6. basement geology

6. Basement Geology

by : Awang Harun Satyana

Petroleum Geology of Java Area :Re-Visit Prolific Areas and Disclose Under-Explored Areas

Bandung, 15 17 June 2009

Hamilton (1979)

Crustal Composition

Manur and Barraclough (1994)

West Java Crustal Cross-section

Koesoemadinata (2006)

East Java Crustal Cross-section


Java Plate and Crustal Composition


Java Basement : Recent Trends

Recent studies on sedimentary provenances of southern Java indicated the contribution from Proterozoic continental fragments. Regional gravity traverses and modelings across

Java show presences of continental basement. Recent tectonic reconstruction involves

continent collision in Java before subduction.

Smyth et al. (2007)

East Java and Western AustraliaEast Java and Western Australia

Age (Ma)

400 800 1200 1600 2000 2400 2800 3200

R

e

l

a

t

i

v

e

P

r

o

b

a

b

i

l

i

t

y

Neoproterozoic Mesoproterozoic Paleoproterozoic Archean

East Java

Perth Basin, Western Australia

Smyth et al. (2005)

Phanerozoic Fold Belts

Archean Block

Proterozoic Basins & Blocks

Potential Australian SourcesPotential Australian Sources

Pinjara Orogen

Yilgarn Craton

Capricorn Orogen

Albany-Frazer Orogen (Pell et al. 1997; Brugier et al. 1999)

Relavtive

Probability

40

35

30

25

20

15

10

5

500 1000 1500 2000 2500 3000

N

u

m

b

e

r

s

o

f

g

r

a

i

n

s

Age (Ma)

CAPRICORN OROGEN

YILGARN CRATON

Zircon U-Pb SHRIMP ages from Sircombeand Freeman, 1999; and Bruguier et al.,

1999.

Phanerozoic Neoproterozoic Mesoproterozoic Paleoproterozoic Archean

PINJARA OROGEN

ALBANY FRAZER OROGEN

What lies beneath East Java?

continental fragment beneath the arc

subducted continental fragment

subducted sediments

Hall (2007)

Archean Continental Crust

Probably ophiolitic and arc type, not thinned

Continental?Cretaceous accreted ophiolitic and arc rocks

Archean Continental Crust

Progo-Muria Lineament

Smyth et al. (2007)

Hamilton (1979)

Architecture :constructions, geometry, thickness, depth, extent

Costraints - provide some degree of controls to the analysisprimitive crusts (geometry & density)

Bathymetry & topography

sedimentary thickness from seismic profiles and boreholes

Analysis : 2-D forward modeling fitting models to observed data

CRUSTAL ARCHITECTURE JAVA ISLAND, INDONESIAan approach via constrained gravity modelling

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7

TRANSECTS OF GRAVITY ANALYSISTRANSECTS OF GRAVITY ANALYSIST1. T1. BayahBayah Dome (Dome (CiletuhCiletuh))T2. T2. BandungBandung BasinBasinT3. Caldera T3. Caldera PrianganPrianganT4. T4. KarangsambungKarangsambungT5. T5. LawuLawu MuriaMuriaT6. T6. KendengKendeng ZoneZoneT7. T7. MaduraMadura

Sardjono (2006)

-400 -300 -200 -100 100 200 300 400Distance (Km)

0

G

r

a

v

i

t

y

(

m

G

a

l

s

)

FUNDAMENTAL CONSTRAINTFUNDAMENTAL CONSTRAINTPRIMITIVE / STANDARD CRUSTSPRIMITIVE / STANDARD CRUSTS(REFERENCE CRUSTAL MODELS)(REFERENCE CRUSTAL MODELS)

( Reference density = 2.67 g/cc )( Reference density = 2.67 g/cc )3

D

e

p

t

h

(

K

m

)

0zero level Bouguer gravity

continental shield transition zone open marine environment

zero level Bouguer gravity zero level free-air gravity

0

10

20

30

40

50

-50

100

-100

Granitic rocks2.67 g/cc

Andesitic rocks2.72 g/cc

upper mantle material3.07 g/cc

3 upper mantlematerial

3.07 g/cc3

upper mantle material3.07 g/cc

3

seawater = 1.03 g/cc

Basalt layer 2.77 g/cc

standard thicknesscontinental crust

Sardjono (2006)

T1 T1 CiletuhCiletuh--BayahBayah DomeDome

T2 T2 BandungBandung BasinBasin

T3 Caldera T3 Caldera PrianganPriangan

T5 T5 LawuLawu--MuriaMuria

T4 T4 KarangsambungKarangsambung

T6 T6 KendengKendeng ZoneZone

T7 T7 MaduraMadura StraitStrait

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7

approx100km

Sardjono (2006)

5km

40 km

30

20

10

0

-600 -500 -400 -300 -200 -100 0 100

-600

-400

-200

0

200

400 mGal

digitizedcomputed

Indian Ocean1.03 g/cc

Java Sea 1.03 g/cc

Sundaland2.67 g/cc

standard thickness

of continental crust

50km

upper mantle3.07 g/cc

5

k

m

50km

5

k

m

Constrained gravity modelling Crustal Architecture, Transect Ciletuh-Bayah Dome

T1

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)

5km


Indian Ocean Crust2.77 g/cc

Sundaland2.67 g/cc


Java Sea 1.03 g/cc

digitizedcomputed

0 100 200 300 400 500 600 km

Neogenesediments2.37 g/cc

standard thickness

continental crust

40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

50km

5

k

m


T1

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)

5km50km

5

k

m



Sundaland2.67 g/cc

FragmentedSundaland2.67 g/cc

Neogenesediments2.37 g/cc TransitionalCrust

2.72 g/cc(andesitic)


Java Sea 1.03 g/cc

digitizedcomputed

0 100 200 300 400 500 600 km


40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

50km

5

k

m

Constrained gravity modelling Crustal Architecture, Transect Ciletuh-Bayah DomeT1

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)

5km



Sundaland2.67 g/cc


upper mantle

3.07 g/cc

Java Sea 1.03 g/cc

digitizedcomputed

0 100 200 300 400 500 600 km


40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

50km

5

k

m

Constrained gravity modelling Crustal Architecture, Transect Ciletuh-Bayah DomeT1

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)




Java Sea 1.03 g/cc

Sundaland2.67 g/cc

2.67 g/cc



Neogene sediments2.37 g/cc


40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

digitizedcomputed

0 100 200 300 400 500 600 km

standard thicknesscontinental crust5km

50km

5

k

m


T1

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)

Crustal Architecture, Transect Karangsambung

5km

Indian Ocean 1.03 g/cc


Sundaland2.67 g/cc


Java Sea 1.03 g/ccNeogene sediments

2.37 g/cc

40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

digitizedcomputed

0 100 200 300 400 500 600 700 km

50km

5

k

m

standard thicknessof continental crust

T4

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)

5km

Crustal Architecture, Transect Madura Strait

0 100 200 300 400 500 600 km40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

digitizedcomputed


Sundaland2.67 g/cc


Neogene sediments2.37 g/cc

Java Sea 1.03 g/cc

MaduraStrait

1.03 g/cc

Indian Ocean 1.03 g/cc

50km

5

k

m

standard thicknessof continental crust

T7

SW NE

T1T1

T2T2

T3T3

T4T4

T5T5

T6T6

T7T7Sardjono (2006)

CONCLUSIONSCONCLUSIONS

Java is constructed primarily of continental crust which is Java is constructed primarily of continental crust which is believed to be the southern part of the believed to be the southern part of the SundalandSundaland (?)(?)

The continental crust experienced thinning, attenuation The continental crust experienced thinning, attenuation and fragmentation due to the tectonics which in turn, and fragmentation due to the tectonics which in turn,

promote formation of sedimentary basins and volcanismspromote formation of sedimentary basins and volcanisms High gravity with long wavelengths along the southern High gravity with long wavelengths along the southern

part of Java should be attributed to the elevated part of Java should be attributed to the elevated MohoMoho The shorter wavelengths with a high level of gravity The shorter wavelengths with a high level of gravity

anomaly, especially in the southwest, represents high anomaly, especially in the southwest, represents high level or exposure of level or exposure of ultrabasicultrabasic slices slices slab break slab break (?)(?)

Sardjono (2006)

CRUSTAL ARCHITECTURE JAVA ISLAND, INDONESIAan approach via constrained gravity modelling

Seubert and Sulistianingsih (2008)Regional Gravity Traverses and Crustal Modelling

Seubert and Sulistianingsih (2008)

Possibility of Presence of Continental Fragments at Southern Java




Java Sea 1.03 g/cc

Sundaland2.67 g/cc

2.67 g/cc



Neogene sediments2.37 g/ccIndian Ocean1.03 g/cc

40 km

30

20

10

0

-200

-100

0

100

200

300 mGal

digitizedcomputed

0 100 200 300 400 500 600 km


50km

5

k

m

SW NE

Sardjono (2006)

Seubert and Sulistianingsih (2008)

Similar Gravity Data but Different Modelling

Granath et al. (2009)

Crustal Architecture of

the Eastern Java

Granath et al. (2009)

Crustal Architecture of

the Eastern Java Based on Long-

Offset 2D Seismic Imaging

Tectonic Evolution of Western Indonesia

rafted microcontinent from Gondwana (?) collisional boundary at southeastern margin

Budiyani et al. (2003)

Tectonic Evolution of Western IndonesiaTectonic Evolution of Western IndonesiaTectonic Evolution of Western Indonesia

Budiyani et al. (2003)

Tectonic Evolution of Western Indonesia

SERIBU PLATFORMKARIMUNJAWA ARC

BOGOR TROUGH

KENDENG TROUGH

Basement Depth Structure Map

Sapiie et al. (2003)

Java Basement : Preliminary Conclusions

Two schools of thought : transitional (intermediate) (Manur and Barraclough, 1994; Koesoemadinata, 2006) vs. continental (Budiyani et al., 2003; Smyth et al., 2005, 2007; Seubert and Sulistianingsih, 2008)

Composition of Quaternary volcanic arc (andesitic) indicate intermediate composition, not continental composition

No strong support for continental basement, no continental exposure Gravity modelings are various for same data and traverse There is indication for presence of continental fragments at southern Java,

but not as extent as recent publications (Budiyani et al., 2003; Smyth et al., 2005, 2007; Seubert and Sulistianingsih, 2008)

Expected continental slivers (small fragment) at southern Java : Jampang, Nanggulan, Bayat, south Cilacap

Petroleum Geology of Java Area :Re-Visit Prolific Areas and Disclose Under-Explored Areas Bandung, 15 17 June 2009Crustal CompositionWest Java Crustal Cross-sectionEast Java Crustal Cross-sectionJava Plate and Crustal CompositionJava Basement : Recent TrendsEast Java and Western AustraliaPotential Australian SourcesWhat lies beneath East Java?Java Basement : Preliminary Conclusions

6. basement geology

Documents

java basement

java plate

western australiaeast

thinned continental

crustal compositionmanur

regional gravity traverses

gcc reference density

recent trends recent