Regional geology of study areas 3

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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, 1 9 8 2 ; v a n L e e u w e n a

1 1 Introduction Central part Indonesia 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, ; v a n L e e u w e n a n d Muhardjo, 2005). Metatonalites expose in Nangapinoh area of West 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 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.

Bantimala and Barru Complexes Regional geology of study areas 3 Modified from Sukamto (1982) Bantimala Complex is

Metamorphic rocks are intercalated with melange deposits.

been reported 1.8 2.4 GPa at 580 650 ºC from eclogite and Grt-Gln rock (Miyazaki et al., 1996; Setiawan et al.

K-Ar ages from phengite on Grt-Gln rock and eclogite yield Early Cretaceous (137 to 113Ma) (Wakita et al.

3 Bantimala and Barru Complexes Regional geology of study areas 3 Modified from Sukamto (1982) 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 GPa at 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 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). Barru Complex is located 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).

4 Modes of occurences 4

5 Eclogite Photomicrographs 5 Grt-Gln rock Grt-Gln-Ph-Qz schist Grt-Bt-Ms-Qz schist Scale bar indicates 1 mm

Luk Ulo Complex Regional geology of study areas 6 Luk Ulo Complex is located in Karangsambung area of Central Java. Metamorphic rocks are intercalated with melange deposits.

6 Luk Ulo Complex Regional geology of study areas 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 GPa at 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)

7 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 Meratus Complex is located in southwestern part of Meratus Mountains, South Kalimantan with the shape of NE- SW.

8 Regional geology of study areas 8 Meratus Complex Meratus Complex is located in southwestern part of Meratus Mountains, South Kalimantan with the shape of NE- SW. 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 ( Ma) (Wakita, 1998; Sikumbang and Heryanto (2009). Modified from Sikumbang and Heryanto (2009)

9 Mode of occurences & photomicrographs 9 Scale bar indicates 1 mm

10 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. The granitoids intruded low-grade 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)

11 Mode of Occurences & photomicrographs 11 Metatonalite Metatonalite Scale bar indicates 1 mm

12 Summary of petrography and occurences Jd-Gln-Qz rock Jd, Gln, Qz ~2.2 ~530 Miyazaki et al. Grt-Gln schist Grt, Gln, Ph, Ep Gln-Ep schist Gln, Ph, Ep Grt amphibolite Grt, Hbl, Zo Grt-Ms-Qz schist Grt, Ms, Qz Gln-Ep-Qz schist Gln, Ep, Qz, Ph Meratus, Grt-Ep-Act-Qz schist Grt, Ep, Act, Ms, Ep, Qz South Kalimantan Grt-Cld schist Grt, Cld, Ms, Qz ~1.8 Parkinson et al Act-Tlc schist Act, Tlc, Qz Serpentinite Srp, Spl Nangapinoh, Metatonalite Pl, Bt, Ms, Hbl, Cpx West Kalimantan Amphibolite Hbl, Pl, Bt Crd-And-Bt hornfels Crd, And, Bt, Qz And-Bt hornfels And, Bt, Qz 12 Geochemical analyzes U-Pb zircon age determination

13 Major element consentration High-P metamorphic and associated rocks 13 Winkler (1979) Irvine and Baragar (1971) Winchester and Floyd (1977)

14 Trace and rare-earth elements High-P metamorphic and associated rocks 14 Pearce and Cann (1973) Meschede (1986) McDonough and Sun (1995) C1 Chondrite Norm.

15 High-P metamorphic and associated rocks Summary of the protolith metamorphic rocks from South Sulawesi, Central Java and South Kalimantan 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. 15 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

430 390 Ma (Silurian Devonian), 309 ± 9 Ma (Carboniferous) and

16 High-P metamorphic and associated rocks 16 LA-ICP-MS U-Pb detrital zircon Bantimala Complex Age data concentrate at ca Ma (Silurian Devonian), 309 ± 9 Ma (Carboniferous) and 199 ± 6 Ma (Jurassic) from 6 analyses of 6 grains. Scale bar indicates 10 µm

17 High-P metamorphic and associated rocks LA-ICP-MS U-Pb detrital zircon Barru Complex Scale bar indicates 10 µm 17 Age data ranging at ca Ma (Permian Cambrian) and Ma (Proterozoic) from 42 analyses of 42 grains.

18 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 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.

(2006) 1550 Ma (Proterozoic) might indicates source provenance from Indochina craton

19 High-P metamorphic and associated rocks 19 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).

20 Schwaner Mountains, Metatonalite 20

and Baragar (1971) Barker and Arth (1979) Sun and

21 Trace and rare-earth elements Schwaner Mountains, Metatonalite 21 Defant and Drummond (1990) Irvine and Baragar (1971) Barker and Arth (1979) Sun and McDonough (1989) MORB Norm. Pearce et al. (1984)

22 Schwaner Mountains, Metatonalite ) 2013) Sun and McDonough (1989) MORB Norm. Defant and Drummond (1990)

23 LA-ICP-MS U-Pb magmatic zircon Schwaner Mountains, Metatonalite 23 Concordant age at 233 ± 3 Ma (Triassic) from 23 analyses of 11 grains! Magmatic zircon Scale bar indicates 10 µm

24 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 ( 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 ( Ma; Williams et al. 1988).

25 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.

Conclusion High-pressure metamorphic rocks 1. Protolith of metabasic rocks derived from MORB and within-plate basalt with tholeiite nature. 2.

436 280 Ma) that have possibility derived from the similar provenance.

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 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 ( 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 ( Ma; Williams et al. 1988) and Triassic eastern range granite of Indochina craton. 26

27 THANK YOU FOR YOUR ATTENTION

P-T estimation compiled 28 Rock Type Prograde Peak Retrograde Bantimala Complex Eclogite - 1.8 2.

7 GPa 720 760 ºC ~1.0 GPa 350 ºC ~0.5 GPa 350 ºC ~1.0 GPa 500ºC Eclogite Gln stability field (Setiawan et al., 2012) 2.2 2.

28 P-T estimation compiled 28 Rock Type Prograde Peak Retrograde Bantimala Complex Eclogite GPa ºC Grt-Gln rock (Miyazaki et al., 1996) Grt-Jd-Qz rock (Parkinson et al., 1998) GPa ºC - >2.7 GPa ºC ~1.0 GPa 350 ºC ~0.5 GPa 350 ºC ~1.0 GPa 500ºC Eclogite Gln stability field (Setiawan et al., 2012) GPa ºC Act stability field Luk Ulo Complex Jd-Qz-Gln rock - 2.2±0.2 GPa 530±40 ºC - (Miyazaki et al., 1998) Eclogite GPa ºC GPa ºC GPa ºC (Kadarusman et al., 2007)

Harker Diagram Major element consentration 29 The SiO2 contents of metabasic rocks are ranging from 37.38 53.10 wt%.

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.

29 Harker Diagram Major element consentration 29 The SiO2 contents of metabasic rocks are ranging from wt%. However, condidering the petrographical observations and the o t h e r e l e m e n t concentrations (e.g., MgO = wt%, Mg# = , Ni = ppm, and Cr = 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.

30 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.

1 Potassic adakite magmas and where they come from: a mystery solved?

1 Potassic adakite magmas and where they come from: a mystery solved? 2 3 John Clemens Kingston University (London) Long Xiao China University of Geosciences (Wuhan) 4 Adakites are volcanic and intrusive