Description
North west of Haystack Mountain, Sierra Nevada, California, the Carboniferous Peale Formation separates the Upper Devonian to Lower Mississippian Sierra Buttes Formation from the Lower to Middle Jurassic Sailor Canyon Formation. Described in this thesis are the geochemistry and lithostratigraphy of two newly recognized members of the Peale Formation. Both members are well exposed and mapped northwest of Haystack Mountain, but their extent beyond this area is not known at this time. Member 1 consists of thick-bedded iron-stained chert interstratified with thin laterally discontinuous seams of black to brown argillite. Member 2 is characterized by more abundant argillite and lesser amounts of chert. Member 2, because of its large argillaceous component, has previously been included in the lower portion of the overlying Sailor Canyon Formation. In order to specifically address the question of whether or not member 2 is part of the Peale or part of the Sailor Canyon Formation, four samples from member 1 (three cherts, 1 argillite), five samples from member 2 (four argillites, 1 chert), and four argillite samples from the Sailor Canyon Formation were collected and analyzed for major, trace, and REE. For comparison purposes, averages of geochemical data were calculated using the Aitchison Measure of Location (AML). Uncertainties in the AML were estimated by the bootstrap technique. The results of the geochemical and statistical work show that argillites within members 1 and 2 have similar ma3or, trace, and REE chemistry. Similarly, the chemistry of cherts within both members is nearly identical. In contrast, the chemistry of argillites in both members is distinctly different than the chemistry of argillites in the overlying Sailor Canyon Formation. Thus, geo chemic al data support field o bse rv a tions which allowed the Peale Formation to be subdivided into the two distinctive members, but are inconsistent with the alternative hypothesis that member 2 1s a part of the Sailor Canyon Formation.
