Petrology,geochemistry and tectonic significance of serpentinized ultramafic rocks from the South Arm of Sulawesi,Indonesia |
| |
| Institution: | 1. University of Patras, Department of Geology, Section of Earth Materials, GR-265 00 Patras, Greece;2. University of Cyprus, Department of Mechanical and Manufacturing Engineering, 1678 Nicosia, Cyprus;3. Universiti Brunei Darussalam, Faculty of Sciences, Physical and Geological Sciences Group, Jalan Tungku Link, Gadong BE1410, Bandar Seri Begawan, Brunei Darussalam;4. University of Athens, Department of Geology and Geoenvironment, GR-157 84 Athens, Greece;1. SE Asia Research Group, Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, United Kingdom;2. Pertamina University, Jl. Teuku Nyak Arief, Kawasan Simprug, Kebayoran Lama, Jakarta Selatan 12220, Indonesia |
| |
| Abstract: | Serpentinized ultramafic rocks occur in two separate basement complexes in the South Arm of Sulawesi, the Bantimala and Barru Blocks. We present petrographic, mineral chemical and geochemical data for these rocks, and interpret them in terms of petrogenesis and tectonic setting. The rocks of both blocks show strong serpentinization of original anhydrous silicates. The Bantimala ultramafics consist mainly of peridotite (harzburgite and dunite) and clinopyroxenite, with lenses of podiform chromitite. Metamorphism is evidenced by the occurrence of amphibolite-facies tremolite schist. In contrast, the Barru ultramafics consist of harzburgite peridotite and podiform chromitite, which also show an amphibolite-facies overprint that in this case may be related to intrusion by a large dacite/granodiorite body. Whole-rock trace element analyses and spinel compositions show that the Barru harzburgite is depleted relative to primitive mantle, and has had some melt extracted. In contrast, the Bantimala dunite, harzburgite and clinopyroxenite are cumulates. Both are derived from a supra-subduction zone environment, and were obducted during the closure of small back-arc basins. If there has been no rotation of the blocks, then the Bantimala ultramafics were emplaced from an ENE direction, while the Barru ultramafics were emplaced from the WNW. The ultramafic suites from these two blocks are juxtaposed with metamorphic assemblages, which were later intruded by younger volcanics, particularly in the Barru Block. |
| |
| Keywords: | Petrology Geochemistry Ultramafic South Sulawesi Indonesia |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
