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Fault-controlled hydrothermal dolomitization of the Late Aptian to Early Albian Benassal Fm shallow water carbonates resulted in the seismic-scale stratabound dolostone geobodies that characterize the Benicàssim case study (Maestrat Basin, E Spain). Petrological and geochemical data indicate that dolomite cement (DC1) filling intergranular porosity in grain-dominated facies constituted the initial stage of dolomitization. The bulk of the dolostone is formed by a replacive nonplanar-a to planar-s dolomite (RD1) crystal mosaic with very low porosity and characteristic retentive fabric. Neomorphic recrystallization of RD1 to form replacive dolomite RD2 occurred by successive dolomitizing fluid flow. The replacement sequence DC1-RD1-RD2 is characterized by a depletion in the oxygen isotopic composition (mean δ 18 O (V-PDB) values from -6.92, to -8.55, to -9.86‰), which is interpreted to result from progressively higher temperature fluids. Clear dolomite overgrowths (overdolomitization) precipitated during the last stage of the replacement. Strontium isotopic composition suggests that the most likely origin of magnesium was Cretaceous seawater-derived brines that were heated and enriched in radiogenic strontium and iron while circulating through the Paleozoic basement and/or Permo-Triassic red beds. Burial curves and analytical data indicate that the replacement took place at burial depths between 500 and 750 m, which correspond to the Late Cretaceous post-rift stage or early Tertiary extension of the Maestrat Basin, and by hydrothermal fluids likely exceeding temperatures of 80ºC. Following the partial dolomitization of the host rock, porosity considerably increased in dolostones by burial corrosion related to the circulation of acidic fluids likely derived from the emplacement of the Mississippi Valley-Type deposits. Acidic fluids, probably overpressured, circulated along faults, fractures and stylolites. Saddle dolomite and ore-M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 stage calcite cement filled most of the newly created vuggy porosity. Subsequent to MVT mineralization, precipitation of calcite cements resulted from the migration of meteoric-derived fluids during uplift and subaerial exposure. This late calcite cement destroyed most of the dolostone porosity and constitutes the main cause for the present day poor reservoir quality of the Benassal Fm dolostones.

i ExxonMobil (FC) 2 Alliance_Fundamental Controls on Flow in Carbonates, USA Syn-rift shallow-marine carbonates of Late Aptian to Early Albian age in the southern Maestrat Basin (E Spain) register the thickest Aptian sedimentary record of the basin, and one of the most complete carbonate successions of this age reported in the northern Tethyan margin. The host limestones (Benassal Formation) are partially replaced by dolostones providing a new case study of fault-controlled hydrothermal dolomitization. The syn-rift sediments filled a graben controlled by normal basement faults. The Benassal Fm was deposited in a carbonate ramp with scarce siliciclastic input. The lithofacies are mainly characterized by the presence of orbitolinid foraminifera, corals and rudist bivalves fauna. The succession is stacked in three transgressiveeregressive sequences (TeR) bounded by surfaces with sequence stratigraphic significance. The third sequence, which is reported for the first time in the basin, is formed by fully marine lithofacies of Albian age and represents the marine equivalent to the continental deposits of the Escucha Fm in the rest of the basin. The dolomitization of the host rock is spatially associated with the basement faults, and thus is faultcontrolled. The dolostone forms seismic-scale stratabound tabular geobodies that extend several kilometres away from the fault zones, mostly in the hanging wall blocks, and host Mississippi Valley Type (MVT) deposits. The dolostones preferentially replaced middle to inner ramp grain-dominated facies from the third TeR sequences consisting of bioclastic packestones and peloidal grainstones. Field and petrology data indicate that the replacement took place after early calcite cementation and compaction, most likely during the Late Cretaceous post-rift stage of the basin. The dolostone registers the typical hydrothermal paragenesis constituted by the host limestone replacement, dolomite cementation and sulfide MVT mineralization. The Aptian succession studied provides a stratigraphic framework that can be used for oil exploration in age-equivalent rocks, especially in the València Trough, offshore Spain. Moreover, this new case study constitutes a world class outcrop analogue for similar partially stratabound, dolomitized limestone reservoirs worldwide.

17The Puig-reig anticline, located in the South Pyrenean fold and thrust belt, developed during 18 the Alpine compression, which affected the upper Eocene-lower Oligocene sediments of the 19 Solsona and Berga Formations. In this study, we highlight the controls on formation of joints 20 and reverse, strike-slip and normal faults developed in the crest domain of the Puig-reig 21 anticline as well as the relationships between fluids and these fractures. We integrated 22 structural, petrographic and geochemical studies, using for the first time in SE Pyrenees the 23 clumped isotopes thermometry to obtain reliable temperatures of calcite precipitation. 24Structural and microstructural analysis demonstrate that at outcrop scale fracturing was 25 controlled by rigidity contrasts between layers, diagenesis and structural position within the 26 anticline, whereas grain size, cementation and porosity controlled deformation at microscopic 27 scale. Petrographic and geochemical studies of calcite precipitated in host rock porosity and 28 fault planes reveal the presence of two migrating fluids, which represents two different stages 29 of evolution of the Puig-reig anticline. During the layer-parallel shortening, hydrothermal fluids 30 with temperatures between 92 and 130⁰C circulated through the main thrusts to the 31 2 permeable host rocks, reverse and most of strike-slip faults precipitating as cement Cc1. 32During the fold growth, meteoric waters circulated downwards through normal and some 33 strike-slip faults and mixed at depth with the previous hydrothermal fluid, precipitating as 34 cement Cc2 at temperatures between 77 and 93⁰C. 35Integration of the results from the Puig-reig anticline in this work and the El Guix anticline 36indicates that hydrothermal fluids did not reach the El Guix anticline, in which only meteoric 37 and evolved meteoric waters circulated along the fold. 38