Aleutian Island Arc Magmagenesis: Geochemical Variability and U-Pb Dating of Zircons in Unalaska Volcanic and Plutonic Rocks

• Main Author: Trim, Charelle
• Language: English
• Published: University of Florida 2017
• Subjects: alaska; aleutians; arcs; geochemistry; magmagenesis; volcanoes; Sedanka; Aleutian Island; Alaska
• Online Access: http://ufdc.ufl.edu/UFE0051582/00001

Arcs are important for understanding crustal development. This study focuses on Unalaska Island, an island in the Central-Eastern Aleutians. Plutonic and volcanic samples collected during a 1975-76 field excursion from the Unalaska Formation, Captains Bay Pluton and Shaler Pluton on Unalaska Island and plutons from nearby Sedanka Island. Major element, trace element and isotopic analyses were performed on these samples and the data was modeled and compared to other Central-Eastern Aleutian samples. Seven of the samples from Unalaska were also dated using U-Pb geochronology. Results show that the plutonic and volcanic rocks originated from a similar magma source and they both formed ca. 10 Ma. The implication of these results is that the volcanic rocks on Unalaska Island are the extrusive equivalent of the underlying plutons.