Geologic description
The country rocks in the area of this prospect are the Triassic Texas Creek Granodiorite, which underlies and locally intrudes pelitic metasedimentary and subordinate andesitic metavolcanic strata of the Jurassic or older Mesozoic Hazelton Group; the Eocene Boundary Granodiorite, which intrudes the Hazelton and Texas Creek rocks; and still-younger Tertiary lamprophyre dikes, which cut all the other rocks (Smith, 1973, 1977; Koch, 1996).
The deposit (Buddington, 1925, p. 87, and 1929, p. 93; summarized by Cobb, 1978, p. 61) is in a breccia zone in a Texas Creek granodiorite dike in interbedded slate and quartzite. The breccia zone is about 5 feet thick and was traced in outcrop for about 200 feet. The zone consists of reticulating quartz stringers and veinlets that aggregate 12-14 inches in thickness that contain galena, sphalerite, a little chalcopyrite, and sparse tetrahedrite. A 63-foot adit was driven to intersect the lode, but there is no record of any production. Maas and others (1995, p. 254) suggest that the age of the Ninety-six (96) prospect is Eocene, based on similarities in mineralogy, structural setting, and hostrock, to isotope-dated Eocene deposits in the Hyder district (see, for example, BC086). If so, the deposit is contemporaneous with emplacement of the Boundary Granodiorite. |
Age of mineralization |
Maas and others (1995, p. 254) suggest that the age of the Ninety-six (96) prospect is Eocene, based on similarities in mineralogy, structural setting, and hostrock, to isotope-dated Eocene deposits in the Hyder district (see, for example, BC086). If so, the deposit is contemporaneous with emplacement of the Boundary Granodiorite. |