Organic maturation of shales from Toca da Moura Volcano-Sedimentary Complex (Ossa Morena Zone, Portugal)

摘要

The Ossa Morena Zone (OMZ) is a major geotectonic unit located at the southern sector of the Iberian Massif. During Middle Devonian to Lower Carboniferous times, the OMZ underwent igneous activity related to the convergence and collision with the South Portuguese Zone. The Beja Massif, a large calc-alkaline suite, testifies this activity, outcropping at the Portuguese part of the OMZ, near its southwestern border. It is composed of basic to felsic intrusions and a main volcano-sedimentary complex named Toca da Moura, which dates from Late Tournaisian to Late Visean (Pereira et al., in press). This volcano-plutonic suite has been interpreted as corresponding to a volcanic arc (or arcs) associated with the development of a subduction zone dipping northwards, at the southwestern edge of OMZ (Munha et al., 1986; Santos et al. 1987; Santos et al. 1990).