Publications

Aeromagnetic data help provide the underpinnings of a hydrogeologic framework for Fort Irwin by locating inferred structural features or grain that influence groundwater flow. Magnetization boundaries defined by horizontal-gradient analyses coincide locally with Cenozoic faults and can be used to extend these faults beneath cover. These boundaries also highlight the structural grain...

Reconnaissance field visits and rock sampling were conducted at eight geologically selected locations within Mesozoic rocks on the eastern flank of the Rutbah Uplift, Anbar Province, western Iraq, in an attempt to determine if these rocks have been affected by a Mississippi Valley-Type (MVT) lead-zinc mineralizing system. Samples subsequently were studied by carbonate mineral staining...

Geologic investigations of late Miocene–early Pliocene deposits in Mohave and Cottonwood valleys provide important insights into the early evolution of the lower Colorado River system. In the latest Miocene these valleys were separate depocenters; the floor of Cottonwood Valley was ∼200 m higher than the floor of Mohave Valley. When Colorado River water arrived from the north after 5.6...

This publication contains the complete results of U-Pb zircon age dating studies of sedimentary and metasedimentary units from northern and central Alaska that are discussed and interpreted in other reports by the author. Most of the U-Pb ages are of detrital zircons from sandstones, although U-Pb ages from igneous and sedimentary clasts from conglomerates in some of those same units are...

This report describes preliminary three-dimensional geostatistical modeling of a lava-flow aquifer system using a multiple-point geostatistical model. The purpose of this study is to provide a proof-of-concept for this modeling approach. An example of the method is demonstrated using a subset of borehole geologic data and aquifer test data from a portion of the Calico Hills Formation, a...

Damage to pavement and near-surface utility pipes, caused by the 17 October 1989, Loma Prieta earthquake, provides evidence for ground deformation in a 663 km2 area near the southwest margin of the Santa Clara Valley, California (USA). A total of 1427 damage sites, collected from more than 30 sources, are concentrated in four zones, three of which lie near previously mapped faults. In...

Until recently, the rare-earth elements (REEs) were familiar to a relatively small number of people, such as chemists, geologists, specialized materials scientists, and engineers. In the 21st century, the REEs have gained visibility through many media outlets because of (1) the public has recognized the critical, specialized properties that REEs contribute to modern technology, as well...

Analysis of a sediment core from Lago Puerto Arturo, a closed basin lake in northern Peten, Guatemala, has provided an ∼8700 cal year record of climate change and human activity in the southern Maya lowlands. Stable isotope, magnetic susceptibility, and pollen analyses were used to reconstruct environmental change in the region. Results indicate a relatively wet early to middle Holocene...

We present the software package MTpy that allows handling, processing, and imaging of magnetotelluric (MT) data sets. Written in Python, the code is open source, containing sub-packages and modules for various tasks within the standard MT data processing and handling scheme. Besides the independent definition of classes and functions, MTpy provides wrappers and convenience scripts to...

The northern Shoshone and Toiyabe Ranges in north-central Nevada expose numerous areas of mineralized Paleozoic rock, including major Carlin-type gold deposits at Pipeline and Cortez. Paleozoic rocks in these areas were previously interpreted to have undergone negligible postmineralization extension and tilting, but here we present new data that suggest major post-Eocene extension along...

Foraminiferal assemblages in the stratigraphically lower part of the Bouse Formation in the Blythe Basin indicate marine conditions whereas assemblages in the upper part of the Bouse Formation indicate lacustrine conditions and suggest the presence of a saline lake. Benthic foraminiferal assemblages in the lower part of the Bouse Formation are similar to lagoonal and inner neritic...

Rock falls from steep, exfoliating cliffs are common in many landscapes. Of the many mechanisms known to trigger rock falls, thermally driven deformation is among the least quantified, despite potentially being a prevalent trigger due to its occurrence at all times of year. Here we present the results of a field-based monitoring program using instrumentation, ground-based lidar, and...