The White Pine-Grant Range area is a 400 sq mile region located in east-central Nevada, east of the Antler erogenic front, and west of the Sevier-Laramide thrust belt. About 20,000 feet of Paleozoic rock are overlain by 3000 to 5000 feet of Eocene-Oligocene sedimentary and volcanic rocks, and 0 to 10,000 feet of Mio-Pliocene sedimentary rocks. The near concordance of Paleozoic and early Tertiary strata indicates that the major deformation of the area is post-Oligocene in age. Mesozoic tectonic movements were limited to the formation of gentle folds and high-angle faults of limited displacement.

The structure of the area is dominated by north-trending folds, some overturned, which involve both Tertiary volcanic and Paleozoic rocks. These folds are cut by a series of low-angle faults emplacing younger rocks over older; six faults are present in the White Pine Range and two in the northern Grant Range. A series of complex discrete slide masses 1 to 3 miles long characterizes the southwestern Horse Range; a relatively unfaulted overturned Paleozoic section characterizes the southeastern Horse Range. Displacement along these faults increases from the center toward the ends of the ranges; the faults are not continuous throughout the length of the range, and probably do not represent features of a regional d écollement. Relations suggest that deformation or movement on these faults was probably nearly surficial, partly a product of uplift of the ranges and partly the result of basement extension. Much observable movement took place during deposition of Mio-Pliocene sediments, accompanied by emplacement of gravity slide masses and monolithic breccia of Paleozoic and volcanic rock in the Mio-Pliocene sedimentary basin. Differences in intensity of folding and degree of low-angle faulting in the White Pine, Horse Range, and northern Grant Ranges suggest that these areas were deformed separately. The north-trending folds may be the result of gravity effects on the flanks of major uplifted blocks, but probably reflect a period of postvolcanic crustal shortening in this region.

This content is PDF only. Please click on the PDF icon to access.

First Page Preview

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