The history of Cenozoic magmatism and collision in NW New Guinea – New insights into the tectonic evolution of the northernmost margin of the Australian Plate |
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| Institution: | 1. SE Asia Research Group, Department of Earth Sciences, Royal Holloway, University of London, Egham TW20 0EX, United Kingdom;2. Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, United Kingdom;1. Southeast Asia Research Group, Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK;2. Research School of Earth Sciences, The Australian National University, Canberra 0200, Australia;3. Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK;4. School of Environmental and Rural Sciences, University of New England, Armidale, New South Wales 2351, Australia;5. Department of Earth and Planetary Sciences, McGill University, Montreal, Canada;6. Department of Earth Sciences, Yamaguchi University, Yamaguchi, Japan;7. Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK;8. Faculty of Mineral Technology, UPN Veteran Yogyakarta, Jalan SWK104, 52283 Yogyakarta, Indonesia;1. Guangdong Key Lab of Geodynamics and Geohazards, School of Earth Sciences and Engineering, Sun Yat-sen University, Guangzhou 510275, China;2. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China;3. School of Earth, Atmosphere and Environment, Monash University, Melbourne, VIC 3800, Australia;4. Department of Geology, University of Malaya, Kuala Lumpur, Malaysia;1. Key Laboratory of Petroleum Resource Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;1. LFCR, Université de Pau et des Pays de l''Adour, 64013 Pau Cedex, France;2. Group of Dynamics of the Lithosphere, Institute of Earth Sciences Jaume Almera ICTJA – CSIC, Lluís Solé i Sabarís s/n, 08028 Barcelona, Spain;3. Petronas CariGali, Twin Tower KLCC, 50088 Kuala Lumpur, Malaysia;4. Univ Rennes, CNRS, Géosciences Rennes - UMR 6118, F-35000 Rennes, France;5. Repsol Exploration, Jakarta, Indonesia;6. School of GeoSciences, University of Edinburgh, Drummond St., Edinburgh EH8 9XP, UK |
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| Abstract: | Evidence of Cenozoic magmatism is found along the length of New Guinea. However, the petrogenetic and tectonic setting for this magmatism is poorly understood. This study presents new field, petrographic, U–Pb zircon, and geochemical data from NW New Guinea. These data have been used to identify six units of Cenozoic igneous rocks which record episodes of magmatism during the Oligocene, Miocene, and Pliocene. These episodes occurred in response to the ongoing interaction between the Australian and Philippine Sea plates. During the Eocene, the Australian Plate began to obliquely subduct beneath the Philippine Sea Plate forming the Philippine–Caroline Arc. Magmatism in this arc is recorded in the Dore, Mandi, and Arfak volcanics of NW New Guinea where calc-alkaline and tholeiitic rocks formed within subduction-related fore-arc and extension-related back-arc settings from 32 to 27 Ma. Collision along this plate boundary in the Oligocene–Miocene jammed the subduction zone and caused a reversal in subduction polarity from north-dipping to south-dipping. Following this, subduction of the Philippine Sea Plate beneath the Australian Plate produced magmatism throughout western New Guinea. In NW New Guinea this is recorded by the middle Miocene (18–12 Ma) Moon Volcanics, which include an early period of high-K to shoshonitic igneous activity. These earlier magmatic rocks are associated with the subduction zone polarity reversal and an initially steeply dipping slab. The magmatic products later changed to more calc-alkaline compositions and were emplaced as volcanic rocks in the fore-arc section of a primitive continental arc. Finally, following terminal arc–continent collision in the late Miocene–Pliocene, mantle derived magmas (including the Berangan Andesite) migrated up large strike-slip faults becoming crustally contaminated prior to their eruption during the Plio–Pleistocene. This study of the Cenozoic magmatic history of NW New Guinea provides new data and insights into the tectonic evolution of the northern margin of the Australian Plate. |
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