Luk Ulo Complex - Nugroho Imam Setiawan

1
Introduction
•  C e n t r a l p a r t I n d o n e s i a
geographically is including
Kalimantan, Sulawesi and Java
islands.
•  Accretionary and metamorphic
complexes expose in the Central
Java, South Kalimantan and
South–Central Sulawesi.
•  N o r t h w e s t e r l y - d i r e c t e d
Cretaceous subduction was
suggested responsible to build
these formations (Sukamto,
1982; van Leeuwen and
Muhardjo, 2005).
•  M e t a t o n a l i t e s e x p o s e i n
N a n g a p i n o h a r e a o f We s t
Kalimantan, which associated as
later granitods event. The
granitoids were generated by the
intrusion related of subduction
during earlier Jurassic to Early
Cretaceous (Williams et al.,
1988).
2
Introduction
•  The protolith and emplacement-timing of the
metamorphic rocks in central part of Indonesia have
remained obscure.
•  This presentation will discuss about geochemical
character of the high-P metamorphic rocks and other
related rocks from South Sulawesi, Central Java, South
Kalimantan and the results of LA-ICP-MS U-Pb zircon
dating from metapelites of Bantimala and Barru
Complexes.
•  The geochemical character of metatonalites from
Schwaner Mountains of West Kalimantan also will be
discussed and the first report of LA-ICP-MS U-Pb zircon
dating.
Regional geology of study areas
3
•  Bantimala Complex is located
approximately 40 km northeast of
Makassar, South Sulawesi.
•  Metamorphic rocks are intercalated
with melange deposits.
•  Mainly consist of high-P metabasites
and pelitic rocks (eclogite, Grt-Gln
rock, Grt-Jd-Qz rock)
•  Peak metamorphic have been reported
1.8–2.4 GPa at 580–650 ºC from
eclogite and Grt-Gln rock (Miyazaki et
al., 1996; Setiawan et al. 2012) and
VHP metamorphic rock from Coe bg
Grt-Jd-Qz rock reported >2.7 GPa at
720–760 ºC (Parkinson, 1998).
•  K-Ar ages from phengite on Grt-Gln
rock and eclogite yield Early
Cretaceous (137 to 113Ma) (Wakita et
al., 1994, 1996; Parkinson et al.,
1998).
•  B a r r u C o m p l e x i s l o c a t e d
approximately 30 km north of the
Bantimala area.
•  Mainly consist of garnetiferous mica
schist.
•  K-Ar ages from phengite yield Early
Cretaceous (106 ± 5 Ma ) from quartzmica schist (Wakita et al., 1994).
Bantimala and
Barru Complexes
Modified from Sukamto (1982)
Modes of occurences
4
Photomicrographs
Eclogite
Grt-Gln-Ph-Qz schist
5
Grt-Gln rock
Grt-Bt-Ms-Qz schist
Scale bar indicates 1 mm
Regional geology of study areas
Luk Ulo Complex
6
•  Luk Ulo Complex is located in Karangsambung area of Central
Java.
•  Metamorphic rocks are intercalated with melange deposits.
•  Mainly consist of high-P metabasites and pelitic rocks (eclogite,
Grt-Gln schist, blueschist).
•  Peak metamorphism have been reported to 1.8–2.2 GPa at
359–570 ºC from eclogite and Jd-Qz-Gln rock (Miyazaki et al.,
1998; Kadarusman et al. 2007).
•  K-Ar ages from phengite on Grt-Gln rock and eclogite yield Early
Cretaceous (124 to 110 Ma) (Miyazaki et al., 1998; Parkinson et
al., 1998).
Modified from Asikin et al. (2007)
Mode of occurences & photomicrographs
7
Grt-Ms-Qz schist
Eclogite
Grt amphibolite
Scale bar indicates 1 mm
Regional geology of study areas
8
Meratus Complex
•  M e r a t u s C o m p l e x i s l o c a t e d i n
southwestern part of Meratus Mountains,
South Kalimantan with the shape of NESW.
•  Metamorphic rocks are tectonic blocks in
fault contact with ultramafic and
sedimentary rocks (Sikumbang and
Heryanto, 2009).
•  Mainly consist of serpentinite and various
low-grade schists (Parkinson, 1998).
•  Tentative pressure estimation from Mg-rich
Cld is ~1.8 GPa (Parkinson, 1998).
•  K-Ar dating from various mica schists
yielded Early Cretaceous (119–10 Ma)
(Wakita, 1998; Sikumbang and Heryanto
(2009).
Modified from Sikumbang and Heryanto (2009)
Mode of occurences & photomicrographs
9
Scale bar indicates 1 mm
Regional geology of study areas
10
Nangapinoh
•  Metatonalites expose in Nangapinoh area,
which associated as later granitoids event.
•  Strike of foliation metatonalites ranges from
E–W to NE–SE (Amiruddin and Trail, 1993).
•  The granitoids formed a belt of 200 km wide
and 500 km long with E–W directions.
•  T h e g r a n i t o i d s i n t r u d e d l o w - g r a d e
metamorphic rocks and formed local contact
metamorphism.
•  K-Ar of granitoids from Schwaner Mts ranging
from 157 to 77 Ma (Late Jurassic–
Cretaceous), while NW block are from 320 to
204 Ma (Carboniferous–Triassic) (Haile et al.,
1977; William et al., 1988; Amiruddin and
Trail, 1993).
Modified from Amiruddin and Trail (1993)
Mode of Occurences & photomicrographs
Metatonalite
11
Metatonalite
Scale bar indicates 1 mm
Grt-Gln rock
Grt-Jd-Qz rock
Glaucophanite
Grt-Gln-Ph-Qz schist
Gln-Ph-Qz schist
Grt-Bt-Ms-Qz schist
Eclogite
Jd-Gln-Qz rock
Grt-Gln schist
Gln-Ep schist
Grt amphibolite
Grt-Ms-Qz schist
Gln-Ep-Qz schist
Grt-Ep-Act-Qz schist
Grt-Cld schist
Act-Tlc schist
Serpentinite
Metatonalite
Amphibolite
Crd-And-Bt hornfels
And-Bt hornfels
Grt, Gln, Ph, Ep
Grt, Jd, Qz, Ep
Gln, Ph, Ep
Grt, Gln, Ph, Qz, Ep
Gln, Ph, Qz, Ep
Grt, Bt, Ms, Qz
Grt, Omp, Gln, Ph, Ep
Jd, Gln, Qz
Grt, Gln, Ph, Ep
Gln, Ph, Ep
Grt, Hbl, Zo
Grt, Ms, Qz
Gln, Ep, Qz, Ph
Grt, Ep, Act, Ms, Ep, Qz
Grt, Cld, Ms, Qz
Act, Tlc, Qz
Srp, Spl
Pl, Bt, Ms, Hbl, Cpx
Hbl, Pl, Bt
Crd, And, Bt, Qz
And, Bt, Qz
1.8–2.4
>2.7
580–640
720–760
Summary of petrography and occurences
Barru, South Sulawesi
Luk-Ulo, Central Java
Meratus,
South Kalimantan
Nangapinoh,
West Kalimantan
Geochemical analyzes
U-Pb zircon age determination
1.8–2.2
~2.2
~1.8
359–442
~530
Miyazaki et al. (
Parkinson et al. (
12
Kadarusman et a
Miyazaki et al. (
Parkinson et al. (
High-P metamorphic and associated rocks
Major element consentration
Winkler (1979)
Irvine and Baragar (1971)
Winchester and Floyd (1977)
13
High-P metamorphic and associated rocks
Trace and rare-earth elements
Pearce and Cann (1973)
Meschede (1986)
McDonough and Sun (1995) C1 Chondrite Norm.
14
High-P metamorphic and associated rocks
Summary of the protolith metamorphic rocks from South
Sulawesi, Central Java and South Kalimantan
15
•  The geochemical signatures on the metamorphosed sedimentary rocks indicate protolith of pelite to
greywacke.
•  Based on the trace and rare-earth elements analyses, the protolith of the basic metamorphic rocks from
South Sulawesi and Central Java derived from MORB and within-plate basalt with tholeiite nature.
•  From South Sulawesi, all analyzed samples contain both MORB and within-plate basalt signature. It
might indicate that several hot spots were existed and formed ocean islands that subducted together
oceanic floor composed of MORB.
•  From Central Java, eclogite and blueschist mostly show within-plate basalt signatures, whereas protolith
of relatively low-P/T metamorphic rocks (amphibolites and Grt amphibolites) are characterized by MORB.
The results suggest several possibilities;
1.  Different component between upper and lower oceanic crusts
2.  Difference of the metamorphic age between eclogite- and amphibolite-facies metamorphism
3.  Change of the subduction angle between two metamorphic events
High-P metamorphic and associated rocks
16
LA-ICP-MS U-Pb detrital zircon Bantimala Complex
•  Age data concentrate at ca. 430–390 Ma
(Silurian–Devonian), 309 ± 9 Ma
(Carboniferous) and 199 ± 6 Ma (Jurassic)
from 6 analyses of 6 grains.
Scale bar indicates 10 µm
High-P metamorphic and associated rocks
17
LA-ICP-MS U-Pb detrital zircon Barru Complex
Scale bar indicates 10 µm
•  Age data ranging at ca. 280–550 Ma
(Permian–Cambrian) and 1400–1600 Ma
(Proterozoic) from 42 analyses of 42 grains.
High-P metamorphic and associated rocks
18
LA-ICP-MS U-Pb detrital zircon from Bantimala and Barru Complexes
• 
• 
Detrital zircons were recognized on
the pelitic rocks from Bantimala and
Barru Complexes. Both areas give
similar clustering ages of Silurian to
Permian (ca. 436–280 Ma) that have
possibility derived from the similar
provenance. The youngest ages from
Bantimala Complex is show (199 ± 6
Ma) Early Jurassic, therefore the
metamorphic age still has possibility
of Cretaceous ages and the
subduction has possibility generate
during Jurassic.
Detailed age determinations of both
protoliths (MORB and within-plate
basalt) and both metamorphisms
(blueschist-eclogite and amphibolite)
from Central Java are needed and
also be compared with South
Sulawesi.
High-P metamorphic and associated rocks
LA-ICP-MS U-Pb detrital zircon from Bantimala and Barru Complexes
Bantimala and
Barru Complexes
Leeuwen et al. (2006)
1550 Ma (Proterozoic) might indicates source
provenance from Indochina craton
Compared with detrital zircon from Central
Sulawesi, have similar clustering age at ~400 Ma
(Devonian) and ~1550 (Proterozoic).
19
Schwaner Mountains, Metatonalite
20
Schwaner Mountains, Metatonalite
21
Trace and rare-earth elements
Defant and Drummond (1990)
Irvine and Baragar (1971)
Sun and McDonough (1989) MORB Norm.
Barker and Arth (1979)
Pearce et al. (1984)
Schwaner Mountains, Metatonalite
2013)
2013)
Sun and McDonough (1989) MORB Norm.
Defant and Drummond (1990)
22
Schwaner Mountains, Metatonalite
23
LA-ICP-MS U-Pb magmatic zircon
•  Concordant age at 233 ± 3 Ma (Triassic)
from 23 analyses of 11 grains ! Magmatic
zircon
Scale bar indicates 10 µm
24
Summary of metatonalite in Schwaner Mountains
• 
• 
The trace element normalized pattern,
discrimination diagrams, and the calcalkaline rock signature indicate that
the protolith of metatonalites were
derived from volcanic-arc tectonic
environments.
The magmatic age of one sample
adakitic metatonalite yield Triassic age
(233 ± 3 Ma). The age are older than
the reported K-Ar granitoids age from
Schwaner Mountains (77–157 Ma)
(Haile et al., 1977; Williams et al.,
1988; Amiruddin and Trail, 1993) but
still in a range of the K-Ar granitoids
ages from northwest Kalimantan (204–
320 Ma; Williams et al. 1988).
25
Implication for subduction-related felsic
magmatism during Mesozoic
•  The chemical characteristics and the determined age strongly
suggest that the subduction mechanism and felsic magma genesis
changed between the Early Triassic and Cretaceous or magmatism
of granitoids of several parts in Schwaner Mountains was
contemporaneous with the northwest Kalimantan domain and
Triassic eastern-range granite of Indochina craton.
•  Some metatonalites, excepting adakite rock, show similar signature
to Cretaceous granite, indicating the subsequent metamorphism
occurred during Cretaceous in this area.
•  It is proposed that the Schwaner Mountains, composed of
metamorphic and granitic complexes, were not formed by a
consecutive subduction system and much more geochemical data
for metatonalites and each protolith age with the P-T evolution and
the age of metamorphism are highly significant to realize the
Mesozoic tectonic evolution in this region.
26
Conclusion
High-pressure metamorphic rocks
1.  Protolith of metabasic rocks derived from
MORB and within-plate basalt with tholeiite
nature.
2.  Detrital zircons were recognized on the pelitic
rocks from Bantimala and Barru Complexes.
Both areas give similar clustering ages of
Silurian to Permian (ca. 436–280 Ma) that
have possibility derived from the similar
provenance. The youngest ages from
Bantimala Complex is show (199 ± 6 Ma)
Triassic–Jurassic, therefore the metamorphic
age still has possibility of Cretaceous ages.
Metatonalites in Schwaner Mountains
1.  Protolith of metatonalites were derived from
volcanic-arc tectonic environments with two
samples indicate adakite nature.
2.  The magmatic age of one sample adakitic
metatonalite yield Triassic age (233 ± 3 Ma).
The age are older than the reported K-Ar
granitoids age from Schwaner Mountains (77–
157 Ma) (Haile et al., 1977; Williams et al.,
1988; Amiruddin and Trail, 1993) but still in a
range of the K-Ar granitoids ages from
northwest Kalimantan (204–320 Ma; Williams
et al. 1988) and Triassic eastern range granite
of Indochina craton.
THANK YOU FOR YOUR
ATTENTION
P-T estimation compiled
Rock
Type
28
Prograde
Peak
-
1.8–2.4 GPa
580–640 ºC
1.8–2.4 GPa
580–640 ºC
~1.0 GPa
350 ºC
~0.5 GPa
350 ºC
Grt-Jd-Qz
rock
(Parkinson et al., 1998)
>2.7 GPa
720–760 ºC
~1.0 GPa
500ºC
Eclogite
2.2–2.4 GPa
580–650 ºC
Act stability
field
2.2±0.2 GPa
530±40 ºC
-
1.8–2.2 GPa
359–442 ºC
0.8–1.0 GPa
350–400 ºC
Bantimala
Complex
Eclogite
Grt-Gln
rock
(Miyazaki et al., 1996)
Gln stability
field
(Setiawan et al., 2012)
Luk Ulo
Complex
Jd-Qz-Gln
rock
-
Retrograde
(Miyazaki et al., 1998)
Eclogite
1.5–2.1 GPa
283–415 ºC
(Kadarusman et al., 2007)
Major element consentration
Harker
Diagram
•  The SiO2 contents of
metabasic rocks are
ranging from 37.38–53.10
w t % . H o w e v e r,
condidering the
p e t r o g r a p h i c a l
observations and the
o t h e r e l e m e n t
concentrations (e.g., MgO
= 1.63–18.04 wt%, Mg# =
0.22–0.58, Ni = 48.34–
943.32 ppm, and Cr =
41.73–1222.37 ppm), the
SiO2 value <45 wt% are
not likely ultramafic rocks.
•  The wide range and
scattered values for major
elements should suggest
the elemental migration
from protolith due to the
later metamorphism and
fluid-assisted alteration.
29
30
Whole Rock Chemistry
• 
• 
Major, trace and rare-earth element contents of metamorphic rock
samples were analyzed by X-ray fluorescence spectrometry (XRF)
and laser ablation-inductively coupled plasma-mass spectrometry
(LA-ICP-MS) at Division of Earth Sciences, Faculty of Social and
Cultural Studies, Kyushu University
Totally 84 metamorphic rocks samples as follows; 34 samples
from South Sulawesi (13 eclogites, 9 Grt-Gln rocks, 5
glaucophanites, 5 Grt-Gln-Ph-Qz schists, and 2 Grt-Bt-Ms-Qz
schists), 21 samples from Central Java (1 eclogites, 6 Grt-Gln
schists, 3 Gln schists, 4 Grt amphibolites, 2 amphibolites, and 5
Grt-Ms-Qz schists), 3 samples of Grt-Ep-Act-Qz schists from
South Kalimantan, and 4 samples of metatonalites from West
Kalimantan.

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