Publications

The late Cenozoic stratigraphic and tectonic history of the Santa Clara Valley illustrates the dynamic nature of the North American–Pacific plate boundary and its effect on basin and landscape development. Prior to early Miocene time, the area that became Santa Clara Valley consisted of eroding Franciscan complex basement structurally interleaved in places with Coast Range ophiolite and...

Brittle shear zones/fault zones are usually defined by curved brittle P-planes bound by usually straight Y-planes. These shears may affect as a narrow zone within the rock bodies. Brittle sheared lenses of rocks vary in geometry, and the P-planes may curve only near the Y-planes. Fault gouge zones sometimes contain P-planes that help to deduce the shear sense. Fault planes/Y-planes may...

This study, covering the Bureau of Land Management (BLM) Central Yukon Planning Area (CYPA), Alaska, was prepared to aid BLM mineral resource management planning. Estimated mineral resource potential and certainty are mapped for six selected mineral deposit groups: (1) rare earth element (REE) deposits associated with peralkaline to carbonatitic intrusive igneous rocks, (2) placer and...

The Susitna basin is a poorly-understood Cenozoic successor basin immediately north of Cook Inlet in south-central Alaska (Kirschner, 1994). The basin is bounded by the Castle Mountain fault and Cook Inlet basin on the south, the Talkeetna Mountains on the east, the Alaska Range on the north, and the Alaska–Aleutian Range on the west (fig. 2-1). The Cenozoic fill of the basin includes...

The composite Sunrise Butte pluton, in the central part of the Blue Mountains Province, northeastern Oregon, preserves a record of subduction-related magmatism, arc-arc collision, crustal thickening, and deep-crustal anatexis. The earliest phase of the pluton (Desolation Creek unit) was generated in a subduction zone environment, as the oceanic lithosphere between the Wallowa and Olds...

No abstract available.

Truncorotalia crassaformis has been identified in Pliocene-Holocene assemblages globally but there has been little analysis of specimens from its type locality at Lomita Quarry, California. This has led to confusion about some diagnostic criteria, particularly the presence of a peripheral keel. To better understand variation specimens are studied from the type locality (Pleistocene, c...

Three ore deposits databases from previous studies were evaluated and combined with new known mineral occurrences into one database, which can now be used to manage information about the known mineral occurrences of Mauritania. The Microsoft Access 2010 database opens with the list of tables and forms held within the database and a Switchboard control panel from which to easily navigate...

Over the past 25 years, luminescence dating has become a key tool for dating sediments of interest in paleoseismic research. The data obtained from luminescence dating has been used to determine timing of fault displacement, calculate slip rates, and estimate earthquake recurrence intervals. The flexibility of luminescence is a key complement to other chronometers such as radiocarbon or...

This paper describes a framework to conduct a “metal-recovery feasibility assessment” for mining influenced water (MIW) and associated treatment sludge. There are multiple considerations in such a determination, including the geologic/geochemical feasibility, market feasibility, technical feasibility, economic feasibility, and administrative feasibility. Each of these considerations...

The Alaska Division of Geological & Geophysical Surveys (DGGS) conducted fieldwork during the summer of 2014 in the Susitna basin as part of an ongoing evaluation of the hydrocarbon potential of frontier basins, particularly those near the Railbelt region (for example, Decker and others, 2013; Gillis and others, 2013). Topical studies associated with this recent work include sedimentary...

The Upper Jurassic and Lower Cretaceous part of the Brookian sequence of northern Alaska consists of syntectonic deposits shed from the north-directed, early Brookian orogenic belt. We employ sandstone petrography, detrital zircon U-Pb age analysis, and zircon fission-track double-dating methods to investigate these deposits in a succession of thin regional thrust sheets in the western...