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Intraplate strike-slip deformation belts: an introduction. In: Intraplate strike-slip deformation belts. F. Storti, R. Holdsworth & F. Salvini Editeurs
No full textIntraplate strike-slip deformation belts are typically steeply-dipping structures that develop in both oceanic and continental lithosphere where they form some of the largest and most spectacular discontinuities found on Earth. In both modern and ancient continental settings, intraplate strike slip deformation belts are of major importance in accomodating horizontal displacements where they additionally form very persistent zones of weakness that substantially influence the rheological behavior of the lithosphere over very long time periods (up to 1 Ga or more). These deformation zones provide a fundamental geometric, kinematic and dynamic link between the more rigid plate-dominated tectonics of the oceans and the non-rigid, complex behaviour of the continents. During convergence, they help to transfer major displacements deep into the plate interiors. During divergence, they act as transfer zones that segment rifts, passive continental margins and, ultimately, oceanic spreading ridges. Such belts are also of great economic importance, controlling the location of many destructive earthquakes, offshore and onshore hydrocarbon deposits and metalliferous ore deposits. In the oceans, intraplate strike-slip movements are relatively minor along transform-related fracture zones, but there are an increasing number of documented examples that may reflect spatial and temporal variations in spreading rate along individual active ridge segments
Particle size distributions in natural carbonate fault rocks: insights for non-self-similar cataclasis
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Earth and Planetary Science Letters
Volume 206, Issue 1-2, 30 January 2003, Pages 173-186
Particle size distributions in natural carbonate fault rocks: Insights for non-self-similar cataclasis (Article)
Storti, F. , Billi, A., Salvini, F.
Dipartimento Scienze Geol., Univ. degli Studi 'Roma Tre', Rome I-00146, Italy
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Abstract
Particle size distributions of cataclastic rocks influence the mechanical and fluid flow behaviour of fault zones. Available data from natural cataclastic rocks are still controversial and do not fully support a self-similar evolution for the cataclastic process, a concept derived from laboratory experiments and micromechanical modelling. Our analyses of particle size in carbonate fault rocks show power law distributions with fractal dimensions spanning a broad range. This confirms that the idea of a persistent fragmentation mechanism for describing the entire evolution of natural cataclastic fault cores in carbonate rocks is inadequate. Conversely, we propose that the fragmentation mechanism progressively changes with the intensity of comminution. Slip localisation within narrow shear bands is favoured when a favourable cataclastic fabric with fractal dimensions D ∼ 2.6-2.7 is achieved in the fault zone. Intense comminution in the narrow shear zones produces the preferential formation of small diameter particles resulting in particle size distributions characterised by D values approaching or exceeding 3. The non-self-similar evolution of natural cataclastic rocks has an important impact on the frictional and permeability properties of fault zones
<i>Editorial Note</i><br><br>A case of plagiarism: "Modelling of the wave fields by the modification of the matrix method in anisotropic media" published in Solid Earth Discuss., 6, 1–19, 2014
No full textNo abstract available
Incredulità e 'malsana curiosità' dell'opinione pubblica : la logica dell'istruttoria tra politica legislativa e giurisprudenza di Cassazione (1898-1930)
No full textPrendendo avvio dal fenomeno ampiamente documentato della sfiducia dell’opinione pubblica nazionale nella giustizia penale dell’epoca e dall’aspro contrasto tra i soggetti coinvolti nella repressione penale, il contributo esamina i difetti della legislazione unitaria in tema di procedimento di istruzione e il lungo lavoro di elaborazione del codice di procedura penale ‘liberale’ del 1913 teso ad eliminare tali difetti e l’inversione di tendenza attuata dal successivo codice fascista del 1930. La giurisprudenza non univoca della corte di Cassazione nell’interpretazione e nell’applicazione dei ‘nodi’ critici della normativa (sezione d’accusa, camera di consiglio, nullità, ruolo e funzioni del difensore e della giuria nei processi in assise) ebbe, per lo più, un ruolo decisivo nelle scelte del legislatore
Structural architecture and displacement accommodation mechanisms at the termination of the Priestley Fault, northern Victoria Land, Antarctica
No full textWe present the results of field investigations carried out at the southern termination of the Priestley Fault, a major Cenozoic right-lateral strike-slip fault system in northern Victoria Land, Antarctica. The Priestley Fault was originally traced from offshore seismic profiles. Its onshore prosecution was inferred from the regional geological picture. Our work provides the first robust dataset on the kinematics and structural architecture of the Priestley Fault. The fault system includes a principal displacement zone (PDZ), where most horizontal displacement is accounted for, and a transtensional splay zone (TSZ) in the southern side consisting of a major basin at the fault tip, the Terror Rift, and minor ones paralleling it cratonward. Part of the strike-slip displacement is transferred by fault splaying from the principal displacement zone to the basin-boundary faults in the transtensional splay zone. The principal displacement zone is characterised by strongly transpressive deformation and this contrasts with the extensional component occurring in the transtensional splay zone. Such a contrast is only apparent because the two regions are kinematically linked. Transfer of the residual right-lateral strike-slip displacement from the tip region of the principal displacement zone to the basin-boundary fault systems of the Terror Rift represents the most effective displacement compensation mechanism at the termination of the Priestley Fault. It provides an additional solution for reducing the well known and still fully unsolved discrepancy between large translations of adjacent crustal blocks and the lack of comparable displacement values in their boundary strike-slip fault systems. The unquestionable evidence of intense Cenozoic brittle deformations in north Victoria Land imposes a re-examination of the regional tectonic framework, commonly interpreted as the mere result of the Early Paleozoic Ross Orogeny
Three-dimensional architecture of growth strata associated to fault-bend, fault-propagation, and decollement anticlines in non-erosional environments
No full textThe evolution of surficial structures at the toes of orogens arises from the complex interplay between tectonic and surface processes. The internal architecture of syntectonic sediments has been shown to provide useful insights on the kinematic mechanism of folding. Two-dimensional templates of growth strata patterns associated to thrust-related anticlines are available in the literature. In this paper, we show the results of three-dimensional numerical modelling of growth fault-bend folds, fault-propagation folds, fixed limb length décollement folds and fixed limb dip décollement folds. We point out that total thickness contour maps, single syntectonic layer contour maps, and above all, the computation of their directional first-derivative maps, provide useful templates for inferring the kinematic mechanism of folding when compared with similar maps from natural examples. Application of these three-dimensional numerical models includes the comparison and supervised best fit with three-dimensional seismic reflection data sets. Numerical results are contrasted with the growth strata map patterns of the Mediano, Oliana and Pico del Aguila anticlines, in the Spanish Pyrenees
Modelling growth stratal architectures associated with double edge fault-propagation folding
No full textFault-related folds in fold-and-thrust belts and accretionary prisms are commonly simulated by three end-member classes of
geometric models: décollement folding, fault-propagation folding, and fault-bend folding. A given model produces a fold shape
that depends on the amount of shortening, the fault shape and, eventually, the fault propagation history. The great variety of
geometric solutions implies that the final fold shape is adequate to distinguish among different folding mechanisms only in a
limited suite of cases. Additional information to better constrain fold kinematics is provided by the analysis of growth strata
patterns, which passively register the progressive evolution of deformation in the substratum. Availability of growth strata pattern
templates associated with different geometric and kinematic solutions provides a useful tool for inferring the dominant kinematic
pathways of natural thrust-related structures.
In this paper, we present growth strata patterns associated with double-edge fault-propagation folding. The influence of the
sedimentation rate, the fault shape, and the fault S/P ratio (i.e. slip versus ramp propagation rate) on growth strata architectures are
investigated. Geometrical modelling and application to natural examples indicate that double-edge fault-propagation anticlines are
characterised by growth triangles on both limbs. Their position and geometry relate to the ramp shape and propagation history, and
on the sedimentation rate
Intraplate strike-slip tectonics as alternative to mantle plume activity for the Cainozoic rift magmatism in the Ross Sea Region, Antarctica
No full textDouble-edge fault-propagation folding: geometry and kinematics
No full textFault-bend folding is a common folding mechanism in thrust and fold belts worldwide. The widely used kink-band geometric model of
fault-bend folding necessitates complex ramp segmentations to reproduce the rounded shape of many natural thrust related anticlines.
Curvilinear hinge sectors provide a geometric and kinematic alternative solution to kink bands for modelling curved-hinge folds. We
developed an analytical solution for modelling fault-bend folding using circular hinge sectors. The velocity field of this kinematic solution is
different from that associated with the classical, kink-style model. Our solution predicts the development of curvilinear anticlines above
staircase fault geometries, the occurrence of limb rotation and, consequently, the development of rotational syngrowth wedges on both the
forelimb and the crest. Conversely to the kink-style kinematics, curvilinear hinge sectors imply a dependence of deformation intensity from
the fold shape and stratigraphic position of the folded layer. Application to natural thrust-related anticlines validates the effectiveness of
curvilinear fault-bend folding
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