Depiction of Faults on Stratigraphic Isopach Maps: GEOLOGICAL NOTE

ABSTRACT Isopach maps generally are more difficult to draw than structure contour maps. Many geologists have problems depicting the patterns of faults on such maps; this paper demonstrates proper technique. Expressions of faults are of much greater width on isopach maps than on accompanying structure maps. Moreover, isopach lines do not stop at a fault trace, but continue across it in a distinctive fashion which is quite different from that of structure contours. Where faults cross or bifurcate, or die out within a formation, they also exhibit characteristic patterns on isopach maps. Isopach lines near the ends of faults, and in situations where bed thickness equals or exceeds fault throw show typical attitudes, as do isopach-map features produced by high angle reverse faults.