Abstract

The heretofore unmapped rock sequence on Wolf Creek provides a useful section for correlation of Canadian Yukon and Alaskan formations. The oldest rock, massive Devonian marble at least 1000 feet thick, is overlain by several thousand feet of Devonian-Mississippian slate, phyllite, schist, fissile marble, granulite, and greenstone. An unconformity separates 1500 feet of well-bedded Permian limestone, sandstone, and tuff from the older rocks, and the Permian is overlain discordantly by 4600 feet of well-layered Tertiary volcanics, about half acidic pyroclastics and half andesite and basalt flows.

Pennsylvanian (?) gabbro intrudes the pre-Permian rocks, and large bodies of late Mesozoic or early Tertiary granite and quartz monzonite are exposed. The youngest intrusives are mafic plugs and dikes associated with the Tertiary volcanism. The contact zones of the granitic and monzonitic bodies are pyritized, and a highly fractured silicified area in quartz monzonite contains molybdenite.

The Paleozoic metamorphics are compressed into east-northeast isoclinal folds. The Permian beds are tilted gently northward, and the Tertiary volcanics are largely horizontal. Two sets of high-angle reverse faults trending northwest and northeast near Wolf Creek mouth and an east-northeast monoclinal flexure with upthrow to the south along lower Wolf Creek are major features in the relatively simple structural pattern. The monocline and faults developed in the middle or late Cenozoic and may be the product of adjustments within the St. Elias block during its last major uplift.

First Page Preview

First page PDF preview
You do not currently have access to this article.