Resumen de Un nuevo método de análisis de paleoesfuerzos a partir de poblaciones de fallas sin estrías
Luis Eduardo Arlegui Crespo, Richard J. Lisle, T. Orife
In numerous cases, the use of standard methods of palaeostress inversion from fault-slip data is prevented by the absence of slickenlines on the fault surfaces; structures that are necessary for determining the direction of slip on the fault. In such instances, the offset along the fault of planar markers, such as beds, often allows the sense of dip separation (normal or reverse) to be observed. Where such displaced markers are horizontal, it can be readily demonstrated that the sense of the dip-slip component of net slip is the same as the sense of dip separation.
Ways are explored for characterising the stress tensor from data consisting of the orientations of a collection of faults, each of known dip-slip sense (normal or reverse). Based on the properties of the stress quadric, the relationship between dip-slip sense, fault plane orientation and the stress tensor is discovered. The relationship forms the basis of a grid-search method of stress inversion, in which a large number of stress tensors differing in orientation and shape are systematically considered. Those tensors that best explain the senses of offset on the observed faults are potential solutions to the palaeostress problem. Examples of the different applications of the new stress inversion method are described, including the analysis of fault data from boreholes.
