Abstract

This guide provides outcrop descriptions for a one-day field-trip leaving from Anchorage, Alaska and ending at Sheep Mountain, Alaska. The field trip route provides opportunities to observe exceptional outcrops of three bedrock sequences that record the accretionary tectonic development of southern Alaska: (1) Lower to Middle Jurassic igneous and metamorphic rocks comprising the Talkeetna arc, one of the most complete accreted oceanic arc crustal sequences known world-wide, totaling 7 km of section; (2) A >3,800 m thick sequence of Middle Jurassic-Upper Cretaceous marine forearc basinal deposits that record accretion of the Talkeetna arc against the former continental margin; and (3) a >2,900 m thick succession of Paleocene-Oligocene alluvial-fluvial strata deposited in remnant continental forearc depocenters coeval with post-accretionary transpressional tectonics and near-trench magmatism. Outcrop descriptions emphasize the sedimentology and detrital geochronology of sedimentary strata exposed near the Glenn Highway. Field guides for linked trips during this meeting describe correlative strata exposed inboard (north) and outboard (south) of the Matanuska forearc strata in the Alaska Range suture zone and Chugach accretionary prism, respectively.