Isotopic dating of these minerals has been used extensively in the last 20 years to assess the timing of faulting episodes and to reconstruct the tectonic evolution of mountain belts ( Lyons and Snellenburg, 1971 Clauer et al., 1997 Vrolijk and van der Pluijm, 1999 Zwingmann and Mancktelow, 2004 Solum et al., 2005 Schleicher et al., 2006 van der Pluijm et al., 2006 Siebel et al., 2010 Zwingmann et al., 2010a, 2010b Duvall et al., 2011 Surace et al., 2011 Verdel et al., 2011a, 2011b Zwingmann et al., 2011 Tagami, 2012 Clauer, 2013 Viola et al., 2013 Middleton et al., 2014 Torgersen et al., 2015). The occurrence of authigenic and synkinematic clay-mica minerals is a common feature in fault zones. The whole history of orogenic wedge construction is preserved in the El Doctor fault. Based on our data, we conclude that the El Doctor thrust fault recorded a complex, multi-phase structural evolution, characterized by a phase of activation during the Campanian period, and at least one post-Cretaceous reactivation event. The most recent reactivation phases, including diagenesis, are constrained to an age of 50-40 Ma obtained from the finest illite subfractions. Subsequent tectonic phases produced the reactivation of the El Doctor shear zone, which produced folding and crenulation of the previous foliation, successively cut by meterscale extensional shear bends. This phase is constrained at 80-75 Ma, which is the range of K-Ar ages obtained by illite-mica from the coarse-grained subfractions collected at the core of the shear zone. The first phase consists of the shear zone activation, which produced a main foliation pervasive at the submillimeter-scale defined by neoformed illite-mica. Our data indicate that the El Doctor thrust fault records a complex structural evolution, which is represented by at least three superposed deformation phases. The mesostructural and microstructural analyses, supported by K-Ar geochronologic data, permitted reconstruct of the crystallization history of phyllosilicate phases related to the tectonic activity of the shear zone. Grain-size subfractions were separated from 11 selected samples, which were subsequently used for K-Ar dating. The samples were characterized petrographically and detailed mineralogy was determined by X-ray diffraction. A total of 17 lutite samples were collected from different structural levels of the shear zone. The crystallization ages of neoformed clay-micaceous minerals from the core of this shear zone are used to constrain the tectonic activity along the selected shear zone. Such a structure is a brittle-ductile shear zone characterized by subgreenschists facies peak conditions. The aim of this paper is to present mineralogical and K-Ar geochronologic data of illite-mica from the El Doctor thrust fault, a kilometer-scale structure exposed in the central-western Mexican Fold and Thrust Belt. My code is almost fully automated, and I have to keep it that way.The tectonic history of the Mexican Fold and Thrust Belt exposed in the Sierra Madre Oriental can be assessed in detail by dating the activation of the major shortening structures. I've thought about somehow having this domain change for different peaks but not sure how to implement that. I've restricted the domain on which this intersecting line is defined:ĭomain = īut this domain restriction is the same for all peaks. I'm having problems calculating peak width consistently and that's because sometimes the line intersects with points on different peaks. Intersection_lengths=Ĭalculated_width = max(intersection_lengths) It looks like this: roots = indeces_of_intersections I'm calculating peak width as the greatest distance between the intersection of the signal and a line at half the max. However, I've fitted a cubic polynomial to the valleys of the signal, and so I've defined a peak as the distance from this baseline at same index as the peak to the peak. I define a peak width as FWHM (full width at half maximum). I've got hundreds of signals of this form on which I have
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