Stratigraphy of the Balsas Group in the Amacuzac area, southern Mexico: relationship with Eocene volcanism and deformation of the Tilzapotla-Taxco sector
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| Format: | Artículo científico |
| Language: | en |
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Universidad Nacional Autónoma de México
2007
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| author | Dante J. Morán Zenteno |
| author_facet | Dante J. Morán Zenteno |
| contents | Stratigraphy of the Balsas Group in the Amacuzac area, southern Mexico: relationship with Eocene volcanism and deformation of the Tilzapotla-Taxco sector Dante J. Morán Zenteno Ahiram Monter Ramírez Leticia A. Alba Aldave Jesus Solé Elena Centeno García Ciencias de la Tierra Eocene Balsas Group Southern Mexico Tilzapotla caldera terrestrial sedimentation The Zapalco-Amacuzac area in the Morelos and Guerrero states, southern Mexico, constitutes oneof the classic sectors where Paleogene continental beds of the Balsas Group were originally described. Theexposed succession has an apparent thickness of ~2,500 m and it is constituted by two distinct sedimentaryunits separated by a slightly angular unconformity and by two intercalated ignimbrites (35.1 ± 0.4 and38.5 ± 0.7 Ma, sanidine, K-Ar). The basal beds of the lower sedimentary unit (Tepetlapa Formation) areconstituted by matrix-supported conglomerates that grade upwards to sandstone with a poorly definedplanar parallel stratification and some intercalated andesitic and mafic lava flows. One of the andesitesyielded a whole rock K-Ar date of 44.5 ± 0.7 Ma. Intercalations of conglomerate beds increase againtoward the top of this unit. The upper sedimentary unit (Huajintlán Formation) is constituted by a~300 m thick succession of matrix-supported conglomerate with some lenses of conglomeratic sandstone.This unit unconformably underlies the Tilzapotla ignimbrite whose best age estimate is 34.3 Ma (sanidineAr-Ar). The beds of the two sedimentary formations dip east to northeast with higher dips for the lowerunit (5030º). Recognized facies in both units are indicative of an alluvial fan environment with moreproximal facies for the Huajintlán Formation.The studied succession is located immediately northwest of a large elliptical (50×30 km) domestructure that resulted from the tumescence stage, in the early evolution of the Tilzapotla caldera, previousto the collapse. The northwestern termination of the dome merges and interferes with the NNE-trendingLaramide fold and thrust front of the Iguala Cacahuamilpa highs, near Taxco. In the study area, the domecontours display a local inflection defined by a change in the dip direction of the Morelos and basal bedsof the Tepetlapa Formation from north to east. The slight angular unconformity between the TepetlapaFormation and the overlaying units indicates a first stage of eastward tilting related to an uplift episodein the Taxco area, probably originated by the emplacement of silicic magmas (ca. 38 Ma). The proximalfacies of the overlaying Huajintlán Formation and the age (35.1 ± 0.4 Ma) of the Piedras Altas Tuff ,indicate that this formation resulted from the rejuvenation of the source area triggered by the tumescenceand the initiation of the volcanic activity in the nearby Tilzapotla caldera area. This is confirmed by thehigher dips (~50º) of the Tepetlapa Formation near the dome structure and the decreasing dips towardthe northeast. The age of one andesite lava flow (44.5 Ma) intercalated in the lower unit is indicative ofan Eocene age for the beginning of the Balsas Group accumulation in this area. 2007 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57224106 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.1 Vol.24 |
| format | Artículo científico |
| id | redalyc_57224106 |
| institution | Redalyc |
| language | en |
| publishDate | 2007 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Stratigraphy of the Balsas Group in the Amacuzac area, southern Mexico: relationship with Eocene volcanism and deformation of the Tilzapotla-Taxco sector Dante J. Morán Zenteno Ciencias de la Tierra Eocene Balsas Group Southern Mexico Tilzapotla caldera terrestrial sedimentation Stratigraphy of the Balsas Group in the Amacuzac area, southern Mexico: relationship with Eocene volcanism and deformation of the Tilzapotla-Taxco sector Dante J. Morán Zenteno Ahiram Monter Ramírez Leticia A. Alba Aldave Jesus Solé Elena Centeno García Ciencias de la Tierra Eocene Balsas Group Southern Mexico Tilzapotla caldera terrestrial sedimentation The Zapalco-Amacuzac area in the Morelos and Guerrero states, southern Mexico, constitutes oneof the classic sectors where Paleogene continental beds of the Balsas Group were originally described. Theexposed succession has an apparent thickness of ~2,500 m and it is constituted by two distinct sedimentaryunits separated by a slightly angular unconformity and by two intercalated ignimbrites (35.1 ± 0.4 and38.5 ± 0.7 Ma, sanidine, K-Ar). The basal beds of the lower sedimentary unit (Tepetlapa Formation) areconstituted by matrix-supported conglomerates that grade upwards to sandstone with a poorly definedplanar parallel stratification and some intercalated andesitic and mafic lava flows. One of the andesitesyielded a whole rock K-Ar date of 44.5 ± 0.7 Ma. Intercalations of conglomerate beds increase againtoward the top of this unit. The upper sedimentary unit (Huajintlán Formation) is constituted by a~300 m thick succession of matrix-supported conglomerate with some lenses of conglomeratic sandstone.This unit unconformably underlies the Tilzapotla ignimbrite whose best age estimate is 34.3 Ma (sanidineAr-Ar). The beds of the two sedimentary formations dip east to northeast with higher dips for the lowerunit (5030º). Recognized facies in both units are indicative of an alluvial fan environment with moreproximal facies for the Huajintlán Formation.The studied succession is located immediately northwest of a large elliptical (50×30 km) domestructure that resulted from the tumescence stage, in the early evolution of the Tilzapotla caldera, previousto the collapse. The northwestern termination of the dome merges and interferes with the NNE-trendingLaramide fold and thrust front of the Iguala Cacahuamilpa highs, near Taxco. In the study area, the domecontours display a local inflection defined by a change in the dip direction of the Morelos and basal bedsof the Tepetlapa Formation from north to east. The slight angular unconformity between the TepetlapaFormation and the overlaying units indicates a first stage of eastward tilting related to an uplift episodein the Taxco area, probably originated by the emplacement of silicic magmas (ca. 38 Ma). The proximalfacies of the overlaying Huajintlán Formation and the age (35.1 ± 0.4 Ma) of the Piedras Altas Tuff ,indicate that this formation resulted from the rejuvenation of the source area triggered by the tumescenceand the initiation of the volcanic activity in the nearby Tilzapotla caldera area. This is confirmed by thehigher dips (~50º) of the Tepetlapa Formation near the dome structure and the decreasing dips towardthe northeast. The age of one andesite lava flow (44.5 Ma) intercalated in the lower unit is indicative ofan Eocene age for the beginning of the Balsas Group accumulation in this area. 2007 artículo científico 1026-8774 https://www.redalyc.org/articulo.oa?id=57224106 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.1 Vol.24 |
| title | Stratigraphy of the Balsas Group in the Amacuzac area, southern Mexico: relationship with Eocene volcanism and deformation of the Tilzapotla-Taxco sector |
| topic | Ciencias de la Tierra Eocene Balsas Group Southern Mexico Tilzapotla caldera terrestrial sedimentation |
| url | https://www.redalyc.org/articulo.oa?id=57224106 |