Geologic descriptionAs exposed in 1991 (D.J. Grybeck, unpublished field notes, 1991), the site was in a large quarry. The walls of the quarry consisted mostly of excellent exposures of folded and metamorphosed calcareous sandstone and siltstone with minor limestone of the Klawock Formation of Pennsylvanian age (Churkin and Eberlein, 1975). Thick, probably post-metamorphic, hornblende latite- to dacite-porphyry dikes generally parallel the north-south trend of the sedimentary rocks. Locally, small skarn bodies with garnet, epidote, and diopside (?), and banded skarn are developed in calcareous horizons. No obviously plutonic rocks were exposed in the quarry but the pronounced metamorphic effects (and the dikes?) are probably related to a Permian syenite body which is exposed just a few hundred yards to the south along the Klawock-Craig road (Churkin and Eberlein, 1975). Two quartz veins 6 to 8 inches thick with moderate sulfides including arsenopyrite, pyrite, and pyrrhotite, cut the skarn. There is little indication of significant quantities of metals in the quarry but it represents a distinct type of mineral deposit that may occur elsewhere in the area. A subsequent visit several years later found that the quarry had been expanded and little outcrop remained. Maas and others (1991) also examined the quarry but did not find any significant mineralization. Their samples contained up to 20 parts per billion gold, 1.9 part per million (ppm) silver, 182 ppm copper, 130 ppm lead, and 400 ppm zinc. |
