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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.
11

Structure and petrology pertaining to a beryl deposit, Baboquivari Mountains, Arizona

Clark, Jackson Lutellus, 1918- January 1956 (has links)
No description available.
12

GEOCHEMICAL EVIDENCE FOR CRUSTAL MELTING IN THE ORIGIN OF THE IGNEOUS SUITE AT THE SIERRITA PORPHYRY COPPER DEPOSIT, SOUTHEASTERN ARIZONA (UNITED STATES, STRONTIUM, PIMA COUNTY, TRACE ELEMENTS, NEODYMIUM).

ANTHONY, ELIZABETH YOUNGBLOOD. January 1986 (has links)
Numerical values for parameters which characterize melting regimes and differentiation history have been determined for a suite of genetically-related calc-alkaline rocks. Isotopic ratios of Nd and Sr vary sympathetically, with the least differentiated and oldest rocks having ε(Nd) = -4.3 and ⁸⁷/Sr⁸⁶Srₒ = 0.7069 and the most differentiated and youngest characterized by ε(Nd) = -8.5 and ⁸⁷Sr/⁸⁷/Srₒ = 0.7092. These observations imply that a process which might relate the various units is that of invasion of the crust by mantle-derived magmas and progressive assimilation. The most negative Nd values may well represent the isotopic signature of the crustal rocks which melted. Melting of a 1.8 Ga source region (an age characteristic of the basement in southeastern Arizona) which had a ¹⁴⁷Sm/¹⁴⁴Nd ratio of .13 would yield Laramide melts with and ε(Nd) of -8.5. This Sm/Nd ratio is characteristic of a somewhat mafic (lower?) crust, a character consistent with petrological and chemical evidence which suggest that the source was intermediate to mafic in composition and of amphibolite grade. Solution of the isotopic data yields a value of r (that instantaneous ratio of assimilated material to crystallizing magma) equal to 0.6 to 0.9. These values are reasonable considering heat budgets of crystallization and fusion in the lower crust. Solution of the set of equations for changes in concentration of the trace elements yields numeric values for the f, fraction of remaining melt for each unit in the series. The values are: andesite, f-0.63; granodiorite, f-0.42 to 0.32; and the final granite stocks and dikes, f-0.34. The modeling provides insight into the way an igneous suite intimately associated with copper mineralization has evolved. The porphyry ore bodies are related to long-lived and large magma systems. At the level of mineralization and observation, we sample only a small portion of the system. The importance of subduction to metallogenesis may be that it provides a heat source, in the form of mantle-derived magma, which allows extensive melting of hydrous crust. Thus, as is becoming evident from other studies as well, assimilation and crustal anatexis are major processes in generating granitoid rocks at convergent plate boundaries.
13

A microstructural study of S-C mylonites of part of the Tanque Verde Mountains, Tucson, Arizona

Martins, Verónica E. de Sousa Carvalho January 1984 (has links)
No description available.
14

Petrology and crystal chemistry of the Ruby Star granodiorite, Pima County, Arizona

Hess, Nancy Jane, 1959- January 1986 (has links)
No description available.
15

Petrology of the Devonian rocks in eastern Pima and Cochise Counties, Arizona

Wright James J., 1914- January 1964 (has links)
No description available.
16

The petrology and stratigraphy of the Earp Formation, Pima and Cochise Counties, Arizona

Lodewick, Richard Ballard, 1933- January 1970 (has links)
No description available.
17

Stratigraphy and sedimentary petrology of the Mesozoic rocks of the Waterman Mountains, Pima County, Arizona

Hall, Dwight Lyman, 1953- January 1985 (has links)
No description available.

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