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Description
Geochemical similarities between metasedimentary rocks collected from Snow Lake roof pendant, the western sequence of the Boyden Cave roof pendant and upper Precambrian to Cambrian miogeoclinal meta-mudstones of the Nopah Range, California support the proposal made by M. M. Lahren and R. A. Schweickert that the roof pendants of the central Sierra Nevada are part of a large tectonically displaced fragment of the Cordilleran miogeocline. Geochemical data obtained from samples of Snow Lake pendant, Boyden Cave pendant, and the Nopah Range were transformed into a continuous-variable format using logratio techniques. Parametric statistical analyses were performed on the geochemical data. When differences in means of Snow Lake and Nopah Range samples were compared, 83% of the 42 elements analyzed were found to be statistically similar. Comparison of the means of Boyden Cave and Nopah Range showed 9 elements to be statistically dissimilar. When differences in the means of Snow Lake and Boyden Cave were compared, 86% of the 42 elements analyzed were found to be statistically similar. The combined Snow Lake and Boyden Cave data were compared to that of Nopah Range samples and 36 of 42 elements were found to have no statistically significant differences at the 95% confidence level. When geochemical systematics relative to Al were evaluated on elements that were statistically dissimilar, the differences were shown to be most likely due to variable initial protolith composition and to mobilization during diagenesis and/or metamorphism. The remarkable compositional similarities between Snow Lake, Boyden Cave, and Nopah Range samples suggest that the metasedimentary rocks of the central Sierra Nevada batholith are composed of elastic detritus shed from the western North American interior during the development of the latest Precambrian to Cambrian Cordilleran miogeocline. The results presented in this study support the regional correlations and tectonic model proposed by M. M. Lahren and R. A. Schweickert, and further demonstrate that rigorous statistical analyses of geochemical data transformed into a continuous-variable format can be a powerful tool in evaluating plausible lithostratigraphic correlations between metamorphosed, complexly deformed and displaced metasedimentary rocks.
