Ultramafic Mass in New Zealand — Malahoff 
2) and appear to be faulted against the ultra- 
mafic rocks. Dikes of dense, white, fine-grained 
grossular diopside and chlorite rodingites 
(Grange, 1927) outcrop in stream beds of the 
Red Hills. The amphibolite which also outcrops 
in the same area is dark grey in the hand speci- 
men and equigranular with aligned green horn- 
blende crystals. 
Upper Te Anau V ole antes 
The breccia, spilite, and dolerite of the Top- 
house district are similar to those in the belt 
of volcanics (Livingstone volcanics) between 
the Red Mountain ultramafics and the Howden 
formation of the Hollyford and Pyke Valleys 
in Otago (Table 2). The belt is cut off at the 
head of Pyke Valley by the Alpine Fault. In 
both Otago and South Nelson, the volcanics 
outcrop immediately above the serpentinite of 
the ultramafic belts and immediately below the 
Maitai limestone. 
Distinctive red and green volcanic breccia 
outcrops immediately west of the Wairau ultra- 
mafic mass and is in direct contact with the 
serpentinites. The breccia consists of sub- 
angular fragments of spilite and dolerite peb- 
bles, up to 15 cm in diameter but averaging 2 
cm, surrounded by an igneous reaction rim. 
The pebbles are set in a fine-grained, dark-red 
hematitic base with vugs of calcite, and magne- 
tite relicts. The breccia band is only 1,000 ft 
wide, dips steeply east, and strikes at 330°. 
To the east, the breccia is in direct contact with 
the serpentinites. 
A belt of spilite, cut by dolerite dikes, lies 
between the breccia and the Maitai limestone. 
Directly beneath the limestone, the spilite is 
hematized and, in thin section (vuw 10667), 
shows vugs filled with spherulites of quartz and 
chlorite as well as phenocrysts of augite and 
serpentinized olivine set in a hematitic base. 
In the groundmass, acicular pyroxene crystals 
are aligned parallel to igneous flow structures. 
Magnetite, originally abundant, has been 
changed to hematite, giving the rock a red 
coloring. Away from the limestone contact, the 
spilites are green-grey in color. Texture is non- 
vesicular with a medium grain size. 
Maitai Series ( Group ) 
The lower formation of this series is the 
137 
Maitai limestone in both the Tophouse district 
and in West Otago. The upper formation in 
these districts consists of volcanically derived 
sandstone. The four formations in the Maitai 
series in the Tophouse district may be corre- 
lated with those of Nelson and those of Otago 
(Grindley, 1958), which they match closely 
(Table 2). The oldest formation is Lower 
Permian in age (Wellman, 1952) and the 
youngest formation is Upper Permian. The 
Maitai formations have distinctive lithology and 
are easily mapped. 
Rangitoto Formation 
The formation is 3,800 ft thick and is well 
exposed along hill crests, west of the Red 
Hills. The base is marked by grey calcareous 
sandstone (30-40% calcite) with casts of 
Atomodesma impressions. The rocks show slaty 
cleavage and dip steeply east. The strike varies 
from 345° near the Wairau Fault to 025° two 
miles north. The calcareous sandstone grades up 
into coarse-grained massive limestone which in 
turn has a gradational contact with the Greville 
formation. 
Greville Formation 
The Greville formation consists wholly of 
laminated grey argillite and is exposed in a 
continuous sequence about 9,000 ft thick. 
Banding is regular, between 0.1 and 0.2 inches 
thick, and similar to that of varves. The darker 
bands consist of graded, coarse sandstone and 
lighter bands of fine siltstone. Slaty cleavage is 
well developed in parts of the formation. The 
strike of the rock is 015° and the dip ranges 
from 80° to 100°. Strike faulting is prominent 
and much of the drainage over the formation 
is aligned with the strike direction. 
Laminations are graded, but much thinner 
than graded bands in greywacke. The resem- 
blance between the laminations of the Greville 
argillites and those of varves shows up even 
more clearly under the microscope than in the 
hand specimen. It is likely that the bands rep- 
resent annual layers. 
Waiua Formation 
The Waiua formation occurs as a faulted in- 
lier near the Tophouse Hotel, where 2,500 ft 
of the rock is exposed. The rock consists of red- 
and green-banded argillite and sandstone with 
