Uranium (U), a naturally-occurring radioactive element, may be present in mineral deposits in sufficient concentrations that in itself constitutes ore. It may also be present in ores of other metals at concentrations that exceed average crustal abundances. Any uranium that is not completely removed from these ores in the mining and milling process may be available for mobilization into ground or surface waters via the weathering and oxidation of solid tailings or mine waste piles. This chapter discusses the relative importance of various geochemical processes that control uranium mobility via weathering in both mined and unmined mineralized environments. The data presented in this paper focus on mined areas because the great extent of historic mining in the field areas examined for this study preclude extensive consideration of undisturbed areas.

Book chapter↗
USGS1990

Geology and geochemistry of epithermal precious metal vein systems in the intra-oceanic arcs of Palau and Yap, western Pacific

The Palau and Yap arcs are part of an intra-oceanic island-arc-trench system which separates the Pacific and Philippine plates in the western Pacific Ocean. The 350-km-long Palau arc consists of over 200 islands while the 400-km-long Yap arc located to the north has only four major islands exposed. Four of the largest islands in Palau are composed primarily of early Eocene to mid-Miocene volcanic rocks and the four islands comprising Yap contain only Miocene volcanic rocks. Basalt and basaltic andesites of the Babelthuap Formation are the oldest volcanic rocks in Palau and are characterized by high MgO, Ni and Cr and low TiO 2 and have a boninitic affinity. They form the central and southeastern parts of Babelthuap Island. Oligocene arc tholeiite flows having an age of 34–35.5 Ma comprise most of the three smaller volcanic islands in Palau and the western part of Babelthuap. The youngest volcanic rocks are dacitic intrusions having an age of 22.7–23.2 Ma. The Yap arc is unusual in that metamorphic rocks up to amphibolite grade form most of the islands. These are underlain by a melange composed of igneous and volcanic clasts as well as clasts from a dismembered copper-gold skarn deposit. Miocene volcanic rocks consisting of flows and volcaniclastic deposits overlie the melange and metamorphic complex.

Journal of Geochemical Exploration↗
USGS1990

Map showing distribution of gold in stream-sediment samples, Richfield 1° x 2° quadrangle, Utah

This map of the Richfield 1° x 2° quadrangle, Utah, shows the regional distribution of gold in the less-than-0.180-mm (minus-80-mesh) fraction of stream sediments. It is part of a folio of maps of the Richfield 1° x 2° quadrangle, Utah, prepared under the Conterminuous United States Mineral Assessment Program. Other published geochemical maps in this folio are listed in the Selected References of this report. The Richfield quadrangle is located in west-central Utah and includes the eastern part of the Pioche-Marysvale igneous and mineral belt, which extends from the vicinity of Pioche in southeastern Nevada, east-northeastward for 155 miles into central Utah. The western two-thirds of the Richfield quadrangle is part of the Basin and Range province, whereas the eastern third is part of the High Plateaus of Utah, a subprovince of the Colorado Plateau. Bedrock in the northern part of the Richfield quadrangle consists predominantly of Late Proterozoic and Paleozoic sedimentary strata that were thrust eastward during the Sevier orogeny in Cretaceous time onto an autochthon of Mesozoic sedimentary rocks located in the eastern part of the quadrangle. The southern part of the quadrangle is largely underlain by Oligocene and younger volcanic rocks and related intrusions. Extensional tectonism in late Cenozoic time broke the bedrock terrain into a series of north-trending fault blocks; the uplifted mountain areas were eroded to various degrees and the resulting debris was deposited in adjacent basins. Most of the mineral deposits in the Pioche-Marysvale mineral belt were formed as a result of igneous activity in the middle and late Cenozoic time. A more complete description of the geology and a mineral-resource appraisal of the Richfield quadrangle appears in Steven and Morris (1984 and 1987). The regional sampling program was designed to define broad geochemical patterns and trends that can be utilized along with geological and geophysical data to assess the mineral-resource potential for this quadrangle. Reconnaissance geochemical surveys are valuable tools in mineral exploration, especially when used in conjunction with data obtained from other earth science disciplines. Identifying specific exploration targets generally involves additional, more detailed investigations.

Utah↗