USING THE SPATIAL ANALYSIS OF A STRUCTURE CONTOUR MAP TO COMPARE FOLD HINGE AND FAULT ORIENTATIONS WITHIN THE HARPETH RIVER FAULT ZONE, A CRATONIC FAULT AND FOLD ZONE IN CENTRAL TENNESSEE
Application of the Directional Distribution Tool showed that 8 of 26 hinges (31%) trend 335o-350o, closely approximating the published 331o-358o strike of macroscale HRFZ faults. Also, the 1st and 4th most linear hinges coincide with segments of the Arno fault zone, the zone associated with the greatest structural relief within the HRFZ. Two hinges (ranking 21st and 22nd in linearity) coincide with two of the five segments of the McDaniel fault zone, the zone associated with the 2nd greatest structural relief. However, 11 of 26 hinges (42%) trend 000o-030o, including the 3rd most linear hinge. Although these hinges do not parallel macroscale HRFZ faults, they share the published trend of many Midcontinent faults and folds, indicating that the folds may have formed through the reactivation of cratonic basement structures. Most of the rest of the hinges (23%) trend 055o-085o, and this group includes the 2nd most linear hinge. These hinges are approx. orthogonal to the HRFZ faults and, therefore, folding may have accommodated along-strike variations in extension.