Abstract
Microscopic shear zones have been found in the groundmass of glassy rocks of a Miocene submarine dacite dome in southwest Japan. Similar textures have been reported previously but only in dykes. These textures give a valuable insight into the deformation of the dome during its emplacement by recording the orientations of the principal strains. Detailed textural analysis indicates that the microshear zones formed as a result of flattening and stretching of the magma simultaneously with quenching. Measured stretching directions are near-parallel suggesting the magma flowed in one dominant direction rather than in a radial pattern. The strain is believed to also be influenced by high magma pressure inside the dome being imposed on the high viscosity outer part of the dome.
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Present address: Faculty of Resource Science and Management, University of New England-Northern Rivers. P. O.Box 157 Lismore NSW 2480 Australia
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Smith, J.V., Yamauchi, S. & Miyake, Y. Microshear zones in a Miocene submarine dacite dome of southwest Japan. Bull Volcanol 55, 438–442 (1993). https://doi.org/10.1007/BF00302003
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DOI: https://doi.org/10.1007/BF00302003