2013 Spring Geologic Field Work,
South Island of New Zealand

CWU Geology Professor Jeff Lee and colleague Nick Mortimer, GNS Science, New Zealand spent parts of February and March, 2013 conducting field studies to examine and document evidence for ductile and brittle extensional exhumation of the Otago Schist in the central part of the South Island. The Otago Schist is a metamorphosed accretionary prism, similar to accretionary prism rocks exposed in the Olympic Mountains, that developed within the eastern Gondwana subduction zone. Marine sediments that were metamorphosed to ~25-30 km depth and ~500°C are the protolith for the Otago Schist. Several different processes have been proposed for the development of these strongly ductilely deformed and metamorphosed rocks and for the exhumation of these rocks to the Earth’s surface. Jeff and Nick are combining field studies, mesoscopic and microscopic structural studies, and thermochronology to determine whether ductile and brittle extensional deformation contributed to the formation of the schist and to its exhumation history.

Tors atop the Dunstan Range
The tors on top of the Dunstan Range provide excellent exposure of strongly ductilely extended (vertically thinned and horizontally stretched) metamorphic rocks.

Strongly foliated metamorphic rocks
Jeff taking field notes besides strongly foliated metamorphic rocks (foliation dips towards Jeff) cut by quartz veins.

Top of the Cairnmuir Mountains
The top of the Cairnmuir Mountains defines the hanging wall of a normal fault and is underlain by less deformed rocks compared to those exposed in the tors.

Remarkable folds in The Remarkables
Incredible (remarkable?) folding in the The Remarkables.

Summer snow on the Dunstan Range
The southerlies bring snow to the Dunstan Range during the summer months.

Beware of armed goats
No rattlesnakes, no scorpions, and no predators to worry about, but armed goats?