Structure Contour Maps University of Sulaimani School of Science Department of Geology Practical Structural Geology Instructor: Halko M. Mahmoud 2014-2015 Lab No 13 Structure Contour Maps

Structure contour lines A topographic contour line is a line that connects points of equal elevation on the topographic surface, while a structure contour line is a line that connects points of equal elevation on the top or bottom of stratigraphic unit. Examples of such surfaces include the top or bottom of a stratigraphic unit; marker beds and horizons; and surfaces of unconformity, of mineral deposits or of aquifers. The data used in constructing a structure-contour map may be obtained from geological surveys, the drilling of holes, mining, or geophysical investigations.

Structure contour lines 400 300 200 100 N 400 300 200 100 N (Horizontal Plane) 400 300 200 100 400 m 300 m 200 m 100 m

Structure contour lines Sometimes the bed is cut by a fault in such case the structure contours drawn for the top or the bottom of the stratigraphic unit has discontinuities and intersect the fault plane. Structure contour maps are highly significant to map horizons of interest at certain depth and to recognize structures at the subsurface.

Exercise

Structure of the Bed The structural geology of the bed: Dip angle between any two points = tan-1 (ΔE / X * scale) The structural geology of the bed: There are of 4 folds that have a general trend of NW-SE. Two plunging anticlines in the NW and South. The anticlines are rather symmetrical. Another anticline on the East of the map that plunges to the NW. There is also a syncline between the eastern and the southern anticlines.