Calc-alkaline volcanic rocks in the pre-Upper Jurassie basement of south-central Mexico —a late Paleozoic-early Mesozoic convergent plate margin?

Abstract

The limited extension of geological map coverage, the metamorphism of varying degrees that affected the rocks and their almost complete lack of fossils, make the basement beneath the marine fossiliferous Upper Jurassic and/or Lower Cretaceous sedimentary and volcanic cover rocks to be an unsolved geological problem in south-central Mexico, a región comprising about 20,000 km² (Figure 1). Radiometric ages (Pb-α, K-Ar, Rb-Sr, U-Pb) obtained from these rocks are apparently contradictory or not conclusive (de Cserna et al., 1962; de Cserna, Fries, Rincón-Orta, Westley, Solorio-Munguía and Schmitter-Villada, 1974; de Cserna, Fries, Rincón-Orta, Solorio-Munguía and Schmitter-Villada, 1974; Guerrero-García et al., 1978; Urrutia-Fucugauchi and Linares, 1981; López-Infanzón and Grajales-Nishimura, 1984; Morán-Zenteno et al., 1990; Morán-Zenteno, 1992)... In order to continue, download full text in PDF.