PETROLOGIC CHARACTERISTICS AND TECTONIC SETTING OF QUATERNARY VOLCANIC ROCKS IN SAN LUIS POTOSI, MEXICO

The San Luis Potosí volcanic field is located at the southeastern part of the Mesa Central is mainly composed of lavas and pyroclastic flows formed during different volcanic episodes that occurred from the Middle Eocene to the Quaternary (Tristán-González, et al., 2009). The San Luis Potosí volcanic field activity has been associated with different extensional tectonic events. The main volcanic episode took place during the early Oligocene to Miocene, this event was characterized by the extrusion of lavas and ignimbrites of felsic composition, as well as the eruption of mafic and intermediate volcanism. The last volcanic episode occurred during the Quaternary and its characterized by lavas of basaltic composition. This study focuses on the petrography and geochemistry of mafic-intermediate lavas that crops out near Pozo del Carmen, San Luis Potosí México, these lavas are related with the most recent volcanic events. Petrographically, the lavas consist in different amounts of plagioclase and pyroxene on a glomeroporphyritic texture. Samples display a tephrite, picrobasalt, and andesite composition. Chondrite-normalized rare-earth element patterns of basic and intermediate rocks display an enrichment in light rare earth elements with slightly flat patterns in heavy rare earth elements. Slightly Eu negative anomalies are display at intermediate rocks (Eu/Eu*=0.37-0.93). Even doe, several authors have described the basaltic lavas, detailed petrological and geochemical characterization has not been reported. We will provide new data on the petrogenesis of these rocks and their association with the most recent tectonomagmatic processes in the region. The region consists on a complicated volcanic area and according with a recent age of 311 ± 19 ky volcanic activity, has been considered as an evidence of a risk of volcanic reactivation in the region (Saucedo-Girón et al., 2017).