42-1 Occurrence of metallic particles beneath the Mexican Central Plateau: Evidence for mantle and crustal fertility from xenoliths in maars of San Luis Potosí

Session: Cordilleran Mineral Systems: Interdisciplinary Perspectives on Critical Metal Ore Deposits

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Maars in the state of San Luis Potosí represent a window into the upper mantle and lower crust of the Mexican Central Plateau, as they host xenoliths of diverse origins transported during the ascent of basaltic magmas. This region contains some of the most important mineral deposits in Mexico; therefore, the study of its lithospheric roots and metal sources represents a relevant, yet poorly explored, field of research. Using fieldwork, petrography, and electron probe microanalysis (EPMA), this study documents the presence of metallic particles in crustal and mantle xenoliths from maars such as Joya Honda, Joya Prieta, Laguna de los Palau, and El Toro. Preliminary results indicate that the xenoliths are mainly lherzolites (mantle), hornblendites (metasomatized mantle), and mafic granulites (lower crust). Metallic particles occur as (1) solidified sulfide-rich melt inclusions associated with silicate melt inclusions that follow intragranular fractures in pyroxene and olivine, (2) interstitial phases between rock-forming minerals in association with glass, and (3) fillings of microfractures; the latter being the most common. These observations suggest that partial melting and mantle metasomatism may have enriched the resulting magmas in metal-rich sulfide phases. This mantle and deep crustal “fertilization” could have contributed to the formation of mineral deposits in the upper crust.  

Geological Society of America Abstracts with Programs. Vol. 58, No. 3, 2026

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