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V.E. Langenheim

Publications and source records attributed to V.E. Langenheim.

At least 55 records · Page 3Linked to original sources
USGS1999

Thickness of Cenozoic Deposits of Yucca Flat Inferred from Gravity Data, Nevada Test Site, Nevada

The basin-basement contact for Yucca Flat was modeled using isostatic gravity data, a linear density-depth function for the basin deposits, and drill-hole constraints to produce a digital database of both the depth to basement and the gravitational anomaly associated with the basement rocks. The model predicts a depth of roughly 2,500 m in the deepest, southern part of the basin. The model shows offsets in the basement rocks along both the Carpetbag and Yucca faults. The basement rocks of Yucca Flat have a higher gravity anomaly west of the N-S trending Carpetbag fault, suggesting higher density rocks on the west side of the valley.

Open-File Report↗
USGS1999

Inversion of gravity data to define the pre-Tertiary surface and regional structures possibly influencing ground-water flow in the Pahute Mesa-Oasis Valley region, Nye County, Nevada

A three-dimensional inversion of gravity data from the Pahute Mesa–Oasis Valley region reveals a topographically complex pre-Tertiary basement surface. Beneath Pahute Mesa, the thickness of the Tertiary volcanic deposits may exceed 5 km within the Silent Canyon caldera complex. South of Pahute Mesa in Oasis Valley, basement is shallower (< 1 km) but between this valley and the Timber Mountain caldera complex is a basin that probably represents, in part, a moat related to the Timber Mountain caldera complex. Of particular interest is a NE-trending lineament, named here the Thirsty Canyon lineament (TCL), separating terranes at significantly different elevations. Southeast of the TCL, a highly undulating basement surface descends deeply into several calderas, whereas NW of the TCL basement is relatively flat and shallow. Because as many as four calderas seem to abruptly terminate at the TCL, the TCL may reflect a major buried fault zone, which influenced caldera growth. This inferred Thirsty Canyon fault zone and several EW basement ridges in the derived 3-dimensional basin thickness model may influence the flow of ground water from the Pahute Mesa region to Oasis Valley.

Nevada↗
USGS1998

Implications of seismic reflection and potential field geophysical data on the structural framework of the Yucca Mountain-Crater Flat region, Nevada

Seismic reflection and gravity profiles collected across Yucca Mountain, Nevada, together with geologic data, provide evidence against proposed active detachment faults at shallow depth along the pre-Tertiary–Tertiary contact beneath this potential repository for high-level nuclear waste. The new geophysical data show that the inferred pre-Tertiary–Tertiary contact is offset by moderate- to high-angle faults beneath Crater Flat and Yucca Mountain, and thus this shallow surface cannot represent an active detachment surface. Deeper, low-angle detachment surface(s) within Proterozoic-Paleozoic bedrock cannot be ruled out by our geophysical data, but are inconsistent with other geologic and geophysical observations in this vicinity. Beneath Crater Flat, the base of the seismogenic crust at 12 km depth is close to the top of the reflective (ductile) lower crust at 14 to 15 km depth, where brittle fault motions in the upper crust may be converted to pure shear in the ductile lower crust. Thus, our preferred interpretation of these geophysical data is that moderate- to high-angle faults extend to 12–15-km depth beneath Yucca Mountain and Crater Flat, with only modest changes in dip.

Nevada↗
USGS1995

Gravity of the New Madrid seismic zone; a preliminary study

In the winter of 1811-12, three of the largest historic earthquakes in the United States occurred near New Madrid, Mo. Seismicity continues to the present day throughout a tightly clustered pattern of epicenters centered on the bootheel of Missouri, including parts of northeastern Arkansas, northwestern Tennessee, western Kentucky, and southern Illinois. In 1990, the New Madrid seismic zone/Central United States became the first seismically active region east of the Rocky Mountains to be designated a priority research area within the National Earthquake Hazards Reduction Program (NEHRP). This Professional Paper is a collection of papers, some published separately, presenting results of the newly intensified research program in this area. Major components of this research program include tectonic framework studies, seismicity and deformation monitoring and modeling, improved seismic hazard and risk assessments, and cooperative hazard mitigation studies.

Professional Paper↗
USGS1995

Geophysical expression of the Ghost Dance fault, Yucca Mountain, Nevada

Gravity and ground magnetic data collected along surveyed traverses across Antler and Live Yucca Ridges, on the eastern flank of Yucca Mountain, Nevada, reveal small-scale faulting associated with the Ghost Dance and possibly other faults. These studies are part of an effort to evaluate faulting in the vicinity of a potential nuclear waste repository at Yucca Mountain.

Conference Paper↗