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ABSTRACT: Sandbox experiments of inverted listric faults with differential displacement

Yamada, Yasuhiro and Ken McClay
Royal Holloway, University of London, Egham, Surrey, United Kingdom

The displacement pattern of detachment fault affects the geometry and kinematic evolution of its hangingwall deformation. The relation between the fault displacement and the hangingwall deformation is investigated by a series of 3D analogue experimental models.

The results of the sandbox experiments show a concave listric detachment with an along-strike variation in the displacement produces characteristic structures during extension and subsequent inversion. During extension, crestal collapse graben systems develop at the region where the displacement of the underlying detachment is greater. Strike slip faults develop where the detachment fault has a discontinuity in the displacement pattern. After inversion, the former graben area is uplifted by contractional reactivation of the master detachment fault. The uplifted hangingwall is commonly faulted perpendicular to the detachment by its collapsing toward the surrounding undeformed region. Although the over-all section geometry of the hangingwall deformation is generally controlled by the vertical profile of the underlying detachment, the development of the hangingwall structures is strongly controlled by the amount of displacement.

These experimental results may explain not only the geometric characters but the mechanics of fault/fold development associated with natural inversion structures, such as a number of normal faults perpendicular to the axis of inversion anticlines in the West Natuna Basin and in the north Sinai Peninsula. This study shows how analogue experiments are useful in providing templates for use as predictive tools and for structural interpretations in poorly constrained seismic surveys.

AAPG Search and Discovery Article #90913©2000 AAPG International Conference and Exhibition, Bali, Indonesia