TrackDip: a multi-scale processing of dipmeter data. Method, tests, and field example for 3D description of gravity-driven deformations in the Eocene foreland basin of Ainsa, Spain
Résumé
This paper presents TrackDip, a new method for dipmeter data processing. This method selects, localizes and measures significant tilts from the comparison at various scales of the changes of orientation of sedimentary beddings. We tested this method on simple cases (unconformity, gradual tilt, successive tilts, without and with additional random noise) and on a field example, along three sections in the Eocene Sobrarbe delta, Ainsa foreland basin, northern Spain. For synthetic data sets, the method clearly identifies and measures the introduced tilts. On the field, sedimentary and tectonic structures, especially three main syn-sedimentary sliding surfaces (S1 to S3), were successfully identified from processed dipmeter data. The tilt axis are mainly trending N-S in sandstones, associated to westward transport of sediments. The sliding surfaces S1 and S3 correspond to E-W-trending tilt axis, tentatively correlated either to the flexural subsidence of the basin, or to anticline growth during sedimentation south of the studied area. Combination of these sedimentary and tectonic directions results in a NE-SW striking submarine slope, which locally controls the gravity-driven deformations, especially on the S2 sliding surface. Finally, NNW-SSE-trending tilts above the uppermost S3 sliding surface are interpreted as the result of infilling on the side of the scar produced by sliding.
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