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Syntectonic porphyroblast growth in phyllites: textures and processes
Author(s) -
PRIOR D. J.
Publication year - 1987
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/j.1525-1314.1987.tb00367.x
Subject(s) - geology , deformation (meteorology) , geochemistry , mineralogy , cleavage (geology) , phyllite , quartz , calcite , metamorphic rock , mineralization (soil science) , tectonics , schist , paleontology , oceanography , fracture (geology) , soil science , soil water
Porphyroblast textures in a Karakorum phyllite reveal that porphyroblast growth was syn‐tectonic with respect to a cleavage forming deformation. During and after porphyroblast growth it partitions the deformation such that zones of intensified cleavage are developed which wrap around the porphyroblast whilst the porphyroblast and its strain shadow undergo little deformation. Porphyroblast strain shadows comprise quartz, calcite and felspar with little mica, and are probably formed by solution transfer during deformation. Unless the deformation is so strongly partitioned that no deformation of the porphyroblasts and their immediate surrounds occurs, inequidimensional porphyroblasts will rotate. Porphyroblasts undergo some dissolution after they have finished growing.