Active deformation and relief evolution in the western Lurestan region of the Zagros mountain belt: new insights from tectonic geomorphology analysis and finite element modeling

none7noopenBasilici, M.; Ascione, A.; Megna, A.; Santini, S.; Tavani, S.; Valente, E.; Mazzoli, S.Basilici, M.; Ascione, A.; Megna, A.; Santini, S.; Tavani, S.; Valente, E.; Mazzoli, S

Non-volcanic CO2 and CH4 degassing in an actively extending orogen, southern Apennines, Italy

The southern Apennines fold and thrust belt has been undergoing post-orogenic extension since ca. 700 kyr. Crustal extension controls active tectonics and seismogenesis in the mountain chain [1], with seismicity being characterized by low to moderate magnitude events punctuated by strong earthquakes [2]. Effective decoupling between deep and shallow structural levels is related to the strong rheological contrast produced by a fluid-saturated, clay-rich mélange zone interposed between buried autochthonous carbonates – continuous with those exposed in the Apulian foreland – and the allochthonous units. This mélange zone also acts as a seal preventing the migration of deep-seated aqueous fluids – as well as oil in the Basilicata region, which hosts the largest Europe’s onshore oil fields – towards the surface. On the other hand, the mountain belt is characterized by substantial gas flow, recorded as both distributed soil gas emissions and vigorous gas vents, associated with active faults at the surface. We measured a CO2 flux up to 34000 g/m-2 per day at a gas vent, as well as large amounts of He (up to 52 ppm), Rn (up to 228 kBq/m3) and CH4 (up to 5000 ppm). Overpressured CO2, which has been proposed as triggering normal fault earthquakes in the Apennines, has been interpreted as mostly of mantle origin. However, our new results from isotope analyses carried out on the carbon contained in both CO2 and CH4 indicate a dominant thermogenic origin for these gases, probably associated with the emplacement of magmatic sills within the lower section of the thick carbonate platform succession occurring at the base of the sedimentary cover in the southern Apennines. Our results bear major implication concerning the postulated occurrence of crustal faults allowing fluids to migrate directly from mantle depths to the surface

Paleomagnetic and magnetic fabric data from Lower Triassic redbeds of the Central Western Carpathians: new constraints on the paleogeographic and tectonic evolution of the Carpathian region

In the Central Western Carpathians (CWC), most published paleomagnetic results from Permo-Mesozoic rocks document extensive remagnetizations and come from thin-skinned thrust units that have undergone multistage deformation.We present results from lower Triassic redbeds from the autochthonous cover overlying the basement that carry a primary magnetization. Petromagnetic results indicate that the dominant ferromagnetic carrier is hematite, while magnetic susceptibility and its anisotropy are controlled by both ferromagnetic and paramagnetic minerals. Magnetic fabrics document weak deformation related to Late Cretaceous shortening. The directions of the high unblocking temperature remanence components pass both reversal and fold tests, attesting to their primary nature. Paleomagnetic inclinations are flatter than expected from reference datasets, suggesting small latitudinal separation between the CWC and stable Europe. Paleomagnetic declinations are mostly clustered within individual mountain massifs, implying their tectonic coherence. They show only minor differences between the massifs, indicating a lack of significant vertical-axis tectonic rotations within the studied central parts of the CWC. The paleomagnetic declinations are therefore representative of the whole of the CWC in terms of regional paleogeographic interpretations, and imply moderate counterclockwise rotations (c. 26°) of the region with respect to stable Europe since the Early Triassic

Controls of Radiogenic Heat and Moho Geometry on the Thermal Setting of the Marche Region (Central Italy): An Analytical 3D Geothermal Model

none7sìopenSantini, S.; Basilici, M.; Invernizzi, C.; Jablonska, D.; Mazzoli, S.; Megna, A.; Pierantoni, P.P.Santini, S.; Basilici, M.; Invernizzi, C.; Jablonska, D.; Mazzoli, S.; Megna, A.; Pierantoni, P. P

thermal structure of the outer northern apennines along the crop 03 profile

In this study, we elaborated a 2D model that reproduces the thermal structure of the central-northern Adriatic offshore and adjacent onshore area of the Italian peninsula. Based on the crustal structure along the trace of the CROP-03 deep section, the geotherms offshore Gabicce (northern Marche region) were obtained by an analytical procedure taking into account the role of thrusting within the sedimentary cover. Basement involvement at depth beneath the neighbouring Mondaino area to the SW, where a crustal thrust ramp dips towards the hinterland, required the use of a different analytical procedure. The results obtained in this study allowed us to define a satisfactory description of the thermal state of the northern Marche coastal area and adjacent Adriatic offshore. These results, integrated with those obtained by previous studies, confirm that the isotherms of 250°C and 400°C are placed in the stable Adriatic lithosphere at depths of about 11 km and 22 km, respectively. Furthermore, the 400°C isotherm is deeper in the onshore area, reaching a depth of about 30 km in the zone comprised between Gabicce and Mondaino, whereas the 250°C isotherm deepens towards the SW along the Adriatic Sea sector, to reach a maximum depth of 13 km in coastal area, rising again at a depth of 11 km in the innermost sector of the studied section

Quaternary deformation in SE Sicily: Insights into the life and cycles of forebulge fault systems

Integrated geological, geomorphological, and differential interferometry synthetic aperture radar (DInSAR) data are used to constrain the timing and modes of activity of Quaternary fault systems in the Hyblean Plateau. This area, which represents a unique natural laboratory for studying surface deformation in relation to deep slab dynamics, has grown since middle Miocene times as a doubly plunging forebulge associated with slab rollback during NW-directed subduction. Bimodal extension has produced two mutually orthogonal normal fault systems. The detailed stratigraphic record provided by synrift sediments and postrift marine terraces allowed us to define the timing of activity of an early Pleistocene, flexure-related fault system, thus constraining the duration of a typical foreland extensional tectonic event to ~1.5 m.y. Subsequent late Quaternary to present deformation was dominated by strike-slip faulting associated with NW-oriented horizontal compression. During this latest stage, regional uplift progressively increased toward the thrust front to the NW and was accompanied by differential uplift accommodated by dip-slip components of motion along active NNW-trending faults. The general active tectonic setting of the study area, characterized by NW-oriented horizontal compression consistent with major plate convergence, and the regional uplift pattern can both be explained within the framework of intraplate shortening and foreland rebound following complete slab detachment, a major geodynamic event interpreted to have taken place at ca. 0.7 Ma in southern Italy