The kinematic evolution of the Coffee Soil Fault

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Abstract
This paper addresses the problem of the dating of motion on large, extensional faults, from the seismic expression of the sedimentary sequences deposited during and after the extensional deformation. A general discussion of the interpretational methods and pitfalls involved in a seismically based, kinematic analysis is made by reference to a case study of the Coffee Soil Fault. The Coffee Soil Fault forms the eastern boundary of the Central Graben of the North Sea Rift, and is located in the Danish Sector. From a comparison of the stratigraphy of the hanging wall and footwall blocks, it is suggested that rifting commenced in the Late Permian/Early Triassic. The rifting proceeded in two distinct phases, a non-rotational Triassic phase, resulting in parallel reflection configurations, and a rotational Mid-Late Jurassic phase, resulting in divergent reflection configurations. Basin-floor and fault-scarp relief that resulted from a Late Jurassic acceleration of motion across the fault was infilled in a parallel-onlap configuration by the post-rift Lower Cretaceous sequence. The case study is used to demonstrate that onlap of remnant fault scarps can easily be mistaken for syn-rift deposition, and that this can lead to considerable errors in the timing of the end of rifting.