Publications

A study is made of the relationships between geomagnetic and geoelectric field variation, Earth-surface impedance, and operational interference (anomalies) experienced on electric-power systems across the contiguous United States during the March 13-14, 1989 magnetic storm. For this, a 1-minute-resolution sequence of geomagnetic field maps is constructed from magnetometer time series...

Stakeholders need scientific data, analysis, and predictions of how drought the will impact the Colorado River Basin in a format that is continuously updated, intuitive, and easily accessible. The Colorado River Basin Actionable and Strategic Integrated Science and Technology Pilot Project was formed to demonstrate the effectiveness of addressing complex problems through stakeholder...

Hydrothermal explosions are significant potential hazards in Yellowstone National Park, Wyoming, USA. The northern Yellowstone Lake area hosts the three largest hydrothermal explosion craters known on Earth empowered by the highest heat flow values in Yellowstone and active seismicity and deformation. Geological and geochemical studies of eighteen sublacustrine cores provide the first...

Although carbonatites are the primary source of the world’s rare earth elements (REEs), the processes responsible for ore-grade REE enrichment in carbonatites are still poorly understood. In this study, we present a petrologic, geochemical, and isotopic evaluation of the Elk Creek carbonatite in southeast Nebraska to constrain the origin of REE mineralization. The Elk Creek carbonatite...

Erebus volcano, Antarctica, with its persistent phonolite lava lake, is a classic example of an evolved, CO2-rich rift volcano. Seismic studies provide limited images of the magmatic system. Here we show using magnetotelluric data that a steep, melt-related conduit of low electrical resistivity originating in the upper mantle undergoes pronounced lateral re-orientation in the deep crust...

Permafrost degradation is rapidly increasing in response to a warming Arctic climate, altering landscapes and damaging critical infrastructure. Solutions for monitoring permafrost thaw dynamics are essential to understand biogeochemical feedbacks as well as to issue warnings for hazardous geotechnical conditions. We investigate the feasibility of permafrost monitoring using permanently...

An airborne electromagnetic survey west of the Poso Creek oil field, located in the southeastern San Joaquin Valley, California, was flown in October 2016 to improve understanding of the hydrogeologic setting and the distribution of groundwater salinity in the area. The airborne electromagnetic data were used to develop resistivity models of the subsurface, where the mean depth of...

The clean energy transition will require a vast increase in metal supply, yet new mineral deposit discoveries are declining, due in part to challenges associated with exploring under sedimentary and volcanic cover. Recently, several case studies have demonstrated links between lithospheric electrical conductors imaged using magnetotelluric (MT) data and mineral deposits, notably Iron...

Bedrock property quantification is critical for predicting the hydrological response of watersheds to climate disturbances. Estimating bedrock hydraulic properties over watershed scales is inherently difficult, particularly in fracture-dominated regions. Our analysis tests the covariability of above- and belowground features on a watershed scale, by linking borehole geophysical data...

No abstract available.

Over the past ~30 years, hyperspectral remote sensing of chemical variations in white mica have proven to be useful for ore deposit studies in a range of deposit types. To better understand mineral deposits and to guide spectrometer design, this contribution reviews relevant papers from the fields of remote sensing, spectroscopy, and geology that have utilized spectral changes caused by...

The western North American Great Basin's Carlin-type deposits represent the largest accumulation of gold in the Northern Hemisphere. The controversy over their origins echoes the debate between Neptunists and Plutonists at the birth of modern geology: were the causative processes meteoric or magmatic? Sulfur isotopes have long been considered key to decoding metal cycling in the Earth's...