Late Miocene to Pleistocene source to sink record of exhumation and sediment routing in the Gulf of Alaska from detrital zircon fission-track and U-Pb double dating
Nathaniel Bootes, Eva Enkelmann, Richard O. Lease
2019, Tectonics (38) 2703-2726
We investigate the late Miocene‐Pleistocene offshore sedimentary record of the Yakutat microplate to evaluate the spatial and temporal variations in rock exhumation and sediment routing patterns at the heavily glaciated and actively converging plate boundary in southeast Alaska. We present 1,456 new fission track ages and 1,372...
Differentiating anthropogenic and natural sources of uranium by geochemical fingerprinting of groundwater at the Homestake Uranium Mill, Milan, New Mexico, USA
Johanna Blake, Philip Harte, Kent Becher
2019, Environmental Earth Sciences (78)
A multiparameter geochemical-isotopic fingerprinting approach was used to differentiate natural and anthropogenic signatures of uranium contamination near the Homestake uranium mill site (Site), near Milan, New Mexico, USA. The Site consists of two tailings piles from milling operations and groundwater contamination from these tailings have been noted. The Site lies...
The antiquity of the Sahara Desert: New evidence from the mineralogy and geochemistry of Pliocene paleosols on the Canary Islands, Spain
Daniel R. Muhs, Joaquin Meco, James R. Budahn, Gary L. Skipp, Juan F. Betancort, Alejandro Lomoschitz
2019, Palaeogeography, Palaeoclimatology, Palaeoecology (533)
The Sahara is the largest warm desert in the world, but its age has been controversial, with estimates ranging from Miocene to Holocene. Mineralogical and geochemical data show that paleosols of Pliocene to mid-Pleistocene age on Fuerteventura and Gran Canaria in the Canary Islands have developed in part from inputs...
Petrologic and mineral physics database for use with the U.S. Geological Survey National Crustal Model
Theron Sowers, Oliver S. Boyd
2019, Open-File Report 2019-1035
We present a petrologic and mineral physics database as part of the U.S. Geological Survey National Crustal Model (NCM). Each of 209 geologic units, 134 of which are currently part of the geologic framework within the NCM, was assigned a mineralogical composition according to generalized classifications with some refinement for...
Enhanced landslide mobility by basal liquefaction: the 2014 SR530 (Oso), Washington landslide
Brian D. Collins, Mark E. Reid
2019, Geological Society of America Bulletin (132) 451-476
Landslide mobility can vastly amplify the consequences of slope failure. As a compelling example, the March 22, 2014 landslide near Oso, Washington (USA) was particularly devastating, traveling across a 1-km+ wide river valley, killing 43 people, destroying dozens of homes, and temporarily closing a well-traveled highway. To resolve causes...
Ten-million years of activity within the Eastern California Shear Zone from U-Pb dating of fault-zone opal
Perach Nuriel, David M. Miller, Kevin M. Schmidt, Matthew A. Coble, Kate Maher
2019, Earth and Planetary Science Letters (521) 37-45
Reconstructions of long-term fault activity are essential for understanding both the mechanisms controlling fault behavior and accurate earthquake hazard assessments. Increasing evidence for temporal variations in strain accumulation suggests non-uniform strain rates over a range of historic to geologic timescales. The paucity of long-term records of fault activity has limited...
Benthic foraminiferal biotic events related to the Paleocene–Eocene Thermal Maximum along the California Margin
Kristin McDougall-Reid, Cedric M John
2019, Marine Micropaleontology (150)
The faunal expression of the Paleocene-Eocene Thermal Maximum (PETM) is well documented in deep-sea sediments. However, few studies have examined continental margin sections, especially active margins. The Moreno and Lodo formations, Central California, were deposited along the eastern margin of a north-south trending forearc basin on the convergent margin of...
Problems of Large Spatial Databases
E. Lynn Usery
2019, Book chapter, Geographic Information Science & Technology Body of Knowledge
Large spatial databases often labeled as geospatial big data exceed the capacity of commonly used computing systems as a result of data volume, variety, velocity, and veracity. Additional problems also labeled with V’s are cited, but the four primary ones are the most problematic and focus of this chapter (Li...
Dam effects on bedload transport on the upper Santa Ana River, California, and implications for native fish habitat
Scott Wright, J Toby Minear
2019, River Research and Applications 1-14
Dams disrupt the flow of water and sediment and thus have the potential to affect the downstream geomorphic characteristics of a river. Though there are some well‐known and common geomorphic responses to dams, such as bed armouring, the response downstream from any particular dam is dependent...
Assessment of coal mine methane (CMM) and abandoned mine methane (AMM) resource potential of longwall mine panels: example from Northern Appalachian Basin, USA
C. Ozgen Karacan, Peter D. Warwick
2019, International Journal of Coal Geology (208) 37-53
"Coal mine methane (CMM) and abandoned mine methane (AMM), are by-products of underground coal mining. The quantity and the emission rate of CMM and AMM may vary depending on the type of mine, gas content of the mined coal seam, and gas sourced from strata and coal beds in overlying...
Relaxation response of critically stressed macroscale surficial rock sheets
Brian D. Collins, Greg M. Stock, Martha-Cary Eppes
2019, Rock Mechanics and Rock Engineering (52) 5013-5023
Rock environments both underground and on Earth’s surface show indications of energetic macroscale fracture. In tunnels and excavations, these manifest as rockbursts—energetic explosions of rock that can damage engineering projects, and may pose ongoing financial and safety risk as rock stresses adjust during post-failure relaxation. In...
Postfire population dynamics of a fire-dependent cypress
Teresa J. Brennan, Jon Keeley
2019, Plant Ecology (220) 605-617
Tecate cypress (Hesperocyparis forbesii) is a rare species restricted to four metapopulations in southern California, USA and a few isolated stands in northern Baja California, Mexico. It is a closed-cone, fire-dependent tree of conservation concern due to an increase in human-caused wildfires that have shortened the interval between fires in...
Fault initiation in serpentinite
Benjamin L. Melosh
2019, Geochemistry, Geophysics, Geosystems (20) 2626-2646
Serpentinite fault rheology is fundamental to tectonic and earthquake processes, yet links between deformation textures and strength evolution during fault initiation are poorly constrained. Here I present field and petrographic microstructural observations of unsheared and sheared serpentinite that demonstrate a progression of fault development. I compliment observations with a clast...
New geochemical evidence for the origin of North America's largest dune field, the Nebraska Sand Hills, central Great Plains, USA
Daniel R. Muhs, James R. Budahn
2019, Geomorphology (332) 188-212
The Nebraska Sand Hills region is the largest dune field in North America and has diverse aeolian landforms. It has been active during both the late Pleistocene and late Holocene. Despite decades of study, the source of sediment for this large sand sea is still controversial. Here we report new trace element compositions of aeolian sand that are compared to four hypothesized sediment sources, Tertiary rocks of...
China’s domestic and foreign influence in the global cobalt supply chain
Andrew L. Gulley, Erin McCullough, Kim Shedd
2019, Resources Policy (62) 317-323
In addition to increasing interest in the supply risk of minerals produced in China, there is also concern that China’s efforts to mitigate mineral supply risk—through foreign direct investment—may limit mineral availability for other countries in the short-term (due to production capacity constraints). However, little is publicly known about the...
Alaska Shorebird Conservation Plan, Version III
Daniel R. Ruthrauff
2019, Book
In recognition of declines among perhaps half of Alaska’s breeding shorebirds, ongoing or emerging threats to shorebirds and their habitats, and considerable knowledge of Alaska’s shorebirds acquired over the past decade, the Alaska Shorebird Group decided that the Alaska Shorebird Conservation Plan was due for updates. Similar to Version II...
Three-dimensional basin and fault structure from a detailed seismic velocity model of Coachella Valley, Southern California
Rasheed Ajala, Patricia Persaud, Joann M. Stock, Gary S. Fuis, John A. Hole, Mark Goldman, Daniel S. Scheirer
2019, Journal of Geophysical Research (124) 4728-4750
The Coachella Valley in the northern Salton Trough is known to produce destructive earthquakes, making it a high seismic hazard area. Knowledge of the seismic velocity structure and geometry of the sedimentary basins and fault zones is required to improve earthquake hazard estimates in this region. We simultaneously inverted first...
Bioavailable iron production in airborne mineral dust: Controls by chemical composition and solar flux
Eshani Hettiarachchi, Richard L. Reynolds, Harland L. Goldstein, Bruce M. Moskowitz, Gayan Rubasinghege
2019, Atmospheric Environment (205) 90-102
A large part of oceanic biological production is limited by the scarcity of dissolved iron. Mineral dust aerosol, processed under acidic atmospheric conditions, is the primary natural source of bioavailable iron to oceanic life. However,...
Geospatial data mining for digital raster mapping
Bruce K. Wylie, Neal J. Pastick, Joshua J. Picotte, Carol Deering
2019, GIScience and Remote Sensing (56) 406-429
We performed an in-depth literature survey to identify the most popular data mining approaches that have been applied for raster mapping of ecological parameters through the use of Geographic Information Systems (GIS) and remotely sensed data. Popular data mining approaches included decision trees or “data mining” trees which consist of...
Exploring ends of eras in the eastern Mojave Desert: The road log
David M. Miller, G.A. Spaulding, R.E. Reynolds, James Calzia, M.E. Wells, Robert J. Fleck, S. Baltzer
2019, Conference Paper
No abstract available. ...
The MTPy software package for magnetotelluric data analysis and visualisation
Alison Kirkby, Fei Zhang, Jared R. Peacock, Rakib Hassan, Jingming Duan
2019, Journal of Open Source Software (4) 1358-1364
The magnetotelluric (MT) method is increasingly being applied to a wide variety of geoscience problems. However, the software available for MT data analysis and interpretation is still very limited in comparison to many of the more mature geophysical methods such as the gravity, magnetic or seismic reflection methods. MTPy is an open source...
Tectono-magmatic evolution of porphyry belts in the central Tethys region of Turkey, the Caucasus, Iran, western Pakistan, and southern Afghanistan
Lukas Zurcher, Arthur A. Bookstrom, Jane M. Hammarstrom, John C. Mars, Stephen Ludington, Michael L. Zientek, Pamela Dunlap, John Wallis
2019, Ore Geology Reviews (111)
Exploration in the central Tethys region of Turkey, Armenia, Azerbaijan, Georgia, Iran, and western Pakistan has led to the identification of the giant Reko Diq (24 Mt Cu and 1300 t...
Geochemistry of a thermally immature Eagle Ford Group drill core in central Texas
Katherine L. French, Justin E. Birdwell, Katherine J. Whidden
2019, Organic Geochemistry (131) 19-33
The Upper Cretaceous Eagle Ford Group displays significant lateral and vertical geochemical variability. Much of the work on the Eagle Ford Group has been focused southwest of the San Marcos arch. To more fully characterize the Eagle Ford across the entire region, a thermally immature drill core was acquired...
Widespread global peatland establishment and persistence over the last 130,000 y
Claire C. Treat, Thomas Kleinen, Nils Broothaerts , April S. Dalton, Rene Dommain, Thomas A. Douglas, Judith Z. Drexler, Sarah A Finkelstein, Guido Grosse, Geoffrey Hope, Jack Hutchings, Miriam C. Jones, Peter Kuhry, Terri Lacourse, Outi Lahteenoja, Julie Loisel, Bastiaan Notebaert, Richard Payne, Dorothy M. Peteet, A. Britta K. Sannel, Jonathan M. Stelling, Jens Strauss, Graeme T. Swindles, Julie Talbot, Charles Tarnocai, Gert Verstraeten, Christopher J. Williams , Zhengyu Xia, Zicheng Yu, Minna Valiranta, Martina Hattestrand, Helena Alexanderson, Victor Brovkin
2019, PNAS (116) 4822-4827
Glacial−interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks...
Age of the dacite of Sunset Amphitheater, a voluminous Pleistocene tephra from Mount Rainier (USA), and implications for Cascade glacial stratigraphy
Thomas W. Sisson, Axel K. Schmitt, Martin Danisik, Andrew T. Calvert, Napoleon Pempena, Chun-Yuan Huang, Chuan-Chou Shen
2019, Journal of Volcanology and Geothermal Research (376) 27-43
The dacite of Sunset Amphitheater, Mount Rainier (USA), illustrates the difficulties in establishing accurate ages of Pleistocene tephra eruptions. Nearly uniform whole-rock, glass,...
