Estructuras discontinuas y migración de fluidos durante la evolución tectónica paleógena-neógena de los materiales del Jurásico Superior de la Cuenca del Maestrazgo: estudio estructural, mineralógico y geoquímico

• Autores: Meaza Tsige Beyene, Miguel Angel Caja Rodríguez, Rafaela Marfil Pérez, Ramón Salas Roig, Tomás Martín Crespo, Ihsan Al-Aasm
• Localización: Geotemas (Madrid), ISSN 1576-5172, Nº. 6, 1, 2004 (Ejemplar dedicado a: IV Congreso Geológico de España (Zaragoza, 12-15 julio, 2004)), págs. 133-136
• Idioma: español
• Enlaces
  • Texto Completo Ejemplar
• Resumen

  • In the western part of the Maestrat Basin (Iberian Range) dolomite and calclte hydrothermal cements fill fractures and "chimney" structures In Tithonian-Berriasian limestones. The timing of fracture cementation is considered in the context of the structural history of the Alpine Orogeny. Three generations of structures filled with carbonate cements were recognized: A) Fractures formed during the Late EoceneMiocene compressional stage were filled with calcite cement (-8.8%o d180 and +0.8 d13C VPDB) from a fluid of uncertain origin. B) Extensional fractures and C) "pipe-shaped" structures developed during the Miocene-Pliocene extensional phase, are filled with four generations of carbonate cements:

    i) rhombic dolomites; 2) saddle dolomite characterized by high salinity (21.5 to 23.5 % wt. eq. NaCI), high temperatures (Th 110-155BC) and isotopically light d180 ratios (-11.5 to -11.3%o VPDB); 3) calcite replacing (dedolomite) saddle and rhombic dolomite with variable d180 and d13C ratios (-12.2 to -6.8%o d180; -4.4 to +0.2%o d13C), and 4) calcite cement (110-125gC and 160-2609C), with depleted oxygen isotope ratios (-13.4 t o -10 %o d180) and positive carbon ratios (+0.1 to +1.8 %o d13C).

    These data indicate an hydrothermal, saline and dolomitizing fluid linked to the lixiviation of the Triassic-Liassic evaporites, followed by an input of meteoric water (dedolomitization), which evolved to hydrothermal calcite.