Fault spacing in the El Teniente Mine, Central Chile, the fold style inversion method, fold segmentation and fault linkage of the Barrancas/Lunlunta-Carrizal anticlinal complex, Mendoza, Argentina

An interval counting technique and standard cumulative statistics, in concert with residual and differential slope analysis, are employed on multiple parallel scanlines to test the applicability of fractal fault spacing at the El Teniente Mine, Central Chile. A negative exponential distribution best describes fault spatial distribution at the mine, while the interval counting method gives deceptively good fits to a fractal distribution. The results are consistent for the majority of the scanlines over thousands of square meters. These data provide an important counterexample to previously studied fractal spacing distributions and suggest that faulting is not a uniquely self-similar process and/or that faulting is not a consistently self-similar process through time.; The “Fold Style Inversion” (FSI) method is developed to place quantitative bounds on balanced cross-sections used in the analysis of blind thrust faults. The method employs a discretized dip isogon construction, in combination with Monte Carlo simulations of seismic reflection depth-conversion errors, to assess a data sets' goodness of fit to bulk hangingwall similar or parallel fold geometry. This enables an objective choice to be made between the Arbitrarily Inclined Simple Shear (AISS) and Constant Bed Length (CBL) fault inversion routines which are specific to similar and parallel fold geometry, respectively. The method performs successfully for a variety of synthetic examples including a synthetic seismic line.; The FSI method is applied to seismic reflection lines crossing the Barrancas and Lunlunta-Carrizal anticlines, active fault-bend folds in the Andean foreland of Mendoza Province, Argentina, and the proposed site of the 1985 M_w 5.9 Mendoza earthquake. For the Barrancas anticline, FSI analysis establishes a preference for similar fold style whereas no preference can be established for the Lunlunta-Carrizal anticline. With FSI-constrained cross-sections, it is shown that the earthquake most likely did not occur on the fault planes responsible for either the Barrancas or Lunlunta-Carrizal anticlines.; 3-d and 2-d seismic reflection data, balanced cross-sections, and geomorphic observations, demonstrate that the Barrancas/Lunlunta-Carrizal complex is a composite fault-bend fold which has grown laterally by along-strike linkage of three originally independent segments. Fault and fold segmentation is controlled by a Triassic accommodation zone, transversely oriented Triassic normal faults, and background lateral growth processes. Structural relief profiles suggest strongly that all 3 fault segments are now linked and geomorphic criteria suggest that the linkage has occurred substantially later than $\sim$2.3 Ma. The anticlinal complex's small length/slip ratio is likely caused by the transversely oriented Triassic normal faults limiting lateral fault growth. Integration of a new tuff age in rotated Río de los Pozos Formation strata yields a preferred 0.8 mm/a slip rate since $\sim$2.3 Ma. This rate is more than an order of magnitude less than a previous estimate for the neighboring La Pilona anticline.