• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 11
  • 6
  • 1
  • 1
  • Tagged with
  • 36
  • 29
  • 6
  • 5
  • 5
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 2
  • 2
  • 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.
31

<sup>40</sup>Ar/<sup>39</sup>Ar Ages, Compositions, and Likely Source of the Eocene Fallout Tuffs in the Duchesne River Formation, Northeastern Utah

Jensen, Michael Seth 01 November 2017 (has links)
Thin fallout tuffs in the Duchesne River Formation in the Uinta Basin, Utah are evidence that volcanism was active in northern Nevada and Utah in the late Eocene. The Uinta Basin is a sedimentary basin that formed during the Laramide orogeny. Ponded lakes of various salinity filled and emptied and during the late Eocene the northern rim was dominated by a wetland/floodplain depositional setting. Most of the tuffs have rhyolitic mineral assemblages including quartz, biotite, sanidine, and allanite. Rhyolitic glass shards were also found in one of the ash beds. Biotite compositions have Fe/(Fe+Mg) ratios typical of calc-alkaline igneous rocks and clusters of biotite compositions suggest 3 or 4 volcanic events. Sanidine compositions from five samples grouped at Or73 and Or79. Only one sample had plagioclase with compositions ranging between An22 - An49. Some beds also contained accessory phases of titanite, apatite, and zircon. Whole rock compositions of the altered volcanic ash beds indicate these tuffs underwent post-emplacement argillic alteration, typical of a wetland/floodplain depositional setting. Immobile element ratios and abundances, such as Zr/Nb and Y are typical of a subduction zone tectonic setting and rhyolitic composition. 40Ar/39Ar ages constrain the timing of volcanism. One plagioclase and one sanidine separate from two different tuff beds yielded ages of 39.47 ± 0.16 Ma and 39.36± 0.15 Ma respectively. These dates, along with the compositional data seem to limit the eruptive source for these fallout tuffs to the northeast Nevada volcanic field. These new ages, along with previously published ages in the Bishop Conglomerate which unconformably overlies the Duchesne River Formation, constrain the timing of two uplift periods of the Uinta Mountains at 39 Ma and 34 Ma. Finally, the ages also date the fauna of the Duchesnean Land Mammal Age to be about 39.4 Ma as opposed to less precise earlier estimates that placed it between 42 and 33 Ma.
32

40Ar/39Ar Ages, Compositions, and Likely Source of the Eocene Fallout Tuffs in the Duchesne River Formation, Northeastern Utah

Jensen, Michael Seth 01 November 2017 (has links)
Thin fallout tuffs in the Duchesne River Formation in the Uinta Basin, Utah are evidence that volcanism was active in northern Nevada and Utah in the late Eocene. The Uinta Basin is a sedimentary basin that formed during the Laramide orogeny. Ponded lakes of various salinity filled and emptied and during the late Eocene the northern rim was dominated by a wetland/floodplain depositional setting. Most of the tuffs have rhyolitic mineral assemblages including quartz, biotite, sanidine, and allanite. Rhyolitic glass shards were also found in one of the ash beds. Biotite compositions have Fe/(Fe+Mg) ratios typical of calc-alkaline igneous rocks and clusters of biotite compositions suggest 3 or 4 volcanic events. Sanidine compositions from five samples grouped at Or73 and Or79. Only one sample had plagioclase with compositions ranging between An22 - An49. Some beds also contained accessory phases of titanite, apatite, and zircon. Whole rock compositions of the altered volcanic ash beds indicate these tuffs underwent post-emplacement argillic alteration, typical of a wetland/floodplain depositional setting. Immobile element ratios and abundances, such as Zr/Nb and Y are typical of a subduction zone tectonic setting and rhyolitic composition. 40Ar/39Ar ages constrain the timing of volcanism. One plagioclase and one sanidine separate from two different tuff beds yielded ages of 39.47 ± 0.16 Ma and 39.36± 0.15 Ma respectively. These dates, along with the compositional data seem to limit the eruptive source for these fallout tuffs to the northeast Nevada volcanic field. These new ages, along with previously published ages in the Bishop Conglomerate which unconformably overlies the Duchesne River Formation, constrain the timing of two uplift periods of the Uinta Mountains at 39 Ma and 34 Ma. Finally, the ages also date the fauna of the Duchesnean Land Mammal Age to be about 39.4 Ma as opposed to less precise earlier estimates that placed it between 42 and 33 Ma.
33

Computer Modeling of Geology in the Sparta and Montpelier Quadrangles of Clay and Chickasaw Counties, Mississippi: A Tantalizing Near Miss

Defibaugh y Chávez, Jason 07 August 2004 (has links)
This project attempted to combine digital data sets to define and map geologic features in the Sparta and Montpelier quadrangles of Chickasaw and Clay counties in northeastern Mississippi. LANDSAT TM, digital elevation, and soil permeability data was used in conjunction with reference data for the Sparta quadrangle to build a computer model. Variables used in the model were: geology, slope, soil permeability, vegetation indices, the first three bands of a tasseled cap transformation, and drainage frequency. The data used was LANDSAT TM 30 meter imagery, digital elevation models, also at 30 meter resolution, Penn State STASGO soils data, and the existing map of the Sparta quadrangle. The purpose of this project was to use digital data to remotely map geologic features through heavy vegetation using a computer model. While the results of this project were not completely successful, the methods used show some potential for future application.
34

Carbonate Lake Deposits in the Fluvial Bridger Formation of the Greater Green River Basin, Wyoming

Blakeman, Audrey A. 22 September 2014 (has links)
No description available.
35

The Surficial Geology of Fulton County, Ohio: Insight into the Late Pleistocene-Early Holocene Glaciated Landscape of the Huron-Erie Lake Plain, Fulton County Ohio, USA

Blockland, Joseph D. January 2013 (has links)
No description available.
36

Vnější ekonomická rovnováha České republiky / The external economic equilibrium of the Czech republic

Šedivý, Ctibor January 2011 (has links)
This thesis focuses on the theoretical conception of the Balance of Payment, its method of adjustment and stress the development of the Czech republic's Balance of Payment in period 2000 -- 2010 via analytical-descriptive approach. It defines its basic terms practical relations within framework of the horizontal and vertical outlook. Thesis's Attention is spread out between status and flow quantity. Thesis is also consist of three boxes that contain a short profile of intertemporal approach to the Common Account, sustainability of investment position and excursion to the essential theories of foreign currency exchange rate that is related to the Balance of payment tight. The end is dedicated to the "traditional" indicators of external equilibrium of the Czech republic in pre-monetary crisis era and in the present.

Page generated in 0.0438 seconds