Description
In 1994, R. W. Murray developed chemical criteria for identifying the depositional environment of chert. In brief, Murray's model predicts that Al and Ti should decrease in cherts deposited in successively more oceanward directions, while Fe and Mn should become more enriched. In addition, Ce depletion relative to Pr and La should be evident in sediment deposited in more distal and near-ridge environments. Thus, Murray argued that the geochemistry of cherts can be used to recognize continental margin, pelagic, and near-ridge depositional environments. To determine whether or not Murray's models are applicable to older cherts, I have applied his chemical criteria to data collected from samples of the Carboniferous Peale Formation from northwest of Haystack Mountain, Sierra Nevada, California. The Peale Formation has been divided into two members. 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. Application of Murray's model to data obtained during this study indicate that the Peale Formation was deposited either in a distal continental margin or transitional continentalmargin/pelagic setting.
