Geologic description
Malachite and azurite are present in calcareous hornfels adjacent to the Jago stock. The host rock is Cambrian sandstone near contact with the granite. An isolated stock of granite of Early Devonian age intrudes the Neruokpuk Schist of Leffingwell (1919) near the headwaters of the Jago River; although not so indicated on the geologic map of Reiser and others (1980), this probably the is Jago stock as described here. The same map unit, the Neruokpuk Schist of Leffingwell (1919) was examined along the U.S.-Canada border where it consists of arkosic sandstone in which labile clasts including most of the potassium feldspar grains have been altered to white micas, quartz, other minerals (Kelley and others, 1995). This same unit likely is Cambrian in age along the border (Lane and othes, 1995) rather than Precambrian as indicated by Reiser and others (1980) (Lane and others, 1995). |
