The Bortoluzzi Mud Volcano (Ionian Sea, Italy) and its potential for tracking the seismic cycle of active faults

The Ionian Sea in southern Italy is at the center of active interaction and convergence between the Eurasian and African-Adriatic plates in the Mediterranean. This area is seismically active with instrumentally and/or historically recorded Mw > 7:0 earthquakes, and it is affected by recently discovered long strike-slip faults across the active Calabrian accretionary wedge. Many mud volcanoes occur on top of the wedge. A recently discovered one (called the Bortoluzzi Mud Volcano or BMV) was surveyed during the Seismofaults 2017 cruise (May 2017). High-resolution bathymetric backscatter surveys, seismic reflection profiles, geochemical and earthquake data, and a gravity core are used here to geologically, geochemically, and geophysically characterize this structure. The BMV is a circular feature ' 22 m high and ' 1100 m in diameter with steep slopes (up to a dip of 22). It sits atop the Calabrian accretionary wedge and a system of flower-like oblique-slip faults that are probably seismically active as demonstrated by earthquake hypocentral and focal data. Geochemistry of water samples from the seawater column on top of the BMV shows a significant contamination of the bottom waters from saline (evaporite-type) CH4-dominated crustal-derived fluids similar to the fluids collected from a mud volcano located on the Calabria mainland over the same accretionary wedge. These results attest to the occurrence of open crustal pathways for fluids through the BMV down to at least the Messinian evaporites at about-3000 m. This evidence is also substantiated by helium isotope ratios and by comparison and contrast with different geochemical data from three seawater columns located over other active faults in the Ionian Sea area. One conclusion is that the BMV may be useful for tracking the seismic cycle of active faults through geochemical monitoring. Due to the widespread diffusion of mud volcanoes in seismically active settings, this study contributes to indicating a future path for the use of mud volcanoes in the monitoring and mitigation of natural hazards

Lower plate geometry controlling the development of a thrust-top basin: The tectonosedimentary evolution of the ofanto basin (Southern Apennines)

The Ofanto basin is a Pliocene-Pleistocene thrust-top basin that formed with an unusual east-west orientation along the frontal part of the Southern Apennine Allochthon during the latest stages of tectonic transport. Its tectonic and sedimentary evolution was studied integrating field surveys, biostratigraphic analyses and the interpretation of a large seismic grid. Well data and seismic interpretation indicate that a large east-west-trending normal fault underlies the northern margin of the basin, displacing the Apulian carbonates that form the foreland and the footwall of the Southern Apennine Allochthon. In our reconstruction the Ofanto basin formed at the rear of the bulge caused by buttressing of the Southern Apennine Allochthon against this normal fault. In a second stage of contraction, the footwall of the Southern Apennine Allochthon was involved in deformation with a different trend from the normal faulting and buttressing. This caused eastward tilting of the basin and broad folding around its eastern termination. Good stratigraphic constraints permit the age of buttressing to be defined as Early Pliocene, and that of the shortening in the Apulian carbonates as Early Pleistocene. This study highlights the importance of early orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges.This is a contribution of the Group of Dynamics of the Lithosphere (GDL) supported by the projects TopoMed CGL2008e03474-E/BTE, ESF-Eurocores 07-TOPOEuROPE-FP006, and Consolider-Ingenio 2010 Topo-Iberia (CSD2006e00041).Peer Reviewe

Structural inheritance of pre- and syn-orogenic normal faults on the arcuate geometry of Pliocene-Quaternary thrusts: examples from the Central and Southern Apennine chain, Italy

In the frontal sector of the Central-Southern Apennines, surface geological data integrated with seismic line interpretation provide new constraints into the reconstruction of the structural inheritance of Mesozoic pre-orogenic and Messinian-Pliocene syn-orogenic normal faults on the salient geometry of the Pliocene-Quaternary thrust system. In the Umbria-Marche-Abruzzi area, pre-orogenic normal faults commonly juxtapose the complete Jurassic succession (about 900 metres in thickness) onto coeval condensed successions (about 50 metres in thickness) deposited over structural highs. In the Sibillini Mts and Gran Sasso area, pre-orogenic normal faults are truncated and rotated into Pliocene thrust-sheets according to simple short-cut trajectories. In particular the foreland-dipping Jurassic normal faults in the Sibillini Mts area have been rotated and reactivated during the thrust propagation forming high-angle blind-thrusts in the east verging overturned folds. The Maiella anticline, which involves the Mesozoic-Miocene Apulian carbonate succession and the related slope deposits, joins the Central Apennine fold-and-thrust system to the Apulian Chain buried below the allochthonous Units of the Southern Apennines. Seismic line interpretation allowed us to reconstruct the three-dimensional pattern of the Apulian thrusts, oriented N-S, NNW-SSE and E-W, that are parallel to normal faults related to the Pliocene-Quaternary flexural extension in the foreland. Detailed reconstruction of the Setteporte and Monte Taburno structures shows main N-S/NNE-SSW trending thrusts, branching into NW-SE/E-W trending minor thrusts and back-thrusts, characterized by push-up geometry, typically referable to a transpressive deformation and/or to the positive reactivation of normal faults. Moreover, the sharp westward deepening of the base of the Apulian sedimentary succession (from 4.5 to 6.0 sec in TWT), based on the interpretation of the CROP 11 seismic reflection profile, and the concomitant increase in thickness of the Triassic sequence along the Maiella-Casoli transect, suggest the existence of west-dipping (?)Permian-Triassic normal faults that strongly controlled the distribution and thickness variation of syn-rifting sediments. An inversion of the deepest low angle portions of the pre- and syn-orogenic normal faults is in agreement with surface data (i.e., the structural elevation of the carbonate succession in the Casoli-Bomba anticline) and seismic line interpretation (i.e., deep seated location of the base of Apulian sedimentary succession below the same anticline). In the reconstructed inversion tectonics model, the N-S trending pre-thrusting normal faults are fully inverted as N-S transpressive segments of the salient structures of the chain, whereas, the NW-SE trending thrusts inverted the low angle portion of pre-thrusting normal faults in the middle-lower crust and displaced with a short-cut the normal faults in the upper portion of the crust. As a result, the pattern of the pre-existing normal faults is inherited on the salient structures of the Central and Southern Apennine Chain

The Pliocene-Quaternary salient structures of the Central and Southern Apennine chain inherited from pre-thrusting normal faults

The central Apennine Chain has been described as a fold- and-thrusts belt dominated by a thin-skinned tectonic style, that implies high estimates of orogenic shortening or according to a thick- skinned tectonic style, that implies a more conservative estimate of contraction. Several Authors have recently documented the inheritance of the Mesozoic paleomargin on the Neogene- Quaternary evolution of the Central Apennine Chain, emphasizing buttressing geometries and short-cut trajectories of the thrust planes through the pre- and syn-orogenic normal faults. A total, reverse-reactivation of the pre-existing normal faults has been proposed by a group of Authors. The aim of this paper is to reconstruct a crustal scale 3D model of tectonic inversion of the pre-thrusting normal faults (i.e., the Mesozoic pre-orogenic and the Messinian-Pliocene syn-orogenic normal faults) on the Pliocene-Quaternary development of salient structures in the outer Central Apennines (i.e., the Sibillini Mts-Olevano-Atrodoco, Montagna dei Fiori-Gran Sasso and Maiella-Sangro-Volturno thrusts) and in the buried chain of the Southern Apennines (e.g., the Setteporte structure) based on surface geological and structural data, and on seismic interpretation of industrial and public deep reflection profiles

The role of Adria paleomargin architecture on the geometry and kinematics of the Central-Southern Apennine during the Neogene-Quaternary evolution

The outer zones of the central Apennines are charac- terized by arcuate thrusts and related NE-verging folds that affect at least 2000 m thick Mesozoic-Neogene sedi- mentary succession (LAVECCHIA, 1981; GHISETTI & VEZ- ZANI, 1990). The base of the succession is represented by a massive 800 m thick carbonate platform unit of Early Liassic age (Calcare Massiccio Fm.), that grades upwards into well-bedded pelagic carbonates, marls and silicicla- stics. The Jurassic portion of the succession displays thickness and facies variations, that are controlled by syn- sedimentary normal faults: these dismembered the Early Liassic carbonate platform into differently subsiding sea- mounts and troughs. The subsequent onset of Neogene orogenic deformation was responsible for the contraction of the sedimentary succession. A detailed analysis of some anticlines reveals the oc- currence of high-angle thrusts within the Calcare Massic- cio Fm., whose displacements are accommodated by fol- ding within the overlying pelagic succession

Reservoir characteristics of fault-controlled hydrothermal dolomite bodies: Ramales platform case study

Hydrothermal dolomite (HTD) bodies are known as high-quality hydrocarbon reservoirs; however few studies focus on the geometry and distribution of reservoir characteristics. Across the platform-to-basin transition of the Ramales Platform, fault-controlled HTD bodies are present. Three kinds of bodies can be distinguished based on their morphology, that is, elongated HTD corridors, a massive HTD body (Pozalagua body) and an HTD-cemented breccia body. The differences in size and shape of the HTD bodies can be attributed to differences in local structural setting. For the Pozalagua body, an additional sedimentological control is invoked to explain the difference in HTD geometry. A (geo)-statistical investigation of the reservoir characteristics in the Pozalagua body revealed that the HTD types (defined based on their texture) show spatial clustering controlled by the orientation of faults, joints and the platform edge. Porosity and permeability values are distributed in clusters of high and low values; however, they are not significantly different for the three HTD types. Two dolomitization phases (i.e. ferroan and non-ferroan) can be observed in all HTD bodies. In general, the HTDs resulting from the second non-ferroan dolomitization phase have lower porosity values. No difference in permeability is found for the ferroan and non-ferroan dolomites. © The Geological Society of London 2012.Peer Reviewe

Active faulting in the Maiella massif (central Apennines, Italy)

The Maiella Massif is the outermost carbonate anticline of the central Apennines, and it is considered as the epicentral area of two major historical earthquakes: the 1706 (Maw = 6.60) and 1933 (Maw = 5.7) events. Geological and geomorphological surveys have defined the geometry and kinematics of the Late Pleistocene-Holocene faults in the Maiella area. These faults show mainly normal kinematics and are organised as a complex dextral en-echelon fault system. The north-eastern fault (the Palena fault) trends N110°-120° and cuts the southern sector of the Maiella Massif transversally, displacing debris deposits that have been radiocarbon dated to 36,300 ±1,300 yr BP. The southwestern fault affects the western slope of Mt. Porrara and is composed of three NNW-SS-oriented en-echelon segments, placing the Mesozoic-Cenozoic carbonate bedrock in contact with Late Pleistocene continental deposits. These normal faults of the Maiella area represent the eastern-most extensional structures of the chain. Geomorphic evidence suggests that the onset of the fault activity probably occurred more recently than along other central Apennine Quaternary faults. This supports the traditional view of an outward (eastward) propagating extensional deformation during the Pliocene-Quaternary. Moreover, the evidence of re-use of pre-existing faults in the cases investigated indicates that this migration of the extensional domain generally occurs through the reactivation of faults inherited from previous tectonic phases, the geometry for which is consistent with the present (N)NE-(S)SW direction of extension. Moreover, the structural framework appears to have been conditioned by the NNE-SSW crustal Ortona-Roccamonfina Line, the present expression of which is seen in a complex dextral oblique fault zone of Late Pliocene age (i.e., the Sangro-Volturno thrust zone). Finally, the integration of our field structural data with the subsurface data available for the on-shore Periadriatic area have allowed the identification of a more external zone (Apulian foreland) that is deformed by lateral and extensional active structures, and an inner zone east of the Maiella Massif that is affected only by the most recent buried thrusts of the chain. This evidence suggests no kinematic interactions at the upper crustal level between the active oblique faulting of the Apulian foreland and the extensional structures of the Apennine chain.Published57-733.2. Tettonica attivaN/A or not JCRrestricte

Active faulting in the Maiella massif (central Apennines, Italy)

The Maiella Massif is the outermost carbonate anticline of the central Apennines, and it is considered as the epicentral area of two major historical earthquakes: the 1706 (Maw = 6.60) and 1933 (Maw = 5.7) events. Geological and geomorphological surveys have defined the geometry and kinematics of the Late Pleistocene-Holocene faults in the Maiella area. These faults show mainly normal kinematics and are organised as a complex dextral en-echelon fault system. The north-eastern fault (the Palena fault) trends N110°-120° and cuts the southern sector of the Maiella Massif transversally, displacing debris deposits that have been radiocarbon dated to 36,300 ±1,300 yr BP. The southwestern fault affects the western slope of Mt. Porrara and is composed of three NNW-SS-oriented en-echelon segments, placing the Mesozoic-Cenozoic carbonate bedrock in contact with Late Pleistocene continental deposits. These normal faults of the Maiella area represent the eastern-most extensional structures of the chain. Geomorphic evidence suggests that the onset of the fault activity probably occurred more recently than along other central Apennine Quaternary faults. This supports the traditional view of an outward (eastward) propagating extensional deformation during the Pliocene-Quaternary. Moreover, the evidence of re-use of pre-existing faults in the cases investigated indicates that this migration of the extensional domain generally occurs through the reactivation of faults inherited from previous tectonic phases, the geometry for which is consistent with the present (N)NE-(S)SW direction of extension. Moreover, the structural framework appears to have been conditioned by the NNE-SSW crustal Ortona-Roccamonfina Line, the present expression of which is seen in a complex dextral oblique fault zone of Late Pliocene age (i.e., the Sangro-Volturno thrust zone). Finally, the integration of our field structural data with the subsurface data available for the on-shore Periadriatic area have allowed the identification of a more external zone (Apulian foreland) that is deformed by lateral and extensional active structures, and an inner zone east of the Maiella Massif that is affected only by the most recent buried thrusts of the chain. This evidence suggests no kinematic interactions at the upper crustal level between the active oblique faulting of the Apulian foreland and the extensional structures of the Apennine chain