Topic > Murri Fold - 1251

The main field work was to measure the orientation and dip angle of the strata in order to analyze the Murri anticline. All measurements were taken with a compass. Furthermore, the description and characteristics of the layers were noted such as colour, lithology, type of rock and presence of any fossils. Subsequently, the data collected in the field were analyzed.2.2. Data Analysis To analyze the fold, field measurements were plotted in the Schmidt Stereonet. The poles of the measured layers were plotted. On the basis of these poles, the most suitable line, known as the "profile plane", was drawn. The profile plane is always perpendicular to the bend axis. Therefore, the bending axis was determined by tracing the pole of the profile plane. To obtain the angle between limbs, two limbs were drawn closer to the fold axis, which intersected and opposed each other from the measured layers. The angle between the limbs was measured to determine the bisector (which is half the total angle). Finally, the axial plane containing the fold axis and bisector was drawn. The fold attitude was determined by referring to the fold stress-curvature correspondence figure. To draw a cross section, the points from which measurements were taken were marked on an aerial map of the waidi. A profile line (NE-SW) (fig.3) was drawn perpendicular to the fold axis. The projection (parallel to the fold axis) of the measurements was marked on the profile. The projection altitude of each measurement was calculated. The tangent formula of trigonometric functions is used. (Equation 1) Tanα = H/D → H = D.tanαWhere (α) is the dip angle of the fold axis, H is the altitude and D is the distance between the measured point and the profile plane. So to get the projected altitude (Hprojection), the