The Contact Between the Granitic Kocks and the Cardup Series 
AT Armadale. 43 
The seGioii exposed in this tnnuel irulicMtes that the Cardup sediments 
have been eoiitaet metaniori>hosed over limited distanees by both the ehlorite- 
albite ei)idioi'ite and the later quartz-dolerites. It also indicates that the 
development of the epidote-aetiiujlite-quart/ite noted near the ^Tanile contact 
is a contact effeid due to the quai-tz-dolerites and not to the gTanitic rocks. 
(E). The bmic of p<)!<i-Cardn]} age. 
The following types have been recognised: — 
(i) Chlorite-albite epidiorites. 
This ty[)e has been noteil in one place only, vi/., in a sill like intrusion 
into the .slates in the west wall of the slate quarry. This body is itself in- 
truded by a naiTow “silT^ (12 inches wide) of a micropor]>hyrilie epidiorite, 
which is descrilied below. 
The chlorite-albite epidiorite is of interest because it can undoul)tedly 
b(^ correlated with the porphyritic alliite epidiorite (referred to as albite 
por])hyrite by Esson, 1927, p. (i) which occurs at various localiti(*s (Wun- 
gong', Cai'dup, Whitby Falls and Mundijong) extending some 15 miles to 
the south along the Darling Scarp. The rock at Armadale is not por[)hyritic 
but its texture and mineralogical composition (both of Avhich ditTer con- 
siderably from the normal (juartz-dolerites) are similai- to those of the rocks 
from the areas to the south. 
The Ai’ma<lale rock is medium, even grained ami almost indistinguish- 
able in hand s])ecimen from tlie uralitiscal quartz-dohu’ites. It consists of 
a plexus ot clear albiti* })risms (figure 5B) with interstitial aggregates of 
chlorite, nralite and biutile together with some tui’bid epidotie material and 
a little hmcoxfnie. The chlorite forms a line grained mesh enclosing patches 
of green nralitic amphil)ole and occasional flakes of pale greeiiish-brown 
biotite. It is a i>ale greenish prochlorite, very slightly pleocliroic and almost 
isotropic (with very weak anomalous colf)urs) — the optic character is 
neutral and the refractive index 1.633 rk ,002. This mineral agrees 
with the chlorites of the low grade epidiorites desf-rihed liy Wiseman (1934, 
]n 360.) Tile albite is fresh (althongli slightly dustc'd with inclusions and 
penetrated by acicular amphibole) and thus differs considerably from the 
epidotised plagioclase of the other basic igneous rocks of the area. 
The analysis of this rock is recorded below : — 
Table ITT. 
SiO., ... 
47-08 
Norm. 
AlA- 
14-78 
Fe.,0, 
1-32 
Or 
0-12 
FeO ... 
13-80 
Ah 
20-20 
MsO ... 
7-45 
An 
18-35 
CaO ... 
4-24 
Na.,0 ... 
3-10 
C 
1-84 
K.O ... 
1-03 
H.,0 H- 
3-89 
hv 
20-49 
H,0 — 
0-22 
oi' 
9-47 
TiO., ... 
2-49 
P.0, ... 
0-41 
mg 
1-86 
MnO ... 
0-31 
il 
4-71 
BaO ... 
Nil 
ap 
1-01 
Cr.A ... 
Nil 
py 
0-14 
FeS., ... 
0-14 
100-20 
Analyst : 
K. 
T. Prider. 
Chlorite-albite epidiorite (20532), 78 feet from east end of tunnel, Slate 
quarry, Armadale. 
