Physical Sciences and Mathematics Commons^™

A Faunal Composition Of The Late Cretaceous Blue Springs Site In Northeastern Mississippi And Evidence For Potential Paleoenvironmental Differences Between Beds, Ginger Trochesset

Honors Theses

The Maastrichtian-age Blue Springs locality of the Coon Creek Member of the Ripley Formation is known for abundant, well-preserved marine fossils, including many genera of microfossils, bivalves, gastropods, decapods, cephalopods, actinopterygians, and other vertebrate organisms. This research contributes to the understanding of the paleontology of the site, as well as the changing paleoenvironmental conditions of the beds throughout deposition.

This project analyzed bulk material collected in 2021 from three fossiliferous beds at Blue Springs: the Lower Corbula Bed (Bed C), the Pebble Bed (Bed G), and the Exogyra-Pycnodonte Bed (Bed J). Unconsolidated material from Beds C and J was processed …

Stable Carbon And Oxygen Isotopes Of Early Silurian Pentameride Brachiopods From Québec, Ontario, And Nunavut, And Paleoenvironmental Implications, Jordan N. Siewnarine

Electronic Thesis and Dissertation Repository

Analysis of low-Mg calcite brachiopod shells for δ¹⁸O and δ¹³C signatures provide quantitative independent geochemical data for paleoenvironmental interpretations. We analyzed 59 brachiopod shells from lower Silurian carbonate rocks of Anticosti Island, the Hudson Bay Lowlands and Niagara regions for spaciotemporal isotopic trends for the early Silurian. Screening tests using scanning electron microscopy, cathodoluminescence and trace element analysis demonstrate exceptional preservation, suggesting retention of primary isotopic values.

δ¹³C and δ¹⁸O values of shells range from 0.2‰ to 2.9‰ and -6.9‰ to -4.3‰ (VPDB), respectively. Temporally, increases in δ¹³C and δ …

Experimental Insights Into The Origin Of Microcrystalline Calcites, Mohammed Hashim

Dissertations

A significant proportion of modern marine calcium carbonate sediments is dominated by metastable aragonite and high Mg calcite that either dissolves or stabilizes to low-Mg-calcite (calcite) or dolomite during diagenesis. Sediment dissolution and stabilization have implications for the CaCO3 budget in the ocean and carbon burial rates. Yet, the diagenetic conditions that promote each process and their relative importance are poorly understood. Further, stabilization most commonly produces calcite microcrystals that exhibit various textures and host micropores. Despite their ubiquity in the rock record, the controls on microcrystal textures remain unclear. Here, laboratory experiments were used to investigate aragonite-to-calcite stabilization as …

Fire-Vegetation-Climate Interactions Across The Holocene On The U.S. Southeastern Coastal Plain, Mathew S. Boehm

Doctoral Dissertations

This dissertation research examined multiple proxy indicators in sediment cores from one lake and one wetland to reconstruct long-term relationships between fire, vegetation, and climate in the southeastern U.S.

At Lake Balboa (30.6992 N, 83.2031 W; 48 m elevation), a sinkhole pond located in southern Georgia, Bølling-Allerød conditions were sufficiently wet to maintain a shallow wetland at the site. Evidence for fire was minimal. Between 12,600 and 9200 cal yr BP, water availability declined, leading to a potential hiatus in sedimentation. During the early Holocene moisture availability increased, leading to greater primary productivity within and outside the lake, triggering an …

Vegetation Prior To And During Onset Of East Antarctic Glaciation: High Resolution Palynological Insights From Sabrina Coast, East Antarctica, Meghan L. Duffy

LSU Master's Theses

The Aurora Subglacial Basin (ASB) contains an estimated 3.5 m of global sea-level equivalent ice volume and is primarily drained by the Totten Glacier system, which terminates at the Sabrina Coast, East Antarctica. Thinning and retreating of the Totten Glacier indicate that this region is highly susceptible to oceanographic and atmospheric warming. The paleoclimate reconstruction of these changes, conducted in the context of this MS thesis, will improve understanding of East Antarctic Ice Sheet (EAIS) dynamics in this sensitive system. A recent study used seismic and sediment core data to document a dynamic early evolution of the EAIS in the …

Photometric Investigations Of Weathering Rinds And Coatings With Implications For Mars, Kathleen Hoza

WWU Graduate School Collection

Reflectance spectroscopy is a major technique for characterizing the composition of planetary surfaces, and has led to many key findings in planetary geology. In laboratory measurements, reflectance spectrometers typically acquire data using a standard, fixed viewing geometry. Measurements from spacecraft, however, may be acquired at a wide range of viewing geometries, depending on the orientation of the instrument relative to the target surface and the Sun. For many materials, the impact of viewing geometry on reflectance is minor; however, some materials’ spectral signatures can be influenced by these photometric effects. In particular, spectra of weathering rinds and rock coatings are …

Stratigraphic Reconstruction Of A Late Pleistocene Bald Cypress Forest Discovered On The Northern Gulf Of Mexico Continental Shelf, Suyapa Michell Gonzalez Rodriguez

LSU Master's Theses

A previously buried bald cypress forest (Taxodium distichum) was discovered on the continental shelf, offshore of Orange Beach, Alabama, USA, in ~20 m water depth. The forest was exhumed by Hurricane Ivan in 2004, and is now exposed as stumps in life position in a trough located in the northern Gulf of Mexico continental shelf seafloor. We are investigating the local stratigraphy, paleo-landscape, and mode of forest preservation of this unique site. In August 2015 and July 2016, submersible vibracores (18 in total) were collected. Core analysis included: bulk density and imaging via Geotek multi sensor core logger, …

Paleogene-Early Neogene Palynomorphs From The Eastern Equatorial Atlantic And Southeastern Florida, Usa: Biostratigraphy And Paleoenvironmental Implications, Walaa K. Awad

Doctoral Dissertations

"The transition from greenhouse conditions (Paleocene-Eocene Thermal Maximum, PETM) to icehouse conditions (Early Oligocene) is not well documented in tropical-subtropical regions. One hundred and five samples from Ocean Drilling Program (ODP) Site 959 (Hole 959A and Hole 959D) in the Cote d'Ivoire-Ghana Transform Margin, Alo-1 Well in the northern Niger Delta (Anambra) Basin, Nigeria, and W-17001 in southeastern Florida were studied for their palynological contents. Dinoflagellate cysts were mainly utilized for age refinement and to detect subtle changes in paleoenvironment and paleoclimate during the Paleocene-Early Eocene (ODP Hole 959D and Alo-1 Well) and Late Eocene-Early Miocene (ODP Hole 959A and …

A Method For The Geometric Analysis Of Rugose Coral Growth Ridges As Paleoenvironmental Indicators In The Middle Devonian Hungry Hollow Member Of Widder Formation, Michigan Basin, Andrew Thomson

Electronic Thesis and Dissertation Repository

Skeletons of Devonian rugose corals feature submillimetre-scale growth ridges on their outer surface (epitheca) that record the successive positions of the coral polyp during longitudinal corallite growth. Specimens of rugose corals Eridophyllum and Cystiphylloides from the Hungry Hollow Member of the Middle Devonian Widder Formation were sectioned longitudinally and imaged by SEM, and image processing techniques were applied to extract a line representing the epithecal surface. Local extrema found through peak detection allowed growth ridges to be represented as simplified triangles, so that geometric measurements (area, length) could be related to coral growth and analyzed in reference to possible paleoenvironmental …

An Early Paleogene Palynological Assemblage From The Sabrina Coast, East Antarctica: New Species And Implications For Depositional History, Catherine Davies Smith

USF Tampa Graduate Theses and Dissertations

Palynological analyses of 13 samples from two sediment cores retrieved from the Sabrina Coast, East Antarctica, provide the first information regarding the paleovegetation within the Aurora Subglacial Basin. The assemblages, hereafter referred to as the Sabrina Flora, are dominated by angiosperms, with complexes of Gambierina (G.) rudata and G. edwardsii representing 38–66% of the assemblage and an abundant and diverse Proteaceae component. The Sabrina Flora also includes Battenipollis sectilis, Forcipites sp. and Nothofagidites spp. (mostly belonging to the N. cf. rocaensis-flemingii complex), along with a few fern spores, including Laevigatosporites ovatus, a moderate presence of conifers, and …

Late Permian Paleoenvironmental Factors Expounded Through Analysis Of A Forest-Floor Paleosol Profile, Karoo Basin, South Africa, Cassi Knight

Honors Theses

Beaufort Group paleosols from the Karoo Basin, South Africa, record the paleoenvironmental conditions that existed prior to and after the Permian-Triassic extinction event. Paleosol exposures from Wapadsberg Pass, Eastern Cape Province, represent a well- preserved forest-floor litter overlying an interpreted inceptisol, a condition unique to the basin. Vegetation that colonized this landscape included a canopy of the gymnosperm Glossopteris and an understory of sphenopsids (Phyllotheca and Trizygia). Wapadsberg Pass paleosol sites were sampled for petrographic and geochemical analyses to constrain interpretations of Late Permian paleoenvironmental conditions that existed ~ 70 m below the Permian-Triassic Boundary (PTB). This project focuses on …