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Emergence breccia in platform limestones of the Zicapa Formation, from outcrops south of Tlapa de Comonfort (Guerrero state). The breccia is composed of angular clasts of a grainstone up to 50 cm in diameter, occasionally containing abundant rudist and bivalve fragments replaced by silica, in a quartz-rich sandstone matrixwith pigmentary hematite. See article in this number by Sierra Rojas and Molina-Garza. Photograph: Roberto Stanley Molina-Garza.