Abstract

A detailed paleontologic study in the Hoffman Canyon area was undertaken to determine the degree of tectonic interlayering in a thick succession of largely deep-water chert, argillite, and silty limestone composing the Havallah sequence of the Mesozoic Golconda allochthon of western and north-central Nevada. The study focused on the type area of the Havallah Formation which, as originally defined, was considered to be largely a conformable sequence of Permian(?) rocks. The results indicate that the Havallah sequence in the Hoffman Canyon area consists of a complex tectonic accumulation characterized by repetition of Mississippian, Pennsylvanian, and Permian rocks in at least 12 superposed thrust plates. Such a style of deformation may be characteristic of much of the Golconda allochthon, although paleontologic evidence of this style is clear in only a few areas and is probably best defined in the Hoffman Canyon area. Detailed stratigraphic and paleontologic studies of the Havallah sequence at a few other localities in Nevada indicate considerable lithologic variability of comparable-age rocks in the sequence from area to area, indicating a complex depositional setting that at present is only partly understood.

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