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Articles 331 - 360 of 1880

Full-Text Articles in Earth Sciences

Htgcd Well Evaluation: Dripping Springs Water Supply Co. Test Well 1 & Stratigraphic Evaluation Of The Trinity Aquifer Units In Wester Hays County And Implications For Hydrological Variations, Nicholas J. Soto-Kerans, A. Broun, J. Watson Jan 2019

Htgcd Well Evaluation: Dripping Springs Water Supply Co. Test Well 1 & Stratigraphic Evaluation Of The Trinity Aquifer Units In Wester Hays County And Implications For Hydrological Variations, Nicholas J. Soto-Kerans, A. Broun, J. Watson

School of Geosciences Student Publications

The Trinity Aquifer is a very important groundwater resource for the Dripping Springs area and Central Texas as a whole. Evidence in recent studies show increased levels of aquifer stress and pumping due to higher influx of population and demand for potable water in the area.

In addition to high levels of pumping, groundwater appears to be influenced by facies change. There is little information on how certain geological units affect the presence of groundwater in the Trinity Aquifer – this study is purposed to bring a better understanding of how groundwater resources are stored and moved through the subsurface …


Developing High Resolution Baseline Coast Resource Maps Using World View 2 Imagery For A Coastal Village In Fiji, Ashneel Ajay Singh, Anish Maharaj, Michelle Kumar, Priyatma Singh, Sanjay Singh, Frank Muller-Karger, Matthew James Mccarthy, Lionel Joseph, Herve Damlamian, Zulfikar Begg Jan 2019

Developing High Resolution Baseline Coast Resource Maps Using World View 2 Imagery For A Coastal Village In Fiji, Ashneel Ajay Singh, Anish Maharaj, Michelle Kumar, Priyatma Singh, Sanjay Singh, Frank Muller-Karger, Matthew James Mccarthy, Lionel Joseph, Herve Damlamian, Zulfikar Begg

Marine Science Faculty Publications

In Fiji, like most Pacific Island countries, there have been numerous reports of degradation of coastal resources, including adverse changes in abundance and stock distribution of numerous aquatic species associated with the coastal habitat. To develop effective management plans, assessment of existing coastal resources is pertinent. High spatial resolution satellite imagery, combined with geographic information systems allow for efficient and synoptic mapping of coastal resources to provide a baseline for developing effective and improved management plans. The purpose of this study was to develop a baseline habitat map of the intertidal benthic cover in Komave Village, Coral Coast, Sigatoka, Fiji. …


Tubex Data, Sanaz Esmaeili Jan 2019

Tubex Data, Sanaz Esmaeili

School of Geosciences Student Publications

No abstract provided.


Is Ghana Ready To Attain Sustainable Development Goal (Sdg) Number 7?—A Comprehensive Assessment Of Its Renewable Energy Potential And Pitfalls, Michael Acheampong, Qiuyan Yu, Funda C. Ertem, Lucy E.D. Enomah, Shakhawat H. Tanim, Michael Eduful, Mehrdad Vaziri, Erick Ananga Jan 2019

Is Ghana Ready To Attain Sustainable Development Goal (Sdg) Number 7?—A Comprehensive Assessment Of Its Renewable Energy Potential And Pitfalls, Michael Acheampong, Qiuyan Yu, Funda C. Ertem, Lucy E.D. Enomah, Shakhawat H. Tanim, Michael Eduful, Mehrdad Vaziri, Erick Ananga

School of Geosciences Student Publications

Ghana has declared support for the UN Sustainable Development Goal (SDG) number seven which most importantly target ensuring universal access to affordable, reliable and modern energy services. This target presents a formidable challenge to Ghana because the country still relies mainly on traditional biomass as its primary source of energy coupled with a chronically fragile hydropower sector. In this study, we assess Ghana’s potential in achieving sustainable goal number seven. Specifically, we comprehensively review the breakthroughs and impediments Ghana has experienced in its efforts towards improving its renewable energy potential. We note that while Ghana has made significant stride toward …


Mobile Terrestrial Photogrammetry For Street Tree Mapping And Measurements, John Roberts, Andrew Koeser, Amr Abd-Elrahman, Benjamin Wilkinson, Gail Hansen, Shawn M. Landry, Ali Perez Jan 2019

Mobile Terrestrial Photogrammetry For Street Tree Mapping And Measurements, John Roberts, Andrew Koeser, Amr Abd-Elrahman, Benjamin Wilkinson, Gail Hansen, Shawn M. Landry, Ali Perez

School of Geosciences Faculty and Staff Publications

Urban forests are often heavily populated by street trees along right-of-ways (ROW), and monitoring efforts can enhance municipal tree management. Terrestrial photogrammetric techniques have been used to measure tree biometry, but have typically used images from various angles around individual trees or forest plots to capture the entire stem while also utilizing local coordinate systems (i.e., non-georeferenced data). We proposed the mobile collection of georeferenced imagery along 100 m sections of urban roadway to create photogrammetric point cloud datasets suitable for measuring stem diameters and attaining positional x and y coordinates of street trees. In a comparison between stationary and …


Rapid Iceberg Calving Following Removal Of Tightly Packed Pro-Glacial Mélange, Surui Xie, Timothy Dixon, David M. Holland, Denis Voytenko, Irena Vaňková Jan 2019

Rapid Iceberg Calving Following Removal Of Tightly Packed Pro-Glacial Mélange, Surui Xie, Timothy Dixon, David M. Holland, Denis Voytenko, Irena Vaňková

School of Geosciences Faculty and Staff Publications

Iceberg calving is a major contributor to Greenland’s ice mass loss. Pro-glacial mélange (a mixture of sea ice, icebergs, and snow) may be tightly packed in the long, narrow fjords that front many marine-terminating glaciers and can reduce calving by buttressing. However, data limitations have hampered a quantitative understanding. We develop a new radar-based approach to estimate time-varying elevations near the mélange-glacier interface, generating a factor of three or more improvement in elevation precision. We apply the technique to Jakobshavn Isbræ, Greenland’s major outlet glacier. Over a one-month period in early summer 2016, the glacier experienced essentially no calving, and …


Tracing And Constraining Anthropogenic Aerosol Iron Fluxes To The North Atlantic Ocean Using Iron Isotopes, Tim Conway, Douglas S. Hamilton, Rachel U. Shelley, Ana M. Aguilar-Islas, William M. Landing, Natalie M. Mahowald, Seth G. John Jan 2019

Tracing And Constraining Anthropogenic Aerosol Iron Fluxes To The North Atlantic Ocean Using Iron Isotopes, Tim Conway, Douglas S. Hamilton, Rachel U. Shelley, Ana M. Aguilar-Islas, William M. Landing, Natalie M. Mahowald, Seth G. John

School of Geosciences Faculty and Staff Publications

Atmospheric dust is an important source of the micronutrient Fe to the oceans. Although relatively insoluble mineral Fe is assumed to be the most important component of dust, a relatively small yet highly soluble anthropogenic component may also be significant. However, quantifying the importance of anthropogenic Fe to the global oceans requires a tracer which can be used to identify and constrain anthropogenic aerosols in situ. Here, we present Fe isotope (δ56Fe) data from North Atlantic aerosol samples from the GEOTRACES GA03 section. While soluble aerosol samples collected near the Sahara have near-crustal δ56Fe, soluble aerosols from near North America …


Research On Land Use Changes And Ecological Risk Assessment In Yongjiang River Basin In Zhejiang Province, China, Peng Tian, Jianlin Li, Hongbo Gong, Ruiliang Pu, Luodan Cao, Shuyao Shao, Zuoqi Shi, Xuili Feng, Lijia Wang, Riuqing Liu Jan 2019

Research On Land Use Changes And Ecological Risk Assessment In Yongjiang River Basin In Zhejiang Province, China, Peng Tian, Jianlin Li, Hongbo Gong, Ruiliang Pu, Luodan Cao, Shuyao Shao, Zuoqi Shi, Xuili Feng, Lijia Wang, Riuqing Liu

School of Geosciences Faculty and Staff Publications

Studying land use changes and ecological risk assessment in Yongjiang River Basin in Zhejiang Province, China, provides theoretical references for optimal configuration of land resources and maintaining stability of ecosystems. Given impacts of land use changes on landscape patterns in the Yongjiang River Basin, ecological risk assessment indexes were constructed and used to analyze temporal and spatial variation characteristics of ecological risk within different periods. Results show that (1) the construction land area was increased quickly, while the cultivated area decreased sharply. A prominent characteristic of land use changes was manifested by transforming cultivated area and forestland into construction land. …


The Second Decade Of Numeracy: Entering The Seas Of Literacy, H. L. Vacher Jan 2019

The Second Decade Of Numeracy: Entering The Seas Of Literacy, H. L. Vacher

Numeracy

This multipurpose editorial explores and tries to count the many types of literacy that are referred to by name in Wikipedia and Numeracy. Wikipedia’s Category:Literacy page identifies 44 kinds of literacy that are the subject of articles, ranging from numeracy and graphicacy to braille literacy and diaspora literacy. In addition, searching Google finds more than 30 adjective-literacy or noun-literacy collocations, including quantitative literacy, adult literacy, and document literacy, that do not have Wikipedia pages of their own but are mentioned on other Wikipedia pages. The sum puts this modest literacy count in line with the more than 70 bodies …


The Role Of Mites In The Construction And Weathering Of Siliceous Biospeleothems, María José López-Galindo Nov 2018

The Role Of Mites In The Construction And Weathering Of Siliceous Biospeleothems, María José López-Galindo

International Journal of Speleology

Acarines are well-documented as formative elements in the biocenosis of soils. However, their role in the construction and weathering of siliceous speleothems has received very little attention in previous research. The present study describes different groups of cavities (nesting/molting sites) excavated by these organisms in the surface of siliceous speleothems that are deposited in the fissures between various granite boulders in Southern Spain. There is evidence that there are immature stages that would survive the heat and drought of summer in the form of small larvae, or euedaphic nymphs, in the soil. This study provides the first description of how …


High-Precision Lead Isotope Analysis On Modern Populations To Determine Geolocation Reliability, Gennifer M. Goad Nov 2018

High-Precision Lead Isotope Analysis On Modern Populations To Determine Geolocation Reliability, Gennifer M. Goad

USF Tampa Graduate Theses and Dissertations

Forensic anthropologists increasingly use chemical isotope analysis in the investigation of unidentified human remains, as biochemical georeferencing continually improves with the development of modern reference data of known origins. Isotope variations in trace elements such as strontium (Sr) and lead (Pb) in human teeth are some of the most useful indicators of past domicile in archaeological research and thus have high potential for modern, forensic applications. In this study, high-precision lead isotope analysis was conducted on 63 modern human teeth, which were previously analyzed for strontium isotopes. The results present new lead isotope data for the following countries: United States …


The Utility Of The Conductivity Mass-Balance Method For Base Flow Separation In Rivers And Streams, Darline Alegria Lott Nov 2018

The Utility Of The Conductivity Mass-Balance Method For Base Flow Separation In Rivers And Streams, Darline Alegria Lott

USF Tampa Graduate Theses and Dissertations

Freshwater for ecosystems, drinking water, and water for various businesses are important resources and those resources are rapidly diminishing globally due to drought and overuse. In order to manage the availability of water for all concerned, good estimates of base flow (groundwater) is required. Base flow, a component of streamflow, is deduced by separating a stream hydrograph into two components, base flow and runoff. There are several techniques used to perform base flow separation; however two techniques are used in this study, chemical mass-balance and analytical methods. This dissertation explains how an analytical technique was derived from a mass-balance method, …


Evolution Of Noble Gas And Water Isotopes Along The Regional Groundwater Flow Path Of The Konya Closed Basin, Turkey, N. Nur Ozyurt, C. Serdar Bayari Nov 2018

Evolution Of Noble Gas And Water Isotopes Along The Regional Groundwater Flow Path Of The Konya Closed Basin, Turkey, N. Nur Ozyurt, C. Serdar Bayari

International Journal of Speleology

Noble gas and water isotope compositions of regional groundwater were investigated along two transects in the Konya Closed Basin (KCB) of central Turkey. According to the 3He/4He versus Ne/He plot of samples, crust (up to 86%) and mantle (up to 26%) appear to be the primary and secondary sources of dissolved He in groundwater, respectively. After the beginning of both transects where the flow domain is confined, both 3He and 4He accumulate steadily in groundwater. Thereafter, the intermediate recharge from the surface in the unconfined part of regional flow system disrupts the steady accumulation trend …


Interpreting The Origin And Evolution Of ‘Karst’ Features From A Siliceous Hydrothermal Terrane: A Case Study From The Upper Geyser Basin In Yellowstone National Park, Usa, Kevin W. Blackwood, Lainee A. Sanders, Stacy I. Gantt-Blackwood Nov 2018

Interpreting The Origin And Evolution Of ‘Karst’ Features From A Siliceous Hydrothermal Terrane: A Case Study From The Upper Geyser Basin In Yellowstone National Park, Usa, Kevin W. Blackwood, Lainee A. Sanders, Stacy I. Gantt-Blackwood

International Journal of Speleology

The Upper Geyser Basin in Yellowstone National Park occurs over a siliceous hydrothermal terrane containing numerous hot springs and geysers. The pool and vent-conduit geometries of these hydrothermal features share a resemblance to conventional karst features known from other rock types, suggesting karst processes could be responsible for their origin and/or evolution. Hypogene speleogenesis is a cave-forming process in which the formation of caves is decoupled from and occurs independently of surface recharge. The geologic setting for hypogene speleogenesis typically occurs at the distal end of regional groundwater systems wherein the hydrogeology is manifested by ascending fluids and/or by geochemical …


Assessing The Cooling Effects Of Urban Vegetation On Urban Heat Mitigation In Selected U.S. Cities, Qiuyan Yu Nov 2018

Assessing The Cooling Effects Of Urban Vegetation On Urban Heat Mitigation In Selected U.S. Cities, Qiuyan Yu

USF Tampa Graduate Theses and Dissertations

Urban Heat Island (UHI) is a growing problem worldwide. Mitigation of UHI is necessary for cities to adapt to climate change and enhance sustainable development at a city scale. Cooling cities with urban vegetation management is a sustainable solution for urban heat mitigation. Urban vegetation influences urban microclimate through the shading effect, surface roughness, and evapotranspiration. The differences in horizontal and vertical structures of urban vegetation determine the shading effect, surface roughness, and evapotranspiration. Enhancing the cooling effect of urban vegetation requires a comprehensive understanding of how vegetation structure affects UHI. The effects of horizontal structure on land surface temperature …


Optical Remote Sensing Of Oil Spills In The Gulf Of Mexico, Shaojie Sun Nov 2018

Optical Remote Sensing Of Oil Spills In The Gulf Of Mexico, Shaojie Sun

USF Tampa Graduate Theses and Dissertations

Assessment of oil spills in the ocean using passive remote sensing (i.e., reflected sun light) faces two challenges: detect oil presence/absence and quantify oil volume. While the optical properties of oil allow it to be differentiated from the surrounding marine environment, sun glint can facilitate oil presence/absence detection because the oil-water spatial contrast is enhanced due to wave dampening. However, sun glint also modulates the magnitude and shape of the spectral reflectance of surface oil. In addition to this difficulty, the most critical challenge is how to quantify oil volume (or thickness) through remote sensing. To date, such quantifications have …


Enhancement Of Rainfall-Triggered Shallow Landslide Hazard Assessment At Regional And Site Scales Using Remote Sensing And Slope Stability Analysis Coupled With Infiltration Modeling, Thilanki Maneesha Dahigamuwa Rajaguru Mudiyanselage Nov 2018

Enhancement Of Rainfall-Triggered Shallow Landslide Hazard Assessment At Regional And Site Scales Using Remote Sensing And Slope Stability Analysis Coupled With Infiltration Modeling, Thilanki Maneesha Dahigamuwa Rajaguru Mudiyanselage

USF Tampa Graduate Theses and Dissertations

Landslides cause significant damage to property and human lives throughout the world. Rainfall is the most common triggering factor for the occurrence of landslides. This dissertation presents two novel methodologies for assessment of rainfall-triggered shallow landslide hazard. The first method focuses on using remotely sensed soil moisture and soil surface properties in developing a framework for real-time regional scale landslide hazard assessment while the second method is a deterministic approach to landslide hazard assessment of the specific sites identified during first assessment. In the latter approach, landslide inducing transient seepage in soil during rainfall and its effect on slope stability …


A Review Of Fractals In Karst, Eulogio Pardo-Igúzquiza, Peter A. Dowd, Juan J. Durán, Pedro Robledo-Ardila Nov 2018

A Review Of Fractals In Karst, Eulogio Pardo-Igúzquiza, Peter A. Dowd, Juan J. Durán, Pedro Robledo-Ardila

International Journal of Speleology

Many features of a karst massif can either be modelled using fractal geometry or have a fractal distribution. For the exokarst, typical examples include the geometry of the landscape and the spatial location and size-distribution of karst depressions. Typical examples for the endokarst are the geometry of the three-dimensional network of karst conduits and the length-distribution of caves. In addition, the hydrogeological parameters of the karst massif, such as hydraulic conductivity, and karst spring hydrographs may also exhibit fractal behaviour. In this work we review the karst features that exhibit fractal behaviour, we review the literature in which they are …


Do Slow Slip Events Trigger Large And Great Megathrust Earthquakes?, N. Voss, Timothy H. Dixon, Z. Liu, Rocco Malservisi, M. Protti, S. Schwartz Oct 2018

Do Slow Slip Events Trigger Large And Great Megathrust Earthquakes?, N. Voss, Timothy H. Dixon, Z. Liu, Rocco Malservisi, M. Protti, S. Schwartz

School of Geosciences Faculty and Staff Publications

Slow slip events have been suggested to trigger subduction earthquakes. However, examples to date have been poorly recorded, occurring offshore, where data are sparse. Better understanding of slow slip events and their influence on subsequent earthquakes is critical for hazard forecasts. We analyze a well-recorded event beginning 6 months before the 2012 Mw (moment magnitude) 7.6 earthquake in Costa Rica. The event migrates to the eventual megathrust rupture. Peak slip rate reached a maximum of 5 mm/day, 43 days before the earthquake, remaining high until the earthquake. However, changes in Mohr-Coulomb failure stress at the hypocenter were small (0.1 …


Remote Estimation Of Surface Water PCo2 In The Gulf Of Mexico, Shuangling Chen Oct 2018

Remote Estimation Of Surface Water PCo2 In The Gulf Of Mexico, Shuangling Chen

USF Tampa Graduate Theses and Dissertations

Surface ocean partial pressure of CO2 (pCO2) is a critical parameter in the quantification of air-sea CO2 flux, which further plays an important role in quantifying the global carbon budget and understanding ocean acidification. The demand for a clearer understanding of how, and how fast, the ocean is changing due to atmospheric CO2 absorption, requires accurate and synoptic estimation of surface pCO2.

Surface ocean pCO2 is mainly controlled by four oceanic processes – thermodynamics, ocean mixing, biological activities, and air-sea CO2 exchange. Surface ocean pCO2 …


Ice And Guano Deposits In El Malpais Lava Tubes: Potential Paleoclimate Archives For The Southwest United States, Dylan S. Parmenter Oct 2018

Ice And Guano Deposits In El Malpais Lava Tubes: Potential Paleoclimate Archives For The Southwest United States, Dylan S. Parmenter

USF Tampa Graduate Theses and Dissertations

Three ice cores and one guano core were obtained from lava tubes in El Malpais National Monument, New Mexico, in the Southwest United States. A large hiatus in the Bat Cave guano record, resulting from mining activities in the early 1900's, left us with only ~50 years of data (from AD 1955-2006) to use in analysis. 13C values in guano (-18 to -11.6‰) primarily fall within the range of C4 plants, and likely indicate a tendency of Tadarida brasiliensis to feed on insects over grasslands to the North or South of the park. Variations in 13C values for this period …


Morphodynamics Of Shell Key And Mullet Key Barrier Islands: Their Origin And Development, Zachary J. Westfall Oct 2018

Morphodynamics Of Shell Key And Mullet Key Barrier Islands: Their Origin And Development, Zachary J. Westfall

USF Tampa Graduate Theses and Dissertations

Shell Key and Mullet Key are two sandy barrier islands on the West Central Florida coast near the mouth of Tampa Bay. These islands are part of an interconnected barrier-inlet system that includes Pass-a-Grille (PAG) and Bunces Pass. Shell Key is a relatively new island about 40-years of age that formed in between the two inlets of Bunces Pass and PAG. Mullet Key is an island to the south of Shell Key situated between Bunces Pass and the main Tampa Bay channel that has demonstrated large scale upward shoaling events. Using numerical modeling, the wave and tidal conditions at the …


The Cyrilka Cave—The Longest Crevice-Type Cave In Czechia: Structural Controls, Genesis, And Age, Jan Lenart, Martin Kašing, Petr Tábořík, Natalia Piotrowska, Jacek Pawlyta Oct 2018

The Cyrilka Cave—The Longest Crevice-Type Cave In Czechia: Structural Controls, Genesis, And Age, Jan Lenart, Martin Kašing, Petr Tábořík, Natalia Piotrowska, Jacek Pawlyta

International Journal of Speleology

The Cyrilka Cave is the second longest pseudokarst cave and the longest crevice-type cave in Czechia. Developed within the headscarp area of a deep-seated landslide, the cave became a focus of scientific research in recent years when new passages were discovered. Structural analysis provided a general tectonic plan of the cave, as well as more detailed data on geometry and kinematics of the relaxed rock massif. The primary structure of NNE- to ENE-striking bedding is broken by a system of NNE-striking fissures interconnected by two continuous ENE-striking dextral fracture zones. Abundant signs of recent sinistral strike-slips within the rock massif …


Application Of Image Recognition Technology To Foraminiferal Assemblage Analyses, Christian Helmut Gfatter Oct 2018

Application Of Image Recognition Technology To Foraminiferal Assemblage Analyses, Christian Helmut Gfatter

USF Tampa Graduate Theses and Dissertations

Analyses of foraminiferal assemblages involve time consuming microscopic assessment of sediment samples. Image recognition software, which systematically matches features within sample images against an image library, is widely used in contexts ranging from law enforcement to medical research. At present, scientific applications such as identification of specimens in plankton samples utilize flow through systems in which samples are suspended in liquid and pass through a beam of light where the images are captured using transmitted light. Identification of foraminifers generally utilizes reflected light, because most shells are relatively opaque.

My goal was to design and test a protocol to directly …


On Biospeleothems From A Venezuelan Tepui Cave: U-Th Dating, Growth Rates, And Morphology, Joyce Lundberg, Charles Brewer-Carías, Donald A. Mcfarlane Oct 2018

On Biospeleothems From A Venezuelan Tepui Cave: U-Th Dating, Growth Rates, And Morphology, Joyce Lundberg, Charles Brewer-Carías, Donald A. Mcfarlane

International Journal of Speleology

Seven silica biospeleothems from Cueva Charles Brewer, Chimantá Plateau, Venezuela have been successfully U-Th dated despite very low U and high detrital Th concentrations. Growth rates are low, between ~100 to ~800 µm/ka, and are greater closer to water level. Dates in unaltered material are in good stratigraphic order, but secondary silicification may compromise the U-Th system, yielding unreliable sequences of ages. Detritally-enriched layers correlate with global climate cycles of the Late Quaternary, in particular the cooler, drier phases of MIS 5d, 5a, and 4. SEM studies indicate that the peloidal material is made up of silica nano-particles assembled to …


Correlates Of Rate Heterogeneity In Avian Ecomorphological Traits, A. M. Chira, C. R. Cooney, Jen A. Bright, E. J. R. Capp, E. C. Hughes, C. J. A. Moody, L. O. Nouri, Z. K. Varley, G. H. Thomas Oct 2018

Correlates Of Rate Heterogeneity In Avian Ecomorphological Traits, A. M. Chira, C. R. Cooney, Jen A. Bright, E. J. R. Capp, E. C. Hughes, C. J. A. Moody, L. O. Nouri, Z. K. Varley, G. H. Thomas

School of Geosciences Faculty and Staff Publications

Heterogeneity in rates of trait evolution is widespread, but it remains unclear which processes drive fast and slow character divergence across global radiations. Here, we test multiple hypotheses for explaining rate variation in an ecomorphological trait (beak shape) across a globally distributed group (birds). We find low support that variation in evolutionary rates of species is correlated with life history, environmental mutagenic factors, range size, number of competitors, or living on islands. Indeed, after controlling for the negative effect of species' age, 80% of variation in species‐specific evolutionary rates remains unexplained. At the clade level, high evolutionary rates are associated …


Sulfur (34S/32S) Isotope Composition Of Gypsum And Implications For Deep Cave Formation On The Nullarbor Plain, Australia, Matej Lipar, Mateja Ferk, Sonja Lojen, Milo Barham Sep 2018

Sulfur (34S/32S) Isotope Composition Of Gypsum And Implications For Deep Cave Formation On The Nullarbor Plain, Australia, Matej Lipar, Mateja Ferk, Sonja Lojen, Milo Barham

International Journal of Speleology

Large deep caves with little relation to surface topography are distinctive karst features on the Nullarbor Plain of Australia. The presence of gypsum deposits and chemoautotrophic bacteria within the caves have been suggested as evidence for cave formation and (or) enlargement via sulfuric acid speleogenesis. To test this hypothesis, the stable sulfur isotope compositions (δ34S) of both cave gypsum and surface gypsum were measured. Analyses yielded relatively high, positive δ34S values from both cave gypsum and surface gypsum, arguing against gypsum genesis via microbial chemoautotrophy, and more broadly, sulfuric acid speleogenesis. Instead, the gypsum is interpreted …


Evidence For Subsurface Origin Of Boulder Caves, Roofed Slots And Boulder-Filled Canyons (Broumov Highland, Czechia), Filip Duszyński, Kacper Jancewicz, Piotr Migoń Sep 2018

Evidence For Subsurface Origin Of Boulder Caves, Roofed Slots And Boulder-Filled Canyons (Broumov Highland, Czechia), Filip Duszyński, Kacper Jancewicz, Piotr Migoń

International Journal of Speleology

The backslope of a sandstone cuesta in the Broumov Highland (Czechia) is cut by a complex network of canyons. Long sections of canyons have thick boulder fills which are difficult to reconcile with simple rock fall and talus development scenario. Boulder caves occur within these fills and their lowermost parts are drained by streams that evacuate fine loose sandy material produced by weathering and mechanical erosion. These boulder fills are explained as largely in situ, residual features, left after subsurface selective disintegration of rock mass, mainly joint-guided, and removal of grains by underground water. Evacuation of fines leaves voids …


Tracking Submarine Volcanic Activity At Monowai: Constraints From Long‐Range Hydroacoustic Measurements, D. Metz, A. B. Watts, I. Grevemeyer, Mel Rodgers Sep 2018

Tracking Submarine Volcanic Activity At Monowai: Constraints From Long‐Range Hydroacoustic Measurements, D. Metz, A. B. Watts, I. Grevemeyer, Mel Rodgers

School of Geosciences Faculty and Staff Publications

Monowai is a submarine volcanic center in the Kermadec Arc, Southwest Pacific Ocean. In the past, activity at the volcano had been intermittently observed in the form of fallout at the sea surface, discolored water, changes in seafloor topography, and T phase seismicity, but there is no continuous record for more recent years. In this study, we investigated 3.5 years of recordings at a hydrophone array of the International Monitoring System, located near Juan Fernández Islands, for long‐range underwater sound waves from Monowai. Results from direction‐of‐arrival calculations and density‐based spatial clustering indicate that 82 discrete episodes of activity occurred between …


Replacement Times Of A Spectrum Of Elements In The North Atlantic Based On Thorium Supply, Christopher T. Hayes, Robert F. Anderson, Hai Cheng, Tim M. Conway, R. L. Edwards, Martin Q. Fleisher, Peng Ho, Kuo-Fang Huang, Seth G. John, William M. Landing Sep 2018

Replacement Times Of A Spectrum Of Elements In The North Atlantic Based On Thorium Supply, Christopher T. Hayes, Robert F. Anderson, Hai Cheng, Tim M. Conway, R. L. Edwards, Martin Q. Fleisher, Peng Ho, Kuo-Fang Huang, Seth G. John, William M. Landing

School of Geosciences Faculty and Staff Publications

The measurable supply of 232Th to the ocean can be used to derive the supply of other elements, which is more difficult to quantify directly. The measured inventory of an element divided by the derived supply yields a replacement time estimate, which in special circumstances is related to a residence time. As a proof of concept, Th‐based supply rates imply a range in the replacement times of the rare earth elements in the North Atlantic that is consistent with the chemical reactivity of rare earth elements related to their ionic charge density. Similar estimates of replacement times for the …