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Articles 1 - 6 of 6
Full-Text Articles in Earth Sciences
Investigation Of Cryptotephra In Polar Ice Cores, Meredith Helmick
Investigation Of Cryptotephra In Polar Ice Cores, Meredith Helmick
Electronic Theses and Dissertations
Volcanic ash (tephra) present within polar ice cores greatly supplements our understanding of past volcanism and its impacts on society and the state of the climate system. This thesis investigates the utility and limitations of ice core tephrochronology in answering questions related to volcanic source identification of ice core glaciochemical signals, tephrostratigraphy of an Antarctic ice core, and the timing of major and climate forcing eruptions. This thesis explores the efficacy of SEM-EDS measurements on ultra-fine (µm) volcanic particles for the purpose of geochemically characterizing a non-visible ice-embedded tephra and the subsequent identification of the volcanic source. In combination with …
The Origin And Evolution Of Impact Crater Lakes: A Case Study Of The Ries Impact Structure, Germany, Matthew J. O. Svensson
The Origin And Evolution Of Impact Crater Lakes: A Case Study Of The Ries Impact Structure, Germany, Matthew J. O. Svensson
Electronic Thesis and Dissertation Repository
Impact events are known to generate hydrothermal systems, which can subsequently vent into an overlying crater lake and potentially create ideal conditions for some microbial life-forms. Thus, early post-impact sedimentary deposits would be excellent targets for Mars sample return, and as such, the robust characterization of such deposits on Earth is critical. In this thesis, we establish an improved understanding of how the Ries crater lake formed, and how an active impact-generated hydrothermal system influenced its early evolution. The ~14.8 Ma Ries impact structure hosts the majority of its paleolake deposits within the structure's central basin with some deposits situated …
Subsurface Correlation Of Lower Silurian Medina Group, Southwestern Ontario, Rhys H. Paterson
Subsurface Correlation Of Lower Silurian Medina Group, Southwestern Ontario, Rhys H. Paterson
Electronic Thesis and Dissertation Repository
The Medina Group succession in southwestern Ontario includes, in ascending order: the Whirlpool, Manitoulin, Cabot Head, Power Glen, Devils Hole-Balls Falls, Grimsby, and Thorold formations. Subsurface mapping in central and eastern Lake Erie has resulted in the recognition of three stratigraphic packages within the Medina Group based upon the integration of sedimentologic, stratigraphic and geophysical borehole logs. The interplay between changing paleoenvironments, sediment provenance, and regional tectonics and associated sea level fluctuations has resulted in the accumulation of a complex mosaic of mixed siliciclastics and carbonates. Manitoulin Formation carbonates and Whirlpool Formation siliciclastics display consistent thicknesses across the study area. …
Stratigraphy, Sedimentology, And Deformational Significance Of Cambrian And Early Ordovician Strata Along The Southeast Wisconsin Arch, Allison Raeann Kusick
Stratigraphy, Sedimentology, And Deformational Significance Of Cambrian And Early Ordovician Strata Along The Southeast Wisconsin Arch, Allison Raeann Kusick
Theses and Dissertations
A detailed study of the stratigraphic units in and around the Wisconsin Arch of central and southeast Wisconsin are presented to refine the sedimentologic record and the geologic implications within the Cambrian and early Ordovician strata. The Cambrian and early Ordovician sediments in central and southeast Wisconsin unconformably overlie a topographic high composed of Precambrian basement rocks, called the Wisconsin Arch, and consist of various clastic deposits, dolostones, and several horizons of deformation. Bedrock cores, made available through the Wisconsin Geological and Natural History Survey (WGNHS), were analyzed, to understand sedimentation in the Cambrian and early Ordovician. My analyses focused …
Characterization Of Quaternary Stratigraphy In The Mississippi Sound To Evaluate The Influence Of Geologic Heterogeneity On Submarine Groundwater Transport And Discharge, Zachary Peoples
Theses and Dissertations
Submarine Groundwater Discharge (SGD) through seafloor sediments is gaining recognition as an important component of coastal water quality. Stratigraphic features creating geologic heterogeneity, such as incised paleochannels, may influence preferential pathways for SGD. The central Mississippi Sound is underlain by paleochannels that were incised into Pleistocene sediments while the area was subaerially exposed during the last glacial maximum and are now buried by transgressive Holocene deposits. In this thesis, newly collected chirp, previously published seismic reflection, and sediment core data are used to characterize the three-dimensional structure of the Holocene-Pleistocene contact. Results indicate that Pleistocene paleochannels cross-cut the study area, …
Conflicting Narratives In Geology: The Current Debate Surrounding The Beginning Of The Anthropocene Epoch, Carter Mitchell
Conflicting Narratives In Geology: The Current Debate Surrounding The Beginning Of The Anthropocene Epoch, Carter Mitchell
Student Writing
Geologists currently debate the addition a new Epoch of geologic time called the Anthropocene. The Anthropocene is characterized by changes in the lithosphere resulting directly from human activity. This paper analyses the arguments in favor of and against the Anthropocene as well as the conflicting narratives concerning the beginning and scope of the Anthropocene.