Award Date
1-1-2000
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Geoscience
First Committee Member
Rodney V. Metcalf
Number of Pages
136
Abstract
The Early Devonian (404 +/- 3 Ma) Porcupine Lake mafic intrusive complex of the Trinity terrane consists primarily of ultramafic-mafic plutonic and dike lithologies. The plutonic rock forms steep intrusive contacts with adjacent Ordovician peridotite, and consists of basal layered peridotite, cumulate clinopyroxenite, and isotropic gabbro. East-west trending mafic-to-felsic aphanitic dikes intrude the plutonic rocks, with high dike concentrations (>80%) in the southern portion of the complex; Gabbro and mafic dikes display subduction-related enrichment of light-ion lithophile elements and high degrees of depletion of high-field strength elements (Nb, Ta ≅ 0.1 NMORB). Trace element mixing models indicate gabbro and mafic dikes are derived from a residual mantle source with enrichment by small amounts of slab-derived aqueous fluids and pelagic sediments. Mafic dikes are also enriched by fertile MORB (asthenospheric) mantle. Subduction zone enrichment of a depleted mantle source suggests the Porcupine Lake mafic intrusive complex formed in a forearc tectonic setting.
Keywords
California; Complex; Intrusive; Lake; Mafic; Northern; Petrogenetic; Porcupine; Study; Terrane; Trinity
Controlled Subject
Geology; Geochemistry
File Format
File Size
4874.24 KB
Degree Grantor
University of Nevada, Las Vegas
Language
English
Permissions
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Repository Citation
Muller, Edward Robert, "Petrogenetic study of the Porcupine Lake mafic intrusive complex, Trinity terrane, northern California" (2000). UNLV Retrospective Theses & Dissertations. 1171.
http://dx.doi.org/10.25669/tnq4-ppc2
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