Topology of Normal Fault Networks in Rift Basins

Faulting is the primary mechanism for accommodating strain generated in the Earth's upper crust. However, faults rarely occur individually or without associated deformation, instead they develop and accommodate strain as a network of numerous faults both major and minor.  Therefore, understanding and characterizing how fault networks behave, grow, develop and interact through time, as well as at a range of scales, is essential for establishing how deformation is accommodated in the Earth's upper crust and sedimentary cover. 

Fig. 1 Subsurface map of a normal fault network from Alaska, image modified from Nixon et al., 2014, AAPG Bulletin

Although the development and growth of individual faults is well understood, the evolution of their arrangement within a fault network has received little attention, and the major controls on it are poorly understood.  Fault network topology describes the relationships between geometrical elements within the network and is essential to characterize networks.  It is related to fault network properties, such as connectivity, providing a key link between the geometry and the behaviour of fault networks.  Hence, investigating the evolution of fault network topology is vital for understanding processes of fault network growth and development.  

The project aims to investigate and characterize normal fault networks in different rift basins at a range of scales, using novel topological concepts, and to examine the geological factors that control the evolution and spatial variation in network topology.  The research will greatly improve topological analyses and understanding of fault network growth, development and connectivity, hence, greatly improving our knowledge of brittle deformation in the Earth's Crust.  This research is directly applicable to hydrocarbon exploration and production as it relates to the geometry and size of structural traps and trap compartmentalisation, and it also relates to fault connectivity and structural controls on fluid flow at geological and production time-scales.

Topologist – mathematician who can not tell difference between a coffee cup and a donut.

Fig. 2 Topology describes relationships between different elements but is invariant with scale and strain. For example the coffee cup and donut in this example can be considered as having the same topology.

Publication:

Morley, C.K., Nixon, C.W., Topological characteristics of simple and complex normal fault networks. Journal of Structural Geology, 84, 68-84.

Peacock, D.C.P., Nixon, C. W., Rotevatn, A., Sanderson, D.J., Zuluaga, L.F.,2016. Glossary of fault and fracture networks. Journal of Structural Geology, 92, 12-29.

Sanderson, D.J., Nixon, C.W., 2015. The use of topology in fracture network characterization. Journal of Structural Geology 78, 55-66. doi:10.1016/j.jsg.2015.01.005