Geology of the Westburn.

Craw, D

Four parallel belts of rocks west of N. Mavora Lake, N. Southland are mapped and described.
The easternmost belt, the West Burn Formation (new name) consists of reconstituted spilites, phyllites and semischists, whose textural grade of metamorphism increases up-section to the west. The two central belts are melanges, one with serpentinite matrix and small tectonic inclusions (Red Mountain Ultramafites), while the other has a spilitic matrix and large (up to several km) tectonic inclusions (Livingstone Melange). The westernmost belt consists of volcanogenic upper Permian sediments (Bryneira Group) whose bedding is overturned.
Regional metamorphism ranges from pumpellyite-actinolite facies over most of the area to lawsonite-albite-chlorite facies in the Bryneira Group. Localized bodies of greenschist facies rocks occur in fault zones.
Metasomatism is very pronounced in the serpentinite melange, and some reactions are suggested. Pectolite, an unusual mineral in New Zealand, is seen as a low temperature metasomatic vein and replacement mineral.
The area has been complexly faulted, with few unfaulted primary contacts remaining. The largest fault, the Livingstone Fault, is of regional significance.

109 leaves. Ill. Map (folded in pocket). 30 cm.

1974Craw

POLYGON ((168.166356344353744 -45.277564260739666,168.066536252706612 -45.273285805069442,168.074909597441547 -45.153250980267607,168.140993651558915 -45.153944961253622,168.150779033714031 -45.175440309896722,168.147929285063071 -45.179248865878066,168.149839948998789 -45.186475448308947,168.151720726306166 -45.194057985226479,168.157277916088248 -45.200010499124332,168.161658277665538 -45.201982898459669,168.160227660078874 -45.206923795489573,168.153117140923285 -45.207336063087524,168.153700061439366 -45.212362513871263,168.159944395911907 -45.216200549564824,168.163076689821878 -45.22097795472331,168.160426157354351 -45.228367881374325,168.166904242613555 -45.235430802370452,168.164616585217971 -45.238549087641807,168.166359705104213 -45.241838392132287,168.168364935032059 -45.247996866732684,168.167971622645894 -45.252624571478648,168.167930914039914 -45.259053528231767,168.167859862828152 -45.265838456080154,168.167909845476004 -45.271199474878237,168.166356344353744 -45.277564260739666))