| Micro-textures in plagioclase from 1994–1995 eruption, Barren Island Volcano: Evidence of dynamic magma plumbing system in the Andaman subduction zone |
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| 作者姓名： | M.L.Renjith |
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| 作者单位： | Marine and Coastal Survey Division, Geological Survey of India, 4th Floor, C-Block, Kendriya Bhavan, Kakkanadu, Cochin,Kerala 682037, India |
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| 摘 要： | A systematic account of micro-textures and a few compositional profles of plagioclase from high-alumina basaltic aa lava erupted during the year 1994-1995,from Barren Island Volcano,NE India ocean,are presented for the frst time.The identifed micro-textures can be grouped into two categories:(i)Growth related textures in the form of coarse/fne-sieve morphology,fne-scale oscillatory zoning and resorption surfaces resulted when the equilibrium at the crystal-melt interface was fuctuated due to change in temperature or H2O or pressure or composition of the crystallizing melt;and(ii)morphological texture,like glomerocryst,synneusis,swallow-tailed crystal,microlite and broken crystals,formed by the infuence of dynamic behavior of the crystallizing magma(convection,turbulence,degassing,etc.).Each micro-texture has developed in a specifc magmatic environment,accordingly,a frst order magma plumbing model and crystallization dynamics are envisaged for the studied lava unit.Magma generated has undergone extensive fractional crystallization of An-rich plagioclase in stable magmatic environment at a deeper depth.Subsequently they ascend to a shallow chamber where the newly brought crystals and pre-existing crystals have undergone dynamic crystallization via dissolution-regrowth processes in a convective selfmixing environment.Such repeated recharge-recycling processes have produced various populations of plagioclase with different micro-textural stratigraphy in the studied lava unit.Intermittent degassing and eruption related decompression have also played a major role in the fnal stage of crystallization dynamics.
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| 关 键 词： | Micro-texture Plagioclase Magma chamber process Barren Island Volcano Andaman subduction zone |
| 收稿时间： | 11 December 2012 |
http://www.sciencedirect.com/science/article/pii/S1674987113000534 |
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| M.L.Renjith.http://www.sciencedirect.com/science/article/pii/S1674987113000534[J].Geoscience Frontiers,2014,5(1):113-126. |
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| Authors: | ML Renjith |
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| Institution: | Marine and Coastal Survey Division, Geological Survey of India, 4th Floor, C-Block, Kendriya Bhavan, Kakkanadu, Cochin, Kerala 682037, India |
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| Abstract: | A systematic account of micro-textures and a few compositional profles of plagioclase from high-alumina basaltic aa lava erupted during the year 1994-1995,from Barren Island Volcano,NE India ocean,are presented for the frst time.The identifed micro-textures can be grouped into two categories:(i)Growth related textures in the form of coarse/fne-sieve morphology,fne-scale oscillatory zoning and resorption surfaces resulted when the equilibrium at the crystal-melt interface was fuctuated due to change in temperature or H2O or pressure or composition of the crystallizing melt;and(ii)morphological texture,like glomerocryst,synneusis,swallow-tailed crystal,microlite and broken crystals,formed by the infuence of dynamic behavior of the crystallizing magma(convection,turbulence,degassing,etc.).Each micro-texture has developed in a specifc magmatic environment,accordingly,a frst order magma plumbing model and crystallization dynamics are envisaged for the studied lava unit.Magma generated has undergone extensive fractional crystallization of An-rich plagioclase in stable magmatic environment at a deeper depth.Subsequently they ascend to a shallow chamber where the newly brought crystals and pre-existing crystals have undergone dynamic crystallization via dissolution-regrowth processes in a convective selfmixing environment.Such repeated recharge-recycling processes have produced various populations of plagioclase with different micro-textural stratigraphy in the studied lava unit.Intermittent degassing and eruption related decompression have also played a major role in the fnal stage of crystallization dynamics. |
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| Keywords: | Micro-texture Plagioclase Magma chamber process Barren Island Volcano Andaman subduction zone |
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