Deformation-fluid multiphase interaction within the fractures of the Barcelona Plain and the Vallès Basin: influence on fault rocks and diagenesis / Interacció multifàsica entre deformació i fluids a les fractures del Pla de Barcelona i de la Conca del Vallès: influència en les roques de falla i en la diagènesi

• Autores: Irene Cantarero
• Directores de la Tesis: Gemma Alías López (dir. tes.), Anna Travé Herrero (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2013
• Idioma: español
• Tribunal Calificador de la Tesis: Antonio Benedicto Esteban (presid.), David Parcerisa (secret.), Anne-Marie Boullier (voc.)
• Materias:
  • Ciencias de la tierra y del espacio
    • Geoquímica
      • Geoquímica de bajas temperaturas
      • Isótopos estables
    • Geología
      • Petrología sedimentaria
      • Geología estructural
• Enlaces
  • Tesis en acceso abierto en:  TDX  Dipòsit Digital de la UB 
• Resumen

  • The faults limiting the Barcelona Plain and the Vallès Half-graben (Catalan Coastal Ranges, NE Spain) have allowed the study of a complex and multiphase tectonic/fluid history from the Hercynian to recent times. Furthermore, this study has allowed to define the factors that control the fluid regime and the fluid flow pathways through faults. A multidisciplinary methodology involving field and petrological observations and microstructural analyses combined with geochemical data has been used to characterize host rocks, fault rocks and fracture-related cements. Four tectonic events that encompass seven deformation phases have been established: Hercynian compression, Mesozoic extension (D1-D2), Paleogene compression (D3) and Neogene extension (D4-D7). Faults affect crystalline Hercynian basement, Triassic dolostones and Miocene detritic rocks. The fault rocks formed in the area include gouges, cataclasites, breccias and pseudotachylytes. Veins are formed by different mineral assemblages that involve calcite, quartz, laumontite, K-white mica, chlorite and iron oxides, depending on the PT conditions and thus, on the age. During the exhumation of the late-Hercynian granodiorite, after the Hercynian compression, M1 and M2 muscovite and microcline crystallized as result of deuteric alteration in joints, at temperatures between 330ºC and 370ºC. During the first Mesozoic rifting (Late Permian-Middle Jurassic), faults controlled the thickness and distribution of the Triassic sediments. Fracture-related dolomite cements precipitated from the Triassic seawater during increasing burial in a relatively closed hydrological regime. The second Mesozoic rifting (Late Jurassic-Late Cretaceous) is characterized by precipitation of M3 and M4 phengite together with chlorite and calcite C1 at temperatures between 190 and 310ºC. During the Paleogene compression, low-temperature meteoric fluids, favored by tectonic uplift, produced calcitization of the Triassic dolomite cements and dolostones. In the Vallès fault, by means of a shortcut, Mesozoic structures were uplifted and a gouge and subvertical stylolites were generated. During the Neogene syn-rift, hydrothermal fluids up to 190ºC ascended through the faults. In the Hospital fault these fluids upflowed within the relay area during fault growth by tip propagation due to a seismic pumping effect. The Neogene post-rift in the Barcelona Plain developed at shallow conditions under low-temperature meteoric regime. At the same period, the Vallès fault was dominated by hydrothermal conditions, which remain active until nowadays. Faults acted as conduits for hot fluids during both Mesozoic and Neogene extensional events. Topographically-driven meteoric fluids warmed at depth and suffered a strong interaction with the host rocks. During the Mesozoic, ascending warm fluids mixed with marine waters in both main faults whereas, during the Neogene, the ascending fluids mixed with marine waters in the Hospital fault and with meteoric waters in the Vallès fault. Pedogenic products precipitated along Neogene faults control cross-fault fluid flow by reducing fault core permeability. This work highlights the presence of fault reactivation from Hercynian to Recent times. Hercynian structures have demonstrated to play an important role on the localization of later structures. The main factors that control this process are: fault orientation, fabric softening, fluid pressure and cementation hardening.