PROVENANCE OF METAMORPHIC QUARTZ FROM THE TLAXIACO ANTICLINORIUM PROVED THE EROSION OF AN ANCIENT CRATON BEFORE THE HISPANIC CORRIDOR WAS FORMED AT THE EARLIER GULF OF MEXICO

Tlaxiaco´s Anticlinorium shows the almost complete Jurassic sequence studied in Mexico. It was divided, by Jiménez-Rentería, in a Lower Liassic Consuelo and the Upper Liassic-Middle Jurassic Tecocoyunca groups.Consuelo Group was considered as continental, because it contains vegetal macrofossils and coal layers; but, lately, its marine palynomorphs content in some units showed a marine influence, confirmed by De Anda-García, who used Miall´s Method and Petrological analysis of Dickinson, W. R. and Suczek, C. A. He established estuarine and shallow marine environments, in an anastomosed river valley, bordered by alluvial fans, gradually invaded, by the “Portal del Balsas” epicontinental sea. Tectonic-sedimentary data allowed to know that this Group was deposited in a SE-NW half-graben, during an incipient “rifting” stage and stated that initialy a source of metamorphic rocks particles was located at a recycled Permian Orogen, raised by continental collision. Lately metamorphic quartz became gradually more abundant upward in the Consuelo Group, coming from a cratonic source, lifted by a hot spot, placed at the present central area of the Gulf of Mexico. It is the main constituent of the Upper Liassic Cuarcítica Cualac Fm, described by Osorio-Nicolás, M., and considered, with Zorrillo and Taberna formations as the Tecocyunca´s Basal Sequence.

In order to determinate paleoenvironmental conditions in the initial part of the Middle Jurassic in this area, Vite-del Ángel, A. O., determine the sedimentary environments of these units using the Miall´s association and succession of lithofacies. So, it was determined a braided river environment for Cuarcítica Cualac Fm, an estuarine environment for Zorrillo Fm and a shallow marine platform for Taberna Fm. The results show for Zorrillo and Taberna formations a series of sedimentary cycles of retrogradation and abandonment (Zorrillo Fm) and transgression and subsidence of the basin (Taberna Fm) which allowed marine invasion of the continent by the sea named " Hispanic Corridor" inferred through the presence of pacific and tethysian ammonites in Taberna Formation. Provenance of metamorphic quartz of sandstones found in these formations corroborated that they were also originated by the erosion of the ancient craton placed at the central part of the present Gulf of Mexico.