Figure F20. Photomicrographs of acicular plagioclase and clinopyroxene. A–C. Increasing lengths of acicular plagioclase with decreasing cooling rate (toward pillow interiors), with a distinctive network of interlocking plagioclase in C. (A) Thin Section 17 (Sample 324-U1346A-7R-1, 52–54 cm); (B) Thin Section 46 (Sample 324-U1346A-13R-1, 85–89 cm); (C) Thin Section 14 (Sample 324-U1346A-6R-1, 115–116 cm). D. Olivine microphenocryst with enclosed Cr spinel that is plated with acicular plagioclase and otherwise indistinguishable in size or morphology from crystals of the surrounding matrix (Thin Section 50; Sample 324-U1346A-14R-2, 36–37 cm). E. Intergrown acicular plagioclase and dendritic blades of clinopyroxene (Thin Section 38; Sample 324-U1346A-11R-1, 34–35 cm). F. Large-scale replacement of material between the arms of a stellate cluster of acicular plagioclase (Thin Section 29; Sample 324-U1236A-8R-1, 86–87 cm). A–E are under transmitted light; F is under cross-polarized light.
Previous | Close | Next | Top of page