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). 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 ' 22m high and ' 1100m in diameter with steep slopes (up to a dip of 22 ). It sits atop the Calabrian accretionary wedge and a system of flowerlike 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 crustalderived 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.Published1-233SR TERREMOTI - Attività dei CentriJCR Journa

Structural seng and sedimentary basins in the Western Margin of the Calabrian Arc

In this work, main tectonic and sedimentary aspects of the western margin of the Calabrian Arc have been described through an integrated approach, involving the analysis of mulchannel seismic lines, mulbeam data and Chirp profiles. Through the idenficaon of several seismic sequences, the characterizaon of basins internal geometry, the lateral variaon of thickness and the syntectonic nature it has been possible to link the sedimentary basins configuraon with the Alfeo Fault System geometry and acvity. On the base of our results, we aributed to the Alfeo Fault System the characteriscs of a Subducon Transform Edge Propagator (STEP) Fault. The distribuon of faults, the main sedimentary basins and the relaonship between deep and superficial deformaon allow us to compare the STEP fault features idenfied in the Calabrian Arc with other fault systems in the arc-shaped subducon zones of the world, finding the major affini es with the Carpathian and Barbados arcs

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

<p>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. </p

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, i.e. elongated HTD corridors, a massive HTD body (Pozalagua body) and a HTD cemented breccia body. The difference 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 dolomitisation phases (i.e. ferroan and non-ferroan) can be observed in all HTD bodies. In general the HTD resulting from the second non-ferroan dolomitisation phase have lower porosity values. No difference in permeability is found for the ferroan and non-ferroan dolomites.status: publishe