Browsing by Author "Weber, Bodo"

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    Petrogenetic characterization of La Vasca alkaline complex and its relationship to the Eastern Mexican Alkaline Province
    (Elsevier Ltd, 2025) Frei, Dirk; Martínez-Salinas, Edgar; Weber, Bodo
    Peralkaline and agpaitic igneous rocks with local eudialyte mineralization have been reported in the La Vasca alkaline complex (LVAC) but no detailed information on its age and relationship to the Eastern Mexican Alkaline Province (EMAP) has been available. We present petrological, geochemical, isotopic, and geochronological data from the LVAC and the surroundings, located in northwestern Coahuila. The main intrusion is composed of ferroan granitoids that are classified by their alumina saturation index into metaluminous and peralkaline. The metaluminous rocks are monzonite and syenite with post-collisional geochemical affinity. Middle Eocene zircon ages of these rocks range between 47.6 ± 0.3 Ma and 45.4 ± 0.3 Ma and are significantly older than other alkaline rocks from the EMAP. The peralkaline rocks are composed of syenite and eudialyte-bearing foid-syenite with intraplate geochemical affinity that probably coevolved with the metaluminous rocks. Both groups show minimal crustal contamination, with affinity to an Ocean Island Basalt mantle source. The LVAC is explained by a similar formation model than other rocks of the EMAP, suggesting its extension into northwestern Coahuila. Furthermore, the eudialyte foid-syenites represent the first occurrence of agpaitic rocks in Mexico