Normal fault displacement characteristics, with particular reference to synthetic transfer zones, Mae Moh mine, northern Thailand

Normal faults in middle Miocene sedimentary rocks of the Mae Moh mine have their geometries and displacement patterns well constrained by outcrop and subsurface data. Seventeen of the largest faults are described and analysed. The 17 faults have very different displacement profiles, with differences between the profiles being explicable in terms of the linkage of initially separate faults. Lateral tip gradients show a large range from 0.035 to 0.6. Fault displacement–length (D–L) relationships plot with considerable scatter. Following previous studies, data points with relatively high D–L ratios are attributed to displacement transfer between overlapping faults; faults with relatively low D–L ratios display linkage of two or more faults. In transfer zones conservation of displacement between the faults ranges from high (> 70%) to low (10–40%). This appears to depend upon whether the faults propagated relatively early (high displacement transfer) or late (low displacement transfer) into overlapping configurations. Where displacement transfer is low, extension appears to be conserved in a broader zone on adjacent mappable faults, with little increase in ductile deformation.