Publications
Products (journal articles, reports, fact sheets) authored by current and past scientists are listed below. Please check the USGS Pubs Warehouse for other USGS publications.
Filter Total Items: 1829
Timing and genesis of ore formation in the Qarachilar Cu-Mo-Au deposit, Ahar-Arasbaran metallogenic zone, NW Iran: Evidence from geology, fluid inclusions, O–S isotopes and Re–Os geochronology
In the Qarachilar Cu-Mo-Au deposit of the Ahar–Arasbaran metallogenic zone (AAMZ), northwest Iran, mineralization occurs as three quartz-sulfide veins that cut granodiorite-quartz monzodiorite rocks of the Qaradagh batholith (QDB). Ore formation can be divided into three stages, with chalcopyrite, molybdenite, and gold-bearing pyrite appearing mainly in the first two stages. The main wall-rock alt
Authors
Hossein Kouhestani, Mir Ali Asghar Mokhtari, Zhaoshan Chang, Holly J. Stein, Craig A. Johnson
Establishing chronologies for alluvial-fan sequences with analysis of high-resolution topographic data: San Luis Valley, Colorado, USA
On active alluvial fans, debris-flow deposits and frequent avulsions produce a rough topographic surface. As is the case in many initially rough landforms produced by catastrophic processes, the topography of alluvial fans is progressively smoothed, producing textural differences useful in establishing relative age criteria for fans. Here, we outline an approach for defining a quantitative, numeri
Authors
Samuel Johnstone, Adam M. Hudson, Sylvia Nicovich, Chester A. Ruleman, Robert M. Sare, Ren A. Thompson
Application of hydrologic-tracer techniques to the Casargiu adit and Rio Irvi (SW-Sardinia, Italy): Using enhanced natural attenuation to reduce extreme metal loads
Hydrologic tracer techniques were applied to Rio Irvi (SW Sardinia), a stream affected by mine drainage, allowing the calculation of stream discharge and metal loads and comparison to other streams. The calculated discharge showed a continuous increase from near 21.2 L/s to 29.1 L/s. Cumulative loads of mine-related constituents, including the Casargiu adit inflow, were large, with more than 9900
Authors
Giovanni De Giudici, Daniela Medas, Rosa Cidu, Pierfranco Lattanzi, Francesca Podda, Franco Frau, Nicola Rigonat, Claudia Pusceddu, Stefania Da Pelo, Patrizia Onnis, Pier Andrea Marras, Richard B. Wanty, Briant A. Kimball
Testing the potential role of brine reflux in the formation of sedimentary exhalative (Sedex) ore deposits
Sedimentary exhalative (sedex) ore deposits are the world’s largest Zn-Pb deposits. While the geologic processes that formed these deposits are generally well understood, the fundamental hydrologic processes that drove these massive hydrothermal systems remain an area of debate. We use numerical modeling to test an emerging hypothesis, supported by recent ore genesis research and sedex basin analy
Authors
Andrew H. Manning, Poul Emsbo
Igneous and detrital zircon U-Pb and Lu-Hf geochronology of the late Meso- to Neoproterozoic northwest Botswana rift: Maximum depositional age and provenance of the Ghanzi Group, Kalahari Copperbelt, Botswana and Namibia
New igneous and detrital zircon laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) U-Pb geochronology and Lu-Hf isotopic data are presented for the Mesoproterozoic Kgwebe Formation and the unconformably overlying Ghanzi Group in northwestern Botswana. The Makgabana Hills porphyritic rhyolite flow from the Ghanzi area yielded a U-Pb concordia age of 1085.5 ± 4.5 Ma and provides
Authors
Wesley S Hall, Murray Hitzman, Yvette D. Kuiper, Andrew R C Kylander-Clark, Christopher Holm-Denoma, Richard J. Moscati, Piret Plink-Bjorklund, Stephen M Enders
Depth to basement and thickness of unconsolidated sediments for the western United States—Initial estimates for layers of the U.S. Geological Survey National Crustal Model
We present numeric grids containing estimates of the thickness of unconsolidated sediments and depth to the pre-Cenozoicbasement for the western United States. Values for these grids were combined and integrated from previous studies or deriveddirectly from gravity analyses. The grids are provided with 1-kilometer grid-node spacing in ScienceBase (https://www.sciencebase.gov).These layers may be u
Authors
Anjana K. Shah, Oliver S. Boyd
Interpretation of low‐temperature thermochronometer ages from tilted normal fault blocks
Low‐temperature thermochronometry is widely used to measure the timing and rate of slip on normal faults. Rates are often derived from suites of footwall thermochronometer samples, but regression of age vs. structural depth fails to account for the trajectories of samples during fault slip. We demonstrate that in rotating fault blocks, regression of age‐depth data is susceptible to significant err
Authors
Samuel Johnstone, Joseph Colgan
Controls on submarine channel-modifying processes identified through morphometric scaling relationships
Submarine channels share morphological similarities with rivers, but observations from modern and ancient systems indicate they are formed under processes and controls unique to submarine settings. Morphologic characteristics of channels—e.g., width, depth, slope, and the relationships among them—can constrain interpretations of channel-forming processes. This work uses morphometric scaling relati
Authors
Lauren E. Shumaker, Zane R. Jobe, Samuel Johnstone, Luke A. Pettinga, Dingxin Cai, Jeremiah D. Moody
Crustal inheritance and a top-down control on arc magmatism at Mount St Helens
In a subduction zone, the volcanic arc marks the location where magma, generated via flux melting in the mantle wedge, migrates through the crust and erupts. While the location of deep magma broadly defines the arc position, here we argue that crustal structures, identified in geophysical data from the Washington Cascades magmatic arc, are equally important in controlling magma ascent and defining
Authors
Paul A. Bedrosian, Jared R. Peacock, Esteban Bowles-Martinez, Adam Schultz, Graham Hill
Rapid late Miocene surface uplift of the Central Anatolian Plateau margin
The Central Anatolian Plateau (CAP), Turkey, is bordered to its south by a steep mountain belt that emerged ∼8–7 Ma ago from the Mediterranean Sea. Knowledge of the onset, duration and rate of surface uplift and orographic barrier formation along the plateau margin is crucial for understanding the geodynamic drivers of plateau uplift. We present a new comprehensive data set that includes 12 40Ar/3
Authors
Maud J.M. Meijers, Gilles Y. Brocard, Michael A. Cosca, Tina Lüdecke, Christian Teyssier, Donna L. Whitney, Andreas Mulch
Mineralogy of uranium and thorium (R.J. Lauf)
As stated by the author in this 352-page book’s preface, the intention is to present “a systematic guide to uranium and thorium minerals and their occurrences for the serious student or mineral collector seeking to better understand the specimens in his or her collection.” A secondary purpose is to provide an up-to-date reference to the mineralogy of radioactive raw materials for the exploration g
Authors
Cliff D. Taylor
Quartz solubility in the H2O-NaCl system: A framework for understanding vein formation in porphyry copper deposits
Porphyry copper deposits consist of low-grade stockwork and disseminated sulfide zones that contain characteristic vein generations formed during the evolution of the magmatic-hydrothermal systems. The present contribution proposes an interpretive framework for the formation of porphyry veins that is based on quartz solubility calculations in the H2O-NaCl system at temperatures of 100° to 1,000°C
Authors
Thomas Monecke, Jochen Monecke, T James Reynolds, Subaru Tsuruoka, Mitchell M. Bennett, Wiley B Skewes, Richard M. Palin