Structural Controls on Shallow Cenozoic Fluid Flow in the Otago Schist, New Zealand

Figure 10

Cartoon interpretation of the formation of the shallow hydrothermal systems at Akatore Creek and Bruce Rocks. (a) Cross-section of the Otago Schist, showing reactivation of Late Cretaceous exhumation joints as post-Early Miocene brittle fault networks that resulted in strongly channelized shallow fluid flow. (b) Structural controls on fluid flow include preferential flow along faults (reactivated joints) and the Mesozoic foliation, causing enrichment in Ca, Fe, Mg, Mn, Sr, Y, and REE within the alteration zone.

(a)

(b)