K-Ar illite-mica age constraints on the formation and reactivation history of the El Doctor fault zone, central Mexico
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Universidad Nacional Autónoma de México
2015
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| author | Diana Elizabeth Garduño-Martínez |
| author_facet | Diana Elizabeth Garduño-Martínez |
| contents | K-Ar illite-mica age constraints on the formation and reactivation history of the El Doctor fault zone, central Mexico Diana Elizabeth Garduño-Martínez Teresa Pi Puig Jesús Solé Michelangelo Martini Jorge René Alcalá-Martínez Ciencias de la Tierra dating Laramide Authigenic illite Sierra Madre Oriental The tectonic history of the Mexican Fold and Thrust Belt exposedin the Sierra Madre Oriental can be assessed in detail by dating theactivation of the major shortening structures. The aim of this paper isto present mineralogical and K-Ar geochronologic data of illite-micafrom the El Doctor thrust fault, a kilometer-scale structure exposedin the central-western Mexican Fold and Thrust Belt. Such a structureis a brittle-ductile shear zone characterized by subgreenschists faciespeak conditions. The crystallization ages of neoformed clay-micaceousminerals from the core of this shear zone are used to constrain thetectonic activity along the selected shear zone. A total of 17 lutite sampleswere collected from different structural levels of the shear zone. Thesamples were characterized petrographically and detailed mineralogywas determined by X-ray diffraction. Grain-size subfractions wereseparated from 11 selected samples, which were subsequently usedfor K-Ar dating. The mesostructural and microstructural analyses,supported by K-Ar geochronologic data, permitted reconstruct of thecrystallization history of phyllosilicate phases related to the tectonicactivity of the shear zone. Our data indicate that the El Doctor thrustfault records a complex structural evolution, which is represented by atleast three superposed deformation phases. The first phase consists ofthe shear zone activation, which produced a main foliation pervasiveat the submillimeter-scale defined by neoformed illite-mica. Thisphase is constrained at 80–75 Ma, which is the range of K-Ar agesobtained by illite-mica from the coarse-grained subfractions collectedat the core of the shear zone. Subsequent tectonic phases producedthe reactivation of the El Doctor shear zone, which produced foldingand crenulation of the previous foliation, successively cut by meterscaleextensional shear bends. The most recent reactivation phases,including diagenesis, are constrained to an age of 50–40 Ma obtainedfrom the finest illite subfractions. Based on our data, we conclude thatthe El Doctor thrust fault recorded a complex, multi-phase structuralevolution, characterized by a phase of activation during the Campanianperiod, and at least one post-Cretaceous reactivation event. The wholehistory of orogenic wedge construction is preserved in the El Doctorfault. 2015 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57240685010 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.2 Vol.32 |
| format | Artículo científico |
| id | redalyc_57240685010 |
| institution | Redalyc |
| language | en |
| publishDate | 2015 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | K-Ar illite-mica age constraints on the formation and reactivation history of the El Doctor fault zone, central Mexico Diana Elizabeth Garduño-Martínez Ciencias de la Tierra dating Laramide Authigenic illite Sierra Madre Oriental K-Ar illite-mica age constraints on the formation and reactivation history of the El Doctor fault zone, central Mexico Diana Elizabeth Garduño-Martínez Teresa Pi Puig Jesús Solé Michelangelo Martini Jorge René Alcalá-Martínez Ciencias de la Tierra dating Laramide Authigenic illite Sierra Madre Oriental The tectonic history of the Mexican Fold and Thrust Belt exposedin the Sierra Madre Oriental can be assessed in detail by dating theactivation of the major shortening structures. The aim of this paper isto present mineralogical and K-Ar geochronologic data of illite-micafrom the El Doctor thrust fault, a kilometer-scale structure exposedin the central-western Mexican Fold and Thrust Belt. Such a structureis a brittle-ductile shear zone characterized by subgreenschists faciespeak conditions. The crystallization ages of neoformed clay-micaceousminerals from the core of this shear zone are used to constrain thetectonic activity along the selected shear zone. A total of 17 lutite sampleswere collected from different structural levels of the shear zone. Thesamples were characterized petrographically and detailed mineralogywas determined by X-ray diffraction. Grain-size subfractions wereseparated from 11 selected samples, which were subsequently usedfor K-Ar dating. The mesostructural and microstructural analyses,supported by K-Ar geochronologic data, permitted reconstruct of thecrystallization history of phyllosilicate phases related to the tectonicactivity of the shear zone. Our data indicate that the El Doctor thrustfault records a complex structural evolution, which is represented by atleast three superposed deformation phases. The first phase consists ofthe shear zone activation, which produced a main foliation pervasiveat the submillimeter-scale defined by neoformed illite-mica. Thisphase is constrained at 80–75 Ma, which is the range of K-Ar agesobtained by illite-mica from the coarse-grained subfractions collectedat the core of the shear zone. Subsequent tectonic phases producedthe reactivation of the El Doctor shear zone, which produced foldingand crenulation of the previous foliation, successively cut by meterscaleextensional shear bends. The most recent reactivation phases,including diagenesis, are constrained to an age of 50–40 Ma obtainedfrom the finest illite subfractions. Based on our data, we conclude thatthe El Doctor thrust fault recorded a complex, multi-phase structuralevolution, characterized by a phase of activation during the Campanianperiod, and at least one post-Cretaceous reactivation event. The wholehistory of orogenic wedge construction is preserved in the El Doctorfault. 2015 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57240685010 en http://www.redalyc.org/revista.oa?id=572 Revista Mexicana de Ciencias Geológicas application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Ciencias Geológicas (México) Num.2 Vol.32 |
| title | K-Ar illite-mica age constraints on the formation and reactivation history of the El Doctor fault zone, central Mexico |
| topic | Ciencias de la Tierra dating Laramide Authigenic illite Sierra Madre Oriental |
| url | https://www.redalyc.org/articulo.oa?id=57240685010 |