Arc-Wide Exhumation of the Aleutian Islands at ~5-7 Ma Revealed By Apatite (U-Th-Sm)/He

We applied apatite (U-Th-Sm)/He (AHe) thermochronology to a total of 171 apatite grains from 43 plutonic samples from six of the Aleutian Islands, covering over 1400 km of the arc. We obtained AHe mean ages (calculated using 3-8 AHe grain dates) from twelve samples from the island of Unalaska, six from Umnak, six from Atka (plus two AHe grain dates from two samples each), two from Kagalaska, nine from Adak, and four from Attu. Nine plutonic samples from Unalaska (UNAK), six samples from Umnak (UMK15), and eight samples from Atka (ATK15) were collected during the NSF funded 2015 GeoPRISMS Aleutian Islands field campaign. All samples from Attu (AT-80), Adak (CC76, BW8), and Kagalaska (KAG76) and three samples from Unalaska (SED) were provided by the Cornell University Kay group collection collected in the 1970’s and 1980’s. The goal of this study was to constrain the timing of Aleutian arc exhumation, test the potential role of varying subduction dynamics along the arc, and investigate potential island arc exhumation mechanisms.