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Photomicrographs of gabbroic rocks in various stages of textural equilibration.
(a) Glass-bearing gabbroic nodule entrained in a basaltic lava flow from Iceland in which the pore spaces between plagioclase grains are almost entirely filled with clinopyroxene. The arrowed junction shows the pyroxene inheriting the original impingement angle between the two plagioclase grains. This is the starting point for fully solidified gabbros. Scale bar is 200 μm long.
(b) Fully solidified gabbro from the Skaergaard Intrusion, East Greenland, in which the plag-plag-cpx junctions (arrowed) are beginning to rotate towards solid-state textural equilibrium. The original angles have been increased to something of the order of 80-90°. Scale bar is 200 μm long.
(c) A fully texturally equilibrated metabasic granulite, with granoblastic texture and ~120° dihedral angles (arrowed). This is the point at which the previous two textures would arrive if they remained sufficiently hot for sufficiently long.
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