IMMOBILE TRACE-ELEMENTS AND ARCHEAN VOLCANIC STRATIGRAPHY IN THE TIMMINS MINING AREA, ONTARIO

Carbonate alteration and hydrolysis of mafic volcanic rocks in the Timmins area were accompanied by mobilization and redistribution of alkalies, CaO, MgO, and FeO. These major oxides are of dubious value in classifying the volcanic rocks, and are of no value in identifying and correlating lithostratigraphic units. The trace elements Y, Zr, TiO//2, and Cr, whose fractionation tendencies parallel those of the alkalies, FeO and MgO, are relatively immobile and display characteristic patterns within different volcanic units. Immobile trace-element data represent a potentially valuable tool in stratigraphic correlation of Archean volcanic rocks, whether altered or unaltered.