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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigations of Macro and Micro Scale Void Spaces: Preservation, Modeling and Biofilm Interactions

Nagel, Athena Marie Owen 15 August 2014 (has links)
Dissolutional voids in the subsurface were examined from three different viewpoints. First, analysis of pseudokarst features on San Salvador Island, Bahamas, uncovered the involvement of organics in the cementation and porosity generation process. This organic material was analyzed using SEM, TEM, and in thin section. While the actual role of organics in the cementation process could not be determined using these tools, the abundance of the material was documented. Holocene samples appear to have more organics than Pleistocene samples. The abundance of this material should have an effect on isotope analyses and needs to be considered in future work on meteoric cements and the environments where they form. Second, work on Mallorca Island, Spain, demonstrated how the placement and abundance of exposed caves could predict subsurface cave distributions. This work measured caves along exposed coastlines and in protected areas known as calas. Results found that caves within the calas have larger volumes and aerial footprints than caves on the exposed cliffs. The cave distributions showed that calas had to form prior to cave formation. Several paleo-slump features were observed and are believed to be the result of collapsed Tortonian flank margin caves, which were later inilled with Messinian sediments, using the caves as limited accommodation space, resulting in these sediment layers unaffected by the collapse further up section. Third, the current method of cave data manipulation to produce cave areal footprints and volume was found to be incorrect and in need of a calibration mechanism. This calibration was determined by reviewing how Compass cave mapping software generates volume estimates, using shapes of known volumes. Cave surveying techniques were also reviewed to determine if survey protocol affected volume outputs. Surveying in straight lines, down the center of a passage, avoiding splay shots, and taking left, right, up and down measurements (LRUDs) were found to generate the most accurate volumes estimates using Compass. These protocols were used to remap caves from paper maps to generate correction factors. Propriety software was used that could “shrink wrap” a 3D cave map rendering to produced values for cave volume and porosity and rock porosity.
2

FILLING THE VOID: THE INTERVAL BETWEEN THE PAST AND THE FUTURE

GRIFFITH, REBECCA LYNN 11 July 2006 (has links)
No description available.
3

Heads and Skulls as Sediment Sorters: An Actualistic, CT-Based Study in Taphonomy

Daniel, Joseph C. 11 September 2012 (has links)
No description available.

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