Earth Sciences Commons^™

Seismic Data Denoising Based On The Convolutional Neural Network With An Attention Mechanism In The Curvelet Domain, Bao Qianzong, Zhou Mei, Qiu Yi

Coal Geology & Exploration

[Objective] Noise in seismic data significantly affects the accurate interpretation of subsurface stratigraphic information. Given that effective signals with pronounced lateral correlations in seismic data are distributed in specific coefficients but random noise typically spreads uniformly over all coefficients in the curvelet domain, more effective separation of signals can be achieved. [Methods] The convolutional neural network based on the attention mechanism can adaptively extract key information by focusing on important features of images. Hence, this study proposed a noise attenuation method for seismic data using a convolutional neural network based on the curvelet transform and attention mechanism (Curvelet-AU-Net). First, the …

Characteristics And Transformations Of Mineral Phases In Burnt Rocks, Yalikun Rexiti, Huang Lei, Yang Fan, Xue Xiaoyuan, Song Shijun, Hu Jian, Zhang Zeyu, Ji Zhongkui

Coal Geology & Exploration

Objective Burnt rocks are special rocks formed by the surrounding rocks that are baked due to the spontaneous combustion of coal seams. They are extensively distributed in the Yan’an Formation on the northeastern margin of the Ordos Basin. However, the characteristics and formation mechanisms of burning-associated mineral phases in these rocks remain unclear. Methods This study conducted analytical tests and high-temperature heating simulations of protolith to analyze the mineral phases of underground burnt rocks in the Zhangjiamao Coal Mine, Shaanxi Province. Results and Conclusions The results indicate that the underground burnt rocks exhibit enrichment in mafic components, abnormal migration of …

A Cylindrical Permeation And Diffusion Model For Bingham Grout In Water-Rich Sand Layers And Its Experimental Research, Wang Xuesong, Cheng Hua, Yao Zhishu, Rong Chuanxin, Xie Bao

Coal Geology & Exploration

Objective The disaster prevention and control for water-rich sand layers pose a major challenge to the safe construction of tunnels and deep foundation pits. Typically, the impermeability and bearing capacity of highly water-rich and weakly cemented sand layers are enhanced through permeation grouting via sleeve valve tubes, with resulting grouting concretions being approximately cylindrical. Methods To explore the cylindrical diffusion mechanism of permeation grouting in sand layers, this study constructed a cylindrical diffusion model of radial tube flow for the permeation grouting of Bingham grout in sand layers while considering the tortuosity effects. Subsequently, this study developed a set of …

Production Characteristics Of Deep Coalbed Methane Wells In The Linxing Block And Associated Their Influencing Factors, Wang Zhizhuang, Wu Peng, Sun Qiang, Liu Rui, Wang Lingbo

Coal Geology & Exploration

Objective The production characteristics of deep coalbed methane (CBM) are significantly distinguished from those of middle-shallow CBM, and even the production wells of deep CBM within the same block exhibit different characteristics. Given that relevant research remains in its exploratory stage, gaining a deeper understanding of the factors influencing the differences in production characteristics of deep CBM is significant for the production capacity prediction and production management of the subsequent large-scale production stage. Methods To determine the production characteristics of deep CBM in the Linxing block and their influencing factors, this study examined geological engineering factors including gas content, coal …

Pore Structure And Differential Fluid Occurrence Of Deep Coal Seams, Wu Jian, Sun Qiang, Shi Xuefeng, Gao Lijun

Coal Geology & Exploration

Objective Breakthroughs have been achieved in deep coalbed methane (CBM) exploration along the eastern margin of the Ordos Basin, exhibiting the characteristics of local breakthroughs but regional differential CBM production in multiple blocks. The pores and fractures in deep coal reservoirs, serving as the material spaces for fluid occurrence and occurrence, are critical to the differential development across deep CBM blocks. Methods In this study, coal samples were collected systematically from the deep part of the Shenfu block located along the eastern margin of the Ordos Basin. Using conventional tests on porosity, permeability, and physical properties, as well as CO …

Technology For Efficient Production Of Deep Coalbed Methane In The Shenfu Block, Li Bin, Yang Fan, Zhang Hongjie, Feng Lei, An Qi, Hao Zhaobing

Coal Geology & Exploration

Objective Deep coalbed methane (CBM), representing one crucial resource successor for ensuring the oil and gas security of China and achieving peak carbon dioxide emissions and carbon neutrality of the country, exhibits broad prospects for production. However, due to the small low universality of CBM production technologies under varying geological conditions, a technology that has been successfully applied in some blocks cannot be directly extended to other blocks. This leads to blind deployment of well types and well patterns in the early-stage exploration and development of new blocks to a certain extent. Given this, it is necessary to develop a …

Microeukaryote Metabolism Across The Western North Atlantic Ocean Revealed Through Autonomous Underwater Profiling, Natalie R. Cohen, Arianna I. Krinos, Riss M. Kell, Rebecca J. Chmiel, Dawn M. Moran, Matthew R. Mcilvin, Paloma Z. Lopez, Brianna A. Alanis, Eric W. Chan, John A. Breier

School of Earth, Environmental, & Marine Sciences Faculty Publications

Microeukaryotes are key contributors to marine carbon cycling. Their physiology, ecology, and interactions with the chemical environment are poorly understood in offshore ecosystems, and especially in the deep ocean. Using the Autonomous Underwater Vehicle Clio, microbial communities along a 1050 km transect in the western North Atlantic Ocean were surveyed at 10–200 m vertical depth increments to capture metabolic signatures spanning oligotrophic, continental margin, and productive coastal ecosystems. Microeukaryotes were examined using a paired metatranscriptomic and metaproteomic approach. Here we show a diverse surface assemblage consisting of stramenopiles, dinoflagellates and ciliates represented in both the transcript and protein fractions, …

Coastal Sedimentary Records Of Extreme Events And Human Activity: Examples From Hurricanes And Microplastics, Nicholas T. Culligan

LSU Doctoral Dissertations

Coastal regions are uniquely vulnerable to a myriad of natural and anthropogenically caused stresses such as hurricane strikes and chronic microplastic pollution. Both hurricanes and microplastics have major negative effects on global coastlines and are forecast to become more damaging in the future. However, current model trends are based on limited modern data and may not provide an accurate or comprehensive view of the future. Therefore, this dissertation investigates coastal stratigraphic records to determine long-term past trends of these presses and pulses so that researchers, stakeholders, and policy makers can use them to enact strategies to mitigate damages from worsening …

Modeling Integrated Soil Fertility Management For Maize Production In Kenya Using A Bayesian Calibration Of The Daycent Model, Moritz Laub, Magdalena Necpalova, Marijn Van De Broek, Marc Corbeels, Samuel Mathu Ndungu, Monicah Wanjiku Mucheru-Muna, Daniel Mugendi, Rebecca Yegon, Wycliffe Waswa, Bernard Vanlauwe, Johan Six

All Peer-Reviewed Publications

Sustainable intensification schemes such as integrated soil fertility management (ISFM) are a proposed strategy to close yield gaps, increase soil fertility, and achieve food security in sub-Saharan Africa. Biogeochemical models such as DayCent can assess their potential at larger scales, but these models need to be calibrated to new environments and rigorously tested for accuracy. Here, we present a Bayesian calibration of DayCent, using data from four long-term field experiments in Kenya in a leave-one-site-out cross-validation approach. The experimental treatments consisted of the addition of low- to high-quality organic resources, with and without mineral nitrogen fertilizer. We assessed the potential …

Signatures Of Fluid-Rock Interactions In Shallow Parts Of The San Andreas And San Gabriel Faults, Southern California, James P. Evans, Kaitlyn Crouch, Caroline Studnicky, Sharon Bone, Nicholas Edwards, Samuel M. Webb

Geosciences Faculty Publications

We examine deformed crystalline bedrock in the upper parts of the active San Andreas and ancient San Gabriel Faults, southern California, to 1) determine the nature and origin of micro-scale composition and geochemistry of fault-related rocks, 2) constrain the extent of fluid-rock interactions, and 3) determine the interactions between alteration, mineralization, and deformation. We used drill cores from a 470 m long inclined borehole through the steep-dipping San Gabriel Fault and from seven inclined northeast-plunging boreholes across the San Andreas Fault zone to 150 m deep to show that narrow fault cores 10 cm to 5 m wide lie within …

Deconvolving Provenance Signatures Of Pliocene-Pleistocene Coastal Loess Deposits Along The Atlantic Margin Of Argentina, Will Robert Quanrud

Theses and Dissertations

Dust derived from southern South America provides critical nutrients for autotropic marine biota in the South Atlantic Ocean, such that fluxes of wind-blown sediment may ultimately affect the concentration of atmospheric CO2. Expansive sand, silt, and loess deposits are exposed in Central Argentina, recording millions of years of eolian processes; however, the provenance and transport pathways of this dust remains unclear. Coastal loess deposits ranging in age from Pliocene to upper Pleistocene are present along the Atlantic margin of Argentina and provide information on sediment transport pathways for the last 4 million years. Nine samples of loess were collected and …

Time-Transgressive Microbial Diversity In A Tropical Bat Guano Accumulation, Deer Cave, Mulu, Borneo, Joyce Lundberg, Donald A. Mcfarlane

International Journal of Speleology

Bat guano accumulations in caves can constitute large deposits of organic material, particularly chitin and its degradation products, that host a diverse microbiome. Previous microbiological studies have not addressed the stratified nature of these deposits in the context of the timeframe of the decomposition process. We present such data (temperature, pH, DNA sampling of eight carbon-dated strata) for a 75 cm-deep tropical guano accumulation that undergoes complete decomposition over a timescale of ~120 years. The aerobic, surface layer of freshly-fallen guano has the greatest diversity of taxa, with Bacteroidota co-dominant with Pseudomonadota, and includes many taxa unique to this …

Investigating Arctic Ocean Freshwater Content And Circulation In A Changing Climate, Emma Louise Hoffman

Theses and Dissertations

The Arctic Ocean is unique among the world’s oceans, characterized by its cold temperatures, salinity-driven vertical structure, and shallow shelf seas. It has warmed intensely since the 1980s at rates exceeding the global average. This Arctic Amplification drives variability in sea ice and salinity, affecting local circulation and exchange with other basins, leading to global changes in oceanic and atmospheric circulation and the biosphere. This thesis explores changing dynamics in the Arctic Ocean, in particular connecting modeled changes in liquid freshwater content (FWC) and its pathways with major ocean circulation patterns, atmospheric drivers, and large-scale climatic changes.

This research combines …

New Techniques For Studying Ocean Eddy Dynamics In The Arabian Sea And The Gulf Of Mexico, Paul Andrew Ernst

Theses and Dissertations

Coherent vortices known as eddies are ubiquitous throughout the world’s oceans and are responsible for modulating regional climates via the transfer of heat, momentum, and salt. Two regions where eddies are particularly prominent are the Arabian Sea (AS) and the Gulf of Mexico (GoM). This dissertation advances the study of eddies in these regions by developing and employing new techniques in conjunction with remotely sensed data and high-resolution ocean models. These models focus particularly on lesser-studied eddy components at the subsurface and the submesoscale (below 25 km in radius).

The first component of this dissertation focuses on the Lakshadweep High …

Assessing Multi-Annual Phytoplankton Community Compositions And Biomass Across Tidal Creek And Open Water Estuarine Habitats In South Carolina, Shannon Elizabeth Powers

Theses and Dissertations

The urbanization of coastal environments in recent decades has caused an accelerating increase in nutrient-rich runoff from the landscape. The presence of these excess nutrients in the aquatic environment can result in degradation of water quality and harmful algal blooms. In South Carolina (SC), coastal development continues to threaten the resiliency of salt marsh estuaries, especially in combination with other stressors like climate change and sea level rise. Estuaries are important nurseries and habitats for fisheries and ecotourism. The South Carolina Estuarine and Coastal Assessment Program (SCECAP) is an ongoing monitoring program that assesses the habitat condition along the coast …

Hypogenic Caves Of Syracuse Area, Sicily (Italy): Geomorphological Evidence Of Co2 Degassing, Fresh-Salt Water Mixing, And Late Condensation Corrosion, Philippe Audra, Jean-Yves Bigot, Didier Cailhol, Pierre Camps, Ilenia M. D'Angeli, Hai Cheng, R. Lawrence Edwards, Fernando Gàzquez-Sanchez, Gabriella Koltai, Giuliana Madonia, Jean-Claude Nobécourt, Marjan Temovski, Marco Vattano, Jo De Waele

International Journal of Speleology

Many caves in Sicily have been shown to have a sulfuric acid or other hypogenic origin. We studied three caves (Palombara, Scrivilleri, Monello) near Syracuse (eastern Sicily), in an area that was strongly uplifted and faulted, creating multiple Pleistocene marine terraces. Mineralogy, stable isotopes and dating methods (paleomagnetism, U/Th) were used to characterize cave sediments, some of which were related to the initial hypogenic phase (Fe and Mn oxides, calcite spar), others were introduced by surface runoff later. Many other sediments are the result of in situ weathering, such as lime sands produced by condensation-corrosion processes on the calcarenite walls. …

Crustal Structure And Evolution Of The Queen Charlotte Plate Boundary, Collin C. Brandl

Earth and Planetary Sciences ETDs

There are many outstanding questions in plate tectonics that remain unanswered because large regions of the Earth are unexplored, both at the surface and in the subsurface. In this dissertation, I processed and analyzed active source seismic reflection data from the historically understudied Queen Charlotte transform plate boundary. Using this dataset, I found that the southern segment of the plate boundary has active underthrusting, is analogous to subduction zone crustal slivers, and is a site of early subduction initiation. Along the entire plate boundary, I constrained the near-surface thermal gradient using the stability of gas hydrate, finding that it is …

Unveiling The Magnetic And Structural Properties Of Hydrohematite : A Potential Water-Bearing Mineral On The Surface Of Mars, Abdullah Al Maruf

Dartmouth College Master’s Theses

Hematite (α-Fe₂O₃) is one of the most prevalent iron oxides in sedimentary rocks and on the surface of Mars. Recent studies suggest that natural "hydrohematite" exists, wherein hematite accommodates cations through compensation at the Fe³⁺–site, forming –OH bonds (i.e., structural water), with important implications for water in arid planetary environments. We present a detailed magnetic characterization to elucidate the magnetic response of H–doping on these samples, corroborating the results with first-principles calculations. First-order reversal curves show a sharp diagonal wing due to triaxial basal plane anisotropy. Low-temperature cooling experiments show the complete suppression of …

Seismic Structure Of The Alaska And Mariana Subduction Zones From Amphibious Data, Zongshan Li

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation utilizes multiple techniques of seismic tomography to investigate the crust and uppermost mantle structure of two prominent convergent margins: the Alaska and Mariana subduction zones. The study of the Alaska subduction zone largely benefits from the Alaska Amphibious Community Seismic Experiment (AACSE) that deployed from May 2018 to September 2019, as well as the EarthScope Transportable Array (TA) that was simultaneously operating across Alaska. Using 271 seismic stations in total, I analyze the Rayleigh wave phase and group velocity dispersion data retrieved from both ambient noise and teleseismic earthquake data. I then determine the shear velocity model by …

Microbial Phosphate Solubilization Mechanisms In P Solubilizing In Andisol, Agustina Erlinda Marpaung, Tengku Sabrina, Abdul Rauf, Dwi Ningsih Susilowati, Luthfi Aziz Mahmud Siregar

Jurnal Kultivasi

Phosphate (P) nutrient plays a significant role in plant growth and yield. P is an essential element that plays an important role in photosynthesis and root development. Phosphate nutrient availability is deficient in some soil types due to retention, such as in Andisol soil types. High phosphate retention in Andisol soil types causes P nutrients to be unavailable to plants and can reduce crop yields. The availability of P in Andisol soils can be done, among others, by applying phosphate solubilizing microbes. Phosphate solubilizing microorganisms are soil microorganisms consisting of bacteria and fungi that can mineralize organic P, dissolve inorganic …

Groundwater Modeling Of The Ogallala Aquifer: Use Of Machine Learning For Model Parameterization And Sustainability Assessment, Tewodros Aboret Tilahun

Dissertations and Doctoral Documents, University of Nebraska-Lincoln, 2023–

Addressing groundwater depletion problems in heterogeneous aquifer systems is a challenge. The heterogeneous Ogallala Aquifer, a critical source of groundwater in the central United States, has undergone decades of decline in water levels due to pumping. This project aims to build a robust groundwater model to evaluate optimal scenarios for sustainable use of the groundwater resource within a section of the Ogallala aquifer located in the Middle Republican Natural Resources District (MRNRD). This study follows a comprehensive approach involving parameterization, construction, and optimization. The model is parametrized using hydraulic conductivity and recharge values obtained from a random forest-based machine learning …

Elemental And Isotopic Studies On Lunar Apollo Samples And High-Temperature Evaporation Experiments, Mason Neuman

Arts & Sciences Graduate Student Theses and Dissertations

This dissertation is largely split into two major parts. The first part, Chapters 2 and 3, touches on stratigraphic analyses of Apollo 17 sample 73001/73002. The second part, Chapters 4 and 5, presents experimental studies on moderately volatile element behavior during high-temperature evaporation experiments. In Chapter 1, I provide some brief background and the motivations for the work that is presented in the ensuing Chapters. In Chapter 2, I present an overview of the stratigraphy of the “light mantle” deposit at the base of South Massif in the Moon’s Taurus-Littrow Valley, uncovered through the analysis of double drive tube 73001/73002. …

Structural Characterization Of The Puma Diapir, Gulf Of Mexico Basin, Rodrigo Velasquez

Electronic Theses and Dissertations

The Gulf of Mexico (GOM) Basin has been a significant target for oil and gas since the 1990s and continues today as a leading exploration target. This super basin is home to an estimated 200 BBOE (Billon barrels of oil equivalent), with current production totaling 60 BBOE for both USA and Mexico. Even though the overall depositional evolution of the GOM has allowed for the key elements for petroleum accumulations to be met, a complex structural framework is present. This framework results from the asymmetric spreading of the North American Plate from the Yucatan block crating the GOM basin we …

Chinese Tallow Long-Term Impact On Stand Dynamics In A Bottomland Hardwood Forest Following Vegetation Management, Nicklaus R. Langlois

Electronic Theses and Dissertations

Chinese tallow (Triadica sebifera (L.) Small) is an invasive tree known to have negative impacts on bottomland hardwood forests. Chinese tallow is proficient in reproducing and surviving in bottomland hardwood forests because it is more flood and shade tolerant than most native trees. The long-term effectiveness of Chinese tallow control is an important topic to research as only a few long-term studies of Chinese tallow control have been conducted. A 10-year re-measurement of 22 paired plots installed in 2012 on the Pineywoods Mitigation Bank near Diboll, Texas following herbicide treatments examined Chinese tallow and native tree stand structure. Each …

Structure Of The South-Central Skagit Gneiss Complex: Implications For Rheological Response To Magmatic Flare-Ups, Jeffery Wegener

Master's Theses

The Skagit Gneiss Complex in the North Cascades magmatic arc consists of Late Cretaceous to Eocene orthogneiss and partially migmatitic paragneiss. Orthogneiss protoliths intruded during two magmatic flare-ups, making the Skagit Gneiss an ideal location to study the relationship between flare-ups and deformation. Geologic mapping, microstructural analysis, and U-Pb dating of zircon were used to construct a timeline of magmatism, metamorphism and deformation in a portion of the Skagit Gneiss. A tonalitic gneiss intruded between ~79-73 at the beginning of the older flare-up and an ~60 Ma, tonalitic to granodioritic, leucocratic orthogneiss intruded at the end of this flare-up. NW-SE …

Assessing The Role Of Steam Explosivity In Shallow And Deep Marine Environments, Frederick Ede

Master's Theses

Volcaniclastic deposits formed in shallow and deep marine environments show strikingly different characteristics resulting from the ability of steam to assist in lava fragmentation. Deep marine deposits come from recent lava flows at Axial Seamount, formed around 1,500 m water depth, while shallow marine samples come from Miocene Columbia River Basalt Group (CRBG) lava flows that were emplaced in a shallow marine to subaerial environment and are now exposed on the Oregon coast. Volcaniclastic material from these two environments was compared using granulometry, componentry, and mapping. Lithofacies from the CRBG contained abundant ash and lapilli sized clasts with a high …

Effects Of Cutting Management On Herbage Production And Tiller Population In Smooth Bromegrass (Bromus Inermis Leyss), J X. Xia, J Hodgson, A.C P. Chu, P Wang, F Y. Liu

IGC Proceedings (1977-2023)

This paper reports the results of an experiment with smooth bromegrass (Bromus inermis Leyss) under cutting management at Beijing Agricultural University, China from June-October 1989. The main treatments were cutting intervals (l month v. 2 months) and cutting height (10 cm v. 30 cm) with 2 additional treatments (uncut control, and delayed first cut) and 4 replications. Frequent cutting decreased tiller population density, herbage accumulation and underground biomass. Tiller populations were greater under lax than hard cutting, though closer cutting resulted in greater green herbage accumulation. Delaying cutting until flowering was completed resulted in a subsequent depression in herbage …

Relative Productivity And Persistense Of White Clover Cultivars Under Cutting Or Continuous Stocking By Sheep, D A. Davies, M Fothergill

IGC Proceedings (1977-2023)

Perennial ryegrass-white clover (Lolium perenne-Trlfollium repens) swards of 3 clover cultivars were studied at a lowland (30 m) and upland (340 m) site in mid Wales over 3 years (1989-91). Lamb production from small-leaved Aberystwyth S 184 at 1021 kg/ha was 25% and 1191, more than from small-leaved Ac3351 and medium-leaved Grasslands Huia respectively. The relative lamb output from Huia was poorer at the upland location. Clover production, survival and morphology under a number of cutting heights and frequencies were different from those in the continuously stocked pastures. Cutting every 10 days at 2-3 cm resulted in poor clover and …

Morphological Changes In Three Clover (Trifolium Repens L.) Cultivars Under Continuous Stocking, M Fothergill, D A. Davies

IGC Proceedings (1977-2023)

Individual plant morphology of 3 white clover (Trifolium repens L.) cultivars was studied during 1990 and 1991. Seasonal shifts were demonstrated by all cultivars towards a higher proportion of less complex plants from winter to mid summer. Over the latter half of the year the population tended lo return towards its original distribution. Seasonal fluctuations in stolon dry weight/plant and root number/plant were also identified, with the small-leaved Ac3351 maintaining a greater stolon OW/plant than Aberystwyth S184 and Grasslands Huia during 1990. Ac3351 and S184 also maintained a larger root number/plant over this period. However, no significant differences were detected …

Response To Defoliation Of Tall Fescue, H Tavakoli, J Hodgson, P D. Kemp

IGC Proceedings (1977-2023)

An experiment studying the behaviour of toll fescue (Fesutca anrundinacea Schreb,) was conducted under steady stale grazing on a sward dominated by this plant. The swards were grazed lo maintain a surface height of 30-40 mm (H), 50-60 mm (M) and 90-100 mm (L). These treatments were applied on swards with and without white clover (Trifolium repens L.) from November 1990 to April 1991. Results showed that leaf growth decreased as the severity of grazing increased. Tiller number was less under H grazing than under M or L grazing, but tiller size remained constant over time in this …