fore arc java sumatra

2
Fore-arc Java-Sumatra extends from southwest of Sumatra to the northeast of java, consisting of various Prism accretions and basins (Fig.1). Geological conditions of Fore-arc Java-Sumatra we can mirror the geological structure and stratigraphy of the basins the area thrive on. Fore-arc Java-Sumatra formed by convergence of the Indo- Australian plate and the Asian Plate during the middle Eocene to late Oligocene, followed by the latest charging transgressive marine and open sediments on the Fore-arc east java and Fluvial-lacustrine sediments developed in NW Java and Sumatra. Geological conditions of Fore-arc in western Indonesia recorded from Aceh basin, with a long (> 200 km) and narrow (< 50 km). Bounded by the West Andaman Fault, a trench-linked strike-slip fault obliquely crossing the northward extension of the Great Sumatran Fault. Research from Atsushi using the seismic method mention that the deposits in the basin are thickest along the boundary fault between the basin and the Outer-arc high, and gradually thin with increasing distance from the faults. And then followed by The Simeulue Basin extends over 260 km in NW-SE direction and 100 km in SW-NE direction, part of a classic example of subduction, Convergence system along the Sunda Arc becomes increasingly oblique from south to north resulting in large-scale, dextral strike-slip fault systems within the fore-arc basins and on Sumatra (Malod and Kemal, 1996; Sieh and Natawidjaja, 2000). The geological conditions of the next West of Fore-arc Java-Sumatra basin can be learned from Nias, Mentawai and Southwest Java. Nias and Mentawai basins accordance in the deliberations of the Matson and Moore (1992) with primarily concerned to seismic stratigraphy and not with geology structure discusses about important roles to the Batee Fault, a featured primarily defined by mapping on the Sumatra mainland, and to a flexure, which can be identified with the Mentawai fault zone which marks the rear margin of the trench- slope break. Due to the geological structure of the Mentawai Islands were quite significantly shows that the marine Oligocene graben fill (Fig.2) at that basin. Basin Southwest of Java had a complicated post-rift Neogene tectonic history, resulting in the Eocene Bayah formation and the Eocene Ciletuh formation, with features of deltaic deposits indicates basin development of syn-rift stage of fore-arc. Figure 1. Tectonic setting of Sumatra Darman and Sidi (2000) modification Figure 2. Sedimentary basins of Sumatra •Awang Harun Satyana modification Page 1 Geology Of Forearc Java Sumatra David Hamonangan

Upload: david-h-butar-butar

Post on 16-Jan-2016

25 views

Category:

Documents


0 download

DESCRIPTION

paper

TRANSCRIPT

Page 1: Fore Arc Java Sumatra

Fore-arc Java-Sumatra extends from

southwest of Sumatra to the northeast of java,

consisting of various Prism accretions and basins

(Fig.1). Geological conditions of Fore-arc Java-Sumatra

we can mirror the geological structure and

stratigraphy of the basins the area thrive on. Fore-arc

Java-Sumatra formed by convergence of the Indo-

Australian plate and the Asian Plate during the middle

Eocene to late Oligocene, followed by the latest

charging transgressive marine and open sediments on

the Fore-arc east java and Fluvial-lacustrine

sediments developed in NW Java and Sumatra.

Geological conditions of Fore-arc in western

Indonesia recorded from Aceh basin, with a long (>

200 km) and narrow (< 50 km). Bounded by the West

Andaman Fault, a trench-linked strike-slip fault

obliquely crossing the northward extension of the

Great Sumatran Fault. Research from Atsushi using

the seismic method mention that the deposits in the

basin are thickest along the boundary fault between

the basin and the Outer-arc high, and gradually thin

with increasing distance from the faults. And then

followed by The Simeulue Basin extends over 260 km

in NW-SE direction and 100 km in SW-NE direction,

part of a classic example of subduction, Convergence

system along the Sunda Arc becomes increasingly

oblique from south to north resulting in large-scale,

dextral strike-slip fault systems within the fore-arc

basins and on Sumatra (Malod and Kemal, 1996; Sieh

and Natawidjaja, 2000). The geological conditions of

the next West of Fore-arc Java-Sumatra basin can be

learned from Nias, Mentawai and Southwest Java.

Nias and Mentawai basins accordance in the

deliberations of the Matson and Moore (1992) with

primarily concerned to seismic stratigraphy and not

with geology structure discusses about important

roles to the Batee Fault, a featured primarily defined

by mapping on the Sumatra mainland, and to a

flexure, which can be identified with the Mentawai

fault zone which marks the rear margin of the trench-

slope break. Due to the geological structure of the

Mentawai Islands were quite significantly shows that

the marine Oligocene graben fill (Fig.2) at that basin.

Basin Southwest of Java had a complicated post-rift

Neogene tectonic history, resulting in the Eocene

Bayah formation and the Eocene Ciletuh formation,

with features of deltaic deposits indicates basin

development of syn-rift stage of fore-arc.

Figure 1.

Tectonic setting of Sumatra Darman and Sidi (2000) modification

Figure 2.

Sedimentary basins of Sumatra •Awang Harun Satyana modification

Page 1

Geology Of Forearc

Java SumatraDavid Hamonangan

Page 2: Fore Arc Java Sumatra

The South Java Fore-arc Basin consist of South

Java which lie between the volcano-plutonic arc and

the arc accretion wedge of the trench system.

According to Dickinson and Seely (1979), the Java Fore-

arc basin from the residual as a Fore-arc (lying on

oceanic crust trapped between the arc massif and the

subduction zone) and developed as a constructed

basin (lying on a structural join between the arc

massif and the accretionary wedge). In contrast to

Fore-arc of Sumatra which is identical with right

lateral strike-slip faults, Java Fore-arc doesn't really

have a shear zones that are so significant, folds and

thrusts (Fig.4) occur seaward side of the basin. A

Prominent structural high separates the present Fore-

arc basin from the arc massif characterized by block

faulting.

There may be differences in stratigraphy and

geologic structure between Fore-arc Southeast Java

and Central-Southwest Fore-arc basins, on these

basins characterize that increasingly in the direction

of South or accretionary zone indicates that the

thrust fault zone became more dominant, on the other

way extensional faults (Fig.3) looks more dominant

towards the Fore-arc basin and volcanic arc.

Stratigraphy in the Fore-arc basin characterizes that

volcanic activity quite significant, on the order of

stratigraphy is characterized by deposits of volcanic

that dominates in the Oligocene and continued with

epiclastic back again with volcanic deposits and

followed by Fore-arc slope-Submarine canyons.

Geological conditions of Fore-arc Java-Sumatra have

different traits in each part, in accordance with the

evolution of the tectonic and sedimentary sources of

roles are evolving in each area. Similarly with

Geological structure characteristics, lateral strike-

slip faults are more dominant in the Fore-arc of

Sumatra-Southwest Java, on the other way dip-slip

faults are more dominant in the Fore-arc Central java

to Fore-arc Southeast Java.Figure 3.

Approximately N-S and E-W seismic line across the East Java Forearc M. Surya Nugraha and Robert Hall modification

Figure 4.

Geoseismic Cross Section Fore-arc Central Java Pertamina modification

Page 2