--> Empirical Constraints on Fault Displacement Vectors and Implications for Fault Mechanics and Strain Prediction, Taranaki Basin, Offshore New Zealand
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Empirical Constraints on Previous HitFaultNext Hit Displacement Vectors and Implications for Previous HitFaultNext Hit Mechanics and Strain Prediction, Taranaki Basin, Offshore New Zealand

Abstract

Individual Previous HitfaultNext Hit segments within Previous HitfaultNext Hit systems often vary in strike direction even though they typically are simultaneously active when subject to a single regional stress direction. This suggests that individual Previous HitfaultNext Hit segments may be characterized by dip-, oblique-, or strike-slip depending on their orientation relative to the regional stress field. However, direct evidence for individual Previous HitfaultNext Hit segment motion as a function of orientation is sparse. Additionally, Previous HitfaultNext Hit segments that are reactivated in a new regional stress direction are often cited as clear candidates for oblique-slip. While this has been demonstrated in several field locales, slip vectors are uncertain due to the lack of kinematic indicators in many cases, especially in subsurface settings. This study utilizes a 3D seismic dataset off the west coast of the north island of New Zealand to help address this challenge. Within the dataset, a well-imaged progradational slope system with distinct channels subsequently offset by a geometrically-complex Previous HitfaultNext Hit system provides a unique opportunity to observe piercing-point constraints on Previous HitfaultNext Hit displacement vectors at a high spatial density. The region is characterized by normal reactivation, with early east-west directed extension followed by later northwest-southeast directed extension, and many Previous HitfaultNext Hit segments of equivalent age vary considerably in strike direction. In order to empirically determine displacement vectors across the dataset, faults, horizons, and slope channels were mapped. At a wide range of depths throughout the dataset, dozens of slope channels are clearly cut by normal faults and serve as piercing points that indicate Previous HitfaultNext Hit displacement vectors. We observe that the sense of strike-slip resolved on faults of a given orientation are generally consistent with predicted values, thus demonstrating that oblique far-field stresses are resolved as oblique displacement on individual Previous HitfaultNext Hit segments, rather than partitioned onto separate dip-slip and strike-slip structures. However, the expected variation in strike-slip magnitude as a function of Previous HitfaultNext Hit dip is not clearly observed. Consideration of interpretational uncertainty immediately adjacent to Previous HitfaultNext Hit zones due to seismic imaging and Previous HitfaultNext Hit zone complexity permits evaluation of the robustness of the observed variations from the predicted values. These observations may then be compared with strain predictions associated with slip on this complex Previous HitfaultTop system.