Open Access. Powered by Scholars. Published by Universities.®
- Institution
- Keyword
Articles 1 - 3 of 3
Full-Text Articles in Stratigraphy
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 …
Precambrian Molar-Tooth Structure: Unraveling The Diagenesis Of Ancient Carbonates, Agustin Kriscautzky
Precambrian Molar-Tooth Structure: Unraveling The Diagenesis Of Ancient Carbonates, Agustin Kriscautzky
Doctoral Dissertations
Molar-tooth structure (MTS) is an enigmatic carbonate fabric that occurs mainly within Proterozoic carbonate host rocks. It is composed of two distinct features: cracks of various morphologies and crack-filling calcite microspar. Although the origins of MTS remain unknown, most previous investigation has focused on the formation of the cracks and mechanisms involved in the void space generation, with less emphasis on the intriguing carbonate fill. In this study I have investigated molar-tooth bearing carbonates from regions that span both paleogeography and geologic time. Analysis at the microscopic scale, including traditional petrography, cathodoluminescence petrography, scanning electron microscopy, and micrometer-scale geochemical analyses …
The Mineralogy And Geochemistry Of Illinois Basin Paleosols: Recognizing Detrital, Pedogenic, And Diagenetic Minerals, Julia A. Mcintosh
The Mineralogy And Geochemistry Of Illinois Basin Paleosols: Recognizing Detrital, Pedogenic, And Diagenetic Minerals, Julia A. Mcintosh
Earth Sciences Theses and Dissertations
The geochemical compositions of minerals in paleosols are assumed to be homogenous and attained through chemical weathering processes during episodes of pedogenesis in the geologic past. As such, the geochemical composition of minerals from paleosols may be used to reconstruct ancient climates and environments. One problem with this assumption is that paleosols were initially clastic sedimentary rocks or substrate prior to pedogenesis, thus it is likely that some portion of the paleosol is still composed of detrital minerals. Secondly, conditions may change in a sedimentary basin as the basin is buried and later uplifted, potentially triggering new mineralization or transformation …