COMMISSION GEOLOGIOUE - Arkisto.gsf.fi

Suomell Geologinen Seura. N: 0 35. Gcologiska Sällskapet i Finland. 45
Table 2. Chemical analysis, expressed as weight per cent and as cation per cent,
and epinorm of subgreywacke vVL 88, with two selected analyses for comparison.
1. 2. 3. 4. 5.
' .
Si0 2
....... 77.1 Si . ........ 77.25 Qz ..- ...... 61.33 Si0 2
. ..... . 76.84 79.30
Ti0 2
....... 0.43 Ti . . . . . . . . . 0.32 Ab ....... .. 8.95 Ti0 2
. ...... - 0.22
Al 2 0 3
..... . 11.1 Al ,. , ...... 13.11 Zo . ........ 0.44 Al 2
0 3
. . . ... 11. 76 9.94
Fe 2
0 3
...... 2.59 Fes + .... .. 1.95 Muse. . . .... 9.45 Fe 2
0 S
. ..... 0.55 1.00
FeO . . . . . . . . 3.61 Fe 2 + . . .... 3.02 Kaol. . ..... 9.13 FeO . .. , .... 2.88 0.72
MnO ...... . 0.02 Mn . ....... 0.02 Chl.l . ... .. . 6.85 MnO . . . . . . . tr 0.02
MgO ....... 0.67 Mg . ..... -, 1.00 Mt .. ' ...... 2.93 MgO . ...... 1.39 0.56
CaO ........ 0.26 Ca ......... 0.28 Il . .... .. ... 0.64 CaO ,' ...... 0.70 0.38
Na 2 0 ., .. .. 0.82 Na . ....... 1. 59 Ap . ... , .... 0.24 Na 2
0 . ..... 2.57 2.21
K 2
0 ....... 1.06 K . .. ...... 1.35 Ce . ... , .... 0.04 K 2 0 . ...... 1.62 4.3 2
P20S ....... 0.11 P . ..... , .. , 0.09 P 2
0 S ....... - 0.05
H 2 O+ ..... 2.26 H . •.••.• o. (7 .5 5) H 2 O+ . .... 1.87 0.55
H 2 O- ..... 0.32 H 2
O- . .... - 0.41
CO 2 ... . .... 0.02 C . . ........ 0.02 CO. . ....... - -
100.37 I 100.00 100.00 I 100.18 I 99.68
1. Subgreywacke WL 88, weight per cent.
2. ,) ,),) , cation per cent.
3. » ,),) , epinorrn.
4. Subgreywacke frorn Pettijohn (1957), Table 5,*, B.
5. Jotnian sandstone frorn Sirnonen and Kouvo (1955) Sandstones in FinJa.nd. BuH. Cornm. gcol.
Finlande 168, p. 57.
Analysis of WL 88 was done in the Ghana Geological Survey laboratories.
while the growth »front» of the blast, being roughly oval, gives the appearance
of anormal corroded quartz phenocryst in hand specimen. In other
rocks examined fragments of quartz-feldspar replacement textures are of
fairly frequent occurrence, though never abundant. Rock fragments occur
in sizes down to fine sandstone but the siltstones and most of the fine sandstones
are basically quartz and plagioclase, the quartz predominating. The
subgreywacke texture is present in the fine-grained rocks, where, on average,
the fragments are more angular. The limonitic matrix is common. Quartz
and feldspar grain boundaries in many rocks have started to break down
but this is considered to be a diagenetic effect (Krynine 1940, James 1955,
Dapples 1962).
A fuH list of rock and mineral fragments recorded from these rocks is
given below:
Fine quartzofeldspathic material (1 groundmass material)
Fine quartz rock (cf. quartzite)
Fine chlorite - opaque - feldspar rock (1 metabasalt)
Fine sericitic rock ± preferred orientation
Black slate or carbonaceous phyllite
Phyllite ± crenulation cleavage
Chlorite-rich metabasite
Feldspar porphyry