Stikine Airborne Geophysical Survey Follow-up, Central Southeast Alaska, 2000

The BLM conducted a geochemically based follow-up of the Stikine airborne geophysical survey in 2000. The geophysical survey was flown in support of the BLM's mineral assessment program of public lands in Alaska and specifically, the Stikine area mineral assessment project. The aim of the follow-up was to define prospective mineralized areas.

The primary targets of the Stikine geophysical survey and BLM follow-up were volcanogenic massive sulfide (VMS) deposits. A belt of related deposits is hosted in Triassic rocks along the eastern margin of the Alexander terrane and extends through the Stikine area from Duncan Canal to Etolin Island.

The BLM collected stream sediment and/or soil samples from 43 geophysically anomalous zones in the Duncan Canal to Etolin Island area in order to evaluate 59 anomalous zones revealed by the geophysical survey. Higher priority was given to anomalous zones that included: 1) discrete geophysical anomalies that indicated strong bedrock responses, particularly sulfide responses; 2) Triassic Hyd Group geology; 3) VMS mineral occurrences; 4) geochemical anomalies from an existing, regional stream sediment sampling program; 5) similar geophysical signatures to other VMS mineral occurrences in the area; and 6) contained resistivity gradients from contacts between conductive and more resistive rocks.

The BLM follow-up defined 10 "Anomalous Areas" based on geochemical sampling that represent areas with elevated potential for hosting VMS mineral deposits. The areas were defined by the presence of samples with anomalous concentrations of elements that characterize VMS deposits in the Triassic belt. The most prospective include the Taylor Creek area, Woewodski Island, the RD8 area northwest of Duncan Canal, and the southeast side of Duncan Canal. Of these, the RD8 area and the southeast side of Duncan Canal are newly defined as representing areas with an elevated potential for hosting mineral occurrences.