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2018 AAPG International Conference and Exhibition

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Polygonal Fault System in Great South Basin, New Zealand: Implications for Lithology Prediction

Abstract

A well-developed multi-tier polygonal fault system is located in the Great south Basin offshore South Island New Zealand. The system has been characterized using a high-quality three-dimensional seismic survey tied to available exploration boreholes using regional two-dimensional seismic data. The polygonal faults are demonstrated to be controlled by depositional facies, specifically offshore bathyal deposits characterized by fine grained clays, marls and muds. The faults crosscut thin embedded deep-marine sandstones but stop at facies boundaries between bathyal and clinothem slope facies, suggesting the presence of polygonal faulting can be used as a depositional setting indicator in the absence of direct well control and also contradicts previous studies that used cessation polygonal faulting to infer deep-marine sand bodies. Most likely the efficiency of polygonal faulting as a lithology indicator in deep water is improved with increased sand thickness.