Publications

Initial in situ sulfur (S) isotope measurements of the Martian bedrock in Gale Crater have revealed an unexpectedly wide range of δ34S values (−47 to +28%). Generally, it is unclear what processes could have contributed to these large isotope fractionations. Therefore, we studied S sources and aqueous SO2−4 cycling in the Valles Caldera volcanic complex, New Mexico to better understand S...

The southwest Guizhou Province, China, contains numerous sediment-hosted Au deposits with Au reserves greater than 700 tonnes. To date, the source of ore fluids that formed the Guizhou sediment-hosted Au deposits is controversial, hampering the formulation of genetic models. In this study, we selected the Shuiyindong and Jinfeng Au deposits, the largest strata-bound and fault-controlled...

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...

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...

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...

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...

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...

We present numeric grids containing estimates of the thickness of unconsolidated sediments and depth to the pre-Cenozoic basement for the western United States. Values for these grids were combined and integrated from previous studies or derived directly from gravity analyses. The grids are provided with 1-kilometer grid-node spacing in ScienceBase (https://www.sciencebase.gov). These...

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...

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...

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...

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...