Geologic description
This occurrence is in an area that was covered by a large blocks of claims that were variously held from 1965 to 1981 by Bunker Hill Mining Company, Humble Oil and Refining Company, El Paso Natural Gas Company, and AMAX Exploration (Still and others, 2002). There apparently was no exploration of these particular occurrences by these companies beyond areal mapping and sampling, or at least there is no notable record of any.
The country rocks in the area of the prospects include Tertiary to Cretaceous biotite schist, biotite-garnet-quartz schist, quartzofeldspathic gneiss, and minor marble and calc-silicate gneiss metamorphosed from Mesozoic to Paleozoic protoliths (George and Wyckoff, 1973; Brew, 1997). The metamorphic rocks near the prospect are cut by several large Tertiary felsic dikes and sills that have been dated nearby at about 16.2 Ma (see PE043), and by a large Cretaceous tonalite pluton that intrudes the metamorphic section just to the east. Still and others (2002) briefly examined the ridge west of the terminus of the Nelson Glacier and identified a 2-foot-wide vuggy, silicified zone that cuts gneiss. The silicified zone extends for about 80 feet and locally contains pyrite, chalcopyrite, galena, and sphalerite. A 0.2-foot-thick chip sample across what appeared to be the most mineralized section of the zone contained 4.39 ounces of silver per ton, 2.70 percent lead, 9, 577 parts per million (ppm) zinc, and 8.63 ppm arsenic. (The mineralization is similar to or an extension of the mineralization in the prospect about 0.3 mile to the northeast across the terminus of the Nelson Glacier (BC001)). |
