a preliminary view of metamorphic rocks from schwaner ......metamorphic rocks are intruded by...

A Preliminary View of Metamorphic Rocks from Schwaner Mountains, West

Kalimantan and Bantimala Complex, South Sulawesi in Indonesia

Nugroho I Setiawan, Y. Osanai, N. Nakano, T. Adachi, K. Yonemura, A. Yoshimoto (Kyushu University), and Joko

Wahyudiono (GRDC Indonesia)

Kyushu University UI project Kyudai Taro,2007

Location of Indonesia 95° - 141°E and 6°N – 11°S. Boundaries three major plates: Eurasia, Indo-Australia, and Pacific-Philippine Sea

Indonesia

Papua Sulawesi

Kalimantan Sumatera

Java Timor

Tectonic framework on the Indonesia region

Hall, 2008

Indonesia

Kalimantan

Study Area Japan

Indonesia

Schwaner Mountains West Kalimantan

South Sulawesi

Central Java

Regional Geology of West Kalimantan Williams, et al. (1988) divided

geology of West Kalimantan into three geological domains:

1.  Schwaner Mountains in the south: granitic and metamorphic rocks

2.  Northwest Kalimantan domain: schist and deformed granite

3.  Melange and associated accretionary deposits

Regional Geology of West Kalimantan Schwaner Mountains

!  Chemical composition indicate I-type calc-alkaline nature !  There is a gap in composition from 67% SiO2 to 72% SiO2, which suggests at least two

batholiths are present also supported by K-Ar ages data !  Haile, et al (1977) obtained K-Ar ages ranging from Jurassic (157 Ma) to Late Cretaceous (77

Ma) !  Williams, et al (1988) obtained K-Ar ages on 33 specimens ranging from Early Cretaceous (129

Ma) to Late Cretaceous (87 Ma)

Northwest Kalimantan domains !  Metamorphic rocks comprising schist, phyllite and quartzite with garnet grade greenschist facies !  Metamorphic rocks are intruded by deformed biotite granite, which yields K-Ar ages from Permian (320

Ma) to Late Triassic (204 Ma) (Williams, et al., 1988)

Melange and associated accretionary deposits !  Comprise of deformed flysch, melange and marine outer shelf deposits !  Dominantly east-trending outcrop belts !  Two zones of melange defined in this region are Boyan and Lubok Antu melange

Radiometric Age Data Granitoids of West Kalimantan

Williams, et al (1988)

General Strat igraphy of West Kalimantan

Williams, et al (1988)

Current Samples Location

1.  84MS89A (Metatonalite) 2.  841U22A (Metatonalite) 3.  84BH236A (Metagranitoid) 4.  84BH354B (Biotite schist)

Mineral Assemblages

From the textures and mineral assemblages, can be divided into two groups: 1.  Metatonalite sample no.84MS89A and 841U221A 2.  Metagranitoid (84BH236A) and Biotite schist (84BH354B)

No# Sample#No# Loca,on# Rock#Type#Mineral#Assemblages#

Major#Minerals# Minor#Minerals# Others# Relict#Qz# Pl# Kfs# Hbl# Bt# Bt# Opq# Ttn# Ep# Ap# Ms# Chl# Ser# Cpx#

1" 84MS89A"Nangataman"/"Schwaner"Mountain" Metatonalite" " # �� " /" �� # /" �� /" /" /" (#)"

2" 841U221A"Nangataman"/"Schwaner"Mountain" Metatonalite" " # �� # # /" �� /" �� /" /" /" /"

3" 84BH236A"Nangataman"/"Schwaner"Mountain" Metagranitoid" " # �� /" # /" �� /" �� /"

4" 84BH354B"Nangataman"/"Schwaner"Mountain" BioCte"Schist" " �� # /" " /" �� /" �� /" �� /" /" /"

" Abundant,"# Moderate,"��Poor,"/""absent,"("")"in"relict"minerals"or"inclusion"

Representative Photomicrograph

Metagranitoid Biotite schist

Metatonalite

Chondrite normalizing value are from Thompson (1982). Upper continental crust are from Taylor and McLennan (1981). Lower continental crust are from Waver and Tarney (1984)

Diagrams of Bulk Chemical Analysis

Age Determination by Zircon LA-ICPMS on Metatonalite (84MS89A)

Tentative Conclusion of metamorphic rocks from Schwaner Mountains

Metatonalite from the Schwaner Mountains (Central Kalimantan) suggests the same group with NW Kalimantan metamorphic rocks

The evidence of age dating, metamorphism on metatonalite from Schwaner Mountains suggests simultaneous synmetamorphic igneous activity

Field observation and comprehensive field sampling are needed in order to understanding more detail metamorphism and tectonic condition in Schwaner Mountains

Geological Background of South Sulawesi

Bantimala

Modified from Sukamto, 1982

Simplified Geological Map of Bantimala Area

Simplified Geological Map of Barru Area

Outcrop Photograph of Bantimala Complex Grt blueschist

Grt blueschist Eclogite

Grt-Jd-Qtz rock

Representative Photomicrograph of Eclogites in Bantimala

Mineralogy of Grt – Jd rock

Ternary Cpx Nomenclature of Eclogite and Grt-Jd rock

Okamoto, et al. (2000)

Matrix

Inclusion

Leake, B. E., et al. (1997)

Amphibole Nomenclature of Eclogite and Grt-Jd rock

Eclogite Eclogite Grt-Jd rock

Grt-Jd rock Eclogite Eclogite

Ternary Diagrams for Grt compositions

Grt-Jd rock

Eclogite Grt-Jd rock

Eclogite

Zoning Profile in Garnet

Grt-Jd rock [110309T01D] Eclogite [110310T03F]

Eclogite [110310T03I] Eclogite [UNHAS 3] Eclogite [UNHAS 5]

Tentative P-T Path Diagram on Bantimala Area

•  The Jd-Grt rock from Bantimala Complex, South Sulawesi suggests that the rock passed through Jd + Qz stability field during metamorphic evolution

•  Pseudomorph of coesite indicates that the eclogite passed through Coe stability field

•  Peak of metamorphism of Eclogite represented by garnet rim and omphacite in the matrix

•  Grt – Cpx thermometer (Krogh, 1988., Pattison & Newton, 1989., and Ravna, 2000) yield a temperature of 670 ± 20 °C for pressure of 25 kbar on the sample of eclogite UNHAS 2.

•  The occurrence of Gln in the core and mantel inclusion of Grt on Bantimala eclogite indicates the former stability field of blueschist area

•  Retrogression observed in the Bantimala eclogites represented by replacement of Omp and Gln by Bar, Wnc and Act

Photomicrograph of metamorphic rocks from Central Java Eclogite

Grt-Mica schist

THANK YOU FOR YOUR ATTENTION

Karangsambung

Yogyakarta

Samples Location in Central Java

Gambar-1. Peta geologi daerah Bayat (Prasetyadi, 2007).

Gambar-2: Kronostratigrafi Jawa Tengah selatan (termasuk Bayat)(Prasetyadi & Indranadi, 2007).

Simplified Geological Map of Bayat Area

Prasetyadi, 2007

Simplified Geological Map of Karangsambung Area

Modified from Prasetyadi, 2007

Mineral Assemblages of Metamorphic Rocks in Central Java

Loca,on# Rock#Name# Tot#

Mineral#Assemblages# ""No# Major#Minerals# Minor#Minerals# Secondary# Remark#

"" Grt# Gln# Qtz# Amp#Omp# Ep/Zoe# Ph# Srp# Ttn# Rt# Opq# Ap# Other# ## ""

1"Bayat,"Central"Java" SerpenCnite" 3" �� " �� Spl" Chl,"Cal" ""2"Bayat,"Central"Java" Greenschist" 2" �� " �� Tlc" Act" Chl"abundant"3"Bayat,"Central"Java" Carbonate"bg"schist" 2" �� " �� Cal" ""4"Bayat,"Central"Java" Metadolerite" 2" �� # �� # �� Act" Tlc,"Ab" Relict"of"Pl"and"Cpx"5"Karangsambung,"Central"Java" Eclogite" 1"# # # �� # �� Δ �� # �� Chl" ""6"Karangsambung,"Central"Java" Grt"Amphibolite" 14" Δ �� " # �� Pl" Chl,"Ab" ""7"Karangsambung,"Central"Java" Amphibolite" 6" �� # " �� # # �� Chl" ""8"Karangsambung,"Central"Java" Grt/"Mica"schist"(Fine"grain)" 8" �� " �� Δ �� # �� Δ Pl,"Act" Chl,"Cal,"Ab"""9"Karangsambung,"Central"Java" Blueschist" 11" �� Δ Δ �� " �� Δ �� Cal,"Chl" ""10"Karangsambung,"Central"Java" Greenschist" 4" �� " �� Act" Cal" Chl"abundant"11"Karangsambung,"Central"Java" SerpenCnite" 5" �� " �� Spl" Chl,"Cal" ""12"Karangsambung,"Central"Java" Grt"blueschist" 7"# " �� # # �� Δ �� Ab,"Chl" ""13"Karangsambung,"Central"Java" Grt/Mica"schist" 23"# �� " �� Δ �� # �� Chl,"Cal" ""14"Karangsambung,"Central"Java" Metagraywacke" 3" �� " �� Chl" Ab" Chl"abundant"15"Karangsambung,"Central"Java" Talc"schist" 1" �� " �� # �� Act,"Chl" Ab" Tlc"abundant"16"Karangsambung,"Central"Java" Metadolerite" 1" �� # �� # �� Tlc,"Ab" Relict"of"Pl"and"Cpx"17"Karangsambung,"Central"Java" Riversand" 1" �� $ �� $ �� "" ""

94#" Abundant,"Δ"Rich,"# Moderate,"��Poor,"/""absent,"±"occurs"in"some"sample"

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