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Articles 31 - 60 of 2663
Full-Text Articles in Earth Sciences
Differences In Gas-Bearing Properties Of Deep And Shallow Coal Reservoirs And Their Implications For Coalbed Methane Production In The Western Section Of The Southern Margin Of The Junggar Basin, Xinjiang, Mi Julei, Zhao Changyong, Yang Zhaobiao, Wang Pengli, Li Erting, Zhang Baoxin, Bai Haifeng, Gao Xiuwei, Wang Jianan
Differences In Gas-Bearing Properties Of Deep And Shallow Coal Reservoirs And Their Implications For Coalbed Methane Production In The Western Section Of The Southern Margin Of The Junggar Basin, Xinjiang, Mi Julei, Zhao Changyong, Yang Zhaobiao, Wang Pengli, Li Erting, Zhang Baoxin, Bai Haifeng, Gao Xiuwei, Wang Jianan
Coal Geology & Exploration
Background In recent years, breakthroughs have been constantly achieved in the production of coalbed methane (CBM) at burial depths exceeding 2 000 m in China, with the gas-bearing properties of coal reservoirs identified as a primary geological parameter controlling the CBM production. The western section of the southern margin of the Junggar Basin (also referred to as the study area) hosts abundant CBM resources. In this section, the burial depths of extensive coal seams exceed 2 000 m. However, limited explorations of deep coal reservoirs have restricted a systematic understanding of the gas-bearing properties of coal reservoirs in the study …
Sensitivity Analysis Of Factors Influencing Water Redistribution In Vadose Zones Under Coal Mining Disturbance In Ecologically Vulnerable Areas, Wang Ao, Liu Shiliang, Wang Shanlin, Zheng Yusheng, Wang Tengye, Wang Zuzhen, Mao Deqiang
Sensitivity Analysis Of Factors Influencing Water Redistribution In Vadose Zones Under Coal Mining Disturbance In Ecologically Vulnerable Areas, Wang Ao, Liu Shiliang, Wang Shanlin, Zheng Yusheng, Wang Tengye, Wang Zuzhen, Mao Deqiang
Coal Geology & Exploration
Objective Coal mining-induced disturbance leads to water redistribution in the vadose zones of mining areas. The sensitivity analysis of the factors influencing this redistribution holds critical significance for the reconstruction of eco-geological environments and the sustainable economic development in mining areas. Methods Against the engineering background of the Yushen mining area characterized by wind-blown sandy terrain in northern Shaanxi Province, this study analyzed the primary factors influencing water redistribution in the vadose zone under coal mining disturbance. Accordingly, 18 COMSOL Multiphysics numerical models for water redistribution in the vadose zone under coal mining disturbance were constructed through orthogonal experiments. Using …
Simulation Of Groundwater Flow Field Evolution And Water Inrush Risks Under The Deep-Well Reinjection Of High-Tds Mine Water, Liu Qi, Sun Yajun, Fan Jianguo, Tan Xianfeng, Xiao Shengxin, Yang Chuanwei, Chen Weiyang, Chen Ge
Simulation Of Groundwater Flow Field Evolution And Water Inrush Risks Under The Deep-Well Reinjection Of High-Tds Mine Water, Liu Qi, Sun Yajun, Fan Jianguo, Tan Xianfeng, Xiao Shengxin, Yang Chuanwei, Chen Weiyang, Chen Ge
Coal Geology & Exploration
Objective The deep-well reinjection of mine water results in a regional groundwater level rise to varying degrees, possibly inducing hydrogeological hazards such as floor water inrushes or water inrushes along faults. In this context, determining the evolutionary pattern of the groundwater flow field under long-term mine water reinjection and conducting reinjection safety assessments play a critical role in ensuring both the safety of mine water reinjection and water conservation-based coal mining.Methods This study examined the reinjection of mine water in a coal mine within the Juye coalfield, North China. Based on the geological conditions for mine water reinjection in …
Current Status And Future Trend Of Research On Underground Borehole Measurement Technology For Coal Mines, Chen Long, Yang Dongdong, Li Quanxin, Chu Zhiwei, Zhang Jiguan, Chen Xiang
Current Status And Future Trend Of Research On Underground Borehole Measurement Technology For Coal Mines, Chen Long, Yang Dongdong, Li Quanxin, Chu Zhiwei, Zhang Jiguan, Chen Xiang
Coal Geology & Exploration
Background Underground borehole measurement emerges as a core technology for the safe production of coal mines. Its multi-parameter measurements, data accuracy, data transmission rate, and reliability directly influence the timeliness of early warning for disasters, the operating stability of instruments, the accuracy of borehole assessment, and the scientific rigor of intelligent decision-making under complex deep geological conditions. Advances So far, the measurement while drilling (MWD) and post-drilling borehole visualization techniques have developed into a diversified technological system. Specifically, the MWD technique has achieved a leap from wireline to wireless transmission, obviating the reliance on wireline drill rods in traditional measurement …
An Automated Attitude Control Method For The Rotary Steerable System And Its Validation Through Hardware-In-The-Loop Simulation, Zhang Nan, Ren Bai’An, Li Fei, Liu Ziqi, Lyu Fangxing
An Automated Attitude Control Method For The Rotary Steerable System And Its Validation Through Hardware-In-The-Loop Simulation, Zhang Nan, Ren Bai’An, Li Fei, Liu Ziqi, Lyu Fangxing
Coal Geology & Exploration
Objective The traditional manual control mode of a rotary steerable system (RSS) faces challenges, including response delay and low control efficiency. To address these challenges, this study proposed a closed-loop automated attitude control method for the RSS and verified its effectiveness through hardware-in-loop (HIL) simulation. Methods This study focuses on the drilling process of a point-the-bit RSS. In the case of deviations between measured and target attitudes, the control parameters were calculated based on the deviation signals using a closed-loop controller, driving the RSS actuator to conduct trajectory correction. Afterward, the actual attitude was yielded and then entered the input …
Co2-Water Displacement Characteristics Of Saturated Sandstones With Different Pore Structures, Liu Ting, Li Jinglin, Li Yi, Dan Wendong, Diao Yujie, Ma Xin
Co2-Water Displacement Characteristics Of Saturated Sandstones With Different Pore Structures, Liu Ting, Li Jinglin, Li Yi, Dan Wendong, Diao Yujie, Ma Xin
Coal Geology & Exploration
Objective The pore structures of clastics play a crucial role in assessing the potential of saline aquifers for geologic CO2 sequestration. Current studies on pore structures during CO2 sequestration focus primarily on artificial cores. However, compared to artificial cores, natural cores feature more complex pore size distributions and stronger heterogeneity. Methods This study examined a natural core from deep reservoirs in the Ordos Basin and two artificial cores with different porosities through CO2-water displacement experiments under water-saturated conditions. Using a nuclear magnetic resonance (NMR) analysis and imaging system for multiphase fluid displacement, this study analyzed the …
Multi-Field Coupling-Based Numerical Simulations Of Co2 Storage In Saline Aquifers: A Case Study Of The Dingji Coal Mine, Huainan Mining Area, Li Dianshang, Zheng Sijian, Liao Qingfa, Miao Wei, Tian Yuchen, Zhang Helong, Liu Yanzhi, Liu Shiqi
Multi-Field Coupling-Based Numerical Simulations Of Co2 Storage In Saline Aquifers: A Case Study Of The Dingji Coal Mine, Huainan Mining Area, Li Dianshang, Zheng Sijian, Liao Qingfa, Miao Wei, Tian Yuchen, Zhang Helong, Liu Yanzhi, Liu Shiqi
Coal Geology & Exploration
Background Saline aquifers are characterized by extensive distribution, abundant reserves, and substantial potential for CO2 storage, establishing them as the most promising geological media for carbon capture, utilization, and storage (CCUS). CO2 storage in saline aquifers plays a crucial role in mitigating the greenhouse effect and achieving the goals of peak carbon dioxide emissions and carbon neutrality. Thoroughly investigating CO2 storage in deep saline aquifers within the Huainan mining area helps alleviate the regional pressure of carbon emission reduction while also providing important support for expanding the technical pathways of CCUS and promoting its engineering applications. Methods …
Environmental Risk Assessment Of Co2 Storage Combined With The Overlying Coal Mining, Gu Leiyu, Li Wenhui, Huang Wei, Zhou Quanchao, Zhu Yalong, Li Xiaying, Liu Guizhen, Li Qi
Environmental Risk Assessment Of Co2 Storage Combined With The Overlying Coal Mining, Gu Leiyu, Li Wenhui, Huang Wei, Zhou Quanchao, Zhu Yalong, Li Xiaying, Liu Guizhen, Li Qi
Coal Geology & Exploration
Objective Carbon capture, utilization, and storage (CCUS) technology serves as a key method for carbon neutrality. However, large-scale engineering applications of CCUS are still confronted with serious challenges of environmental risks. Therefore, systematic environmental risk assessment plays an essential role in ensuring the environmental safety and social acceptability of CO2 geological storage projects. Methods Targeting the CO2 geological storage project combined with overlying coal mining in Zhengning County, Gansu Province, this study performed the environmental risk assessment of CO2 leakage based on the requirements of the Technical Guideline on Environmental Risk Assessment for Carbon Dioxide Capture, Utilization, …
Advances In Research On The Policies, Technologies, And Demonstration Projects Of Geologic Co2 Sequestration In China, Zhao Yue, Yang Xuechao, Chen Xiaodong, Chang Jia, Wei Hengfei, Liu Zhibang, Liu Hui
Advances In Research On The Policies, Technologies, And Demonstration Projects Of Geologic Co2 Sequestration In China, Zhao Yue, Yang Xuechao, Chen Xiaodong, Chang Jia, Wei Hengfei, Liu Zhibang, Liu Hui
Coal Geology & Exploration
Background Carbon capture, utilization, and storage (CCUS) is considered a key technology to promote large-scale carbon dioxide (CO2) emission reduction. Against the backdrop of achieving its goals of carbon neutrality and peak carbon dioxide emissions, China faces a tremendous challenge of CO2 emission reduction. This situation will provide new driving forces for the development of geologic CO2 sequestration while also imposing higher requirements for technical innovation and industrialization of the technology. Methods and Advances This study systematically reviews the development process of policies on CCUS of China over the past two decades, with over 30 policies …
Mechanisms Governing Co2 Mineral Trapping And Cementitious Activity Degradation Of Solid Waste-Based Backfill Materials, Liu Zhifei, Chen Qingting, Li Hongjie, Wang En, Zhao Heming
Mechanisms Governing Co2 Mineral Trapping And Cementitious Activity Degradation Of Solid Waste-Based Backfill Materials, Liu Zhifei, Chen Qingting, Li Hongjie, Wang En, Zhao Heming
Coal Geology & Exploration
Objective This study investigated three types typical alkaline industrial solid waste: steel slag, fly ash, and bottom ash, highlighting the differences in their CO2 mineral trapping efficiency and the degradation patterns of their cementitious activity after carbon fixation. The purpose is to reveal the mechanisms underlying CO2 mineral trapping in solid waste and evaluate their application potential in backfill engineering, thereby promoting the synergistic development of industrial solid waste recycling and carbon emission reduction. Methods Through experiments on CO2 mineral trapping using the direct wet method, the kinetics and product characteristics of solid waste-CO2 interactions were …
Impacts Of Anti-Rock Burst Multistage Hydraulic Fracturing Using Horizontal Wells On Mining Roadways And Fracture Control Techniques: A Case Study Of Mining Facein The Zhaoxian Coal Mine, Shaanxi Province, Liu Xiugang, Jiang Zaibing, Yang Juan, Liu Mingjun, Pang Tao, Wu Weixing, Tu Xiaolong, Mo Haitao, Guo Xiaolong, Du Xinfeng
Impacts Of Anti-Rock Burst Multistage Hydraulic Fracturing Using Horizontal Wells On Mining Roadways And Fracture Control Techniques: A Case Study Of Mining Facein The Zhaoxian Coal Mine, Shaanxi Province, Liu Xiugang, Jiang Zaibing, Yang Juan, Liu Mingjun, Pang Tao, Wu Weixing, Tu Xiaolong, Mo Haitao, Guo Xiaolong, Du Xinfeng
Coal Geology & Exploration
Objective Surface multistage hydraulic fracturing of hard roofs using horizontal wells serves as an important technique for rock burst control in mines. However, fracturing technique under improper control might pose adverse impacts on excavated mining roadways underground, causing roadway deformation, mesh failure with block falling, and the flow of fracturing fluids into the roadways. Methods This study investigated certain mining face of the Zhaoxian Coal Mine in the Yonglong mining area, Shaanxi Province. Targeting different characteristics and phenomena of roadways following hydraulic fracturing, this study analyzed the reasons why fracturing fluids flowed into roadways during hydraulic fracturing using theoretical analysis, …
Lithofacies Paleogeography Of The Ordovician Kelimoli-Lashizhong Formations Along The Western Margin Of The Ordos Basin, Wang Weibin, Ma Zhanrong, Hu Aiping, Zhang Qian, Li Wenhou, Chen Qiang, Ma Yao, Wang Yanbo
Lithofacies Paleogeography Of The Ordovician Kelimoli-Lashizhong Formations Along The Western Margin Of The Ordos Basin, Wang Weibin, Ma Zhanrong, Hu Aiping, Zhang Qian, Li Wenhou, Chen Qiang, Ma Yao, Wang Yanbo
Coal Geology & Exploration
Objective The period during the deposition of the Middle-Late Ordovician Kelimoli-Lashizhong formations witnessed a key transition of the tectonic framework along the western margin of the Ordos Basin. Investigating the lithofacies paleogeography of these formations can reveal the tectono-sedimentary responses during this period, thereby providing a basis for the resource potential prediction, exploration, and exploitation of natural gas in the study area. Methods Using field section observations, core observations, and log interpretations, as well as previous research results, this study comprehensively analyzed the Middle-Late Ordovician strata in the Ordos Basin from the perspectives of stratigraphy, sedimentary system division, and sedimentary …
Physical Simulation Experiments On 4d Visualization Of Dynamic Methane Diffusion And Adsorption In Low-Porosity And Low-Permeability Coals, Liu Tong, Jiao Baizhuo, Lin Baiquan, Sang Shuxun, Yang Wei, Liu Shiqi, Liu Ting, Li He, Yang Mingxing
Physical Simulation Experiments On 4d Visualization Of Dynamic Methane Diffusion And Adsorption In Low-Porosity And Low-Permeability Coals, Liu Tong, Jiao Baizhuo, Lin Baiquan, Sang Shuxun, Yang Wei, Liu Shiqi, Liu Ting, Li He, Yang Mingxing
Coal Geology & Exploration
Objective and Method The diffusivity of methane (CH4) in coal seams significantly influences the surface extraction of coalbed methane (CBM) and underground gas drainage. However, the visualized characterization of the diffusion and migration processes of CH4 in coals remains challenging. To address this issue, this study systematically demonstrated the similarity between krypton (Kr) and CH4 in their adsorption and diffusion behavior in coals. Utilizing Kr—a gas with high X-ray attenuation—as a tracer substitute for CH4, this study achieved the transparent observation of the dynamic gas migration process in low-porosity, low-permeability, and heterogeneous coals using …
Mechanisms Underlying Sodium Enrichment In Coals In The Dananhu Mining Area, Turpan-Hami Basin, Qi Zhenghui, Sun Fanxing, Wang Wenlong, Huang Chunhui, Liang Kaihua, Huang Yangyang, Shao Longyi
Mechanisms Underlying Sodium Enrichment In Coals In The Dananhu Mining Area, Turpan-Hami Basin, Qi Zhenghui, Sun Fanxing, Wang Wenlong, Huang Chunhui, Liang Kaihua, Huang Yangyang, Shao Longyi
Coal Geology & Exploration
Background The Dananhu mining area boasts abundant coal resources, serving as a significant coal-fired power generation base in Xinjiang, China. However, the high sodium (Na) content in coals within the mining area tends to cause fouling and slagging during coal combustion, severely affecting the clean and efficient utilization of coal resources in the area. Methods and Results epresentative samples collected from the major mineable coal seams were subjected to proximate and ash-composition analyses. The analytical results show that the coal samples had low ash and sulfur contents and high volatile content. SiO2 predominated in the ash components, followed by …
Mechanisms Behind Soil Water Evaporation And Infiltration During Long-Term Microbial Reclamation In Coal Mining-Induced Subsidence Areas In Northern Shaanxi Province, China, Ke Zengming, Bi Yinli, Yang Wei
Mechanisms Behind Soil Water Evaporation And Infiltration During Long-Term Microbial Reclamation In Coal Mining-Induced Subsidence Areas In Northern Shaanxi Province, China, Ke Zengming, Bi Yinli, Yang Wei
Coal Geology & Exploration
Background Water scarcity is identified as an important factor restricting ecological restoration in arid and semi-arid mining areas. The application of microbial reclamation technologies, especially inoculation with Arbuscular mycorrhizal fungi (AMF), has achieved encouraging ecological effects in mining areas. In this case, investigating soil water movement and its controlling factors in mining areas undergoing long-term microbial reclamation is a key scientific issue for understanding the long-term ecological restoration mechanisms of AMF. Methods This study investigated the microbial reclamation base in the coal mining-induced subsidence area of the Daliuta coal mine of northern Shaanxi Province, located in the middle reaches of …
Water Quality Characteristics And Reutilization Of Goaf Water From Shallow Coal Seams Within The Datong Mining Area, Shanxi Province, China, Li Jun, Gui Herong, Ding Pengfei, Chen Yongqing, Wan Heyong, Li Weiqi, Huang Dawei, Peng Weihua, Hu Yang, Guo Yan
Water Quality Characteristics And Reutilization Of Goaf Water From Shallow Coal Seams Within The Datong Mining Area, Shanxi Province, China, Li Jun, Gui Herong, Ding Pengfei, Chen Yongqing, Wan Heyong, Li Weiqi, Huang Dawei, Peng Weihua, Hu Yang, Guo Yan
Coal Geology & Exploration
Objective The Datong mining area in Shanxi Province of China faces serious threats from goaf water hazards, while the goaf water drainage is constrained by environmental protection policies. Therefore, the reutilization of goaf water serves as an effective approach to eliminating mine water hazards, protecting water environments, and mitigating water scarcity in the mining area. Methods This study investigated goaf water from shallow coal seams in the Datong mining area. Based on water quality assessment theories and a range of hydrogeochemical indices, including saturation index (SI), chloro-alkaline index (CAI), and sodium adsorption ratio (SAR), this study conducted a joint determination …
Advances In Research And Future Prospects Of Borehole Geophysical Prospecting Technology For Coal Mines, Li Ping, Wei Rong, Fan Tao, Zhao Rui, Jiang Bici, Tian Xiaochao, Wang Bingchun
Advances In Research And Future Prospects Of Borehole Geophysical Prospecting Technology For Coal Mines, Li Ping, Wei Rong, Fan Tao, Zhao Rui, Jiang Bici, Tian Xiaochao, Wang Bingchun
Coal Geology & Exploration
Background Borehole geophysical prospecting technology for coal mines integrates the advantages of both drilling and geophysical prospecting. Accordingly, multiple critical advances have been achieved in its applications to the technologies and equipment for intelligent coal mining in recent years, enabling long-distance, relatively high-precision geological exploration. This technology plays an increasingly important role in a range of fields, including deep mineral resource exploration and the reconnaissance surveys of hidden disaster-causing factors, providing robust support for safe and efficient coal mining. Advances This study systematically reviews the development history of borehole geophysical prospecting technology, elaborating advances in research on the methodology, theories, …
Application Of Seismic-While-Tunnelling Detection In The Identification Of Densely Distributed Sub-Seismic Faults, Li Haodang, Li Kang, Chen Jian, Song Xiaozhong, Jin Dan, Wang Baoli
Application Of Seismic-While-Tunnelling Detection In The Identification Of Densely Distributed Sub-Seismic Faults, Li Haodang, Li Kang, Chen Jian, Song Xiaozhong, Jin Dan, Wang Baoli
Coal Geology & Exploration
Objective and Method Densely distributed sub-seismic faults have emerged as a major hidden disaster-causing geological factor, heavily influencing both the production efficiency and operational safety of coal mines. To achieve precise advance detection of underground sub-seismic faults in coal mines, this study designed a geological model. Using seismic-while-tunneling (SWT) advance detection technology for roadways of coal mines, this study investigated the geological situation of sub-seismic faults through forward modeling. Furthermore, it explored the seismic image characteristics of these faults obtained using the SWT observation system under varying survey line lengths and geophone spacing values. Results and Conclusions The forward modeling …
Aquifer Distribution In Lukobe Ward, Morogoro Municipality, Tanzania: Mapped Resources For Sustainable Water Access, Kelvin K. Kayuni
Aquifer Distribution In Lukobe Ward, Morogoro Municipality, Tanzania: Mapped Resources For Sustainable Water Access, Kelvin K. Kayuni
Tanzania Journal of Science
In response to the ongoing challenges posed by the scarcity of reliable fresh-water sources in Lukobe Ward, Morogoro Municipality, Tanzania, this study applied an integrated approach that combines geospatial and geophysical datasets to identify previously undocumented aquifers. The datasets utilized include an apparent density map generated from high-resolution GGMPlus satellite gravity data, a geological map (Quarter Degree Sheet 183), a water drainage map, and a slope map created from a digital elevation model (DEM). The analysis successfully identified four unconfined, saprolitic aquifers in the study area, designated as aquifers A, B, C, and D. These aquifers span areas of 12.2 …
Fast Dispersion-Curve Inversion Using Automatic Differentiation Gradient-Based Calculation, Theodosius Marwan Irnaka, Eddy Hartantyo
Fast Dispersion-Curve Inversion Using Automatic Differentiation Gradient-Based Calculation, Theodosius Marwan Irnaka, Eddy Hartantyo
Makara Journal of Science
Surface wave inversion is a crucial technique in geophysics for subsurface imaging. However, traditional methods can be computationally intensive, especially for complex models. This study introduces automatic differentiation (AD) as an efficient alternative to finite difference (FD) methods for gradient calculation in surface wave inversion. We compare AD and FD methods using three synthetic examples of varying complexity. Our results demonstrate that AD is significantly faster, with speed improvements of 3 to 12 times over FD, depending on model complexity. Moreover, AD requires up to 3 times less memory than FD. In terms of accuracy, AD provides gradient calculations that …
A Cave In Miocene Conglomerate: The Törökpince-Abaliget Cave System, Hungary, Krisztina Sebe, Piroska Pazonyi, Márton Bauer, Bálint Szappanos, Márton Szabó, Zoltán Szentesi, Mihály Gasparik, Ákos Juhász, Luca Pandolfi, Máté Gregorits, József Haász, Ágnes Novothny, Zsófia Ruszkiczay-Rüdiger
A Cave In Miocene Conglomerate: The Törökpince-Abaliget Cave System, Hungary, Krisztina Sebe, Piroska Pazonyi, Márton Bauer, Bálint Szappanos, Márton Szabó, Zoltán Szentesi, Mihály Gasparik, Ákos Juhász, Luca Pandolfi, Máté Gregorits, József Haász, Ágnes Novothny, Zsófia Ruszkiczay-Rüdiger
International Journal of Speleology
Conglomerate caves are rare, and only a few have been described in the scientific literature. Here, we present a newly discovered and significant cave system in SW Hungary, comprising over 500 m of upper passages and a shorter, lower section of a through-cave developed in Lower–Middle Miocene conglomerates. The formation of these cave passages was controlled chiefly by bedding and fractures. Dissolution has produced typical karstification morphologies, whereas corrasion, granular disintegration, and rock collapse have also played a role in shaping the cave. The cave is dominated by vadose-zone morphologies, but sediment infills indicating upward water flow, along with ceiling …
Macroinvertebrate Community Dynamics In A Recovering, Hypersaline Estuary, Catherine M. Eckert, Claudia A. Tamez, Erin E. Easton, David Hicks
Macroinvertebrate Community Dynamics In A Recovering, Hypersaline Estuary, Catherine M. Eckert, Claudia A. Tamez, Erin E. Easton, David Hicks
School of Earth, Environmental, & Marine Sciences Faculty Publications
The Bahia Grande is a 6,500—acre tidal basin located at the southernmost tip of Texas. Tidal flow into this coastal estuary was cut off in the 1930s, causing the basin to dry up for ~70 y. A pilot channel connecting the Bahia Grande to tidal waters was constructed in 2005, allowing flooding of the basin to occur. Throughout the period reported herein (2005–2019), the system remained characterized by persistent spatial and temporal episodes of extreme hypersalinity (>70)—a critical factor influencing estuarine community composition and driving key ecological processes. With additional rehabilitation actions forthcoming, characterization of the estuary is essential …
What Does Graptolite Origination And Extinction Reveal About The Cause Of The Late Ordovician Mass Extinction?, Charles E. Mitchell, H. David Sheets, Michael J. Melchin, Chris Holmden
What Does Graptolite Origination And Extinction Reveal About The Cause Of The Late Ordovician Mass Extinction?, Charles E. Mitchell, H. David Sheets, Michael J. Melchin, Chris Holmden
Computer and Data Science Faculty Publications
Assesses the macroevolutionary turnover of paleotropical planktic graptolites during the Late Ordovician Mass Extinction (LOME) via automated sequencing and capture-mark-recapture modeling. Graptolites exhibited a succession of turnover pulses (sensu Elizabeth Vrba) that were coincident with the main phases of the Hirnantian glaciation and during which the Diplograptina experienced declining metapopulation size, elevated extinction, zero species originations, and ultimately, complete extermination. Concurrently, the Neograptina (latest Katian temperate zone immigrants) exhibit pulses of both extinction and adaptive radiation. Thus, the LOME involved intense species selection and the wholesale alteration of the clade diversity structure of a major element of the zooplankton. The …
Linking Shoreline Change, Environmental Forcings, And Sedimentological Resilience In Nourished Beaches Of Cape May And Wildwood, New Jersey, Usa: A Multi-Decadal Synthesis, Divomi Balasuriya, Greg Pope
Linking Shoreline Change, Environmental Forcings, And Sedimentological Resilience In Nourished Beaches Of Cape May And Wildwood, New Jersey, Usa: A Multi-Decadal Synthesis, Divomi Balasuriya, Greg Pope
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
Beach nourishment is a widely used strategy to mitigate coastal erosion, yet its long-term geological impacts remain poorly understood. This study provides a multi-decadal synthesis of shoreline change and sedimentological evolution on the nourished beaches of Cape May and Wildwood, New Jersey, USA. Using shoreline positions from 1991 to 2024, we identify contrasting trajectories: Wildwood exhibits ‘persistent transition’ with severe northern erosion (EPR: −10.0 m/yr) feeding southwards accretion, while Cape May demonstrates a ‘managed equilibrium’ with widespread accretion (mean EPR: +1.15 m/yr). Wave energy correlations account for less than 15% of shoreline variability, indicating natural drivers have been superseded by …
First-Principles Insights Into Binary Oxide Systems Under Extreme Pressure, Daniel Schacher
First-Principles Insights Into Binary Oxide Systems Under Extreme Pressure, Daniel Schacher
UNLV Theses, Dissertations, Professional Papers, and Capstones
Pressure is powerful tool by which one can manipulate the properties of materials. In this work we utilize pressure to explore binary oxide systems and characterize their structural and electronic properties. The observation of anomalous structural and electronic behavior in the rutile to CaCl2 phase transition in SnO2 led to the prediction that such behavior is inherent to all oxides experiencing such a phase transition sequence.[1] Here, the ultra-wide band gap semiconductor GeO2 is confirmed to exhibit anomalous behavior during the rutile to CaCl2 phase transition. A phase pure rutile GeO2 sample synthesized under high-pressure, high-temperature, conditions is probed using …
Stability Analysis Of Thermohaline Convection With A Time-Varying Shear Flow Using The Lyapunov Method, Kalin Kochnev
Stability Analysis Of Thermohaline Convection With A Time-Varying Shear Flow Using The Lyapunov Method, Kalin Kochnev
Honors Scholar Theses
This work applies the Lyapunov method to identify instabilities and compute the growth rate of a linear time-varying system. The linear system studied describes cold fresh water on top of hot salty water with a periodically time-varying background shear flow. A time-dependent weighting matrix is employed to construct a Lyapunov function candidate. The resulting linear matrix inequalities are discretized in time using the forward Euler method. As the number of temporal discretization points increases, the growth rate predicted by the Lyapunov method or Floquet theory, used for comparison, will converge to the same value obtained from numerical simulations. Furthermore, the …
Quantifying Biocrust Evaporation In Arid Lands By Combining Thermal Imaging And Lysimeter Measurements, Rebekah C. Magness
Quantifying Biocrust Evaporation In Arid Lands By Combining Thermal Imaging And Lysimeter Measurements, Rebekah C. Magness
UNLV Theses, Dissertations, Professional Papers, and Capstones
Biological soil crusts (biocrusts) are miniature ecosystems of living organisms incorporated within the soil matrix and established in the topmost millimeters of the soil surface. Biocrust plays a critical role in the hydrologic processes in arid lands, yet the extent to which it increases or decreases evaporation remains unclear. To gain a better understanding of the impact of biocrust on evaporation compared to bare soil, I studied a cyanobacteria-dominated biocrust patch surrounded by bare soil atop a lysimeter in the Mojave Desert near Las Vegas, Nevada. Using high-resolution thermal imaging, and the known latent heat flux from the lysimeter, I …
Towards Spatial Inversion Of Aerial Gamma-Ray Survey Data For Measurement Of Naturally Occurring Radioactivity, Daniel A. Haber
Towards Spatial Inversion Of Aerial Gamma-Ray Survey Data For Measurement Of Naturally Occurring Radioactivity, Daniel A. Haber
UNLV Theses, Dissertations, Professional Papers, and Capstones
Aerial gamma-ray surveying (AGRS) is used in geologic and environmental contexts to provide data on the surface spatial distribution of naturally occurring radioactive material (NORM) or other gamma-ray-emitting isotopes. The standard data reduction workflow for AGRS data involves a process whereby pointwise gamma-ray spectral data are denoised, corrected for numerous sources of background radiation and aircraft height, and are finally converted to physical values by empirical conversion factors. The reduced pointwise data are then typically spatially interpolated to form a continuous surface map.
This dissertation introduces and explores a novel spatial inversion method for reduced AGRS data that considers aircraft …
Reconstructing Central American Hydroclimate Changes Across Time From Isotopic Signatures In Modern And Paleo-Rainfall Records, Giuseppe Lucia
Reconstructing Central American Hydroclimate Changes Across Time From Isotopic Signatures In Modern And Paleo-Rainfall Records, Giuseppe Lucia
UNLV Theses, Dissertations, Professional Papers, and Capstones
Tropical monsoon rainfall is a key component of Earth’s climate system and supports the livelihood and economy of billions of people. Yet, projections of future monsoons remain highly uncertain, particularly in regions with distinct physiography and complex land-ocean-atmosphere interactions like Central America, where long and continuous high-resolution paleoclimate data to test climate model simulations are still limited. This series of studies aims to reconstruct monsoon dynamics and underlying forcing controls in Central America on multiple timescales by the analysis and integration of stable isotope data in modern and paleo-rainfall records from Guatemala.
In Chapter 2, I present a daily-resolution, two-year-long …
Fault Structure, Deformation Mechanisms, And Why Fault Zones Matter To Society, Elizabeth S. Petrie, David A. Ferrill, Kelly K. Bradbury, James P. Evans
Fault Structure, Deformation Mechanisms, And Why Fault Zones Matter To Society, Elizabeth S. Petrie, David A. Ferrill, Kelly K. Bradbury, James P. Evans
Geosciences Faculty Publications
Faults are widespread geologic structures that form in sediment and all rock types, occur in all tectonic regimes, and can be a blessing or a curse to society. Faults and fault zones act as conduits for underground movement of water and as plumbing systems for aquifers and springs essential for human habitation in many semi-arid and arid regions worldwide. Faults also provide pathways for natural oil and gas migration and high-permeability zones in hydrocarbon reservoirs, as well as barriers contributing to trapping and reservoir compartmentalization. By enhancing permeability in many geothermal energy systems, faults can be essential for fluid circulation …