Page 84 - Sumatra Geology, Resources and Tectonic Evolution

PRE-TERTIARY VOLCANIC ROCKS 71

Table 6.5. Metavolcanics and meta-ultrabasic rocks in the Medial Sumatra Tectonic Zone
Unit with volcanics Age Description Reference
Pawan Member Carboniferous-Early Permian Intensely folded muscovite, chlorite, tremolite schists (derived from ultrabasic Clarke et al. (1982b)
(Kuantan Fm) rocks), often with carbonate. Interbedded fine-grained chloritic metavolcanics. Rock et al. (1983)
Ganggsal Carboniferous-Permian Serpentinites within slates Andi-Mangga et al. (2000)
Alas Fm Vis6an or younger Rare 'possible green metavolcanics' among striped, slumped shales, siltstones, Cameron el al. (1982a)
cherts, sandstones, conglomerates and wackes

10/o E-,~.,~ l ~ ~ g o ! ~
.---.._~ Malang Formation ._~_~.' ~=~", ",.. ~ii::~..--"--
,,"' ~'., KARIMUN di~!RATAMii.~--),"~S[t ;B)N.~A.N.~.. -ij
',, ,;iiiiihk BESAR _~ ~ ~'~ii:i~.~,[-{ (~:~~----!~
'
'
"~,~', ~', , , ,,'",- 'K"{ ~.~_:!:i:i:f ~ ,...~t ~ ~ " -~*~8~

", ...,..-,...~,~ ~ ~"---~~-': CITILIM ~ centre ~~;~
", L~,ur!,P,,Y,~ ',, ~ ~ k.iiiii..k, v c7

"-.. .... ., ,-, ','.~,, ~.

%~ 2) 0
I I I I I I I-b-,,.

s
SUMATRA "-~ %

o

o Iiiiiiiii 0o_
Main Range Granites I~ Eastern Province Granites
......... (S and A-type) (I-type) ~ ~ _ ~ I ~ ~,

TRIASSIC ~ Volcanics ~ ! ~ A ; i i ~
, ~ ~ "-" LI IN L.~ L~
Sediments
Riau-Billiton C~(E]2~ ~ J'~
PERMIAN Accretionary Complex FK@d l~iHi ;, \
Ill
",',',',
\
9
II
Persing Complex and ,ii[i K
CARBONIFEROUS[]~] Tapanuli Group "":" '
Sl
SINGKEP
50km
104 ~
I
Fig. 6.8. Simplified geological map of the Riau and Lingga Archipelagos. Granite typology after Cobbing et al. (I 992).