<p> Cretaceous Period. There is limited research on organic carbon content of the Pierre Shale in South Dakota. Frequent volcanic eruptions combined with climate change resulted in an increase in carbon dioxide in the atmosphere, leading to decreases in marine oxygen content. Decreasing marine oxygen has been attributed to higher amounts of preserved organic matter in marine sediment. Impact of volcanic ash deposition in the Cretaceous Interior Seaway has not been thoroughly studied. The Pierre Shale also contains the Crow Creek Member, a 5 foot thick layer of unconsolidated sand and rip-up clasts which may indicate a high-energy depositional event. Some hypothesize that it was deposited by a tsunami generated by the Manson impact. Others believe the Crow Creek Member is evidence of a marine low-stand that occurred before the Bearpaw Cyclothem. It is possible that the depositional event that deposited the Crow Creek Member may have led to increases in organic carbon preservation depending on the burial rates and amount of organic carbon preserved. </p><p> To investigate the connection between volcanic ash deposition, the Crow Creek Member deposition, and organic matter preservation of the coastal Cretaceous Interior Seaway, stable isotope geochemistry, trace element geochemistry, and total organic carbon analyses were performed on a 500 foot core drilled near Fort Pierre, South Dakota. Ash beds were identified using X-ray diffraction analysis. Core sampling was driven by location of the Crow Creek Member (above below and within one foot) and by location of ash beds (above below and within one inch), but samples were also taken based on highest and lowest gamma ray values for each five foot (1.52m) core segment. Core sampling was restricted because every other five foot (1.52 meter) section of the Treedam core segement was available for sampling. Statistical T-tests and Z-tests were performed on sample data to determine if there was a significant difference in geochemical signatures between core deposited before and after ash bed deposition and Crow Creek Member deposition. Results and T and Z statistical analyses show no significant changes in stable isotopes nor trace elements as a result of ash bed deposition nor the Crow Creek Member depositional event. Results also indicate that variability of the coastal brackish marine system made any significant trends harder to isolate on such a small scale. Overall &delta;¹³C_org signatures ( -27 to -26 &permil;) indicate that the Cretaceous Interior Seaway was deposited in a brackish shallow marine environment and that there were no drastic changes in sea level throughout the deposition of the Pierre Shale Group that was sampled (Gregory Member up through Virgin Creek Member). The &delta;<p style="font-variant: small-caps">15</p>N data range (-6 to +1 &permil;) show that fixed nitrogen was scarce during the deposition of the Pierre Shale and that most of the available marine nitrogen was likely fixed by cyanobacteria.</p>

<p> Much scientific knowledge already exists on the Cretaceous-Paleogene (K/Pg) Boundary Deposit from outcrop and shallow core near to outcrop. The significance of this study is to learn from the only deep-well core on land, from the northern Gulf of Mexico (GoM) known to preserve this deposit. This core was chosen because of its pristine (unweathered) condition. The aim was to characterize the portion of this core which was influenced by the Chicxulub Impact event 65.5 Ma to enhance the scientific knowledge of the K/Pg boundary. I hypothesized that this core represents three lithofacies: 1) pre-impact chalk, 2) mass wasting deposit and fall back material, 3) Midway Shale; and that the mass wasting deposit and fall back material were deposited as a direct result of the impact event. I tested these hypotheses by employing: 1) Macroscopic descriptions, 2) Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) of selected portions, 3) 10% HCl treatment and microscopic descriptions of the resulting insoluble portions. The findings show that the core can be divided into three main sections in ascending order: 1) a lighter carbonate, 2) a darker carbonate, and 3) a black shale. From optical and SEM analysis, I find that the microfossils and ubiquitous coccoliths found throughout the carbonate sections of this core do not exist in the core above section 2. Section 2 is mostly a Chicxulub Impact induced mass wasting deposit. In order to investigate better the non-carbonate components of the core, representative portions were treated with 10% HCl, an investigative technique not commonly applied to cores of the K/Pg boundary. Under an optical microscope ,10% HCl insoluble portions from the K/Pg boundary reveal no regularly shaped impact spherules. I find no Si-rich spherules and posit that the spherules in this core are almost entirely, Ca-rich.</p><p>

This thesis develops and applies new techniques for reconstructing past environments from the speleothem archive. Chapter 3 introduces Ca isotopes as a novel palaeo-aridity proxy. Recent dripwater, farmed calcite and bedrock data show that, in the modern environment, 36% of initial dripwater Ca is removed by prior calcite precipitation at the HS4 dripsite (Heshang Cave, Central China). A speleothem record spanning the 8.2kyr event suggests this value increased to 60% during the event, in response to a decrease in effective rainfall of approximately a third. Modern Ca isotope systematics, and the cycling of other Group II metals, are studied further in Chapter 4. Data from Heshang Cave monitoring samples explore the temporal and spatial controls on these proxy systems. Results highlight the importance of secondary calcite as a potential source of dripwater metals, as well as the significant contribution of particulate calcite to bulk dripwater chemistry. At the HS4 dripsite, over a third of bulk dripwater Ca is present as particulate calcite. This influences bulk dripwater Ca concentrations and isotopes, as well as potentially impacting speleothem growth and chemistry. Chapters 5 introduces CaveCalc, a new numerical model for dripwater and speleothem chemistry and isotopes based on PHREEQC. Key strengths of CaveCalc include its ability to model multiple proxy systems in a single framework, the ability to quantify the extent of open-system dissolution, and the extensible nature of its design. Chapter 6 applies CaveCalc to disentangling the controls on dripwater and speleothem &delta;¹³C values. Model results are compared with speleothem data. At Heshang Cave, anomalously high &delta;¹³C is quantitatively explained as the result of CO₂ degassing and prior calcite precipitation, an interpretation made possible by the availability of coupled &delta;¹³C, a¹⁴C and Ca isotope data. This approach provides a powerful tool to help researchers better interpret dripwater and speleothem &delta;¹³C data.

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1983. / Vita. Includes bibliographical references (p. 268-279).

<p> The submarine-fan-dominated, proximal Los Angeles basin contains interstratified hemipelagic strata coeval with the widespread Miocene Monterey Formation that accumulated in other California margin basins. Although more detritalrich and containing greater abundance of plagioclase and muscovite than more distal, outboard basins, a four-part compositional zonation is recognized in the fine-grained facies, similar to the stratigraphic succession of the Santa Barbara coastal area. In ascending stratigraphic order, these include a basal interbedded calcareous-siliceous zone, a phosphatic zone, a calcareous-siliceous zone, and an uppermost siliceous zone. To establish these zonations, 125 samples from five wells in a north-south transect across the western basin from East and West Beverly Hills, Inglewood, and Wilmington oil fields were analyzed for bulk chemical composition by XRF and quantitative mineralogy by XRD and FTIR. The mineralogic composition of the fine-grained detrital fraction makes use of geochemical equations for sedimentary components developed elsewhere unsuitable to the Los Angeles basin.</p>

<p> The Waucobi Lake Beds in Owens Valley, California contain two distinct facies representing saline-alkaline and fresh water environments. The potential cause for the change in lacustrine facies is examined through geomorphic, geochemical and sedimentological analyses. An age range for the lake beds was constrained with the dating and &ldquo;fingerprinting&rdquo; of 13 tuffs throughout the Waucobi Lake Bed exposures. 40Ar/39Ar dating completed for this study provides ages of 2.63 to 2.06 Ma for tuff layers found within the lake beds, with the transition from saline-alkaline facies to fresh water facies occurring around 2.5-2.4 Ma. Regional climate during the late Pliocene-early Pleistocene is reflected by the saline-alkaline environment within Waucobi. However, the Waucobi environment deviates from regional climate after 2.5 Ma, implying that the fresh water facies represents a change in lacustrine hydrology. Given the coincidence between a prominent seismite recorded in the lake beds with the facies change, tectonic activity rather than climate is postulated as the cause for the transition in the lake environment.</p>

<p> A study of 230 samples of porcelanite and siliceous mudstone from a single stratigraphic section containing all three silica phases in the Sisquoc and Monterey formations, Casmalia Hills, California, tested established models of silica diagenesis. Analysis of composition, silica phase, and d₁₀₁-spacing using combined EDS/XRF and XRD documented a broad distribution of opal-CT d₁₀₁-spacing values rather than a linear progression for any particular compositional range predicted by prior studies. The data from this thesis study strongly suggest that other variables (e.g., carbonate, organic matter) besides burial depth/temperature and normalized silica:detritus ratios are critical to diagenetic ordering and that the opal-CT d₁₀₁-spacing and silica content of a single sample cannot be used as a geothermometer. Instead, the maximum opal-CT d₁₀₁-spacing in a set of samples for any normalized silica:detritus ratio in a stratigraphic interval may be useful to determine the minimum temperature or maximum burial depth reached prior to tectonic uplift.</p>

Thesis (Ph.D.)--Indiana University, Dept. of Geological Sciences, 2007. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5814. Advisers: Arndt Schimmelmann; Maria Mastalerz. Title from dissertation home page (viewed May 9, 2008).

Thesis (Ph.D.) -- University of Adelaide, Dept. of Geology, 2000. / Includes bibliographical references (10 leaves).

Thesis (Ph.D.)--Washington University, 2005. / (UnM)AAI3181227. Source: Dissertation Abstracts International, Volume: 66-07, Section: B, page: 3604. Chair: Larry A. Haskin.