Page 18 - Sumatra Geology, Resources and Tectonic Evolution

INTRODUCTION 5

I I I I I I
96~ 98 ~ 1 O0 ~ 102 ~ 104 ~ 106 ~
6 ~ -
BandaAceh A Active Volcano

Sumatran Fault System

_4 ~ Deformation Front of the 4 o .
Sumatran Subduction
Complex

~'yY
0 100
Y 200 300 400 500km
..............
2 ~ -
".:.:.:.:.:.:.:.:.

Nias
|j
............
(-:-:.:-:-:-:-:-:.:-:.:[... ...-
:i:~i:i:i:i:i:i:i:i:iQ:i
-0~ 0 o-
Line of
Section
Fig.l.3.

Q 2 ~ -

[ii:iil;i:::i:::i;i;i:~~::iiii~mbang

I
j~.'.ii::.. ~::!:iiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiii.
Bengku[ ::i~'- "'-'" ""'""'"'"'""'"'-'"'"'-'"'"'-
-4 ~ 4 ~ -

Quaternary-Recent volcanics
~
Tertiary Sediments and volcanics pung
/ Pre-Tertiary Basement 6 ~ -

96~ 98 ~ 100 ~ \ 102 ~ 104 ~ 106 ~
i I I \ I I I
Fig. 1.4. Simplified geological map of Sumatra showing the distribution of the main stratigaphic units and the active volcanoes. Toothed line marks the deformation
front of the Sumatran Subduction System. The line of section in Fig. 1.3 is also shown.

became increasingly concentrated in the forearc islands, where (Wajzer et al. 1991; Barber 2000; McCarthy et al. 2001) and a
a series of geological mapping and gravity surveys were study of the Sumatran Fault System throughout the island
completed (Situmorang et al. 1987; Milsom et al. 1990; Harbury (McCarthy & Elders 1997).
& Kallagher 1991; Samuel & Harbury 1996; Samuel et al.
1997). At the same time LEMIGAS collaborated with the
French CNRS (Centre National pour Recherche Scientifique) in Southern Sumatra Project
a number of studies in the forearc region using the Indonesian
Marine Research Vessel Baruna Jaya III (Diament et al. 1992; Geological mapping, gravity surveys and geochemical program-
Izart et al. 1994). Outside the bounds of the NSP, University of mes in Sumatra south of the equator were conducted by GRDC
London Staff and research students with funding from NERC, and DMR during PELITA II (1974-79) and in successive five
ODA and a Consortium of petroleum companies collaborated year development programmes, continuing into the 1980s. In
with LEMIGAS on studies on the Ombilin interarc basin 1988 the Southern Sumatra Geological and Mineral Exploration
in central Sumatra (Lailey 1989; Bartram & Nugrahaningsih Project (SSGMEP) was established, and BGS joined DMR and
1990; Howells 1997b), the Woyla Group in North Sumatra GRDC in the completion of these surveys and in research