Alice springs age shear zones from the southeastern Reynolds Range, central Australia

The southeast Reynolds Range, central Australia, is cut by steep northwest- trending shear zones that ore up to hundreds of metres wide and several kil ometres long. Amphibolite-facies shear zones cut metapelites, while greensc hist-facies shear zones cut metagranites. Rb-Sr and Ar-40-Ar-39 data sugges t that both sets of shear zones formed in the 400-300 Ma Alice Springs Orog eny, with the sheared granites yielding well-constrained Ar-40-Ar-39 ages o f co 334 Ma. These data imply that the shear zones represent a distinct tec tonic episode in this terrain, and were not formed during cooling from the ca 1.6 Ga regional metamorphism. A general correlation between regional met amorphic grade and the grade of slice Springs structures implies a similar distribution of heat sources for the two events. This may be most consisten t with both phases of metamorphism being caused by the burial of anomalousl y radiogenic heat-producing granites. The sheered rocks commonly have under gone metasomatism implying that the shear zones were conduits of fluid flow during Alice Springs times.