Volcano-sedimentary stratigraphy in the Valsequillo Basin, Central Mexico inferred from electrical resistivity soundings
Initial results of an electrical resistivity survey of the volcano-sedimentary sequence of the Valsequillo basin in central Mexico are presented. The volcano-sedimentary deposits preserve rich paleontological, paleoclimatic and paleoenvironmental records, which include extinct megafauna remains asso...
| Autores: | , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2014 |
| País: | México |
| Institución: | UNIVERSIDAD NACIONAL AUTÓNOMA DE MÉXICO |
| Repositorio: | Geofísica Internacional |
| Idioma: | español inglés |
| OAI Identifier: | oai:revistagi.geofisica.unam.mx:article/498 |
| Acceso en línea: | http://revistagi.geofisica.unam.mx/index.php/RGI/article/view/498 |
| Access Level: | acceso abierto |
| Palabra clave: | Cuenca de Valsequillo Tefra Xalnene estratigrafía estudio eléctrico de resistividad sondeos eléctricos verticales centro de México Valsequillo basin Xalnene tuff stratigraphy central Mexico vertical resistivity soundings |
| Sumario: | Initial results of an electrical resistivity survey of the volcano-sedimentary sequence of the Valsequillo basin in central Mexico are presented. The volcano-sedimentary deposits preserve rich paleontological, paleoclimatic and paleoenvironmental records, which include extinct megafauna remains associated with human artifacts. The report of possible 38 ka old human footprint tracks in the Xalnene tuff attracted renewed interest in the basin stratigraphy. We examine the shallow stratigraphic sequence in the Xalnene tuff outcrop plain northwest of Cerro Toluquilla volcano using vertical resistivity soundings (VES). Inversion models of VES soundings show a layered structure of high and low resistivity units, which characterize the Xalnene tuff, lacustrine and fluvial sediments and volcanic rocks. 2-D resistivity cross sections document three major units corresponding to the Xalnene tuff and sediments filling a <30 m deep basin lying on volcanic rocks. Resistivity models provide further support for the association of Xalnene tuff with the Toluquilla volcano and emplacement of the pyroclastic deposits on a shallow lacustrine environment. The resistivity cross sections constrain the thickness of the tuff layers and underlying lacustrine sediments. Observations during the data acquisition field work provide insight on the possible origin of the apparent tracks, which seem to develop from erosion processes acting on quarrying marks. Further analysis and experimental evidence is required to understand the morphology and weathered patterns. The tuff layers are being removed by quarrying operations and the outcrops significantly altered. Adequate conservation measurements should be implemented to preserve the deposits for scientific research. |
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