Quality Control - 3-D Structural Geology - page 290

Fig. 10.14.
Preliminary map of top Mary
Lee structure contours in the
southeast Deerlick Creek co-
albed methane field, Black
Warrior Basin, Alabama. Data
from Groshong et al. (2003b).
Control points are squares .
Easting and northing in
meters, elevations in ft. Trace
of cross section in Fig. 10.15
is shown
Fig. 10.15. Cross section of SE Deerlick Creek coalbed methane field. Horizontal view to NW. No verti-
cal exaggeration. Easting and northing in meters, elevations in ft. a Preliminary interpretation of all
horizons. Arrows point to thickness anomalies. b After locating faults and re-mapping
viously and their correct interpretations are immediately obvious on a cross section. A
valid cross section must be compatible with the structure laterally adjacent to the section
as well. Accurate interpretation in three dimensions is demonstrated by means of maps
and cross sections that are each internally consistent and consistent with each other.
The preliminary structure contour map in Fig. 10.14 shows excessively wiggly con-
tours and some trends that might represent faults. A cross section of the preliminary
contour maps on multiple horizons is constructed by slicing the maps. The section
(Fig. 10.15a) shows numerous thickness anomalies and discontinuities that can be resolved
by inserting faults (Fig. 10.15b). Once the faults are mapped and the marker surfaces re-
mapped (Sect. 8.3.2), the thickness anomalies disappear, and the new marker-surface map
is much simpler (Fig. 10.16).