File:Graywacke turbidites in Seymour Canal Formation.jpg

Summary

Seymour Canal Formation (Cretaceous and Jurassic): Fine grained, rhythmically bedded graywacke turbidites. In map area consists mostly of deep water or distal facies turbidites. Calcareous lenses are common at Baht Harbor on northern Zarembo Island. Augite crystal tuff lenses a few centimeters to several meters thick are sparsely intercalated with silty turbidites in Wrangell narrows area on the eastern coast of Kupreanof Island. Upper and lower contacts of unit are faulted. Unit contains Late Jurassic to mid-Cretaceous (Albian-Cenomanian) pelecypods and ammonites. Oxfordian to Tithonian dinoflagellate cysts and benthic foraminifers were identified in samples from Pybus Bay on Admiralty Island (Cohen and Lundberg, 1993). Regionally recrystallized to subgreenschist sericitic and slate and subphyllite or greenschist facies sericitic and chloritic phyllites, exhibiting isoclinal folding and kink bands. Hornfelsed adjacent to mid-Cretaceous plutons. Aureoles contain quartz, feldspar, biotite, sericite, staurolite, andalusite, sillimanite, and garnet. Kupreanof, Mitkof, Zarembo, Etolin, and Wrangell Islands.

Copyright status:

This image is public domain because it was first published by the U.S. Geological Survey

Source:

http://pubs.usgs.gov/of/1999/of99-168/of99-168-pamphlet.html