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Indiana University, Bloomington Department of Geological Sciences

Works: 136 works in 159 publications in 1 language and 1,273 library holdings
Genres: Academic theses 
Classifications: QE1000,
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Most widely held works by Bloomington Indiana University
Facies and sequence stratigraphic analyses of the Upper Ordovician shales in northeast Indiana and northwest Ohio by Jingqi Xu( )

1 edition published in 2016 in English and held by 64 WorldCat member libraries worldwide

The detailed lithofacies analysis of the Upper Ordovician shales has yielded recognition of a series of genetically related sequences in a seemingly homogenous succession. The lower succession is pyritic laminated/banded organic-rich mudstone that accumulated after the onset of a major flooding event. Cryptobioturbation, bottom current ripples, graded silt/clay couplets and well preserved benthic fossils indicate an oxygen-depleted dysoxic condition. In addition, layers enriched in phosphatic fossils, phosphate and pyritic grains appear to mark flooding surfaces and sediment starvation. The maximum organic-matter enrichment mainly occurred within black homogenized mudstone in the middle succession. Upsection, more extensive bioturbation and carbonate production are observed. The intermittent yet frequent wave and current activity, suggested by cross-lamination, wavy-lenticular stratification and hummocky cross stratification, indicate a shallower and proximal settings with enhanced sediment influx
The seismic structure of southeast Alaska by Mark Bauer( Visual )

2 editions published in 2014 in English and held by 63 WorldCat member libraries worldwide

The convergent motion of the Pacific and North American Plates in Alaska has produced geologic features associated with subduction zones and has transported displaced terranes along the Queen Charlotte-Fairweather fault system that forms the northeastern boundary of the Pacific Plate. These subduction features stop abruptly at the edge of the Yakutat Block displaced terrane, approximately 300 km from the Queen Charlotte-Fairweather fault. The purpose of this study was to determine the type and geometry of the boundary between the Yakutat Block and North American as well as the cause of the offset volcanic arc and missing Wadati-Benioff zone
Refined stratigraphic interpretation of the St. Louis Limestone, south-central Indiana, USA, using sulfur isotopic curves for carbonate-associated sulfate by Walter E Gray( )

1 edition published in 2012 in English and held by 63 WorldCat member libraries worldwide

Carbonate-associated sulfate (CAS) can be used to generate high-resolution, temporal curves reflecting changes in the isotopic composition of seawater sulfate through the Phanerozoic and permitting comparisons with the well-established records for carbon, oxygen, and strontium isotopes. Sulfur isotopic comparisons (delta34S) for 118 samples of CAS and 104 samples of pyrite (pyr) are reported from two cores of the St. Louis Limestone (Middle Mississippian) in south-central Indiana along the eastern margin of the Illinois Basin. The St. Louis Limestone is informally divided into upper and lower sections based on a mappable bed of colonial rugose coral (Acrocyathus proliferum). The lower St. Louis Limestone is inferred to be a restricted and evaporitic depositional environment containing anhydrite and gypsum deposits. The mean value of delta34SCAS (13.2 /) in the lower St. Louis carbonates is about 1.5 / lower (enriched in 32S) than the global secular curve for units of this age. The upper St. Louis (14.2 / delta 34SCAS) is inferred to be an open marine environment with a circulating seaway connected with the ocean to the south. A mean value of delta 34SCAS (13.5 /) for the entire St. Louis Limestone matches the global seawater sulfate isotopic composition during the Middle Mississippian. Values of delta34Spyr generally show an overall upward increase in the St. Louis. The difference between the sulfur isotopic composition of CAS and pyr (Delta34SCAS-pyr) ranges from 13.1 to 50.1 per mil with higher Delta34SCAS-pyr values occurring mostly in the lower St. Louis Limestone. Large differences in Delta34SCAS-pyr are consistent with changing microbial pathways for cycling of sulfur in the sediment and water column as circulation in the seaway evolved from restricted to open. This study demonstrates that high-resolution curves for delta34SCAS are useful indicators of change in local paleooceanographic conditions and are valuable chemostratigraphic tools in carbonates units that lack biostratigraphic markers
The geographic and morphologic response of species and communities to their climate and environment by Lawing. A. Michelle( Book )

1 edition published in 2013 in English and held by 54 WorldCat member libraries worldwide

Understanding the sources, scales and fate of ultrafine particles by Paola Crippa( )

2 editions published in 2013 in English and held by 12 WorldCat member libraries worldwide

The biggest source of uncertainty in understanding anthropogenic forcing of the climate system derives from the role of atmospheric particles. The ability of particles to influence climate both through direct effects (i.e. increasing albedo) and indirect effects (i.e. changing cloud properties) are non-linear functions of the number concentration, size distribution and chemical composition of in situ particles. These are, in turn, determined by particle dynamics processes & iexcl;V nucleation (new particle formation (NPF)), direct emission of particles, condensation, coagulation, and deposition. Each of these processes is incompletely understood. My research has focused on understanding controls on NPF and initial particle growth from initial detectable sizes of 3 nm diameter to climate relevant sizes (& sim;100 nm). NPF events have been observed in numerous locations, but questions remain as to the scale of these events and their importance to regional/global particle number concentrations, size distributions and climate forcing. In my research I improved the understanding of mechanisms responsible for NPF and growth, the spatial scales of, and vertical and horizontal variability in, NPF and growth over eastern North America. Results from my analyses show that NPF events and high concentrations of ultrafine particles (UFP) extend for several hundreds of kilometers as a result of the major role played by the regional background in providing chemical precursors for particle nucleation. Further, the appearance of freshly nucleated particles appears to be strongly linked to boundary layer dynamics and that the nucleation mechanism may be initiated by an increase in turbulence from aloft. Thus, events observed near the surface often result from the entrainment of either freshly nucleated particles or nucleation precursors formed aloft. Given the difficulty of directly measuring continuous particle size distributions (PSDs) at many locations, the use of observations from space would represent a unique tool for predicting NPF occurrence. In this regard I developed and evaluated an innovative algorithm to estimate UFP number concentrations based on satellite retrieved variables which shows good skill for predicting UFP concentrations and relative to global model output
Block modeling of present-day deformation of Anatolia and slip rates along the North Anatolian Fault by Mehmet Kokum( )

2 editions published in 2012 in English and held by 12 WorldCat member libraries worldwide

I use GPS velocity field and published geologic slip rates to constrain an elastic block model for Anatolia and surrounding regions. The elastic block model allows us to define plate motion and both strike and tensile slip rates along the major faults. Previous studies (eg., McClusky et al., 2000; Reilinger et al., 2006) have pointed to the discrepancy between geodetic-derived slip rate estimates of around 25 mm/yr on the North Anatolian Fault (NAF) and geologically-derived slip rate estimates of roughly 18 mm/yr. To address this discrepancy, I conduct two inversions; a geodetic-only inversion and a joint inversion. While I constrain one model with only geodetic data, I constrain the other model with both geodetic data and geologic slip rates. On the basis of the GPS velocity field, the Anatolia and Aegean blocks show counterclockwise motion with respect to the Eurasian plate, and the rate of this motion is increasing towards to the Hellenic arc. The geodetic-only inversion gives higher slip rate and deeper locking depth estimates for the North Anatolian Fault than joint inversion. The geodetic-only inversion gives a North Anatolian Fault (NAF) slip rate of approximately 26-27 mm/yr with locking depths of 20-25 km (preferably 23 km). The joint inversion gives a NAF slip rate of approximately 18-19 mm/yr with a shallower locking depths of 12-16 km (preferably 14 km). The geodetic-only inversion fits the GPS data better than the joint inversion with a normalized chi-square of 2.8-2.9 compared to the joint inversion normalized chi-square value of 3.1-3.2. However, the slip rates in the joint inversion are consistent with the geologic slip rates and the locking depths of 12-16 km are consistent with the depth of background seismicity, suggesting this result is consistent with more observational constraints than the geodetic-only inversion
Modeling groundwater-surface water interaction in areas affected by acid mine drainage : implications for geomorphic reclamation design and optimization by Robert C Waddle( )

2 editions published in 2013 in English and held by 12 WorldCat member libraries worldwide

Coal mining prior to the enactment of the Surface Mining Control and Reclamation Act (SMCRA) in 1977 has left a legacy of Abandoned Mine Land (AML) sites that contribute acidic water and sediments to adjacent streams and lakes. AML sites are hydrologically complex and one goal of reclamation activities is to manipulate the way in which groundwater and surface water (GW-SW) interact in order to mitigate the acid mine drainage (AMD). This dissertation demonstrates how 3-D groundwater-flow modeling is capable of characterizing the complex hydrogeologic environments that exist at AML sites and how the models can be used to preview the hydrologic consequences of pre-existing and proposed geomorphological alterations. The research findings underscore the relevance of the physically-based mathematical approach on understanding the factors controlling GW-SW interaction. Three themes are developed: (1) How proposed geomorphological alterations of a large mine tailings deposit can induce changes in levels of saturation and directions of groundwater flow; potentially minimizing hazards and facilitating passive treatment of AMD. (2) How pre-SMCRA mine-complex topography affects groundwater-flow patterns and dictates site-specific GW-SW interaction. In particular, the modeling shows that the complex topography of an abandoned mine spoil-ridge system, and its relationship to the underlying un-mined bedrock, dictates the locations of seepage zones and the extent and configuration of their contributing groundwater sheds. (3) How the distributions of groundwater-flow paths and transit times through engineered AMD passive treatment systems are governed by design geometry as well as the hydrologic characteristics of how AMD is first introduced into these systems. Together these studies highlight how concepts of geomorphic reclamation developed for post-SMCRA planning are also applicable to AML sites both in understanding the hydrologic consequences of unregulated mining and the planning of post-hoc remedial reclamation
Facies analysis and sequence stratigraphy of the Middle Devonian (Givetian) Geneseo Formation of New York : implications for accommodation during a eustatic sea-level rise by Ryan D Wilson( )

2 editions published between 2012 and 2013 in English and held by 12 WorldCat member libraries worldwide

In addition, nano-scale microscopy of ion-milled shale sections has led to identify three distinct pore-types in the Geneseo Formation. It appears that pore morphology and distribution correlates with distinct mudstone lithofacies as a result of small scale compositional and textural characteristics. Phyllosilicate framework pores are small triangular openings (50--1000 nanometers wide) that are observed throughout the Geneseo succession, however, are better developed in the dark gray mudstones where pressure halos of compaction resistant grains (sand, silt, pyrite, etc.) surround and prevent compression of primary clay fabric. Organic matter porosity is also observed (10--500 nanometers wide), and dominates the lower Geneseo pyritic and banded black shale facies where organic content is highest. Carbonate dissolution pores are observed in the calcareous intervals within the Geneseo (50--500 nanometers wide), and probably reflect partial dissolution of carbonate grains (calcite or dolomite) during catagenetic formation and migration of carboxylic and phenolic acids
A comparison of deformation mechanisms and thermal histories in a modern and ancient arc-continent collision by Martha Rebecca Stokes( )

2 editions published in 2012 in English and held by 11 WorldCat member libraries worldwide

Arc-continent collisions (ACC) are important in the growth of continental crust where accretion occurs through the collision of intra-oceanic volcanic arcs with continental margins. This comparative study of an active and a fossil ACC provides a 4-dimensional (space and time) perspective into the process of ACC and an overall insight into this significant plate tectonic process. Slaty rocks of the active Lishan fault of Taiwan are accommodating upper crustal deformation in the ongoing collision of the Luzon arc with the eastern Chinese continental margin. In contrast, the Blue Ridge Province of North Carolina preserves a relict Paleozoic ACC which experienced high-temperature metamorphism and deformation in the lower crust. These two settings thus record strongly contrasting conditions of metamorphism and deformation
Improved X-ray powder diffraction modeling of interstratified phyllosilicates with application to quantitative analysis by Hongji Yuan( )

2 editions published in 2013 in English and held by 11 WorldCat member libraries worldwide

Phyllosilicate minerals are common constituents of rocks and soils, but quantitative analysis of such materials using X-ray powder diffraction (XRPD) is difficult due to the presence of poorly ordered and interstratified phyllosilicates. Diffraction from interstratified phyllosilicate minerals has been successfully modeled, and several software packages such as NEWMOD, DIFFaX and Sybilla have been developed. However, these programs heavily rely on trial-and-error method, requiring intensive user interaction and making the results sensitive to user input. FITMOD, an automated parametric fitting program based on MacEwan's methodology, has been developed. FITMOD uses the downhill simplex method to minimize discrepancies between experimental and simulated XRPD patterns by simultaneously varying all adjustable model parameters. The application of FITMOD to samples containing multiple phyllosilicate mineral phases is limited by the profile fitting efficiency, demanding a faster algorithm for calculating XRPD patterns of interstratified phyllosilicates. In general, the matrix methodology developed by Kakinoki and Komura is more time-efficient compared with the MacEwan approach. The matrix methodology was improved, resulting in a modified algorithm that is 3X faster than the original one. ClayStrat was developed using the modified matrix methodology and is up to 13.5X faster than FITMOD that is based on MacEwan's approach
Understanding glacial deposits in a bedrock valley with seismic data and well descriptions, Allen County, Indiana by Kimberly A Shoemaker( )

2 editions published in 2012 in English and held by 11 WorldCat member libraries worldwide

Seismic exploration methods provide a non-invasive method of imaging the subsurface. This method is valuable in many fields outside of geophysics and the petroleum industry, such as engineering, geology, archeology and environmental work. This work utilizes seismic data as a tool to understand the geomorphology at a field site in Allen County, Indiana. The field site is the location of an abandoned municipal water field. The site is within a large bedrock valley filled with thick deposits of diamicton and silty sandy gravels; however, the aquifer was unable to produce enough water for municipal usage. Several vertical seismic profiles (VSP) surveys and a P-wave reflection profile were conducted in order to better understand the glacial deposits. Well descriptions described by A. Fleming provide ground truth for interpreting the seismic data. The reflection data was processed using standard seismic processing techniques. The P- and S-wave layer velocities were calculated using a least squares inversion based on the VSP data. The P-wave velocities ranged from ~700--2500 m/s while the S-wave velocities ranged from ~350--500 m/s. Based on the results of the inversion, synthetic VSP and reflection data were produced using wave number integration approximation. The reflectors were correlated to specific strata using the synthetics and approximated arrival times. The deeper reflection events arrived earlier than the shallow reflection event, which resulted in an inverted profile. This inverted profile is the result of the velocity structure and the source-receiver spacing. Recommended future works include conducting and processing more seismic profiles over the boreholes using 3-component geophones, analyzing and inverting recorded surface waves, and collecting more complex borehole surveys such as walkaway VSP and crosshole tomography
Implications of the angiosperm radiation on morphological disparity and taxonomic diversity of Mesozoic mammals by David M Grossnickle( )

2 editions published in 2013 in English and held by 11 WorldCat member libraries worldwide

Fossil discoveries over the past 30 years have radically transformed traditional views of Mesozoic mammal evolution. Similarly, recent research has provided a more detailed account of the mid-Cretaceous diversification of flowering plants. Although studies have speculated about the possible co-evolution of angiosperms and mammals, there have been no recent quantitative paleontological studies that examine parallel patterns between the groups. In this study, three hypotheses were considered: 1) angiosperm radiation had little or no effect on the overall taxonomic and morphological diversity of Cretaceous mammals; 2) angiosperm radiation led to an increase in the overall diversity of mammals, possibly due to food sources that were new (e.g., fruit), increasing (e.g., seeds, pollinating insects), and/or improving (e.g., increased plant matter owing to higher photosynthetic capacity); and 3) angiosperm radiation led to a decrease in mammal diversity, with only herbivorous and small insectivorous mammals remaining viable. Diversity curves were created to analyze taxonomic changes, teeth and jaw lengths were used as a proxy for body size and disparity, and geometric morphometric analysis of jaws was used to examine changes in morphological and dietary disparity. Results indicate significant taxonomic and morphological changes in mammals at the time of angiosperm radiation. There was a negative correlation between flowering plant proliferation and the diversity of two mammal clades, Eutriconodonta and Amphilestheria, as well as evidence that close relatives of therians (stem cladotherians and stem boreosphenidans) also diminished as angiosperms spread. The two mammal clades that appear to have been most successful in the Late Cretaceous are multituberculates, which show a morphological shift toward a plant-dominated diet, and insectivorous therians, which experienced a taxonomic expansion positively correlated with angiosperm diversity. However, lack of a significant taxonomic expansion and evidence from previous studies indicates that multituberculates may not have radiated in accordance with flowering plants. Body size and morphological disparity of non-multituberculate mammals, which are primarily therians by the Late Cretaceous, appear to decline with the advent of angiosperms, suggesting the possible occurrence of a morphological "bottleneck" that resulted in a shift toward small insectivores. Considering the diversity patterns of all mammalian clades leads to the conclusion that the initial angiosperm radiation was more likely to have acted as a stressor for mammals than a catalyst for expansion, with diversification of surviving therians and multituberculates occurring near the end-Cretaceous
Dynamics of deformation at plate boundaries : Taiwan orogen and San Andreas fault system in Southern California by Yun-Ruei Chuang( )

2 editions published in 2014 in English and held by 11 WorldCat member libraries worldwide

To estimate fault slip rates in southern California, I follow the concept of block modeling, which describes present-day surface velocities as the sum of long-term block motion (steady-state component) and interseismic strain accumulation (transient component). I develop improved models of both the steady-state and transient components. I use a viscoelastic layer model for the transient component with consideration of nonsteady mantle flow and deep fault creep to help reconcile discrepancies between the geologic and geodetic slip rates along some faults in southern California. In this model, faults in the early/late earthquake cycles infer higher/lower slip rates than classic elastic block models. For the steady-state component, I improve on the traditional kinematic approach with a dynamic viscoelastic thin-sheet model with imposed stress boundary conditions and lithospheric and fault zone viscosity. This model is used to estimate physically-constrained fault slip rates in southern California. The far-field tectonic load is the main driving force and the model favors high lithospheric viscosity suggesting the blocks of lithosphere between faults tend to be relatively rigid
Analysis of coral reef variation in Bonaire by Robin M Green( )

2 editions published in 2012 in English and held by 11 WorldCat member libraries worldwide

Results of the combined 10 and 20 meter analyses indicated average cover of live coral was 20.4%, diseased coral 0.06%, recent dead coral 5.4%, old dead coral 29.1%, substrate 31.2%, macroalgae 1.9%, microalgae 2.3%, gorgonians 5.4%, sponges 3.0%, and Millepora sp. 0.7%. Dominant families of coral were Faviidae (12.8%), Agariciidae (3.3%), Astrocoeniidae (1.6%), and Poritidae (1.3%). A total of 44 species of coral were identified but most had less than 1% percent cover. Significant small-scale variation in the coral communities was detected between depths and among sites
Stable isotopes from methane and hydrogen sulfide in gas hydrates as source signatures : influence of clay minerals, biosurfactants, and salts on isotopic selectivity by Humberto Carvajal-Ortiz( )

2 editions published in 2013 in English and held by 11 WorldCat member libraries worldwide

Complex physical and chemical interactions between encaged molecules and hydrate-hosting sediments during hydrate formation complicate the use of stable isotopes as source signatures. In this study, hydrates containing methane and hydrogen sulfide are formed in a pressure vessel in order to explore the effects of 1) sodium chloride (NaCl) and magnesium sulfate heptahydrate (MgSO4 & middot;7H2O), and 2) smectite clays and biosurfactants on the fractionation of stable isotopes of carbon (delta13C CH4) and hydrogen (delta2HCH4) in methane and of sulfur in hydrogen sulfide (delta34SH2S). Experiments with NaCl and MgSO4 & middot;7H2O solutions show less than 1 per mil difference in values of delta13C CH4 and up to 6.5 per mil difference in values of delta2H CH4 for free and encaged molecules. Experiments with hydrogen sulfide in similar solutions show up to 4 per mil difference in values of delta 34SH2S for free and encaged molecules, but up to 14 per mil difference between dissolved and either free molecules or encaged molecules. In experiments with methane hydrates formed from solutions in contact with smectite clays or containing biosurfactants, the difference in values of delta13CCH4 between free and encaged molecules is less than 1 per mil, whereas the difference in values of delta 2HCH4 are up to 10 per mil between free and encaged molecules. In addition, efficiency of methane consumption increased in methane hydrates formed from solutions containing biosurfactants alone or biosurfactant-smectite mixtures. In the presence of NaCl and MgSO4 & middot;7H2O salts, smectite clays, and biosurfactants, isotopic fractionation indicated by delta13CCH4 and delta2H CH4 in free and encaged molecules are small and do not complicate interpretations of gas origin. Conversely, in hydrate systems containing hydrogen sulfide molecules, values of delta34SH2S need to be interpreted with caution. Moreover, enhanced consumption of methane in hydrates formed in association with biosurfactant solutions modifies gas wetness, compromising interpretations of gas origin and thermal maturity. Small-vessel pressure experiments demonstrate unexpected complexity in fractionation of stable isotopes during formation of hydrates, complicating the interpretation of source signatures during hydrocarbon exploration and the assessment of biosignatures in other planetary bodies
Quantifying the influence of irrigated agriculture on atmospheric heat content and boundary layer dynamics by Timothy E Wright( )

1 edition published in 2014 in English and held by 10 WorldCat member libraries worldwide

Irrigation delivers about 2,600 km3 of water to the global land surface each year (~ 2% of annual over-land precipitation) (Sacks et al. 2009). This research examines the scales of resulting changes to local and regional climates using in situ and remote sensing measurements. The effects of irrigated agriculture on the overlying atmosphere are compared with adjacent non-irrigated locations using equivalent potential temperature (theta e) and potential evapotranspiration (ETo). These are better metrics for quantifying total atmospheric heat content near the surface than temperature alone because of the effect of latent heat exchange (LE) which separates temperature from total heat content. Satellite-derived surface albedo and emissivity are used to quantify the differences in net radiation at the surface between adjacent irrigated and non-irrigated landscapes. These data are used with theta e and ETo in a spectrum of climates across the United States to quantify impacts of irrigation in each regime. The results indicate the effects depend on both the climate and surrounding land cover. For arid regions, net radiation and theta e are higher over irrigation because of lower albedo; however, higher emissivity offsets much of the warming. Increased LE due to higher water availability results in lower temperatures over irrigation, to a degree that is a function of regional humidity. As one moves from drier to more humid environments, the effects of irrigation transition from large positive forcing on net radiation and LE to near zero. However, the differences in theta e and ET o sometimes far exceed what net radiation and the heat budget suggest and thus clearly indicate a regional response to irrigation and as documented herein that the enhancement of theta e scales with fetch over irrigation. The effects on the boundary layer dynamics due to the change in net radiation and heat fluxes typically are characterized by suppression of convection over irrigation and enhancement over adjacent non-irrigated areas
Low-temperature alteration of the Davis Formation of the Elvins Group and its relationship to the regional Mississippi Valley-type ore genesis in the southeast Missouri Lead District by Joshua Daniel Field( )

1 edition published in 2014 in English and held by 10 WorldCat member libraries worldwide

Low-temperature hydrothermal alteration of carbonates is the subject of intense research due to a myriad of evidence for a relationship between the alteration of carbonates and Mississippi Valley-Type (MVT) ore deposit formation. Correlation between altered carbonate units, particularly those that have been dolomitized, and MVT deposits has been firmly established, although the exact nature of the relationship remains unclear. The Viburnum Trend and the Old Lead Belt of the southeast Missouri lead districts follow this trend and are hosted by gangue dolomite in which Fe-enrichment has been observed, indicating overall metal-rich fluid alteration. The overlying unit, the Davis Formation, is a sandy dolostone and shale unit with minimal, though present, occurrences of sulfides, and it exhibits evidence of repeated episodes of hydrothermal fluid alteration. However, much of the previous research focuses on the shales of the Davis Fm. rather than on the carbonates and fails to provide any explanation as to why the Davis Fm. was only sparsely mineralized in comparison with the Bonneterre. The relationship between the low-temperature alteration minerals such as K-feldspar, dolomite, ferroan dolomite, and sulfide minerals is also unclear. Powder X-ray diffractometry, scanning electron microscopy, and X-ray fluorescence analyses were performed on the carbonate rocks of the Davis Fm. in order to determine mineral compositions, textural relationships between minerals, and whole-rock geochemistry, respectively, to elucidate how the Davis Fm. was affected by hydrothermal fluids flowing upwards from the underlying Bonneterre Fm. X-ray diffraction confirmed the presence of two distinct potassium feldspars, sanidine and microcline. In backscattered-electron imaging (BSE), the feldspar grains exhibited core-and-rim textures. Energy-dispersive spectroscopy (EDS) indicated that the cores were Ba-rich and the rims, conversely, were Ba-poor. The cores also emitted blue fluorescence in cathodoluminescence (CL), further confirming the presence of Ba. These textural and chemical data are interpreted as being the result of two distinct periods of crystallization. Multiple generations of carbonate precipitation were also observed in BSE imaging. A late-stage Fe-enriched ankeritic phase as well as an arrested dedolomitization reaction were identified via BSE in some samples and confirmed using X-ray diffraction. Rietveld refinements indicated a variable degree of Fe-enrichment up to ~27% Fe occupancy of the M1 site of Fe-enriched samples; in dedolomitized samples, calcite comprises between 18 and 70 wt. % of the sample and dolomite comprises between 2 and 55 wt. %. Samples from a given outcrop exhibit the same pattern of Fe-enrichment, indicating that metal-rich fluid(s) only infiltrated the Davis Fm. locally. Dedolomitization reactions were only observed in a single location, further indicating that certain fluid alteration events only locally affected the Davis Fm. Although no direct dolomitic and/or Pb-Zn mineralization of fractures and joints was observed, outcrops along Highway 8 were sometimes found to have thin crusts of calcite crystals on joint surfaces. Panno et al. (1988) asserted that fractures/joints surrounding the main ore body in the Viburnum Trend provided pathways for fluid migration up into the Davis Fm. and were responsible for leaching of metals from the Davis shales. Fractures and jointing were observed in the Davis Fm. at the outcrops used in this study and could have been the pathways by which fluids entered and locally altered the Davis Fm. Therefore the source of these fluids is interpreted as solutions upwelling through cracks and joints through the Bonneterre Fm. into the Davis Fm
Rare Earth Element (REE) - SiO₂ systematics of island arc lower crust amphibolite migmatite from Yakuno Ophiolite, SW Japan : a field evaluation of some model predictions by Xiaofei Pu( )

2 editions published in 2013 in English and held by 10 WorldCat member libraries worldwide

To evaluate the model, natural samples of lower crustal amphibolite migmatite were collected from the Yakuno Ophiolite, SW Japan. According to the regional geology (Suda, 2004), these rocks are considered to represent the partial melting of island arc lower crust. To determine whether the silicic portion of the migmatites actually represent partial melts, a series of high pressure (5Kb) melting experiments were conducted on the freshest natural amphibolite sample. The major element compositions of the experimental melts agree well with those of the silicic portion of the natural migmatite samples, supporting the latter one to be of a partial melting origin. The experimental data were then used to construct an amphibolite melting history which permitted the quantitative modeling of both REE and SiO2 abundances in the evolving melt. The REE abundances modeled with experimental results and observed in the silicic portion of the migmatite shows very good agreement. Thus, Brophy's (2008) general model for REE-SiO2 systematics during the partial melting of lower crustal amphibolite was confirmed
Distribution and sources of polycyclic aromatic hydrocarbons (PAHS) in the Santa Barbara Basin by Amishi Kumar( )

1 edition published in 2015 in English and held by 10 WorldCat member libraries worldwide

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic pollutants originating from both natural and anthropogenic sources through petrogenic, pyrogenic, and biogenic pathways. Their persistence, toxicity, and use as a proxy to trace the anthropogenic impact of fossil fuel combustion make PAHs widely studied. Sediment samples from the Santa Barbara Basin were extracted and analyzed to compare sedimentary PAHs using concentration distributions, diagnostic ratios, and principal component analysis. The Santa Barbara Basin hosts a complex array of PAHs from anthropogenic sources and natural sources such as oil seepages and wildfires. The high sedimentation rates (& ap; 4 mm/yr near the sediment surface) combined with limited sediment redistribution produce a high-resolution sediment record that is varved down to ca. 1700 AD and laminated for at least 2500 years. In addition to varves, distinguishable terrigenous flood layers and marine turbidites with distinctive depositional histories and characteristics were also investigated. A total of 25 parent and alkylated PAHs were identified and quantified by gas chromatography/mass spectrometry (GC/MS) in selected ion mode. Two biogenic PAHs, perylene and retene, provided the most informative concentration values. Perylene concentrations increased in depth down core dramatically in sediments dating older than 300 AD suggesting perylene creation from the in situ degradation of organic matter. However a small increase in perylene concentrations in modern sediments from the late 1960s to the early 1970s suggests an alternative input. Increased retene concentrations in flood layers and turbidites suggest these lithologies were more effective in transporting pyrogenic PAHs and could be interpreted as a proxy for wildfires. A shift in key diagnostic ratios reveal the dominant presence of petroleum PAHs in older sediments change to a strong combustion and/or petroleum combustion signal starting in the latter half of the 20 th century. Principal component analysis was the best way to elucidate a modern, anthropogenic signature and a lithological signature of flood layers. Modern sediments showed a strong, positive relationship to principal component group one. Flood layers showed a strong relationship with principal component group two
The late cretaceous Belle Fourche and Second White Specks formations in west-central Alberta, Canada, as an emerging hybrid source rock/reservoir shale play by Agnieszka Furmann( )

1 edition published in 2015 in English and held by 10 WorldCat member libraries worldwide

Organic-rich mudstones with up to 10 wt. % total organic carbon (TOC) from seven sediment cores in west-central Alberta encompassing the upper Belle Fourche and lower Second White Specks Formations in the Western Canada Sedimentary Basin are being evaluated as a hybrid source rock/reservoir shale play. Geochemistry and organic petrography indicate a normal marine paleoenvironment with deposition of kerogen Type II based on the predominance of marine alginite and amorphous organic matter, limited amounts of terrigenous vitrinite and inertinite macerals, and the presence of marine fossils. The prevalence of short-chain n-alkanes (n-C13 to n-C19), a general predominance of C28 -alphabetabeta(H)-20S steranes, and small concentrations of oleanane confirm the dominantly algal and planktonic origin of organic matter. The thermal maturity increases westward across Alberta with two thermally immature cores (& sim;0.43% Ro vitrinite reflectance), one early mature core (& sim;0.65% Ro), and four cores representing mid-mature stages (& sim;0.78 to 0.90% Ro). A combination of helium porosimetry with low-pressure CO2 and N2 adsorption techniques was used to quantify porosity. The total porosity decreased from & sim;10 vol. % to & sim;1.0 vol. % (from & sim;0.05 cm3/g to & sim;0.005 cm3/g) along the maturation sequence. In general, organic matter is the strongest contributor to microporosity (with <2nm pore diameter). Overall, inter- and intraparticle pores in quartz contribute to greater abundance of micro-, meso- (2-50 nm O diameter), and macropores (>50 nm O), while the increasing content of clay minerals (illite, kaolinite, and chlorite) enhances both micro- and mesopore volumes. In contrast, carbonates (calcite and dolomite) seem to have a negative effect on porosity volumes in the measured shales. All thermally mature cores show good remaining hydrocarbon potential (2-48 mg hydrocarbon/g rock) and are dominantly oil prone as suggested by maceral compositions. Therefore, the Belle Fourche and Second White Specks Formations represent potential targets for unconventional light shale oil production
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