Publications

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 Stillwater Complex is a Neoarchean, ultramafic to mafic layered intrusion exposed in the Beartooth Mountains in south-central Montana. This igneous intrusion contains magmatic mineralization that is variably enriched in strategic and critical commodities such as chromium, nickel, and the platinum-group elements. One deposit, the J-M Reef, is the sole source of primary production and...

A physical property inversion approach based on the use of 3D (or 2D) Fourier transforms to calculate the potential-field within a 3D (or 2D) volume from a known physical property distribution within the volume is described. Topographic surfaces and observations at arbitrary locations are easily accommodated. The limitations of the approach and applications to real data are considered.

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...

Sampling and Monitoring for the Mine Life Cycle provides an overview of sampling for environmental purposes and monitoring of environmentally relevant variables at mining sites. It focuses on environmental sampling and monitoring of surface water, and also considers groundwater, process water streams, rock, soil, and other media including air and biological organisms. The handbook...

Full appropriation of tributary streamflow during summer, a growing population, and agricultural needs are increasing the demand for groundwater in the Willamette Basin. Greater groundwater use could diminish streamflow and create seasonal and long-term declines in groundwater levels. The U.S. Geological Survey (USGS) and the Oregon Water Resources Department (OWRD) cooperated in a study...

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...

Water temperature and streamflow intermittency are critical parameters influencing aquatic ecosystem health. Low-cost temperature loggers have made continuous water temperature monitoring relatively simple but determining streamflow timing and intermittency using temperature data alone requires significant and subjective data interpretation. Electrical resistance (ER) sensors have...

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...

This study estimates the location, quality, and quantity of undiscovered copper in stratabound deposits within the Neoproterozoic Roan Group of the Katanga Basin in the Democratic Republic of the Congo and Zambia. The study area encompasses the Central African Copperbelt, the greatest sediment-hosted copper-cobalt province in the world, containing 152 million metric tons of copper in...