Axial distribution of ellipsoids fitted to miarolitic cavities. N = 1285. Equal area and lower hemisphere projection. Contour interval is 1.0 %/1% area.
The shape of miarolitic cavities was estimated from the contiguous CT images stacked at intervals of 1 mm by computer programs (Ikeda et al., in press). These programs analyze connectivity of voxels with CT number between given lower and upper values and perform cluster labeling of reconstructed objects. Next, a program fits ellipsoids with three arbitrary axes to these objects and outputs lengths and directions of axes of each ellipsoid. The objects with length parallel to the longitudinal axis of core shorter than 3 voxels were excluded from the analysis, because such objects are too small to fit ellisoids. The shortest (a), intermediate (b) and longest (c) axes of ellipsoids fitted to miarolitic cavities prefer to E-W, N-S and vertical respectively.
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