Resumo

BARRIENTOS-ZAVALA, Karen Jazmín et al. Distribution and Characterization of the Mixteca Alta-UNESCO Geopark Dikes as Evidence of an Extensional Tectonic Regime in Western Oaxaca, Mexico. Invest. Geog [online]. 2023, n.111, e60696.  Epub 04-Mar-2024. ISSN 2448-7279.  https://doi.org/10.14350/rig.60696.

The Mixteca Alta UNESCO Global Geopark (GMUMA) is in the western portion of the State of Oaxaca and stands out for having a variety of geological and geomorphological features, some of which represented by intrusive igneous bodies. Among them are the exposed dikes in the towns of Santo Domingo Tonaltepec, Santo Domingo Yanhuitlán, and San Pedro Añañé. These tabular bodies cut unconformably through the subsurface rocks and often develop as swarms of individual dikes with parallel, linear, or radial orientations under the influence of other tectonic events or geological structures.

In this research, the dikes present in the GMUMA were identified and mapped through the analysis of satellite images and taking into account field observations, where their presence was compared, and the associated geological-structural features were identified. Likewise, with the help of the Stereo32 1.0.1 program, a total of 66 directions of the dikes were graphed and rose diagrams were elaborated to visualize the preferential direction of the dikes and relate it to the tectonic regime of the region. Three groups of dikes were identified with longitudinal traces that vary from a few meters to 1 km and with approximate thicknesses of between 4 and 5 m, with a preferential direction towards the northwest. The dikes exhibit three types of morphologies: planar stepped and braided, whose interpretation and directions allowed us to establish that the dikes are associated with an extensive tectono-magmatic event that remained active during the Eocene, with a preferential direction towards the northwest-southeast, like the orientation of the Tamazulapan and Cieneguilla faults.

Palavras-chave : Mixteca Alta UNESCO Global Geopark; dikes; Tamazulapan fault; Cieneguilla fault.

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