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Mafic magma replenishment, unrest and eruption in a caldera setting; insights from the 2006 eruption of Rabaul (Papua New Guinea)

C. Bouvet de Maisonneuve, F. Costa, H. Patia and C. Huber
Mafic magma replenishment, unrest and eruption in a caldera setting; insights from the 2006 eruption of Rabaul (Papua New Guinea) (in Chemical, physical and temporal evolution of magmatic systems, L. Caricchi (editor) and J. D. Blundy (editor))
Special Publication - Geological Society of London (May 2015) 422 (1): 17-39

Abstract

Understanding the magmatic processes that drive unrest at silicic calderas remains a major goal in Volcanology. Rabaul in Papua New Guinea is an exceptional location because after two decades of unrest and a peak in seismicity and deformation in 1983-85, eruptive activity began in 1994 and is still ongoing. A particularly large sub-Plinian eruption occurred from Tavurvur in October 2006. Whole-rock compositions are andesitic and reflect mixing/mingling between basaltic and dacitic magmas from the same system. The magmas that fed the 2006 eruption were stored at about 930 degrees C, with 1-3 wt% H (sub 2) O, 25-520 ppm CO (sub 2) , and 50-2500 ppm SO (sub 2) in the melt. Melt inclusions hosted in pyroxene, and plagioclase phenocrysts record fractional crystallization at < or =200 MPa under relatively dry and poorly oxidizing conditions. Magma mixing/mingling is expressed as heterogeneous glass compositions, strongly zoned phenocrysts, and mafic crystal aggregates. A textural maturation from fine, acicular to large, blocky crystal clots implies different relative ages of formation. Modelling the chemical zoning of plagioclase shows that mafic-silicic interactions started a couple of decades prior to the 2006 eruption and continued until days to weeks prior to eruption. Basaltic replenishments have been driving unrest and eruption at the Rabaul caldera since the 1970s.


ISSN: 0305-8719
EISSN: 2041-4927
Coden: GSLSBW
Serial Title: Special Publication - Geological Society of London
Serial Volume: 422
Serial Issue: 1
Title: Mafic magma replenishment, unrest and eruption in a caldera setting; insights from the 2006 eruption of Rabaul (Papua New Guinea)
Title: Chemical, physical and temporal evolution of magmatic systems
Author(s): Bouvet de Maisonneuve, C.Costa, F.Patia, H.Huber, C.
Author(s): Caricchi, L.editor
Author(s): Blundy, J. D.editor
Affiliation: Nanyang Technological University, Earth Observatory of Singapore, Nanyang, Singapore
Pages: 17-39
Published: 20150514
Text Language: English
Publisher: Geological Society of London, London, United Kingdom
Number of pages: 23
References: 61
Accession Number: 2015-104800
Categories: Quaternary geologyIgneous and metamorphic petrology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 3 tables, sketch maps
S04°22'00" - S04°10'00", E152°05'60" - E152°18'00"
Secondary Affiliation: Rabaul Volcano Observatory, PNG, Papua New GuineaGeorgia Institute of Technology, USA, United States
Source Note: Online First
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 201545
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