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Cenozoic plate tectonics and basin evolution in
Indonesia
M. C. Daly, M. A. Cooper and I. Wilson
BP Exploration, London EC2Y 9BU, UK
D. G. Smith
BP Research Centre, S u n b u r y on T h a m e s TW16 7LN, UK
and B. G. D. Hooper
CRA Exploration, Box 175, Belarant, W. Australia 6104, Australia
Received 3 July 1989
SE Asia comprises a complex array of Cenozoic basins. The chronostratigraphic evolution of
these basins may be understood within the plate tectonic evolution of SE Asia. The relative
motions of India, Australia, the Pacific and Eurasia provide the boundary conditions for this
evolution.
Indian collision and indentation destroyed a subducting northern Tethyan margin and led to
major clockwise rotation of SE Asia. The South China Sea continental shelf developed after
collapse of the West Pacific subducting margin. Crustal extension led to sea floor spreading and
the formation of the Reed Bank Terrane and, at its trailing edge, the South China Sea.
Sumatran basins opened due to back arc extension in the Eocene. Closure of a marginal ocean
basin resulted in a major contractional event in the Late Oligocene.
The Gulf of Thailand basins and Andaman Sea opened in response to rotation of Indochina and
oblique convergence at the precursor to the Sunda trench. Inversion of the southern end of these
basins and uplift in Borneo coincided with the collision of the Reed Bank Terrane with Borneo.
Opening of the Makassar Straits, Kutei, Tarakan and Barito basins occurred during the Eocene.
Inversion of these basins was a result of the collision of Australia and Australian derived
microplates in the Late Miocene/Pliocene.
Pliocene fold and thrust belt and foreland basin formation in New Guinea was a result of
oblique arc collision.
Basin evolution of SE Asia is not a result of major lateral extrusion in front of the Indian
indenter. The major effect of this collision is in terms of the clockwise rotation of Indochina and
extension along the Sumatran active margin.
Keywords: plate tectonics; Indonesia; paleocontinental reconstructions; basin evolution; Cenozoic
Introduction
This paper outlines a model of the tectonic evolution of
a large part of SE Asia during the Cenozoic. The area
of study (Figure 1) is centred on Indonesia but it
incorporates information from a much broader region.
The paper presents an internally and globally consistent
model of plate evolution and outlines the major
constraints on this evolution. The model is presented as
a series of plate reconstruction maps and sections from
70 Ma to the present day. Special reference has been
made throughout to the basin evolution of SE Asia,
with the intention of understanding this evolution in
terms of plate motions and their potential influences.
Published plate tectonic syntheses of the entire study
area are few in number, although numerous scenarios
exist for parts of the region. Parker and Gealey (1983)
published a synthesis, from Permian to Miocene, with a
series of reconstructions. Daines (1985) presented
several reconstructions as part of a paper on the West
Natuna Basin. Most recently, Audley-Charles et al. (in
press) have prepared a series of reconstructions of the
0264--8172/91/010002-20
region using computer modelling techniques.
Hamilton's syntheses of 1979 and 1988 provide the
basic tectonic framework for much of what follows.
Geological and geophysical constraints
It must be stressed from the outset that the geological
and geophysical data available from SE Asia are
insufficient to define a unique plate tectonic model.
However, the data clearly restrict the possible
interpretations. Before discussing the model, we
therefore give an outline of the nature of the
constraints which we consider to be important.
Plate motions
The major constraint on any plate tectonic study is
the relative motion between the plates concerned.
Indonesia is today under the influence of the Eurasian,
Indo-Australian, Philippine and Pacific plates. The
motion of these plates through the Tertiary period
©1991 Butterworth-Heinemann Ltd
2
Marine and Petroleum Geology, 1991, Vol 8, February
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
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1 Regional sketch map of SE Asia showing the major structural features, basins and plate convergence vectors. (HF) Himalayan
Front; (IR) Irawaddy Fold Belt; (CB) Chindwin Basin; (CBB) Central Burman Basin; (ANS) Andaman Sea; (MPF) Mae Ping Fault; (3PF)
Three Pagodas Fault; (MGB) Mergui Basin; (SKF) Semangko Fault; (CBS) Central Sumatran Basin; (SSB) South Sumatran Basin; (SB)
Saigon Basin; (WN) West Natuna Basin; (PB) Penyu Basin; (HB) Hainan Basin; (PRB) Pearl River Mouth Basin; (LS) Lukonia Shoals;
(RB) Reed Bank; (NWB) North West Borneo; (NP) North Palawan; (SLB) Sulu Basin; (TB) Tarakan Basin; (MLB) Melawi Basin; (KB) Kutei
Basin; (MSB) Makassar Basin; (BB) East Java Sea Basin; (TMR) Timor; (SB) Sambu Basin; (FBT) Flores flack Thrust; (WB) Weber Deep;
(SM) Seram; (BTN) Buton; (NB) Bone Basin; (BGS) Bangaai Sula; (SWB) Salawati Basin; (BTB) Bintuni Basin; (RMF) Ramu Markham
Fault; (PTB) Papuan Thrust Belt; and (OSO) Owen Stanley Ophiolite
Figure
is reasonably well understood, being constrained
by ocean-floor magnetic anomalies and by other
paleomagnetic data. Unfortunately, much ocean-floor
of early Paleogene age has been subducted and the
precise plate motions therefore have to be derived by
indirect means. In particular, the motion of India
relative to Eurasia has to be derived via the circuit
India-Antarctica Africa-North America-Eurasia.
The movement histories of the major plates are
described in outline in the next section of this paper,
Continental paleomagnetism
A significant rock paleomagnetic data set exists for SE
Asia; it was reviewed by Halle and Briden (1982). Since
that review, a large number of data, mostly peripheral
to Indonesia, have been published, both supporting
and contradicting the 'reliable' data as outlined by
Halle and Briden (op. cit.). In spite of the
inconsistencies and sparseness of this data set, this
study has identified a small number of paleomagnetic
results which appear to be reliable in that (a) they are
technically acceptable as far as the paleomagnetic
technique is concerned (McElhinny, 1973), and (b)
they are supported by duplicate studies or by other
geological data.
Some control on microplate movements within the
region
under
consideration
is provided
by
paleomagnetic results from the smaller ocean basins:
the South China Sea, Sulu Sea, Celebes Sea and Banda
Sea (Figure 1). The identification of magnetic isochrons
is still controversial for each of these. In the South
China Sea, E W trending magnetic lineations have
been identified as chron 11 (32 Ma) to chron 5D
(18 Ma) (Taylor and Hayes, 1983). This would imply a
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Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
N - S spreading system leading to the formation of the
South China Sea. However, unidentified N E - S W
lineations also exist in the SW arm of the basin,
implying a phase of N W - S E extension. An alternative
interpretation of the E - W anomalies is that they are
actually aligned N E - S W , being generated by N W - S E
extension, but that closely spaced transform faults may
have rearranged the anomalies such that sampling by
the rather few marine traverses available to date has
given a false impression of their azimuth (Briais et al.,
1987). A N W - S E opening for the South China Sea is
preferred here on regional arguments.
Magnetic lineations in the Celebes Sea were initially
identified by Weissel as chron 18 (42 Ma) in the south,
to chron 20 (45 Ma) in the north. Recent ODP work
(Nicol, personal communication) has supported this
Eocene age and also identified a late Miocene age for
the Sulu Sea oceanic crust. The interpretation from this
is that the Sulu Sea is a recently formed oceanic basin
whilst the Celebes Sea represents a portion of trapped
oceanic
crust,
possibly
derived
from
the
Indo-Australian plate (Lee and McCabe, 1986). The
northern Banda Sea may also be part of this trapped
plate (Silver et al., 1985).
Neotectonics and se&mology
The Indonesian region is currently seismically active.
This seismicity indicates active deformation along many
of the major plate and microplate boundaries in the
region. Seismicity commonly relates to upper crustal
deformation (upper 15 km) and is an indicator of the
present deformation of plate boundaries and hence of
the motion of the plates. From earthquake fault plane
solutions, the style of deformation can be deduced and
the neotectonic setting of an area can be determined.
From this present day framework, extrapolation back
through time for periods of 2 to perhaps 5 Ma is
reasonable. Several earthquake studies of Indonesia
have been published, and they form a sound data base
for understanding Indonesian neotectonics (McCaffrey
and Nabelek, 1986; Cardwell and Isacks, 1978;
Hamilton, 1979; Fitch and Molnar, 1970). These data
have been used to constrain the plate scale evolution of
Indonesia back to the Late Miocene, the quality of this
constraint decreasing with increasing age from the
present.
Chronostratigraphy
Although there is controversy over the relative roles of
tectonics and eustatic sea level changes in driving the
stratigraphic development of sedimentary basins, we
here take the view that the role of tectonics is primary,
and that most regional and many local stratigraphic
events relate directly to plate motions and local
structural environment. Hence the plate tectonics of
the region have great potential for elucidating
chronostratigraphy, while regional unconformities may
provide clues to changes in plate motions. The
chronostratigraphy of most of the basins of SE Asia and
Indonesia has been summarized as an integral part of
this paper and, although it is inappropriate to present
the details here, a selected summary of these data are
presented in Figure 2 and are interpreted below in
terms of plate motions wherever reasonable.
By interpreting within-plate basin histories as
relating directly to plate margin activity, we are going
beyond the tenets of 'classical' plate theory, in which
plates are essentially rigid bodies which undergo
deformation only at their margins. This is clearly not
the case in Indonesia, as in many other parts of the
world (Molnar and Chen,
1982). Intra-plate
deformation is often clearly related temporally to plate
boundary deformation, implying the existence of
extensive detachments within the crust that allow the
transmission of displacements across substantial
distances.
Movements of the major plates
The following section briefly reviews the Late
Cretaceous to Recent motion of the major plates
around the Indonesian region (Figure 3).
Eurasia
The apparent polar wander (APW) path for Eurasia
from 100 Ma to the present indicates that Eurasia has
undergone a small clockwise rotation over this period
of time (Irving, 1977). Studies of plate motions with
respect to the hot spot reference frame (Morgan, 1983)
give an essentially similar result, with a 10 degree
clockwise rotation being estimated from 60 Ma to the
present day.
India
Patriat and Achache (1984) have calculated a detailed
relative motion for India from chron 32 (70 Ma) to the
present, based on an analysis of marine magnetic
anomalies in the vicinity of the Antarctica, India and
Australia triple junction. Figure 3 shows this northward
drift with respect to a fixed Eurasia. From this analysis,
there appear to have been three phases to the Tertiary
drift history of India:
(1) From chron 32 to chron 22 (70-50 Ma), India
moved northwards with a mean velocity of between
150 and 200 mm/yr. As Eurasia remained
essentially fixed during this time, this motion of
India approximates to the relative convergence
velocity of the two continents.
(2) From chron 22 to chron 13 (50-37 Ma), the
velocity of India decreased erratically to less than
100 mm/yr, and the relative convergence velocity
stabilized at about 50 ram/yr.
(3) From chron 13 (37 Ma) to the present, India
continued its northward movement at a steady
50 mm/yr whilst undergoing an anticlockwise
rotation.
The marked decrease in convergence velocity
beginning at 50 Ma is taken as the age of the
continental collision between India and Eurasia
(Patriat and Achache, 1984). The broad time interval
occupied by the slowing down of India coincides with
the erratic movements beginning at anomaly 22. These
shifts are interpreted as collisional modifications due to
plate boundary conditions rather than more
fundamental changes in global plate dynamics.
Australia
The break-up of Australia from Antarctica has most
recently been estimated as mid-Cretaceous (95 + 5 Ma)
(Veevers, 1986). This represents a revision of earlier
estimates of 90-112 Ma (Cande and Mutter, 1982),
Marine and Petroleum Geology, 1991, Vol 8, February
5
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
Figure 3 Relativeplate motions of India and Australia with respect to a fixed Eurasia (after Patriat and Achache, 1984) (India positions
Chrons, Australia positions in My)
and precisely coincides with the dating of the break-up
unconformity of the southern Australian margin.
During this early break-up period the motion of
Australia was erratic, and in absolute terms it was
largely eastward. By 50 Ma the motion of Australia had
changed from eastward to northward as rapid
ocean-floor spreading began in the southern Indian
Ocean. The onset of this more rapid ocean-floor
spreading episode is coincident with the onset of the
continental collision between India and SE Asia. The
Cenozoic northward motion of Australia is well
documented by the ocean floor magnetic lineations of
the southern Indian Ocean (Figure 3).
Pacific
The motion of the Pacific Plate can be plotted with
respect to the formation of linear volcanic chains
thought to have formed above relatively stationary
mantle hot-spots (Morgan, 1972). From about 70 Ma to
42 Ma, the Emperor Seamount chain developed as the
Pacific plate moved in a NNW direction. At about
42 Ma, the movement direction changed to WNW.
This resulted in the 42 Ma to present WNW trending
line of the Hawaiian Ridge (Farrar and Dixon, 1981).
The timing of the change in Pacific plate motion
coincides broadly with other events in the evolution of
6
the Pacific. It has been suggested that this
reorganization occurred due to the subduction in the
Aleutian Trench of the Pacific-Kula spreading ridge
(Engebretson et al., 1984). Hilde et al. (1977) suggested
that the sub-perpendicular change in Pacific motion
resulted in the reactivation of many of the older NNW
transform faults as subduction zones. This process is
here taken to account for the origin of the Philippine
plate at about 42 Ma.
Philippine
This plate, which lies between the much larger plates of
Eurasia and the Pacific, consists entirely of oceanic
crust bordered by island arc systems. The evolution of
the Philippine plate is well constrained back to about
17 Ma, from magnetic lineation and paleomagnetic
data. Prior to 17 Ma, the evolution is more speculative.
However, for most of the Philippine plate's existence,
the Eurasian-Philippine pole of rotation has been
situated somewhere close to the northern tip of the
plate. The implication of this is that, for most of its
development, the Philippine plate has been moving
west to NW with respect to Eurasia, as is the case today
(Minster and Jordan, 1978; Ranken et al., 1984).
In the model presented here, the Philippine plate
developed due to the sub-perpendicular change in
Pacific plate motion at 42 Ma. Prior to this the oceanic
Marine and Petroleum Geology, 1991, Vol 8, February
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
VI
Vt
during particular time intervals. The relative velocities
between the major plates are shown in units of ram/yr.
Structures generated during the time slices are shown
diagrammatically, with an emphasis being placed on
the timing of rifting and rift sedimentation, fault
displacements and basin inversions. The maps are
complemented by three plate tectonic evolution
diagrams outlining the model in cross section.
Vu
Vt > Vu
Vt < Vu
Summary of main tectonic events
extensional arc
During the period studied, the tectonic configuration of
the Indonesian area underwent several profound
changes. These are listed below as the major events
influencing the tectonic evolution of Indonesia during
the Tertiary.
compressional
"~"arc]
Figure 4 Sketch showing the subduction zone implications of
the relative velocity of subduction zone rollback (V0 and the
velocity of the upper plate (Vo)
crust that now forms the Philippine plate was part of
the Pacific plate. In general terms, the Philippine plate
has moved approximately to the NW through time, and
a large part of it has been subducted beneath the
eastern Eurasian margin.
Subduction rollback
In the present model an important aspect of Indonesian
tectonics is the formation of back arc basins. Back arc
basins are thought to be generated by extension behind
a subduction zone by oceanward trench migration.
Migration occurs due to rollback of the trench line with
respect to the upper or overriding plate. In a mantle
reference frame, the trench line will retreat oceanward
with a velocity V1 due to vertical sinking of the
subducting plate (Figure 4). Dewey (1980) argued that
the tectonic environment of an arc is a result of the
relative magnitude of rollback velocity Vt and the
velocity of the overriding plate Vo (Figure 4). If Vo is
greater than V, the overriding plate advances over the
trench line resulting in a compressive arc. If Vo is less
than Vt, an extensional arc will be generated and may
result in back arc basin formation.
Absolute values for V,, and Vt are difficult to
estimate. However, in general, the older the slab the
more dense it is and the faster it sinks, thus the more
likely rollback is to occur. A further consideration is
the length of the trench line. A long, straight trench
line will roll back more slowly than a short arcuate
trench line due to the
problem of material
needing to be removed to allow rollback to occur.
Outline of the plate tectonic model
Maps representing seven time intervals from 70 Ma to
the present day are provided as the basis of the
reconstruction model. The reconstructions show the
major tectonic features and basins believed to be active
(1) At about 50 Ma, the southern Eurasian margin
changed from being a convergent margin to a
continent/continent collisional orogenic belt as
India collided.
(2) At 42 Ma, the Pacific plate motion changed from
NNW to WNW, relative to the hot-spot frame of
reference.
(3) At about 40 Ma (Middle to Late Eocene),
extension generated the Sumatran basins in a back
arc setting. During the Late Oligocene the
southernmost of these basins experienced a major
contractional event due to reversal of the arc and
closure of the back arc basin.
(4) At 32 Ma, ocean-floor spreading began in the
South China Sea, with concomitant subduction in
NW Borneo.
(5) At about 25 Ma, the northern passive margin of
Australia came into direct contact with the Pacific
plate.
(6) At 17 Ma, ocean-floor spreading ceased in the
South China Sea as Palawan and the Reed Bank
Terrane collided with Borneo.
(7) At about 8 Ma, the Banda Arcs collided with
northern Australia.
70 Ma reconstruction, Late Cretaceous (Figure 5)
In our first reconstruction, the relative positions and
motions of India, Australia and 'mainland' Eurasia are
well-constrained. The detailed reconstruction of the
northern margins of India and Australia, and the
southern and eastern margins of Eurasia, are
necessarily more speculative.
India at this time had separated from Africa, and was
moving rapidly NNW, converging on Eurasia with a
velocity of between 150 and 200 mm/yr (Patriat and
Achache, 1984). Oceanic crust of the Indian plate was
being subducted to the north beneath Eurasia.
Australia was drifting slowly eastwards. The
reconstruction shows the southern margin of Eurasia
restored as a WNW trending magmatic arc. This
configuration emphasises the effects of the Indian
collision with Eurasia. During the Late Cretaceous, the
southern and eastern margins of Eurasia were
dominantly subducting margins. These arcs are today
seen as the Cretaceous Trans-Himalayan batholith
(Zhang et al., 1984) and the I-type granites of Burma,
Malaya and China (Cobbing et al., 1986). The rapid
northward movement of India presumably led to a fast
subduction rate along the margin of northern Tethys.
The extent of the Eurasian margin shown is a
compromise between geologic (Coward and Butler,
Marine and Petroleum Geology, 1991, Vol 8, February
7
Cenozoic plate tectonics in Indonesia." M. C. Daly et al.
17o Ma
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5 Late Cretaceous reconstruction showing a postulated northern Tethyan and East Asian margin characterized by oceanic
subduction. The Kolistan Island arc had accreted by this time
1985) and plate tectonic interpretations (Klootwijk et
al., 1985). Southern Tibet is returned some 1700 km
southwards, to a latitude compatible with the
paleomagnetic results from the Cretaceous Takena
formation of the Lhasa area (Achache et al., 1984; Lin
et al., 1986). The latitude of Khorat does not appear to
have changed significantly since the Cretaceous, being
comparable to that of South Tibet at this time
(Achache et al., 1983).
The relative positions of the continental units of SE
Asia are shown in what is believed to be their
orientation at this time. The reconstruction has been
arrived at by rotating Indochina anticlockwise so as to
give the Mesozoic paleo-pole of the Khorat plateau a
northward azimuth (Maranate and Vella, 1986). The
continental fragments of Reed Bank and North
Palawan have been restored to a position adjacent to
the southern passive margin of China. This in turn
closes the South China Sea, which (from the evidence
of the magnetic anomalies) is known to have been
closed at that time.
At the southeastern corner of Eurasia the Meratus
terrane of SE Kalimantan was being actively generated
at the convergent margin. This accreted terrane
comprises a melange of blueschists and ocean floor
fragments known as the Meratus thrust belt. Although
8
it mostly comprises material scraped off subducting
oceanic crust, the associated Paternoster granite and
other continental fragments suggest that some
continental material was involved in this accretion
process. We see this margin as an analogue of the
Franciscan terrane of California (Ernst, 1970). The
thrust transport direction of the Meratus terrane
indicates that the margin was open to Pacific
subduction. The reconstruction shows a diagrammatic
north Indian passive margin, the former extent of
which is similar to that proposed by Veevers et al.
(1975).
The northern passive margin of Australia has been
reconstructed with Timor's continental basement in
essentially its present position in relation to mainland
Australia. The positions of Seram and Buru have been
reconstructed by rotating both clockwise and siting
them against the Australian passive margin. This is
compatible with the paleomagnetic results (Haile and
Briden, 1982), which require a Cenozoic anticlockwise
rotation of Seram by 80 degrees. It also agrees with the
stratigraphic similarity between these fragments and
the Australian passive margin, as demonstrated by
Pigram and Panggabean (1984). The microcontinental
fragments of Buton and Banggai Sula (presently part of
or adjacent to Sulawesi) have been restored to a
Marine and Petroleum Geology, 1991, Vol 8, February
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
certain is that there was significant deformation of the
Himalayan arc and associated sediments prior to the
main Indian collision. There is also evidence that the
Trans-Himalayan arc was elevated prior to the collision
of India (Burg and Chen, 1984), much as the Andes are
today. Thus, a contractional regime similar to that of
the Sub-Andean ranges may be expected to have
preceded the collision. Such deformation is expressed
m the Late Cretaceous folding of the Takena
Formation of Tibet.
The relative NW motion of Australia lasted from
about 60 to 40 Ma and it resulted in strike-slip motion
between the oceanic portion of the Australian plate and
SE Borneo. The Meratus terrane together with the
55 Ma reconstruction, E n d Paleocene (Figure 6)
Schwarner Block and western Sulawesi are shown.
In the 55 Ma reconstruction, India continues to
Similarly, Sumatra and Java are shown, also envisaged
converge on Eurasia, and Australia is now moving to
as the products of progressive accretion of material,
the NW.
including the products of volcanism, along a subducting
Prior to the main continent-continent collision
plate margin.
between India and Asia, there was an earlier collision
In the South China Sea area, there is a suggestion of
between the Trans-Himalayan margin and the Kohistan
extension during the Late Cretaceous to Paleocene in
island arc, probably during the Late Cretaceous. There
the Pearl River Mouth Basin. The South China Sea
is much discussion relating to the timing and sequence
Late Cretaceous/Paleocene rifting, although poorly
of collisions in the Himalaya (Brookfield and Reynolds,
understood, occurred in NE/SW trending rifts (Ru Ke
1981; Coward et al., 1986). However, what does seem
and Pigott, 1986). The implied NW/SE extension is
position north of the Kepala Burung (the 'Bird's Head'
peninsula of Irian Jaya). The precise position of these
fragments is poorly constrained; however, they do
show strong stratigraphic evidence of derivation from
the Australian passive margin. An important feature of
the reconstruction of the northern Australian margin is
the eastward displacement of the Kepala Burung and
the northern half of mainland New Guinea by about
200 km with respect to the Australian mainland. This
has the effect of removing the hook-like projection of
this peninsula around the Banda Sea. The Banda Sea is
interpreted to have grown as a minor back-arc basin in
the latest Miocene-Recent.
55 Ma
9'0
-30
30
PACIFIC
\
~N
Lhasa
Accretion of
Meratus terrane
I
I
!
I
INDIA
/
/
J
J
°9
0
90
120
Figure 6 Eocene reconstruction prior to India-Eurasia collision. Borneo in the form of the Schwarner Block has now accreted to the
Asia p r o m o n t o r y isolating the proto-South China Sea. Subduction has ceased along the northern margin of this trapped oceanic basin
Marine and Petroleum Geology, 1991, Vol 8, February
9
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
(a) LATE CRETACEOUS/
EARLY PALEOCENE
Accreted terrane, strong
basement anisotropy
CHINA
\ . . " -.
............::~................................
(b) E O C E N E - O L I G O C E N E
Cessation of subduction
margin collapses
Rift basins
,~
CH,NA
Slab begins
to sink
(c) OLIGOCENE
EARLY MIOCENE
Passive margin
South China
Sea
Reed Bank
Terrene
CHINA
(d) MIDDLE
MIOCENE
Termne collides
Passive margin
~-~
Uplift
(e) LATE MIOCENE
Palawan trench
Figure 7 Plate tectonic sketch showing a s e q u e n c e for the evolution of the South China Sea. The s u g g e s t e d subduction of oceanic
material below the Reed Bank Terrane is not s u p p o r t e d by volcanic evidence
thought to relate to gravitational collapse of a crust
thickened due to Cretaceous terrane accretion (Figure
7).
40 M a r e c o n s t r u c t i o n , L a t e E o c e n e (Figure 8)
Continental India collided with the Eurasian margin at
about 50 Ma. The precise timing and sequence of the
Indian collision is still the subject of debate (Brookfield
and Reynolds, 1981; Honneger et al., 1982); however
50 Ma is the age of the abrupt decrease in India's
northward velocity at chron 22 (Patriat and Achache,
1984). This reduction in velocity is approximately
contemporaneous with the increase in ocean-floor
spreading rate between Antarctica and Australia at
52 Ma; it slightly preceded the change in motion of the
Pacific plate at 43 Ma (Farrar and Dixon, 1981).
The change in motion of the Pacific may have
resulted in the generation of a number of micro-plates
in the W Pacific by reactivation of transforms and
fracture zones as subduction zones (Hilde et al., 1977).
One of these western Pacific 'buffer' plates (between
the Pacific proper and Asia) was the precursor of the
10
present day Philippine plate. Along the western margin
of this plate, eastward subduction gave rise to the arc
terranes of the Philippines and west Sulawesi some
distance (circa 2000 km; Seno and Maruyama, 1984) to
the SE of their present location.
The Eocene collision between India and Eurasia also
corresponded temporally with the initiation of much of
the basin evolution in SE Asia. This coincidence
strongly supports a genetic relationship and has been
modelled as such by Tapponnier et al. (1986). With
regard to the reconstruction, it is sufficient to say that
the block rotations predicted by the extrusion model of
Tapponnier et al. (op. cit.) appear to be acceptable in
that they are supported by the limited paleomagnetic
data. However, the very large displacements on
strike-slip faults which Tapponnier et al. predicted are
geologically unproven. Tapponnier et al. assumed little
N - S shortening in Tibet and therefore postulated that
the large-scale contraction required was achieved by
extrusion along major strike-slip zones. However,
fieldwork in Tibet has demonstrated extensive thrusting
and N - S shortening (Shackleton et al., 1986). The
contractional
deformation
predicted
by
the
Marine and Petroleum Geology, 1991, Vol 8, February
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
40 Ma
oS/"
EASTERN LIMIT
OF MAJOR STRAINS
ASSOCIATED WITH
INDIAN INDENTATION
-30
]
Figure 8 Latest Eocene reconstruction showing the collision of India and Eurasia as well established. Decelerating convergence
resulted in back arc extension and spreading south of Sumatra. Widespread extension occurs elsewhere in SE Asia accompanying
progressive rotation of Indochina and an abrupt change in Pacific convergence direction
paleomagnetic results appears to be distributed, being
dissipated in thrust and extensional belts within Tibet
and mainland Asia, rather than being concentrated on
major fault zones that transported large rigid blocks
thousands of kilometres. Also, recent indentation
experiments have not repeated the extensive lateral
extrusion originally achieved (Davy and Cobbold,
1988). Our reconstruction therefore accepts the
paleomagnetically determined rotations of Indochina
and Sumatra, and it also accepts minor strike-slip
displacements on the major fault structures. However,
it allows most of the hinterland deformation of the
Indian collision to be accommodated by crustal
shortening in Asia rather than by large scale eastward
extrusion. The partitioning of the strains associated
with the Indian collision is a subject of active research
and it cannot be modelled more effectively at present.
The basin systems of Sumatra, Java, Malaysia,
Thailand and Borneo were initiated during this Eocene
period. In Sumatra and Java, basin formation occurred
due to back arc extension. This led to the formation of
a small oceanic basin and offshore island arc in the Late
Eocene and Oligocene (Figures 8 and 9). The present
day Sumatran forearc basins developed as a passive
margin during this phase. A further consequence of this
interpretation is that the Sunda subduction system was
not active until the marginal basin closed in the Late
Oligocene, a feature that explains an apparent lack of
arc volcanics in Sumatra and Java during the Late
Eocene and Oligocene.
The Gulf of Thailand and Malaya basin systems
comprise a sequence of small north-south trending
grabens on land, that pass into the larger Thai and
Malay basins offshore to the SE. This system was
generated by dextral displacements resulting in a series
of dominantly extensional basins on a series of major
E S E - W N W trending faults. The dominantly dextral
sense of displacement on the faults of Thailand and the
Malay Peninsula argue against the extrusion
mechanism proposed by Tapponnier et al. (1986). The
present model envisages them developing as a response
to increasingly oblique subduction due to rotation of
the subducting continental margin by the indentation of
India (Figure 10).
In the Late Eocene, a phase of regional uplift in the
Pearl River Mouth Basin is marked by a major
unconformity. The unconformity is succeeded by a rift
sequence and, in the Oligocene, by a drift or thermal
subsidence sequence (Ru Ke and Pigott, 1986). Rifting
was thus established in the South China Sea region in
M a r i n e a n d P e t r o l e u m G e o l o g y , 1991, Vol 8, F e b r u a r y
11
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
the Late Eocene-Oligocene.
During the Eocene, possibly as early as the
Paleocene, the Tarakan, Kutei and Barito basins of
Borneo were receiving rift sediments. The implied
extension also resulted in formation of the deep basin
of the Makassar Straits by Miocene time. These basins
do not appear to relate directly to the deformation
caused by the collision of India. They comprise large
half-graben systems that face east in the Kutei and
Tarakan basins, and west in the Barito basin. We view
the initiation of these basins as being related to
back-arc extension that occurred along the Pacific
margin, reactivating the earlier Meratus thrust terrane.
The Adang flexure of Borneo marks a major transfer
zone between east and west facing half-graben systems.
The 40 Ma reconstruction also shows the first
appearance of the Sepik Arc, which today forms north
central New Guinea. We have placed the source of the
Sepik Arc along the boundary of the Philippine plate
and Indo-Australian plate. The Philippine plate
migrates NW with time, whilst the western boundary
swings clockwise on a collisional course with Australia.
(a) LATE CRETACEOUS/
PALEOCENE
Northern Tethyan
Margin
(b) MID-LATE EOCENE
(~
Back-arc passive
margin
r~
,4
No
volcanism
__Y
~
lab rollback
(c) OLIGOCENE
r~
Arc
No
reversal
volcanism
!iiiiiiiiiiiii!ii!ili!!!i!iiiiiill
(d) EARLY
MIOCENE
Arc terrane (Burma?)
Collision
Basin
inversion
Volcanism
renewed
/%
(e) PRESENT-DAY
Semangko
fault
CSB
Figure 9 Plate tectonic sketch showing an evolutionary sequence for Sumatra. The closure of the back-arc basin is achieved by a
subduction polarity reversal. The colliding terrane is removed to the west by margin parallel strike-slip and may form a part of
present-day Burma
12
M a r i n e a n d P e t r o l e u m G e o l o g y , 1991, V o l 8, F e b r u a r y
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
Suture
\
\
\
-.......
Gulf of Thailand and Mergui basins initiated
as Asian margin rotated and an increasing
strike-slip couple was generated
by indentation.
.
\
\
\
9
3.
ili?
Rotation of the Asian margin implies
extension parallel to the margin - causes
opening of the Andaman Sea (AS)
and Sunda Basin (SB)
SKF
;B
Figure 10 Sketch showing a rotational, active margin related model to explain basin evolution in the Gulf of Thailand and the Andaman
Sea. Oblique subduction and margin parallel extension is invoked as the basin-forming mechanism, not extrusion. (MPF) Mae Ping
Fault; (3PF) Three Pagodas Fault; (MGB) Mergui Basin; (AS) Andaman Sea; (SKF) Sermangko Fault; (SB) Sunda Basin
Marine and Petroleum Geology, 1991, Vol 8, February
13
Cenozoic p/ate tectonics in Indones/a: M. C. Daly et al.
The NNW to WNW switch in plate motion of the
Pacific and the beginning of rotation of SE Asia are
broadly coincident in time, and are together thought to
be the events that isolated part of the Indo-Australian
plate. Remnants of this 'trapped' oceanic crust, shown
on the reconstruction, are here taken to form the
Celebes Sea. The mechanism of isolation of this piece
of ocean floor from the rest of the Indo-Australian
plate is poorly understood, as is the timing.
30 Ma reconstruction, Oligocene (Figure 11)
Two fundamental changes occurred between the 40 and
30 Ma reconstructions. Firstly, the South China Sea
developed an active sea floor spreading centre, and
secondly the present basins of Sumatra and Java were
placed under a contractional stress that resulted in their
inversion.
The dominant structures of the South China Sea
continental margin are ENE to east-west trending
extensional faults. Subsurface data suggest that many
of these extensional structures formed in a basement
with a strong pre-existing fabric. We interpret the
30 Ma
opening of the South China Sea to be a response to the
'rollback' of pre South China Sea oceanic crust trapped
between the China margin and Borneo. Due to
extension and subsequent sea floor spreading, a
marginal sea was formed and the Reed Bank Terrane
migrated southwards as a detached piece of thinned
continental crust (Figures 7 and 11). The oldest
magnetic anomaly recorded in the South China Sea is
chron 11 (32 Ma). During the sea floor spreading
episode the continental fragments of Reed Bank, North
Palawan and the Macclesfield Bank were rifted off the
South China margin. The subsequent southward
migration of these fragments implies the subduction of
crust along northern Borneo. It has to be assumed that
this was a remnant of older, pre-existing Mesozoic
ocean floor. This postulated subduction helps to
explain the existence of the accretionary complex of
Sarawak and Sabah (Hamilton, 1979). That a major
south dipping thrust exists along the northern margin of
Borneo is well documented by seismic data, but the
detailed evolution of the margin remains poorly
understood.
In Sumatra and Java a major contractional event is
90
\
\
k
\
30
\
\
\
"30
120
.~J~-~,.
Figure 11 Oligocene reconstruction showing closure of the Sumatran back-arc basin and opening of the South China Sea. Subduction
of the proto South China Sea crust is established in Borneo and the Cagayan Ridge and is suggested to occur beneath the Reed Bank
Terrane to generate the terrane by subduction rollback
14
Marine and Petroleum Geology, 1991, Vol 8, February
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
Figure 12 Early Miocene reconstruction showing the emplacement of the Sepik arc on the Australian passive margin of New Guinea.
Onset of tectonic shaving of protuberances from the Australian margin
recorded in the present-day forearc region. This is
interpreted as a result of reversal of the offshore arc
and subsequent closure of the marginal basin and arc
collision (Figures 9 and 11). The collided products may
in part be evident offshore Sumatra and Java today.
However an interesting possibility shown in the present
model is that much of the material was displaced to the
west into what is now Burma.
The Tarakan, Kutei andBa-rito back-arc basins were
subsiding throughout this period, due to thermal
subsidence.
By the Oligocene, the Philippine plate was well
established as the principal buffer plate between the
Pacific plate and Asia. Australia was moving north but
had not yet collided with the Sepik arc. The Philippine
arc swung clockwise with time to subduct part of the
trapped Indo-Australian ocean crust.
After collision with Eurasia, India and Tibet
underwent an anti-clockwise rotation. The timing of
this rotation is poorly understood. The present model
distributes it from 50 to 30 Ma, believing the rotation to
reflect collisional readjustments (Klootwijk et al.,
1985).
20 Ma reconstruction, Early Miocene (Figure 12)
A critically important change had taken place by the
time of this reconstruction. Whereas at least one island
arc system had formerly lain between Australia and the
Pacific proper, those arcs now began to collide with the
northern margin of Australia. This had the effect of
bringing the northern passive margin of Australia into
direct contact with the essentially westward-moving
Pacific/Philippine plate system. At about the same
time, the rate of spreading of the Pacific Plate increased
(Hilde et al., 1977) and spreading ceased in the
Caroline Plate (Weissel and Anderson, 1978).
The collisional events have been modelled here in
two stages, although we recognize that this may be an
oversimplification of a more complex multiphase
process. The oblique collision of the Sepik Arc
occurred at about 25 Ma (Figure 13). This Early
Miocene collision emplaced the New Guinea ultramafic
belt, and is represented by a regional unconformity and
minor basin inversion in Irian Jaya. The Inner
Melanesian Arc collided diachronously from 10 Ma to
the present, beginning in the west. This younger event
Marine and Petroleum Geology, 1991, Vol 8, February
15
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
the mainland has been subjected to oblique
instigated the present-day tectonic regime of New
convergence for most of the Neogene.
Guinea.
Sea floor spreading in the South China Sea continued
The collision of northern Australia with the Pacific
well into the early Miocene, and subduction of a wedge
and its buffer plates instigated the evolution of
of late Mesozoic to Paleocene oceanic crust (Holloway,
Indonesia as we see it today. Probably the most
1982) occurred along NW Borneo. North-facing
important aspect of this collision is the commencement
accretion accompanied this subduction (Hamilton,
of the tectonic erosion of the irregularities of the
1979).
Australian passive margin by the oblique motion of the
Philippine plate. This resulted in the detachment of the
(Australian) Banggai-Sula and Buton microcontinental
10 Ma reconstruction, Middle Miocene (Figure 14)
fragments (and perhaps others as well) in the form of
tectonic flakes. They were transferred from the Kepala
By the middle Miocene the South China Sea had ceased
spreading. This coincided, at 17 Ma, with the collision
Burung (Bird's Head) peninsula on to the
Philippine-Pacific plate, and were transported
of Palawan, Reed Bank and the Dangerous Grounds at
westwards towards their present positions. Their
the subducting boundary of Borneo (Figure 7). The
westward motion caused the rotation of north Sulawesi
collision of this buoyant material is believed to have
and the choking of subduction in west Sulawesi (Figure
been responsible for the cessation of sea floor spreading
11).
in the South China Sea. Uplift in south and central
The configuration of the oceanic microplates
Palawan occurred slightly later, in the Late Middle
between the Pacific plate and New Guinea is extremely
Miocene (Holloway, 1982), suggesting that subduction
complex and its reconstruction prior to 20 Ma is not at
did not terminate until that time.
present possible. However, the tectonic effects of the
By the Middle Miocene, the fragments of Buton and
interaction of those microplates with the mainland are
Banggai-Sula had collided with eastern Sulawesi. The
observable in the stuctural evolution of New Guinea. In
contractional regime that accompanied the collision
general terms, the structures developed indicate that
between Banggai-Sula, Buton and east Sulawesi was
(a) OLIGOCENE
__
Early Mesozoic
passivemargin
Sepikarc
Australian ~ Plate
(b) MIDDLE
MIOCENE
ObliqueSepikarc
collision
Australian
Plate
J
(c) LATE
Oblique
subduction
MIOCENE
Australian ~
Plate
(d) PRESENT-DAY
,ust
16
i:. ,
%
Obliquearc collision
~ RMF
BismarckSea
PTB
,an
Plate
Figure13
~
..
....
~
';;
Plate tectonic sketch showing an evolutionary sequence for the New Guinea passive margin
M a r i n e and P e t r o l e u m G e o l o g y , 1991, Vol 8, F e b r u a r y
J
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
J
~'\
9i)
10 Ma
30
31)-
i!!i!i!!iiiiiiiii
iiii~iiiiii~!?~i~i!i!?i!iiiii!iiii!iii!iiii~i!i?i i!i~ii!iii ili~i~!ii
ii!i~i~i!~i~i~!iiii:i!i!~i~i~!~!~!i~i!iiiiii!
i!iii ?¸¸¸~ii ~ ~:~i
Figure 14 Late Miocene reconstruction s h o w i n g the tectonic shaving and bending of the Banda Arc area. Onset of opening of the
A n d a m a n Sea basin with continued rotation and oblique convergence along the Sunda trench
largely extinct by 15 Ma, as a large proportion of the
thrust belt is overlain by undeformed Mid-Miocene
sediments (Kundig, 1956). However, following the
thrusting, a phase of ENE trending sinistral strike-slip
faulting occurred that cut the thrust belt and displaced
Banggai-Sula to the NW. In the reconstruction, east
Sulawesi moves with the resolved velocity of the Pacific
and Australian plates. Halmahera at this time is
envisaged as a part of the Philippine plate, possibly as
an oceanic plateau or other shallow marine feature.
In the Late Miocene, the northern Philippine
archipelago began to collide with north Palawan. In
New Guinea, the Pacific-related deformation led to the
establishment of the Lengguru thrust belt, and also to
deformation and rotation of the islands of Seram and
Buru. East Sulawesi continued its westward motion,
subducting parts of the trapped Indo-Australian
oceanic crust as it went. Further constriction of the
northern section of the trapped basins was due to
migration of the Philippine arc, ending in collision with
north Palawan in the Late Miocene (10 Ma). This
caused uplift in the outer Sulu Sea, forming the
Cagayan Ridge, and subduction to the south below the
Sulu arch.
The Philippine collision involved a significant
component of sinistral strike-slip deformation. The
collision resulted in a small anti-clockwise rotation of
Luzon and the northern Philippines. A result of the
collision was to choke the west-facing subduction zone
which then flipped to be east facing. A little after
collision in Palawan, the Luzon arc terrane collided
with Taiwan. This resulted in a NW facing thrust
terrane between the Ryukyu and Manila trench
systems.
At the southern end of the Philippine chain,
Sulawesi, under the direct influence of the Pacific,
continued its rapid westward motion. North Sulawesi
rotated clockwise in the process (Otofuji et al., 1981).
The WNW-directed sinistral strike-slip motion between
Buton and Banggai-Sula may have continued through
to this time; however, it appears to have ceased by the
Pliocene.
Under the influence of the oblique relative
convergence of the Pacific plate, New Guinea
deformed during the Late Miocene and continues to do
so today. The oblique convergence has resolved itself
into south to SW directed thrusting, and east trending
sinistral strike-slip (Figure 11).
One of the most important structures within this suite
is the Tarera fault. This east to ENE trending sinistral
Marine and Petroleum Geology, 1991, Vol 8, February
17
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
strike-slip fault links to the Bismarck fault in the E, and
has translated the whole of northern New Guinea to the
west. This displacement is thought to have commenced
by the Late Miocene (Figure 12).
The earlier Andaman Sea strike-slip pull-apart rifting
was generating ocean crust by this time (Curray et al.,
1978). Although poorly constrained due to the thick
sedimentary cover, the age of the oldest oceanic crust
in the Andaman Sea is thought to be about Late
Miocene (11 Ma). At about this time, structural
inversion began in several of the earlier formed
back-arc basins of Sumatra, including the Mergui and
central Sumatran basins; the inversions climaxed
somewhat later, in the Pliocene.
Also in the Late Miocene, the Indo-Burman thrust
belt was well established, imbricating part of the Indian
passive margin sequence, together with sediment
derived along strike from the Himalayan collision. The
westward vergence of the thrusting is thought to be a
result of the pinning and rotation of the thrust belt at
the NE margin of the Indian indenter.
5 Ma
5 Ma reconstruction, Early Pliocene (Figure 15)
The important tectonic event that occurred at about
5 Ma was the northward collision of the NW Australian
passive margin with the Sunda trench and Banda
forearc. This collision generated the Timor allochthon
of Audley-Charles (1981); a detailed account of the
timing and evolution of the collision zone is given in
Milsom and Audley-Charles (1986).
The dynamic effect of the collision was to generate a
SSW-directed thrust belt and foredeep basin on the
Australian passive margin, and NNW-directed
thrusting to the north of Timor. The latter is
represented by the Flores and Wetar thrusts. The
NNW-directed contraction generated a series of major
NNW-trending strike-slip shear zones, north of the
Banda arc in south Sulawesi. This deformation
cross-cuts the earlier thrust and ENE-trending
strike-slip faults and is expressed today as the Walanae
and Palu fault zones. These two anastomosing fault
zones have associated thrust and extensional structures
and locate the centres of active volcanicity in Sulawesi
1;~0
9()
i!i iiii!Z!ilii!iilZ!i il i~i i ii !:i ii !iiiiiili!iii!ii i{i i i i ! ii iil iiiiiiiiiiii{ii i!
.
.............
i
MB
~DF~'
30
"~
~
,0t
Figure 15 Pliocene reconstruction s h o w i n g m a j o r arc collision in New Guinea generating a fold/thrust belt and foreland basin.
Widespread inversion in SE Asia as Australia collides (circa 8 Ma) with the Banda Arc
18
Marine and Petroleum Geology, 1991, Vol 8, February
Cenozoic plate tectonics in Indonesia: M. C. Daly et al.
(Berry and Grady, 1986). The Walanae fault is also
responsible for the deformation of the Bone basin and
the Walanae depression of south Sulawesi.
The temporal and kinematic coincidence of this
NNW-directed displacement in Sulawesi and the
NW-directed inversion of the Kutei, Tarakan and
Barito basins demonstrates that the inversion of these
basins can be directly linked to the contractional
tectonics of the Australian collision with the Banda arc.
The Barito, Kutei and Tarakan basins of east Borneo
developed in response to rifting in the Makassar Strait
during the Eocene, and the Kutei basin experienced a
mild inversion during the Early Miocene. During the
early Pliocene, all three basins experienced major
structural
inversion
by
reactivation
of
the
basin-forming extensional faults.
Hamilton (1979) shows large transfer faults
associated with the margins of the three basins. We
suggest that the inversions must have occurred by
compression at a high angle to the strike of the basins
and to the strike of the original half-graben structures.
The Early Pliocene age of the Kutei basin inversion
correlates temporally with the collision of Australia
with the Banda forearc. This collision resulted in
SE-SSE-directed thrusting of the arc onto the
Australian foreland. Contemporaneous back-thrusting
generated the Flores and Wetar thrusts, and instigated
N W - N N W strike-slip displacements in southern
Sulawesi
along
the
Walanae
fault
system
(Audley-Charles, in press). A feature of this collision is
that the associated contractional displacement dies out
to the west, where the Australian margin is not yet in
contact with the Sumatra-Java trench.
The NW-NNW-directed displacements on the
collisional back-thrust system, the N W - S E contraction
that has caused the basin inversion, and the temporal
association of this collision and inversion, together
indicate that the inversion of the west Borneo basins is
a direct result of Australian collision. This
interpretation implies a mid-crustal connection
between the Banda arc back-thrust system, the
Walanae fault system of Sulawesi, and the reactivated
extensional faults of Borneo. It is suggested that the
connection is by means of a thrust which is structurally
lower than the Wetar-Flores thrust, and which has
carried the whole arc to the NW. The Walanae
strike-slip fault is a lateral ramp within this system and
its displacement does not need to offset the Banda
volcanic arc. This interpretation is supported by the
presence of north-south trending sinistral strike-slip
faults that apparently cut the Banda volcanic arc. From
present day seismicity in the region (Nishimura and
Suparka, 1986), the NNW directed displacements are
continuing today. This argues strongly for the
large-scale transmission of tectonic displacements
across the western part of the Banda Sea. It also
provides a compelling scenario for the dynamics of the
Barito, Kutei and Tarakan inversions. This
interpretation is taken further to suggest that the
generation of the southward-subducting Sulu Arch was
also due to the NNW contraction generated by the
Australian collision.
Also at about 5 Ma, the west-facing Philippine
trench had flipped to be east facing. This resulted in the
westward progression of Halmahera into its present
position and the consequent formation of the Molucca
Sea and its associated accretionary wedges (Silver and
Moore, 1981).-The initial westward subduction of the
plate west of Halmahera led to the generation of the
deep subducted slab below the Sangihe arc (Hatherton
and Dickinson, 1969).
In Irian Jaya, the sinistral strike-slip motion on the
northern margin of New Guinea translated the Kepala
Burung westwards, rotating Seram anticlockwise
(Figure 11) and opening the triangular Teluk Basin in
the process. This displacement led to the present
hook-like appearance of the northern part of New
Guinea and presents a feasible dynamic model for the
evolution of the arcuate nature of the Banda arc. It is
important to note that focal mechanism data indicate
that the subduction zones forming the south and north
arms of the Banda arc are not continuous with each
other. The northerly one is the more recent feature,
and it is not connected to the major Sunda Trench
forming the south Banda arc.
By the Pliocene, the remaining mainland parts of the
reconstruction were essentially established in their
present configuration. The lndo-Burman thrust belt is
wider at the present day, and the Andaman Sea is
larger; however, the kinematics of these systems have
not otherwise changed significantly. In marked contrast
to this, the changing nature of eastern Indonesia is
emphasized by our reconstruction.
Conclusions
Basin formation in Indonesia and nearby areas is
related to the following:
(1) Back-arc extension due to subduction rollback
(Sumatra/Java, South China Sea).
(2) Strike-slip movements due to increasingly oblique
convergence between the Indian plate and Eurasia
(Thai-Malaya basins, Andaman Sea).
(3) Back-arc extension related to subduction rollback
in the west Pacific (Tarakan, Kutei, Barito basins).
The widespread occurrence of structural inversion of
originally extensional and transtensional basins in
Indonesia and neighbouring areas can now be identified
with several quite different dynamic settings, three of
which are time-related and the fourth of which is
time-independent.
(1) Late Oligocene inversion of the Sumatra-Java
forearc basins by marginal basin closure.
(2) Mid-Miocene inversion and uplift in Borneo and
the Natuna basin was due to the collision of
continental fragments in the South China Sea.
(3) Pliocene inversion of the Barito, Kutei and
Tarakan basins of Borneo was due to the collision
of Australia with the Banda arc; structural
connection was provided by strike-slip fault
systems through Sulawesi.
(4) Late Miocene to Recent inversions in Sumatra and
the East Java Sea (Madura) are localized along the
Palaeogene back-arc rift system and are associated
with strike-slip displacements.
Acknowledgement
M.C.D., M.A.C., D.G.S. and I.W. gratefully
acknowledge permission from The British Petroleum
Company to publish this paper.
Marine and Petroleum Geology, 1991, Vol 8, February
19
Cenozoic plate tectonics in Indonesia: M. C. Daly
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