Early Cretaceous intraplate seamounts from Guanajuato, central Mexico: geochemical and mineralogical data

Abstract

An Early Cretaceous submarine volcanic and volcaniclastic sequence is found in the north- western part of the Sierra de Guanajuato, in central Mexico. This sequence is formed by mildly alkaline basaltic pillow lavas interbedded with massive lava flows, pillow breccias, hyaloclastites, lapilli tuffs, and cognate feeder dikes capped by ribbon cherts and other pelagic flyschlike sediments. Mineralogically, the pillow lavas and cognate diabasic dikes are composed of titaniferous salite/augite, albite, ilmenite, titanite, prehnite, and pumpellyite. Geochemically, they are characterized by high contents of TiO2, Zr, Nb, and P2O5, high Ti/V ratios (49-61), and slightly enriched LREE-patterns (2 < LaN/YbN < 4). These rocks are interpreted as remnants of shallow water deposits of intra-plate seamounts formed as a result of hot-spot volcanism.

Keywords

• Pillow lavas, seamounts, hot-spot, Early Cretaceous, Guanajuato, Mexico.