Earth and Atmospheric Sciences

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    Alkali feldspar dissolution and secondary mineral precipitation in batch systems: 3. Saturation states of product minerals and reaction paths
    (Elsevier, 2009-03-26) Lu, Peng; Zhu, Chen
    In order to evaluate the complex interplay between dissolution and precipitation reaction kinetics, we examined the hypothesis of partial equilibria between secondary mineral products and aqueous solutions in feldspar–water systems. Speciation and solubility geochemical modeling was used to compute the saturation indices (SI) for product minerals in batch feldspar dissolution experiments at elevated temperatures and pressures and to trace the reaction paths on activity–activity diagrams. The modeling results demonstrated: (1) the experimental aqueous solutions were supersaturated with respect to product minerals for almost the entire duration of the experiments; (2) the aqueous solution chemistry did not evolve along the phase boundaries but crossed the phase boundaries at oblique angles; and (3) the earlier precipitated product minerals did not dissolve but continued to precipitate even after the solution chemistry had evolved into the stability fields of minerals lower in the paragenesis sequence. These three lines of evidence signify that product mineral precipitation is a slow kinetic process and partial equilibria between aqueous solution and product minerals were not held. In contrast, the experimental evidences are consistent with the hypothesis of strong coupling of mineral dissolution/precipitation kinetics [e.g., Zhu C., Blum A. E. and Veblen D. R. (2004a) Feldspar dissolution rates and clay precipitation in the Navajo aquifer at Black Mesa, Arizona, USA. In Water–Rock Interaction (eds. R. B. Wanty and R. R. I. Seal). A.A. Balkema, Saratoga Springs, New York. pp. 895–899]. In all batch experiments examined, the time of congruent feldspar dissolution was short and supersaturation with respect to the product minerals was reached within a short period of time. The experimental system progressed from a dissolution driven regime to a precipitation limited regime in a short order. The results of this study suggest a complex feedback between dissolution and precipitation reaction kinetics, which needs to be considered in the interpretation of field based dissolution rates.
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    Bedrock River Erosion through Dipping Layered Rocks: Quantifying Erodibility through Kinematic Wave Speed
    (2021-01) Mitchell, Nathaniel; Yanites, Brian
    Landscape morphology reflects drivers such as tectonics and climate but is also modulated by underlying rock properties. While geomorphologists may attempt to quantify the influence of rock strength through direct comparisons of landscape morphology and rock strength metrics, recent work has shown that the contact migration resulting from the presence of mixed lithologies may hinder such an approach. Indeed, this work counterintuitively suggests channel slopes within weaker units can sometimes be higher than channel slopes within stronger units. Here, we expand upon previous work with 1-D stream power numerical models in which we have created a system for quantifying contact migration over time. Although previous studies have developed theory for bedrock rivers incising through layered stratigraphy, we can now scrutinize this theory with contact migration rates measured in our models. Our results show that previously developed theory is generally robust and that contact migration rates reflect the pattern of kinematic wave speed across the profile. Furthermore, we have developed and tested a new approach for estimating kinematic wave speeds. This approach utilizes stream steepness, a known base level fall rate, and contact dips. Importantly, we demonstrate how this new approach can be combined with previous work to estimate erodibility values. We demonstrate this approach by accurately estimating the erodibility values used in our numerical models. After this demonstration, we use our approach to estimate erodibility values for a stream near Hanksville, UT. Because we show in our numerical models that one can estimate the erodibility of the unit with lower steepness, the erodibilities we estimate for this stream in Utah are likely representative of mudstone and/or siltstone. The methods we have developed can be applied to streams with temporally constant base level fall, opening new avenues of research within the field of geomorphology.
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    A Behavioral Study of Locational Changes in Upper Class Residential Areas: The Detroit Example
    (Department of Geography Indiana University Bloomington, Indiana, 1974) Backler, Alan L.
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    Calcaneum gear ratios for North American carnivorans
    (Evolutionary Ecology Research, 2017) Polly, P. David
    These data consist of gear ratio measurements of the calcanea (ankle bones) of all living North American mammal carnivore species and selected extinct species (Vertebrata, Mammalia, Carnivora). The gear ratio is the ratio of the maximum length of the calcaneum to the distance between the distal edge of the sustentacular facet to the proximal end of the calcaneal tuber. Full description is available in the associated publication.
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    Coastal flooding will disproportionately impact people on river deltas
    (Nature Communications, 2020) Edmonds, Doug; Caldwell, Rebecca; Brondizio, Eduardo; Siani, Sacha
    This record contains scripts and readme files needed to reproduce the analyses presented in Edmonds et al., (2020), Nature Communications
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    Compound Specific Carbon and Hydrogen Stable Isotope Ratios of Coalbed Gases in Southeastern Illinois Basin
    (2007-01-12) Strapoc, Dariusz; Schimmelmann, Arndt; Mastalerz, Maria; Eble, Corland
    Coalbed gases and waters from exploratory and production gas wells in the southeastern Illinois Basin were sampled to geochemically assess the origin of coalbed gases, with emphasis on Springfield and Seelyville coal members that are commercially targeted for coalbed methane production. On-line analyses of hydrocarbon gases (methane to butanes: C1, C2, C3, n-C4, i-C4) and CO2 yielded chemical concentrations, Delta-D, and Delta 13C values. The low thermal maturity of Indiana coals (vitrinite reflectance Ro ~ 0.6%) is in agreement with an overwhelmingly biogenic isotopic signature of coalbed gas that has greater than or equal to 96% methane generated via bacterial CO2-reduction. In contrast, thermogenic coalbed gas was generated by the stratigraphically equivalent coalbeds in western Kentucky’s Rough Creek Graben zone where higher maturities of up to Ro ~ 0.8% are reached due to tectonic and hydrothermal activity. No secondary biogenic methane was observed in Kentucky coalbed gases, probably due to greater burial depths and limited recharge of meteoric water. The two differently sourced types of coalbed gases are compositionally and isotopically distinct. Microbial biodegradation of thermogenic C2+ hydrocarbon gases in Indiana coalbeds preferentially targets C3 and introduces isotope fractionation whereby remaining C3 is enriched in heavy hydrogen and carbon isotopes.
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    Connecting fluvial levee deposition to flood-basin hydrology
    (2019) Edmonds, Douglas
    These files contain the data used to conduct the empirical analysis of levees on the Muscatatuck River and the numerical modeling of levee formation with Delft3D from Johnston et al., (2019).
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    Convection-permitting downscaling of climate change 1950-2100
    (2022) Lauer, Abraham; Kravitz, Ben
    We provide a dynamically downscaled and bias corrected dataset at 3 km horizontal resolution over the U.S. Midwest, covering the period 1951-2100 under historical and RCP8.5 conditions. Data is produced using a regional model (WRF 3.9), driven by NCEP/NCAR reanalysis 1 and CESM1 simulations designed for downscaling with WRF. Data provided includes temperature (T2) and precipitation (PRECIP). This is associated with Lauer et al. (2022), doi:XXXX.
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    Coupled alkali feldspar dissolution and secondary mineral precipitation in batch systems: 4. Numerical modeling of kinetic reaction paths
    (Elsevier, 2010-04-27) Ganor, Jiwchar; Zheng, Zuoping; Lu, Peng; Zhu, Chen
    This paper explores how dissolution and precipitation reactions are coupled in batch reactor experimental systems at elevated temperatures. This is the fourth paper in our series of “Coupled Alkali Feldspar Dissolution and Secondary Mineral Precipitation in Batch Systems”. In our third paper, we demonstrated via speciation–solubility modeling that partial equilibrium between secondary minerals and aqueous solutions was not attained in feldspar hydrolysis batch reactors at 90–300 C and that a strong coupling between dissolution and precipitation reactions follows as a consequence of the slower precipitation of secondary minerals (Zhu and Lu, 2009). Here, we develop this concept further by using numerical reaction path models to elucidate how the dissolution and precipitation reactions are coupled. Modeling results show that a quasi-steady state was reached. At the quasi-steady state, dissolution reactions proceeded at rates that are orders of magnitude slower than the rates measured at far from equilibrium. The quasi-steady state is determined by the relative rate constants, and strongly influenced by the function of Gibbs free energy of reaction (DGr) in the rate laws. To explore the potential effects of fluid flow rates on the coupling of reactions, we extrapolate a batch system (Ganor et al., 2007) to open systems and simulated one-dimensional reactive mass transport for oligoclase dissolution and kaolinite precipitation in homogeneous porous media. Different steady states were achieved at different locations along the one-dimensional domain. The time-space distribution and saturation indices (SI) at the steady states were a function of flow rates for a given kinetic model. Regardless of the differences in SI, the ratio between oligoclase dissolution rates and kaolinite precipitation rates remained 1.626, as in the batch system case (Ganor et al., 2007). Therefore, our simulation results demonstrated coupling among dissolution, precipitation, and flow rates. Results reported in this communication lend support to our hypothesis that slow secondary mineral precipitation explains part of the well-known apparent discrepancy between lab measured and field estimated feldspar dissolution rates (Zhu et al., 2004). Here we show how the slow secondary mineral precipitation provides a regulator to explain why the systems are held close to equilibrium and show how the most often-quoted “near equilibrium” explanation for an apparent field-lab discrepancy can work quantitatively. The substantiated hypothesis now offers the promise of reconciling part of the apparent fieldlab discrepancy.
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    Data Files: Bridging the Gap between Locking and ETS in Cascadia
    (2022-04-20) Johnson, Kaj
    Public data files generated for United States Geological Survey funded project G20AP00017 & G21AP10480 (National Earthquake Hazard Reduction Program).
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    Data Files: Early Ridgecrest postseismic deformation reveals viscoelastic flow in weak uppermost mantle in southern California
    (American Geophysical Union, 2020) Dorsett, Jacob
    Data files for JGR-Solid Earth manuscript titled "Early Ridgecrest postseismic deformation reveals viscoelastic flow in weak uppermost mantle in southern California". The data are computed cumulative 4-month postseismic displacements.
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    Data Files: Inferring fault rheology from observations and simulations of transient creep on the central San Andreas fault
    Johnson, Kaj
    Simulation results for USGS funded project (Award No.G20AP00067) titled "Inferring fault rheology from observations and simulations of transient creep on the central San Andreas fault".
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    Data Files: Present-day and Long-term Uplift Across the Western Transverse Ranges of Southern California
    Johnson, Kaj
    This collection contains data files used in a manuscript submitted to Journal of Geophysical Research titled "Present-day and Long-term Uplift Across the Western Transverse Ranges of Southern California". The data include GPS-derived vertical rates, leveling rates, InSAR-derived uplift rates, and geologic vertical rates from the SCEC Vertical Motion Database and a ~1Ma stratigraphic surface from the work of Sorlien and Nicholson.
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    Data for "Quantifying normal fault evolution from river profile analysis in the Northern Basin and Range province, Southwest Montana, USA"
    (2020-09) Armstrong, Ian; Yanites, Brian; Mitchell, Nate; Douglas, Bruce; DeLisle, Clarke
    Over the past few decades, tectonic geomorphology has been widely implemented to constrain spatial and temporal patterns of fault slip, especially where existing geologic or geodetic data are poor. We apply this practice along the eastern margin of Bull Mountain, Southwest Montana, where 15 transient channels are eroding into the flat, upstream relict landscape in response to an ongoing period of increased base level fall along the Western North Boulder fault. We aim to improve constraints on the spatial and temporal slip rates across the Western North Boulder fault zone by applying channel morphometrics, cosmogenic erosion rates, bedrock characteristics, and calibrated reproductions of the modern river profiles using a 1-dimensional stream power incision model that undergoes a change in the rate of base level fall. We preform over 104 base level fall simulations to explore a wide range of fault slip dynamics and stream power parameters. Our best fit simulations suggest that the Western North Boulder fault started as individual fault segments along the southern to middle region of Bull Mountain that nucleated around 3.5 Ma. This was followed by the nucleation of other fault segments in the northern region around 1.5 Ma. We re-create the evolution of the Western North Boulder fault to show that through time, these individual segments propagate at the fault tips and link together to span over 36 km, with a maximum slip of 462 m in the central portion of the fault. Fault slip rates range from 0.02 to 0.45 mm/yr along strike and are consistent with estimates for other active faults in the region. We find that the timing of fault initiation coincides with the timing of the northward propagation of Basin and Range extension and the migration of the Yellowstone Hotspot across the Idaho-Montana border. Furthermore, our range of calibrated bedrock erodibility values are comparable to those calculated from our cosmogenic erosion rates as well as values reported in other studies. Overall, we show that tectonic geomorphology can be used to improve spatial and temporal estimates of fault slip, especially where other geologic or geodetic constraints are poor, proving to be a vital tool for accurate tectonic hazard assessments. ​
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    Data for "Spatially variable increase in rock uplift in the northern U.S. Cordillera recorded in the distribution of river knickpoints and incision depths"
    (2019) Mitchell, Nate; Yanites, Brian
    This study investigates the drivers of transient bedrock river incision in central Idaho. Specifically, we utilize bedrock rivers' steepness, knickpoint elevations, and incision depths to interpret that transience is driven by an increase in rock-uplift rates. We support this interpretation with both analytical and numerical models. For information regarding the methods, see the article "Spatially variable increase in rock uplift in the northern U.S. Cordillera recorded in the distribution of river knickpoints and incision depths."
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    Data for "Testing hypotheses of albite dissolution mechanisms at near-equilibrium using Si isotope tracers"
    (2020-09) Zhu, Chen; Zhang, Yilun; Rimstidt, J. Donald; Gong, Lei; Burkhart, Joseph A.; Chen, Kaiyun; Yuan, Honglin
    Data for paper to be submitted to Geochimica et Cosmochimica Acta.
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    Data for “Influence of floods, tides, and vegetation on sediment retention in Wax Lake Delta, Louisiana, USA”
    (Journal of Geophysical Research – Earth Surface, 2020-01) Olliver, Elizabeth A.
    Each of the zipped subfolders listed above contain all the Delft3D FLOW set up files used to conduct each of the 48 the modeling runs presented in “Influence of floods, tides, and vegetation on sediment retention in Wax Lake Delta, Louisiana, USA” published in Journal of Geophysical Research – Earth Surface. Also included are the history and map data files produced by the modeling runs from which all data presented in the article was extracted for our analyses. Please note that file names in these subfolders with the “_v9” designation are those files representing the version of the model run in which there is no erosion operating, while those file names with the “_v10” designation are those for the version of the model in which erosion is operating. See the Methods section - Experimental design and choice of boundary conditions in the article for discussion of the negligible influence of erosion in the model.
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    Downstream changes in river avulsion style are related to channel morphology: Data and Scripts
    (2020) Valenza, Jeffery; Edmonds, Douglas; Hwang, Taehee; Roy, Samapriya
    Data files and scripts necessary to replicate results from Nature Communications article entitled "Downstream changes in river avulsion style are related to channel morphology" by Valenza, J., Edmonds D., Hwang, T., and Roy, S. Files include annual composited, tasseled cap transformed geoTIFFs, parent and avulsion channel masks, and Matlab and Google Earth Engine scripts to produce and process data.