Block rotation by strike‐slip faulting: Structural and paleomagnetic evidence

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Abstract
Geometric analysis shows that motion of sets of strike‐slip faults should cause block rotation; otherwise the distorted fault domain would not fit with its surrounding. The sense of the block rotation depends on the sense of fault slip and the spacing and orientation of the faults, all of which can be obtained from structural data. The predictions of the geometric model can then be independently tested by paleomagnetic measurements. The model was tested in northern Israel. Structural data reveal several domains of contemporaneous right‐ and left‐lateral strike‐slip faults. Paleomagnetic measurements show that in a domain of NNW trending left‐lateral faults, blocks rotated 23.3°±8.2° clockwise, and in a domain of right‐lateral faults, blocks rotated 22.4°±9.0° anticlockwise. These results are in agreement with the prediction of the geometric analysis of the structure. The combined results of the heterogenous deformation of the area resembles a pure shear which allows N‐S extension by about 1.3. In other domains, rotations of 34.6°±9.1° and 53.1°±11.0° were found. In their original orientation the left‐ and right‐lateral faults intersected at angles of 60°–70°, enclosing the principal axis of shortening, in accordance with theories of brittle failure. As a result of block rotations, this angle is now larger and may reach 110°. The results demonstrate large block rotations, in different senses, in domains of strike‐slip faults. The independent structural and paleomagnetic data can be interpreted within the framework of a simple geometric model. Northern Israel is considered to be a good model for this efficient mechanism of intraplate deformation, which is expected to occur in similar tectonic settings elsewhere.