Fluid transport and shear zones at Scourie,Sutherland: Evidence of overthrusting?

Rocks from some shear zones at Scourie are highly oxidised and enriched in potash relative to adjacent undeformed granulites. Oxidation is considered to result from dissociation of water, and the extent of oxidation is evidence for massive fluid flow through the shear zones. The conditions under which oxidation and reduction occur during fluid flow are discussed and it is thought that progessive oxidation of the shear zones at Scourie indicates that fluid flow took place up a thermal gradient. It is proposed that the inverted thermal gradient resulted from overthrusting, and this is consistent with existing interpretations of the structural evolution of the area.