NORMATIVE CLASSIFICATION OF PELITIC ROCKS.

Authors

  • Julio C. Merodio
  • Luis A. Spalletti

Keywords:

Pelitic rocks, Normative classification,

Abstract

A normative classification oi pelitic rocks based on the proportion of major components (SiO" AI,O" Fe,O" MgO, Cao, Na,O, K,O, P,O. and CO,) is presented in this paper. The proposecl procedure includes two models of norm calculation: smectite present and smectite absent. In hoth models the content of K,O can he lIsed to determina te orthoclase  illite. The pelitic rack classificationis based upon the relative contentsin normative clay minerals,quartz and feldspars. Nine compositionalrock-types,which are clearlydefined in a triangulardiagramwere recognized. The importance of chemical compositionstudies in the interpretation of pelitic rocksis also discussed.

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