1,721,059 research outputs found
Multiscale structural analysis of an Epiligurian wedge-top basin: insights into the syn- to post-orogenic evolution of the Northern Apennines accretionary wedge (Italy)
Full text linkWedge-top basins represent useful tectonic elements for the characterisation of the evolution of their underlying accretionary wedge in space and time, as their final state of deformation sums up the bulk shortening and structural instability conditions of the wedge. Here, we present the geometric and kinematic patterns of deformation structures deforming the wedge-top Epiligurian basins of the Northern Apennines (Italy). Our main goals are to generate an evolutionary model to account for the syn- to post-orogenic evolution of the Epiligurian basins and to infer the building style of the Northern Apennines wedge during continental collision. Mesoscale structural analysis shows that common and widely distributed thrust and normal fault arrays deform the entire Epiligurian stratigraphic succession infilling the broadly E-vergent wedge-top basins. Thrusts are invariably cut by later NW-SE and NE-SW-striking normal and oblique fault systems characterised by fault planes that mutually intersect at all scales to form polygonal patterns. Remote sensing analysis of the tectonic structures affecting the Epiligurian formations confirms the variable orientation of both thrusts and normal faults within the different studied stratigraphic successions. As a whole, results suggest a polyphase tectonic evolution of the Epiligurian wedge-top basins during the widening of the Northern Apennines accretionary wedge towards the foreland by frontal accretion. The recognised main phases are: (i) syn-orogenic compression accommodating overall tectonic transport towards the eastern quadrants; (ii) post-orogenic extension genetically related to the extension of the inner zone of the Northern Apennines; (iii) more recent extension forming collapse-induced normal faults spatially arranged in polygonal patterns
P-T conditions of mylonitic shearing in the Granite Harbour intrusive complex of the Wilson Terrane, Deep Freeze Range, northern Victoria Land, Antarctica
No full textFaulting-hydrothermal circulation relationship constrained by thermogene travertne dating, Albegna Valley, Italy
No full textFluid assisted shearing at the depth of the Brittle-Ductile Transition: an integrated structural, petrological, fluid inclusions study of the Erbalunga shear zone, Schistes Lustrés Nappe, Alpine Corsica (France).
No full textThermal history of the Epiligurian Marzabotto wedge‐top basin records the tectonic development of the Northern Apennines (Italy)
No full textApatite fission track (AFT) and U-Th/He analyses (AHe) of detrital minerals from Eocene to Pliocene siliciclastic deposits in the Northern Apennines were here applied to constrain the tectono-thermal history of the wedge-top Epiligurian Marzabotto Basin (EMB). Detrital AFT age populations from Eocene to Miocene strata cluster between similar to 71 and similar to 58 Ma. AHe ages show a quite variable single grain age distribution ranging from similar to 104 to similar to 7 Ma indicating some degree of post-depositional thermal resetting. Thermal modelling of AFT and AHe data indicates that the EMB experienced a maximum temperature of similar to 90 degrees prior to Oligocene-to-Pliocene cooling. We interpret the Oligocene-Early Miocene cooling signal to represent rock uplift associated with growth of the Apennines orogenic wedge and the late Miocene-Quaternary cooling to track frontal accretion in the orogenic wedge concomitant with rollback-driven extension
Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy
No full textThe controversial relationship between the orogenic segments of the Western Alps and the Northern Apennines is here explored integrating recently published 3D tomographic models of subduction with new and re-interpreted geological observations from the eclogitic domain of the Voltri Massif (Ligurian Alps, Italy), where the two belts joint each other. The Voltri Massif is here described as an extensional domain accommodating the opposing outward migration of the Alpine and Apennine thrust fronts, since about 30–35 Ma. Using tomographic images of the upper mantle and paleotectonic reconstructions, we propose that this extensional setting represents the surface manifestation of an along strike change in polarity of the subducted oceanic slab whose polarity changed laterally in space and in time. Our tectonic model suggests that the westward shift of the Alpine thrust front from the Oligocene onward was the consequence of the toroidal asthenospheric flow induced by the retreat of the Apenninic slab
Uno strumento per il dimensionamento dei radiatori nei sistemi di raffreddamento motoristici
No full textMiocene-to-Quaternary oblique rifting signature in the Western Ross Sea from fault patterns in the McMurdo Volcanic Group, north Victoria Land, Antarctica
No full textMt. Overlord and Mt. Melbourne are part of the fossil-to-active eruptive centre belt of the McMurdo Volcanic Group, located along the western shoulder of the West Antarctic Rift System in north Victoria Land (Antarctica). The formation and localisation of these volcanic centres are intimately connected to the regional fault patterns associated with Neogene transtensional stretching in the West Antarctic Rift System. This study reports about 900 structural data of faults and fault-related joints affecting the Miocene–Pliocene deposits of Mt. Overlord and the Plio-Quaternary deposits of Mt. Melbourne. Fault surfaces strike along three main directions (NW–SE, NE–SW, and N–S) with high (> 70°) dip angles. The reconstructed fault geometries and kinematics document a NW–SE strike-slip fault system having dextral motion in the Mt. Overlord area, which evolves into a more complex structural architecture characterised by transtensional deformations in the Mt. Melbourne area, where volcanism is still active. The fault array can be reconciled with principal and subordinate deformation structures developed at the termination region of NW–SE intraplate strike-slip fault systems inducing oblique rifting in the West Antarctic Rift System. The structural dataset, integrated with available geochronological constraints, gives rise to a two-step (Miocene-to-Holocene) tectonic scenario in which the spatial migration of the volcanic activity towards the eastern boundary of the Transantarctic Mountains occurred during the evolution of the West Antarctic Rift System
Reply to the comment by G. Capponi et al. on “Subduction polarity reversal at the junction between the Western Alps and the Northern Apennines, Italy”, by G. Vignaroli et al. (Tectonophysics, 2008, 450, 34–50)
No full textConstraints on upper crustal fluid circulation and seismogenesis from in-situ outcrop quantification of complex fault zone permeability
Full text linkThe permeability of fault zones plays a significant role on the distribution of georesources and on seismogenesis in the brittle upper crust, where both natural and induced seismicity are often associated with fluid migration and overpressure. Detailed models of the permeability structure of fault zones are thus necessary to refine our understanding of natural fluid pathways and of the mechanisms leading to fluid compartmentalization and possible overpressure in the crust. Fault zones commonly contain complex internal architectures defined by the spatial juxtaposition of "brittle structural facies" (BSF), which progressively and continuously form and evolve during faulting and deformation. We present the first systematic in-situ outcrop permeability measurements from a range of BSFs from two architecturally complex fault zones in the Northern Apennines (Italy). A stark spatial heterogeneity of the present-day permeability (up to four orders of magnitude) even for tightly juxtaposed BSFs belonging to the same fault emerges as a key structural and hydraulic feature. Insights from this study allow us to better understand how complex fault architectures steer the 3D hydraulic structure of the brittle upper crust. Fault hydraulic properties, which may change through space but also in time during an orogenesis and/or individual seismic cycles, in turn steer the development of overpressured volumes, where fluid-induced seismogenesis may localize
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