Page 76 - Sumatra Geology, Resources and Tectonic Evolution

Chapter 6

Pre-Tertiary volcanic rocks

M. J. CROW

Volcanic activity and associated plutonism, ranging in age from the programme directed at determining the ages of the volcanic
Carboniferous to the Late Cretaceous, has made an important rocks, but dating of volcanic episodes in Sumatra has benefited
contribution to the Pre-Tertiary geological evolution of Sumatra. greatly from stratigraphic palaeontological studies on the associ-
This chapter summarizes the known occurrences of Pre-Tertiary ated sedimentary units, summarized by Fontaine & Gafoer
volcanic rocks and their geological settings (Fig. 6.1 & (1989). Unfortunately, little progress has been made in determining
Table 6.1). There has been no systematic isotopic dating the chemistry of the volcanic rocks of Sumatra, subsequent to the

IIII'"' iiillil
i
96OE :, ,, , , , i i ,io5,o i
I. \.
ii
6~ ,, I iilllli, i 6 ~
llll,,,,,ll
III
II
"4 II IIIII
I\ I I II I I II I I I
i S/BUMASU:. I~lll ,11111111
NDOCHINA
.~i-'!~!"~i~i~iNi"~:::: ~ I ~ T T T T I 1 I
llJ!ill llll
:~BLOCK I
EAST SU MATR,~, ,,\,Iiii " III
lllllll III
".',',',
)lllll ill
Tapaktuan ~-.',','.-
~. 9 . .
- III
II ] III
I I I I I I\1 I I I
IIIIlll III
.>1-.I I I I I I~ I I I
Sibolg .~. r-4. i l_k4~ ill
N\%, .'Y~ I r l l~
9 .~'~--~'4-.2%k1-, ,x, 1 I I
9 9 "_'t~'~x"~'.'P I ]xJI I I
Muarasipongl~ 9 :.2.O..'~'N]Sugil ill I
\ . ~-'~,.. t,~'%.'%51 I I I I
0 ~ Panti Fm Pakanbaru M4..-'> .".'t~'N.xlo1 ' ' ' ' b(
INDOCHINA BLOCK .-//,,, ...~).....~-~-N~[TtLingg a
(and Indonesian Islands) ~~--:..-.N~DI i i
""' """'"" "in(kep I
~.c...",.~_- -.'..v_...,,~.
~ Bentong-Raub Suture Zone ~t Jluh(.'-.-. ~lr,~-.b. ~,~. , , I
Riau-Billiton Accretionary Complex [.' I
Silungka :1 2,ond ong..':.." 9 '. ". . I
...ff~..Permian&Carboniferous ~,Member~'<. ~: . :. i i i i
-e~;,'ff, i"..".'.'.~.q.:. : i Bangka:
'
~
'
'
.-.'~..;..~..~...-...k.
'
SIBUMASU - EAST SUMATRA BLOCK ~2~'-''~'~'~'k.'.~ ~ ~I I I I
'Barisan' "."~.J..~'-" "- ". "- ". ".~'-'-
Carboniferous-Early Permian
=~'/____~,~r ,~,.,~,,,.~,.~,.,, .. ~"~ mi n e~-
'Kluet' Formation
~__(b~.~..~.~ i ~..~....
Bohorok Formation (Visean)
3 ~ ~ Alas Formation
Quartzite Terrain and Pcrsing Complex(Singkep)
Hippogri
WEST SUMATRA BLOCK
Carboniferous-M id-Permian t"--"
l Tanjung Puab & Pawan Formations
(tremolite and chlorite schists)
Permian Silungkang Formation (Calcareous Member)
Panti, 'Barisan' & Palapat formations
Kuantan Formation (Visean)
0 300km
Kluet Formation
I i
6 ~ 99 ~ 102 ~ 105 ~ 6 ~
I I I
Fig. 6.1. Simplified Pre-Triassic geology of the West and East Sumatra Blocks and the Indochina Block of Peninsular Malaysia showing the principal Palaeozoic
volcanic units and localities discussed in the text.
63