Publications
Filter Total Items: 1147
An 8700 year paleoclimate reconstruction from the southern Maya lowlands
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 followed b
Authors
David B. Wahl, Roger Byrne, Lysanna Anderson
By
Energy and Minerals Mission Area, Climate Research and Development Program, Energy Resources Program, Groundwater and Streamflow Information Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geology, Minerals, Energy, and Geophysics Science Center, Geosciences and Environmental Change Science Center
MTpy: A Python toolbox for magnetotellurics
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 call standard
Authors
Lars Krieger, Jared R. Peacock
A geologic and mineral exploration spatial database for the Stillwater Complex, Montana
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 reserves f
Authors
Michael L. Zientek, Heather L. Parks
Evidence for large-magnitude, post-Eocene extension in the northern Shoshone Range, Nevada, and its implications for Carlin-type gold deposits in the lower plate of the Roberts Mountains allochthon
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 west-dippi
Authors
Joseph Colgan, Christopher D. Henry, David John
By
Energy and Minerals Mission Area, Energy Resources Program, Groundwater and Streamflow Information Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Geology, Minerals, Energy, and Geophysics Science Center, Geology, Geophysics, and Geochemistry Science Center
Evidence for a marine incursion along the lower Colorado River corridor
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 biofacies of th
Authors
Kristin McDougall, Adriana Yanet Miranda Martínez
Detecting thermally driven cyclic deformation of an exfoliation sheet with lidar and radar
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 ground-based r
Authors
Brian D. Collins, Greg M. Stock
Sediment-hosted stratabound copper assessment of the Neoproterozoic Roan Group, central African copperbelt, Katanga Basin, Democratic Republic of the Congo and Zambia
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 greater than
Authors
Michael L. Zientek, James D. Bliss, David W. Broughton, Michael Christie, Paul Denning, Timothy S. Hayes, Murray W. Hitzman, John D. Horton, Susan Frost-Killian, Douglas J. Jack, Sharad Master, Heather L. Parks, Cliff D. Taylor, Anna B. Wilson, Niki E. Wintzer, Jon Woodhead
A compilation of K-Ar-ages for southern California
The purpose of this report is to make available a large body of conventional K-Ar ages for granitic, volcanic, and metamorphic rocks collected in southern California. Although one interpretive map is included, the report consists primarily of a systematic listing, without discussion or interpretation, of published and unpublished ages that may be of value in future regional and other geologic stud
Authors
Fred K. Miller, Douglas M. Morton, Janet L. Morton, David M. Miller
Digital database of microfossil localities in Alameda and Contra Costa Counties, California
The eastern San Francisco Bay region (Contra Costa and Alameda Counties, California) is a geologically complex area divided by faults into a suite of tectonic blocks. Each block contains a unique stratigraphic sequence of Tertiary sediments that in most blocks unconformably overlie Mesozoic sediments. Age and environmental interpretations based on analysis of microfossil assemblages are key factor
Authors
Kristin McDougall, Debra L. Block
By
Energy and Minerals Mission Area, Energy Resources Program, Mineral Resources Program, National Laboratories Program, Science and Decisions Center, Groundwater and Streamflow Information Program, Geology, Minerals, Energy, and Geophysics Science Center, San Francisco Bay and Sacramento-San Joaquin Delta Estuary
High-resolution topography and geomorphology of select archeological sites in Glen Canyon National Recreation Area, Arizona
Along the Colorado River corridor between Glen Canyon Dam and Lees Ferry, Arizona, located some 25 km downstream from the dam, archaeological sites dating from 8,000 years before present through the modern era are located within and on top of fluvial and alluvial terraces of the prehistorically undammed river. These terraces are known to have undergone significant erosion and retreat since emplace
Authors
Brian D. Collins, Skye C. Corbett, Joel B. Sankey, Helen C. Fairley
Correlated patterns in hydrothermal plume distribution and apparent magmatic budget along 2500 km of the Southeast Indian Ridge
Multiple geological processes affect the distribution of hydrothermal venting along a mid-ocean ridge. Deciphering the role of a specific process is often frustrated by simultaneous changes in other influences. Here we take advantage of the almost constant spreading rate (65–71 mm/yr) along 2500 km of the Southeast Indian Ridge (SEIR) between 77°E and 99°E to examine the spatial density of hydroth
Authors
Edward Baker, Christophe Hémond, Anne Briais, Marcia Maia, Daniel S. Scheirer, Sharon L. Walker, Tingting Wang, Yongshun John Chen
Geologic framework of thermal springs, Black Canyon, Nevada and Arizona
Thermal springs in Black Canyon of the Colorado River, downstream of Hoover Dam, are important recreational, ecological, and scenic features of the Lake Mead National Recreation Area. This report presents the results from a U.S. Geological Survey study of the geologic framework of the springs. The study was conducted in cooperation with the National Park Service and funded by both the National Par
Authors
L. Sue Beard, Zachary W. Anderson, Tracey J. Felger, Gustav B. Seixas