Page 87 - Sumatra Geology, Resources and Tectonic Evolution

74 CHAPTER6

Jurassic-Cretaceous Plutonic-Volcanic Arcs in the Woyla Group is shown in Figure 6.11 and the volcanics
present are described with reference to these assemblages in
Volcanism and the associated plutonism in Sumatra has a a com- Tables 6.8-6.10.
plicated history during the Late Mesozoic. To a large extent this In central Sumatra Late Jurassic-Early Cretaceous I-type
is the history of the Late Jurassic-Early Cretaceous Woyla plutons (Fig. 6.11 ) form a continental margin Andean arc related
Group, as described by Cameron et al. (1980). The stratigraphy to subduction (McCourt et al. 1996). The plutons are better
and current understanding of the geological setting of the Woyla known than their associated volcanics. Lower Cretaceous
Group are discussed by Barber (2000) and by Barber & Crow andesites occur at Palanki in the Tertiary Ombilin Basin
(Chapters 4 & 14). The distribution of the different assemblages (143 + 4Ma, Koning & Aulia 1985) and a new date of

I I I
99~ 102 ~ 105 ~

WOYLA ASSEMBLAGES
I.~DA ACEH
~ Jurassic-Early Cretaceous
Oceanic Island Arc (Bentaro Arc)
Accretionary Complex
(ocean-floor material)
Jurassic-Early Cretaceous Foreland
t:::::::t sequences: Tembesi and Rawas Fms

~ Jurassic-Early Cretaceous
TA PAKTUAN
\ Plutono-Volcanic Arc
te Cretaceous Plutonic
Arc

Parlumpah! n I
NATA
Kanaikan
&'~,
o 0o -
Maninja lanki
Indaru
%

Lubukg~

Q
Kerinc
~ %% '"%
i","-.","',." ~

"~----,,--- Thrusts

Faults

0 100 200 300km

99 ~ 102 ~ 105~
I I I
Fig. 6.11. The distribution of the Woyla Group Assemblages in Sumatra.