Propagation and early growth of normal faults

Baudon, Catherine. 2007. Propagation and early growth of normal faults. PhD Thesis, Cardiff University.

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Abstract

This research project used 3D seismic data located in the Levant Basin, eastern Mediterranean and in the Espirito Santo Basin, offshore Brazil, in order to investigate the early propagation of small normal faults and develop criteria to reconstruct fault kinematics. Detailed interpretation of the 3D geometry of faults, extensive mapping of the throw distribution and investigation of the ductile deformation in the volume surrounding the fault planes provided new insights into the propagation and early growth of normal faults. The Levant survey was used to investigate a unique array of small blind normal faults that were then compared to neighbouring small growth faults in order to better understand their early growth history. Criteria for the recognition of blind faults were defined. Unrestricted blind faults were compared to those that underwent a subsequent mechanical interaction with a major lithological boundary or another structure. The results show that such restrictions affect the throw distribution on most of the fault plane and is not only limited to the proximal zone of interaction. An analysis of growth faults that have recently made the transition from a blind stage to a syn-sedimentary stage suggests that most of the fault surface area formed during the blind propagation phase. A large proportion of the displacement was added during the syn-sedimentary phase as a result of interaction with the free surface. This led to a change in the position of the point of maximum displacement, as well as a shift of the entire vertical throw distribution. These results suggest that the dimensions of the faults were established early in the growth history and that displacement on and surrounding fault planes was added for a near constant dimension. Crestal extensional faults that grew by blind propagation before reaching the surface were investigated from the Espirito-Santo survey. These faults were reactivated by blind propagation after a significant period of quiescence. A reconstruction of the 3D geometry of the fault network and detailed analysis of the throw distribution provided new insights into the kinematics of reactivation. Two distinct modes of reactivation are recognised: a typical reactivation by upward propagation and a reactivation by dip linkage. These are selective processes and factors controlling preferential reactivation are discussed. All these results have wide implications for fault growth models and are applicable to many petroleum systems.

Item Type:	Thesis (PhD)
Status:	Unpublished
Schools:	Earth and Environmental Sciences
Subjects:	Q Science > QE Geology
ISBN:	9781303208652
Date of First Compliant Deposit:	30 March 2016
Last Modified:	09 Jan 2018 20:46
URI:	https://orca.cardiff.ac.uk/id/eprint/56187

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