Document Type

Thesis

Degree

Master of Science (MS)

Major/Program

Geosciences

First Advisor's Name

Rosemary Hickey-Vargas

First Advisor's Committee Title

Committee Chair

Second Advisor's Name

Laurel Collins

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Grenville Draper

Third Advisor's Committee Title

Committee member

Keywords

Volcano, Chile, Ash, Geology, Geochemistry, Petrology

Date of Defense

3-29-2018

Abstract

Recent ocean sediments collected offshore Chile by Ocean Drilling Program Leg 202 contained layers of volcanic ash of unknown origin. These deposits may have originated from sources in the Southern Volcanic Zone (SVZ) within the Andean Volcanic Belt to the east, or from explosive volcanoes in the southwestern Pacific transported by westerly prevailing winds. In this study, mineral and glass textures and compositions of Leg 202 ashes were evaluated to try to determine the sources of the ash layers. Ash fragments were imaged and analyzed for major elements using an SEM with X-Ray detector and for trace elements using LA-ICPMS. Results show that the ash samples are rhyolitic and that they formed in a subduction zone setting or a continental margin. The ash samples have distinct physical and geochemical features that can be used in the future to identify their source(s) by comparison to databases of Pleistocene Recent explosive volcanic eruptions.

Identifier

FIDC006542

Available for download on Wednesday, October 24, 2018

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