TheSouthern Alps in the South
Island of New Zealand are currently rising rapidly as a consequence of
continental collision along the Pacific-Australian plate boundary. Rapid uplift
has resulted in a major thermal anomaly in the shallow crust beneath the alps.
Alpine topography and associated intense precipitation, coupled with the thermal
anomaly are responsible for vigorous combined topographic/convective circulation
of water through the shallow crust.

Uplift
is greatest in a wedge-shaped region between the Alpine Fault and an associated
second-order backthrust system, the Main Divide Fault Zone, approximately 20 km
to the east. The Main Divide Fault Zone is segmented into NNE and NE striking
faults, which are regionally sub-parallel to the Alpine Fault, but dip northwest
in the opposite direction. Reverse oblique-slip on the Main Divide Fault is in
an easterly direction, with a greater component of strike-slip movement on the
NE trending faults. Elevated topography in the Mt Cook region is related to
thrusting of a relatively homoclinal sequence of semi-schistose rocks on top of
lower-grade greywacke, which controls the position of the Main Divide.
Tectonically induced fluid flow resulted in only minor alteration and
hydrothermal mineralisation of fault-rocks in Alpine and Main Divide Faults, and
localised deposition of quartz and/or carbonate in the immediate hangingwall.

The wedge between the Alpine and Main Divide Faults is
segmented by third-order structures north of the
Mount Cook region. A series of right-lateral (-085/700S) and left-lateral
(-150/600SW) faults, which are synthetic and antithetic to the Alpine Fault,
respectively, developed as a conjugate set during uplift. Fluid-flow in the
Southern Alps is controlled by these
third-order fault/fracture systems. Cu-Au mineralisation, hydrothermal veins,
and surface hot spring activity are localised by third-order fault/fractures and
appears to be enhanced where conjugates intersect.