Tools
Breccia of Frog Lakes : reconstructing Triassic volcanism and subduction initiation in the east-central Sierra Nevada, California
- Author
- Roberts, Sarah Elizabeth.
- Title
- Breccia of Frog Lakes : reconstructing Triassic volcanism and subduction initiation in the east-central Sierra Nevada, California / Sarah Elizabeth Roberts.
- Format
- Online Resource Book
- Published
- 2013.
- Description
- v, 57 leaves : ill. (some col.) ; 18 cm. Thesis (M.S.) -- Indiana University, 2013.
- [Description]
- Also available online via IUPUI ScholarWorks.
- URL
- http://hdl.handle.net/1805/4085 - (Connect to resource online)
- Uniform series
- IUPUI theses and dissertations.
- Notes
- Department of Earth Sciences, Indiana University-Purdue University Indianapolis (IUPUI). Advisors: Andrew P. Barth, Gary D. Rosenberg, Gabe M. Filippelli. Includes vitae. Includes bibliographical references (leaves 53-57).
- Abstract
- The Antler and Sonoma orogenies occurred along the southwest-trending passive Pacific margin of North America during the Paleozoic concluding with the accretion of the McCloud Arc. A southeast-trending sinistral transform fault truncated the continental margin in the Permian, becoming a locus for initiation of an east-dipping subduction zone creating the Sierran magmatic arc. Constrained in age between two early Triassic tuff layers, the volcanic clasts in the breccia of Frog Lakes represent one of the earliest records of mafic magmatism in the eastern Sierra Nevada. Tholeiitic rock clasts found in the breccia of Frog Lakes in the Saddlebag Lake pendant in the east central Sierra Nevada range in composition from 48% to 63% SiO2. Boninites produced by early volcanism of subduction initiation by spontaneous nucleation at the Izu-Bonin-Mariana arc are more depleted in trace element concentrations than the clasts while andesites from the northern volcanic zone of the Andes produced on crust 50 km thick have similar levels of enrichment and provide a better geochemical modern analogue. Textural analysis of the breccia of Frog Lakes suggest a subaqueous environment of deposition from a mature magmatic arc built on continental crust > 50 km thick during the Triassic. The monzodiorites of Saddlebag and Odell Lakes are temporal intrusive equivalents of the breccia of Frog Lakes and zircon geochemistry indicates a magmatic arc petrogenesis.
- Subject headings
- Continental margins. Petrology--Research--Methodology--Measurement--Evaluation. Geology, Stratigraphic--Paleozoic--Dating. Geology, Stratigraphic--Permian--Dating. Paleoseismology. Plate tectonics. Volcanic ash, tuff, etc.--Sierra Nevada (Calif. and Nev.) Subduction zones--Sierra Nevada (Calif. and Nev.) Geology, Stratigraphic--Triassic. Geophysics--Pacific Area. Geophysics--Washington (State) Geophysics--Nevada--Sonoma Range. Intrusions (Geology) Paleogeography--Sierra Nevada (Calif. and Nev.)--Paleozoic. Phenocrysts. Roof pendants (Geology)--Research. Breccia--Sierra Nevada (Calif. and Nev.) Orogeny--Nevada. Volcanism--Research--Methodology--Analysis. Magmatism. Breccia of Frog Lakes. Triassic. Volcanism. Subduction initiation. Sierran magmatic arc. Saddlebag Lake pendant. Odell Lake (Or.) Klamath Mountains (Calif. and Or.)