Eocene plutonism along the Denali Fault zone, AK

Map modified from Reed and Lanphere, 1974 showing the interpreted piercing point in red. Detrital zircon results from catchments draining each pluton shown in lower right.

The Foraker and McGonagall plutons have been interpreted as offset fragments of a once coherent plutonic body, indicating ca. 38 km of strike-slip separation since emplacement ca. 38 Ma.  However, this offset is at odds with numerous other estimates including modern slip-rate measurements.  Our research involves detailed field characterization, geochronology, isotopic tracer studies, bulk rock geochemistry, and hornblende barometry to evaluate two major questions: 1) are the Foraker and McGonagall plutons dismembered fragments of the same pluton, and 2) what were the intrusive mechanisms that facilitated melt transfer along a major, long-lived, strike slip system.

Eocene plutonism along the Denali Fault. Modified from S. Roeske
View of the Schist Creek pluton adjacent to the Denali Fault