Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Earth Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 8881 - 8910 of 59446

Full-Text Articles in Entire DC Network

Iron Occurrence In Coal Measures And Its Release Mechanism During Water-Rock Interactions: Taking A Mine In The Eastern Grassland As An Example, Wang Tiantian Jul 2023

Iron Occurrence In Coal Measures And Its Release Mechanism During Water-Rock Interactions: Taking A Mine In The Eastern Grassland As An Example, Wang Tiantian

Coal Geology & Exploration

The mine water with iron out of limit corrodes the water distribution pipeline and the industrial equipment, thereby damaging the liver of human body, and further threatening the human health. The enrichment or dilution of iron in mine water is determined by the iron content and its occurrence in coal measures, as well as its release mechanism during water-coal and water-rock interactions. Herein, 18 groups of coal and rock samples were collected from a mine in the eastern grassland, and had the iron content, occurrence and carrier in the coal measure analyzed with an inductively coupled plasma mass spectrometry (ICP-MS), …

Go to article

Change Detection Of Open-Pit Mines Based On Fm-Unet++ And Gf-2 Satellite Images, Du Shouhang, Li Wei, Xing Jianghe, Zhang Chengye, She Changchao, Wang Shaoyu, Li Jun Jul 2023

Change Detection Of Open-Pit Mines Based On Fm-Unet++ And Gf-2 Satellite Images, Du Shouhang, Li Wei, Xing Jianghe, Zhang Chengye, She Changchao, Wang Shaoyu, Li Jun

Coal Geology & Exploration

Automatic extraction of land use change information in open-pit mines using the remote sensing and deep learning technology is of great significance for the mining monitoring and ecological environmental protection. A novel deep learning model FM-UNet++ was constructed for the change of land use types in complex and heterogeneous mining scenarios, and the automatic change detection of open-pit mines was achieved using the Gaofen-2 (GF-2) satellite images. Firstly, the change detection dataset of open-pit mine was produced through data surveys and visual interpretation, which was augmented by data enhancement. Secondly, the FM-UNet++ for open-pit mine change detection was constructed by …

Go to article

Cambrian Explosion Condensed: High-Precision Geochronology Of The Lower Wood Canyon Formation, Nevada, Lyle L. Nelson, James L. Crowley, Emily F. Smith, Darin M. Schwartz, Eben B. Hodgin, Mark D. Schmitz Jul 2023

Cambrian Explosion Condensed: High-Precision Geochronology Of The Lower Wood Canyon Formation, Nevada, Lyle L. Nelson, James L. Crowley, Emily F. Smith, Darin M. Schwartz, Eben B. Hodgin, Mark D. Schmitz

Geosciences Faculty Publications and Presentations

The geologically rapid appearance of fossils of modern animal phyla within Cambrian strata is a defining characteristic of the history of life on Earth. However, temporal calibration of the base of the Cambrian Period remains uncertain within millions of years, which has resulted in mounting challenges to the concept of a discrete Cambrian explosion. We present precise zircon U–Pb dates for the lower Wood Canyon Formation, Nevada. These data demonstrate the base of the Cambrian Period, as defined by both ichnofossil biostratigraphy and carbon isotope chemostratigraphy, was younger than 533 Mya, at least 6 My later than currently recognized. This …

Go to article

Underground Coal Gasification Field Tests In China: History And Prospects, Qin Yong, Yi Tongsheng, Yang Lei, Zhou Yongfeng, Wang Jun, Wang Lingxia Jul 2023

Underground Coal Gasification Field Tests In China: History And Prospects, Qin Yong, Yi Tongsheng, Yang Lei, Zhou Yongfeng, Wang Jun, Wang Lingxia

Coal Geology & Exploration

To achieve peak carbon dioxide emissions and carbon neutrality in China, a low-carbon and efficient coal energy structure is essential for the sustainable energy development of China. Underground coal gasification (UCG) is an important strategy for transforming the coal energy structure in China. Based on the review of previous literature, this study analyzes the exploration history of the UCG field tests in China and delivers the prospects of UCG industrialization in China. The analytical results show that the development and field tests of UCG technologies in China have experienced five stages, namely the initial attempt, silence/recovery, extensive explorations, making technological …

Go to article

Construction And Engineering Applications Of Block Model For Coal Seam Value Considering The Variations In Coal Seam Thickness And Quality, Liu Feiyue, Yang Ke, Yang Tianhong, Kan Lei, Fu Kai Jul 2023

Construction And Engineering Applications Of Block Model For Coal Seam Value Considering The Variations In Coal Seam Thickness And Quality, Liu Feiyue, Yang Ke, Yang Tianhong, Kan Lei, Fu Kai

Coal Geology & Exploration

The variations in coal seam thickness and coal quality parameters (i.e., calorific value, volatile matter, ash content, and sulfur content) determine the spatial distribution of coal prices. The accurate characterization of coal seams’ economic value plays an important role in the rational mining and utilization of coal resources. This study first determined that the geological attributes of coal seams including their thickness and coal quality are regional variables. Based on this, this study discretized geological bodies in the study area using a block model. Then, using a geostatistical method, this study obtained the experimental semivariograms of coal seam thickness and …

Go to article

Applicability Evaluation Technology Of Perforating Parameters In Different Reservoirs, Bi Gang, Wu Jiemin, Yang Shangyu, Li Mengmeng, Han Fei, Wang Xin, Cui Ying Jul 2023

Applicability Evaluation Technology Of Perforating Parameters In Different Reservoirs, Bi Gang, Wu Jiemin, Yang Shangyu, Li Mengmeng, Han Fei, Wang Xin, Cui Ying

Coal Geology & Exploration

Perforating parameters have an important impact on the productivity of oil and gas wells. Currently, the optimization of perforating parameters is mostly based on single factor analysis, with no multi-factor comprehensive evaluation analysis performed. In this paper, the finite element simulation method was used to analyze and study the influence law of perforating parameters on wellhead flow under different reservoir conditions. Firstly, a geometric model of pressure drop in reservoir with perforation completion was established to simulate the fluid flow after perforation. In this way, the influence laws of perforating parameters, anisotropy parameters and natural fracture parameters on the pressure …

Go to article

Construction And Restoration Technology Of Terrain Remodeling Layer In The Restoration Of Ecological Geological Layer In Open-Pit Mining Areas, Zhao Xin, Wang Tong, Li Congcong, Lin Zhongyue, Li Fei, Wang Weichao, Feng Kangning, Yin Yalei, Jiang Zhe Jul 2023

Construction And Restoration Technology Of Terrain Remodeling Layer In The Restoration Of Ecological Geological Layer In Open-Pit Mining Areas, Zhao Xin, Wang Tong, Li Congcong, Lin Zhongyue, Li Fei, Wang Weichao, Feng Kangning, Yin Yalei, Jiang Zhe

Coal Geology & Exploration

Mining can easily result in a series of change in the geomorphic form, such as irregular mining pits, high and steep slopes, slag hills, primitive soil failure and accumulated water in mining pits in the plateau and alpine mining area, which is in disharmony with the surrounding environment. Such changes of geomorphic form will not only adversely affect the surface ecological environment, but also bring different degrees of influence and damage to the shallow groundwater seepage field and the permafrost. In particular, the geological hazards and disasters such as landslides and collapses may even be resulted in. In response to …

Go to article

Uav Aerial Triangulation: Point Error Distributions And The Influencing Mechanisms Of Ground Control Points On Its Accuracy, Zha Jianfeng, Zhu Pengcheng, Wu Dejun, Ma Chenyang, Zhong Chongwu, Yin Hongwu, Wang Dong Jul 2023

Uav Aerial Triangulation: Point Error Distributions And The Influencing Mechanisms Of Ground Control Points On Its Accuracy, Zha Jianfeng, Zhu Pengcheng, Wu Dejun, Ma Chenyang, Zhong Chongwu, Yin Hongwu, Wang Dong

Coal Geology & Exploration

Unmanned aerial vehicles (UAVs) have been an important means of monitoring the surface deformation in mining areas since they are flexible, are insensitive to weather, and can swiftly acquire images of target areas. However, there is an urgent need to improve UAV-based measurement accuracy. Based on a systematic analysis of factors affecting the accuracy of surface measurement points, this study focuses on the influence of the quality of ground control points on the point error distribution and accuracy of aerial triangulation. Firstly, through a large number of repeated observations and experiments, this study investigated the error distributions of the planar …

Go to article

Research Advances On The Techno-Economic Evaluation Of Ucg Projects, Yi Tongsheng, Qin Yong, Zhou Yongfeng, Wang Lingxia, Jin Jun, Zhou Ze Jul 2023

Research Advances On The Techno-Economic Evaluation Of Ucg Projects, Yi Tongsheng, Qin Yong, Zhou Yongfeng, Wang Lingxia, Jin Jun, Zhou Ze

Coal Geology & Exploration

Underground coal gasification (UCG) is driven by China's development strategy for a clean and efficient coal energy structure. Its industrialization prospect depends on the economic and social benefits of UCG projects. Against this background, this study reviews the research advances on the economic evaluation of UCG projects at home and abroad and summarizes the current insights into the economic competitiveness of UCG projects. Through case analysis, it presents a basic model for the economic evaluation of the UCG-combined-cycle gas turbine (CCGT) - carbon capture and storage (UCG-CCGT-CCS) system and the main understanding of the model. Furthermore, this study discusses the …

Go to article

Ucg Industrialization In The Soviet Union: History And Comments, Kong Weimin, Zhou Yongfeng, Yi Tongsheng, Li Ping, Qin Yong, Zhou Ze Jul 2023

Ucg Industrialization In The Soviet Union: History And Comments, Kong Weimin, Zhou Yongfeng, Yi Tongsheng, Li Ping, Qin Yong, Zhou Ze

Coal Geology & Exploration

China's energy resources are originally poor in oil and gas but rich in coal. The industrialization of underground coal gasification (UCG) technologies, which is an important way of achieving a low-carbon and efficient coal energy structure in China, contributes to the smooth achievement of the peak carbon dioxide emissions and carbon neutrality in China. This study reviews the history of the field tests and industrialization of UCG technologies in the Soviet Union by systematically referencing and sorting literature, aiming to provide a reference for the present development and industrialization of UCG technologies in China. The results show that the development …

Go to article

Ucg Pilot Tests In The United States And Their Contributions To Modern Ucg Technologies, Huang Wan, Wang Jun, Wang Lingxia, Yi Tongsheng, Chen Kexin, Qin Yong Jul 2023

Ucg Pilot Tests In The United States And Their Contributions To Modern Ucg Technologies, Huang Wan, Wang Jun, Wang Lingxia, Yi Tongsheng, Chen Kexin, Qin Yong

Coal Geology & Exploration

The industrialization of underground coal gasification (UCG), which is conducive to the transformation and development of the coal energy structure and the improvement in the low-carbon utilization level of coal resources, is an environmentally friendly energy development technology in line with the sustainable development strategy. The international energy crisis from the 1980s to the 1990s prompted the United States to vigorously develop UCG technologies. Accordingly, this country has successively carried out six series of UCG pilot tests, which contribute greatly to the progress in UCG technologies and provided the critical foundation for the formation of modern UCG technologies worldwide. This …

Go to article

Ucg Pilot Tests In Eu Countries: A Review Of History And Progress, Jin Lili, Yang Lei, Wu Yarong, Wang Xiaofang, Yi Tongsheng, Qin Yong Jul 2023

Ucg Pilot Tests In Eu Countries: A Review Of History And Progress, Jin Lili, Yang Lei, Wu Yarong, Wang Xiaofang, Yi Tongsheng, Qin Yong

Coal Geology & Exploration

Underground coal gasification (UCG) is an important way of transforming China’s coal energy structure. European Union (EU) countries explored UCG for over 80 years, and their rich experience can be used as a reference for promoting UCG industrialization in China. The UK prepared for UCG pilot tests for the first time in the world. From 1944 to 2014, based on the experience of the former Soviet Union and the United States, EU countries successively implemented at least 12 UCG pilot test projects in three stages, making important contributions to the progress in UCG technologies. They invented the blind-hole method and …

Go to article

Ucg Engineering Demonstrations In Australia: History And Its Implications, Zhou Ze, Wang Lingxia, Qin Yong, Jin Jun, Yang Lei, Yi Tongsheng Jul 2023

Ucg Engineering Demonstrations In Australia: History And Its Implications, Zhou Ze, Wang Lingxia, Qin Yong, Jin Jun, Yang Lei, Yi Tongsheng

Coal Geology & Exploration

Underground coal gasification (UCG), which is a revolutionary coal mining technology, is an important direction for achieving a low-carbon and efficient coal energy structure in China and is also a potential explorable way to ensure the smooth realization of the peak carbon dioxide emissions and carbon neutrality in China. Based on a literature survey, this study sorts out the exploration process of UCG technologies in Australia and analyzes the gains and losses using field test cases. The experience in UCG technologies in Australia can provide a reference for the development of the technologies in China. The results show that the …

Go to article

A New Type Of Ordovician Limestone Karst Water Inrush From The Floor Of Old Goaf: Formation Mechanism And The Prevention And Control Technology, Zhou Shuai, Li Shuqian, Yin Shangxian, Liang Manyu, Meng Haopeng, Qi Rongrong, Li Yuanyuan Jul 2023

A New Type Of Ordovician Limestone Karst Water Inrush From The Floor Of Old Goaf: Formation Mechanism And The Prevention And Control Technology, Zhou Shuai, Li Shuqian, Yin Shangxian, Liang Manyu, Meng Haopeng, Qi Rongrong, Li Yuanyuan

Coal Geology & Exploration

The Ordovician limestone water inrush accident occurred in the small coal-pit area in Xin’an Mine of Hebei Fengfeng mining area on October 25th, which resulted in the production level being flooded, with the coal mine shut-down. Specifically, the accident cause was analyzed, and the concept of Ordovician limestone karst water inrush from the floor of old goaf was proposed, with its difference from the connotation and denotation of water inrush from the old goaf or floor water inrush accidents induced by mining summarized. Then, the water inrush mechanism based on the dynamic evolution of stored energy release from …

Go to article

Research And Application Of Fracture Mechanics Model Of Stope Roof Under The Coupling Of Direct Roof And Basic Roof, Li Jinhua, Zheng Chengxian, Gu Shuancheng, Wu Baolin, Wang Xiong, Song Yongjun Jul 2023

Research And Application Of Fracture Mechanics Model Of Stope Roof Under The Coupling Of Direct Roof And Basic Roof, Li Jinhua, Zheng Chengxian, Gu Shuancheng, Wu Baolin, Wang Xiong, Song Yongjun

Coal Geology & Exploration

Periodic weighting is a typical characteristic of mine pressure. Accurate prediction of stope periodic weighting step is an important way to effectively reduce the occurrence of stope accidents. Aiming at the influence of the coupling between the basic roof defects and the direct roof on the periodic weighting step, the stope roof was regarded as a finite plate model with cracks. According to the coordinate deformation mechanism of the overburden rock, the fracture mechanics model of the stope roof was established based on the fracture mechanics theory. On this basis, the periodic weighting step function under the coupling between the …

Go to article

Material Point Method-Based Simulation And Dynamic Characteristic Analysis Of Instability-Induced Landslide Movement: A Case Study Of The Yanguan Landslide In The Three Gorges Reservoir Area, Song Kun, Ruan Di, Lyu Honglin, Han Luyang, Huang Haifeng Jul 2023

Material Point Method-Based Simulation And Dynamic Characteristic Analysis Of Instability-Induced Landslide Movement: A Case Study Of The Yanguan Landslide In The Three Gorges Reservoir Area, Song Kun, Ruan Di, Lyu Honglin, Han Luyang, Huang Haifeng

Coal Geology & Exploration

The dynamic process and influence range of instability-induced landslide movement have important effects on the risk area division and prevention of landslide hazards. To accurately and systematically analyze the changes in the dynamic characteristics of landsides during their instability-induced movement, this study thoroughly investigated and analyzed the instability-induced movement process of the Yanguan landslide in the Three Gorges Reservoir area, Zigui County, Hubei Province. Through laboratory ring shear tests, this study determined the changing pattern of residual strength and the motion parameters of sliding zone soil under different shear rates. Accordingly, using the material point method (MPM), which is suitable …

Go to article

Detection Of Near-Surface Cavities Using The 2d Multi-Parameter Full-Waveform Inversion Of Rayleigh Waves, Li Yu, Wang Jingqi, Guan Jianbo, Yan Yingwei Jul 2023

Detection Of Near-Surface Cavities Using The 2d Multi-Parameter Full-Waveform Inversion Of Rayleigh Waves, Li Yu, Wang Jingqi, Guan Jianbo, Yan Yingwei

Coal Geology & Exploration

The accurate detection of near-surface low-velocity anomalies (such as cavities), which has always been a valuable and challenging research topic in the field of geophysics, holds great significance for the fine-scale near-surface modeling in urban disaster assessment and the seismic exploration of coalfields under complex conditions. The full-waveform inversion (FWI) of surface waves is suitable for high-precision near-surface modeling. However, there still exist many urgent problems with the modeling in practical applications. To solve the key issues of the FWI of surface waves, such as multi-parameter crosstalk, actual data preprocessing, and source wavelet estimation, this study developed a complete method …

Go to article

A Method For Suppressing Casing Coupling Noise In Vsp Data Based On Morphological Component Analysis Of Characteristic Waves, Pan Long, Mao Haibo, Jiang Li, Hu Keyang, Dang Zhimin, Chen Wenchao Jul 2023

A Method For Suppressing Casing Coupling Noise In Vsp Data Based On Morphological Component Analysis Of Characteristic Waves, Pan Long, Mao Haibo, Jiang Li, Hu Keyang, Dang Zhimin, Chen Wenchao

Coal Geology & Exploration

During the acquisition of vertical seismic profile (VSP) data, coupling noise between casing strings frequently emerges due to poor well cementing or the presence of cement annulus between multiple casing layers. This type of noise features high energy, a wide spatial influence range, and slow attenuation. Furthermore, it overlaps effective signals in multiple domains, such as the time and frequency domains. Therefore, casing coupling noise severely affects the signal-to-noise ratio of VSP data. This study first introduces the basic theory of Morphological Component Analysis (MCA). Then, it conducts a comparative analysis of the distribution of effective signals and casing coupling …

Go to article

Influence Of High In-Situ Stress Areas In The Coal Seam Roofs On Microseism-Based Tomographic Inversion, Liu Kaihang, Feng Lei, Yun Meihou, Cao Yunxing, Tian Lin Jul 2023

Influence Of High In-Situ Stress Areas In The Coal Seam Roofs On Microseism-Based Tomographic Inversion, Liu Kaihang, Feng Lei, Yun Meihou, Cao Yunxing, Tian Lin

Coal Geology & Exploration

High in-situ stress areas in the coal seam roofs are prone to induce mine dynamic hazard such as rock bursts. To meet the demand for safe coal mining, this study achieved real-time monitoring and swift early warning of high in situ stress areas. Specifically, based on data transmitted from microseismic stations in real time, this study conducted the inversion of the wave velocities in coal seams and rocks using a fast three-dimensional (3D) tomographic inversion algorithm. The accuracy of tomographic inversion results directly determines the judgment on the locations of high in situ stress areas. Therefore, by building a 3D …

Go to article

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen Jul 2023

Spatial Variations In Ancient Meteoric Water: An Investigation Of The Rattlesnake Tuff, Julian Michael Cohen

Dissertations and Theses

Volcanic glass has been used extensively as a paleoclimate proxy. Deuterium (2H) concentrations in glass have been found to be stable over geologic timescales, making δD a reliable proxy for ancient water chemistry. However, continued work revolves around better understanding how different factors affect preserved water in ash. Here, I analyze δD in the Rattlesnake Tuff (RST), a widespread ca. 7 Ma ashflow tuff, and create an isoscape to assess variations in δD across Oregon during that time. Additionally, I examine compositional data from glass shards to explore the relationship between δD and shard composition. The RST exhibits …

Go to article

Disentangling Groundwater Dynamics At Oregon's Mckenzie River Headwaters, Taylor Nicole Salazar Jul 2023

Disentangling Groundwater Dynamics At Oregon's Mckenzie River Headwaters, Taylor Nicole Salazar

Dissertations and Theses

Widespread mountain snowpack declines have been occurring across the western United States over the last century, and are increasing in duration and severity, with several record-breaking low-snowpack years in the last decade. In the Pacific Northwest, summer streamflow is largely a result of melting snow and groundwater discharge, as summers are typically dry and warm in this Mediterranean bioclimate, thus making spring-fed rivers critical for regional water resources. However, current trends and predictions in hydroclimate modeling indicate spring-fed rivers will experience reduced summer discharge driven by the increasingly larger impact of anthropogenic climate change (warming) on (decreased) mountain snowpack. A …

Go to article

Hydrology Data For Fern Cave, Alabama (2020-2022), Benjamin Tobin, Benjamin V. Miller, Matthew Niemiller, Andrea Erhardt Jul 2023

Hydrology Data For Fern Cave, Alabama (2020-2022), Benjamin Tobin, Benjamin V. Miller, Matthew Niemiller, Andrea Erhardt

Research Data--KGS

Dataset includes water level from four sites within Fern Cave in Jackson County Alabama. Additionally, it includes chemistry of water, sediments and cave-adapted isopods.

Go to article

Sustainability Of Permanent Grassland On A Low Moor Soil With Different N And K Nutrient Management, K. Orlovius, J. Pickert Jul 2023

Sustainability Of Permanent Grassland On A Low Moor Soil With Different N And K Nutrient Management, K. Orlovius, J. Pickert

IGC Proceedings (1977-2023)

After the reunification of Germany fertilisation with P and K was strongly reduced in the eastern states of Germany due to the poor financial situation of the farms. Particularly on sites with a low nutrient delivery capacity, such a nutrient management strategy implies the risk of decreasing soil fertility. On a low moor soil with permanent grassland a 4 - year trial with different N and K fertilisation was set up to study the development of dry matter production and K concentrations in the grass.

Go to article

Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar Jul 2023

Assessing Ecological Relationships Among Late Triassic Vertebrates In Petrified Forest National Park, Alexandra Davis Apgar

Earth and Planetary Sciences ETDs

The complex vertebrate ecosystem of the Late Triassic has not yet been fully understood, largely due to oversimplification of hypothesized trophic hierarchies and limited preservation of direct evidence of faunal interaction. Paleocommunity reconstruction attempts can also fall victim to taphonomic biases, time-averaging inaccuracies, and non-analogue paleoecologies. Utilizing a combination of PAIRS analysis and NMDS ordination, we highlight vertebrate faunal relationships within the Adamanian and Revueltian faunachrons of Petrified Forest National Park, assess the likelihood that these patterns have ecological rather than preservational drivers, and examine how these potential interactions may have been impacted by the Adamanian-Revueltian turnover event. We are …

Go to article

Visualization Of Productivity Zones Based On Nitrogen Mass Balance Model In Narragansett Bay, Rhode Island, Jongsun Kim, Myung Hwangbo, Patricia S. Thibodeau, Georgia Rhodes, Emma Hogarth, Stewart Copeland Jul 2023

Visualization Of Productivity Zones Based On Nitrogen Mass Balance Model In Narragansett Bay, Rhode Island, Jongsun Kim, Myung Hwangbo, Patricia S. Thibodeau, Georgia Rhodes, Emma Hogarth, Stewart Copeland

School of Earth, Environmental, & Marine Sciences Faculty Publications

Primary productivity in the coastal regions, linked to eutrophication and hypoxia, provides a critical understanding of ecosystem function. Although primary productivity largely depends on riverine nutrient inputs, estimation of the extent of riverine nutrient influences in the coastal regions is challenging. A nitrogen mass balance model is a practical tool to evaluate coastal ocean productivity to understand biological mechanisms beyond data observations. This study visualizes the biological production zones in Narragansett Bay, Rhode Island, USA, where hypoxia frequently occurs, by applying a nitrogen mass balance model. The Bay is divided into three zones - brown, green, and blue zones - …

Go to article

What Is A Polygonal Impact Crater? A Proposed Framework Toward Quantifying Crater Shapes, Stuart J. Robbins, Jamie D. Riggs Jul 2023

What Is A Polygonal Impact Crater? A Proposed Framework Toward Quantifying Crater Shapes, Stuart J. Robbins, Jamie D. Riggs

College of Population Health Faculty Papers

Impact craters are used for a wide array of investigations of planetary surfaces. A crater form that is somewhat rare, forming only ∼10% of impact craters, is the polygonal impact crater (or PIC). These craters have been visually, manually identified as having at least two rim segments that are best represented as straight lines. Such straight lines or edges are most often used to infer details about the subsurface crust where faults control the structure of the crater cavity as it formed. The PIC literature is scant, but almost exclusively these craters are identified manually, and the potentially straight edges …

Go to article

Brief Communication: Is Vertical Shear In An Ice Shelf (Still) Negligible?, Chris Miele, Timothy C. Bartholomaus, Ellyn M. Enderlin Jul 2023

Brief Communication: Is Vertical Shear In An Ice Shelf (Still) Negligible?, Chris Miele, Timothy C. Bartholomaus, Ellyn M. Enderlin

Geosciences Faculty Publications and Presentations

Vertical shear is recognized today as a key component of the stress balance of ice shelves. However, the first ice shelf models were built on the neglect of vertical shear. Partly due to its historical treatment, it remains common to discuss vertical shear as though it were still considered negligible in ice shelf models. Here, we offer a historical perspective on the changing treatment of vertical shear over time, and we emphasize the term's non-negligibility in current ice shelf modeling. We illustrate our discussion in the simplest context of an analytic, isothermal, shallow-ice-shelf model.

Go to article

Collapse Of The Bindschadler Ice Stream At 11.5 Cal Kyr Bp Via Marine Ice Cliff Instability, Anna Sivils Jul 2023

Collapse Of The Bindschadler Ice Stream At 11.5 Cal Kyr Bp Via Marine Ice Cliff Instability, Anna Sivils

LSU Master's Theses

Previous studies of the Whales Deep Basin (WDB) outer continental shelf showed that the paleo-ice shelf fronting the Bindschadler Ice Stream broke up at 12.3 cal kyr BP. A calving cliff was subsequently maintained until at least 11.5 cal kyr BP. Slightly after that time, the grounding line rapidly retreated creating a 200 km embayment of grounded ice over the foredeepened middle continental shelf. The rapid opening of the embayment is recorded by a backstepping succession of small-scale morainal ridges on the middle continental shelf. The overlapping and end-to-end spacing of morainal ridges requires that the retreating grounding line experienced …

Go to article

Cratonic Basins As Effective Sediment Barriers In Continent‑Scale Sediment Routing Systems Of Paleozoic North America, Andrea L. Stevens Goddard, Olivia G. Thurston, David H. Malone, Patrick L. Mclaughlin, Jack Stewart Jul 2023

Cratonic Basins As Effective Sediment Barriers In Continent‑Scale Sediment Routing Systems Of Paleozoic North America, Andrea L. Stevens Goddard, Olivia G. Thurston, David H. Malone, Patrick L. Mclaughlin, Jack Stewart

Faculty Publications - Geography, Geology, and the Environment

Provenance studies demonstrate the important control of plate boundary mountain building on continental sediment routing systems. Less well understood is if subsidence and uplift in cratons also has the potential to affect the organization of sediment routing systems on continental scales. New detrital zircon provenance data from the Michigan Basin in the Midcontinent of North America preserve evidence of intrabasin provenance heterogeneity in Cambrian, Ordovician, and middle Devonian strata. These results suggest that cratonic basins serve as effective sediment barriers that prevent mixing within and across basins from 10 to 100 s of millions of years. Internal sediment mixing, sorting, …

Go to article

Holocene Rice Rats (Genus Oryzomys) From The Upper Mississippi River Drainage Basin, Hugh H. Genoways Jul 2023

Holocene Rice Rats (Genus Oryzomys) From The Upper Mississippi River Drainage Basin, Hugh H. Genoways

Zea E-Books Collection

The expansion and collapse of the geographic range of the Texas rice rat (Oryzomys texensis) in the upper Mississippi River drainage basin at the end of the Holocene was a unique event in North American mammals. In a period of about 4000 years with a point of origin near the American Bottom in Illinois, these small rodents extended their geographic range in a straight-line distance of over 950 km to the west into Nebraska and the same distance to the east into Pennsylvania. Then in less than 400 years this range expansion collapsed back to a point where …

Go to article

First Prev Next Last