Resumo

TRISTAN-GONZALEZ, Margarito et al. Geochronology and distribution of the eruptive centers in the San Luis Potosí volcanic field. Bol. Soc. Geol. Mex [online]. 2009, vol.61, n.3, pp.287-303. ISSN 1405-3322.

The San Luis Potosí volcanic field, is located in the southeastern of the Mesa Central, mainly formed by a sequence of lavas and pyroclastic fows with ages between the Middle Eocene until the Quaternary. Generally in the San Luis Potosi Volcanic Field there are fve mainly volcanic stages; the first one restringed to the middle Eocene with the emission of andesitic lavas; the second stage is the more voluminous and occurred between 32 to 28 Ma, dominated by effusive activity that was formed by exogenous domes where the composition are from dacitic to rhyolitic lavas with high silica contain. The formation of these domes were preceded by pyroclastic eruption in minor volume that the lavas fows; the third one stage forming by intermittent felsic volcanism occurred between 28 to 25 Ma formed by pyroclastic eruption of the Panalillo rhyolite associated to normal faults of the maximum extension tectonic event occurred between 28-26 Ma; in some volcanic centers were accompanying by basaltic lava fows showing a bimodal volcanism; the fourth one stage occurred between 23-21 Ma represented by fissural eruptions of basalts extruded through the faults, that mainly occurred in the southern and southwestern of the Sierra de San Miguelito. The last stage was an intraplate volcanism that has overlied to some volcanic centers in the San Luis Potosi Volcanic Field during the Quaternary period; these volcanic centers extruded basanitic composition magmas. The San Luis Potosi volcanic feld volcanism is associated to magmatic diversity and multiepisodic, associated to extensive tectonic events of the central-north of Mexico mainly originated between the Oligocene times. The eruptive complexes, in the same way the main volcanic complexes that forming the volcanic feld, show some difference but are correlationated by petrologic characteristics and by isotopic ages. In this work, we are selected six volcanic complexes: Ahualulco, Pinos, Villa Hidalgo, La Repartición, Sierra San Miguelito and Santa María. We obtained K-Ar isotopic ages in the most unities, and they are concordant with the stratigraphy position.

Palavras-chave : K-Ar ages; Cenozoic volcanism; San Luis Potosí volcanic field; Mesa Central volcanism.

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