1,721,181 research outputs found
Determinazione dei meccanismi deformativi in calcari micritici di basso grado (Appennino meridionale) attraverso analisi al microscopio ottico, elettronico a scansione (SEM) e a trasmissione (TEM)
No full texttutor di Francesco d'Assisi Tramparulo - Tectonic, structural analysis and geodynamic evolution of Maghrebian Flysch Basin and Ligurian Accretionary Complex successions: examples in Western Mediterranean area.
No full textFinite strain estimation from deformed elliptical markers: The minimized Ri- (MIRi) iterative method
No full textA new technique for estimating the finite strain of deformed elliptical markers is presented. This method is based on the property of the arithmetic mean Rf- of the deformed object aspect ratios Rf to reach its minimum value in the undeformed state when they correspond to the initial aspect ratios Ri. The minimized Ri- (MIRi) iterative method furnishes the best results when, in the pre-strain state, the markers are uniformly orientated for every aspect ratio (Ri) class. A Matlab code, provided in this study, finds the best values of strain Rs and maximum stretching direction X that minimize the arithmetic mean Ri- by means of several iterations. In order to define the uncertainties of Rs and X, the code: (i) re-samples h-times the original (Ri, θ) dataset; (ii) assigns random values to the initial long axis angles θ ; (iii) deforms newly the synthetic dataset; (iv) re-applies the MIRi method; and finally (v) estimates the standard deviation for the (Rs, X) values. Tests of the method on synthetic aggregates of elliptical markers and two naturally deformed rocks provide strain values that are compared with estimations from other available methods
Determinazione dei meccanismi deformativi in calcari micritici di basso grado (Appennino meridionale) attraverso analisi al microscopio ottico, elettronico a scansione (SEM) e a trasmissione (TEM)
No full textSedimentology, stratigraphy and tectonics of evolving wedge-top depozone: Ariano Basin, southern Apennines, Italy
No full textThe late Zanclean wedge-top Ariano Basin, located in the external sector of the southern Apennines, was initially characterized by alluvial and fan-delta environments and successively, southward of Benevento-Buonalbergo fault, by a gradual drowning with coastal and alluvial plains evolving to shelf and marine coastal settings, respectively. Basin evolution continued with a synsedimentary uplift of different sectors resulting in variations in the drainage pattern and basin shape, and ultimately leading to complete basin closure and transition to continental depositional environments.
Early Pliocene palaeogeography, previous the Ariano Basin activity, is due to regional subsidence and subsequent differential uplifts resulted from geodynamic processes related to both the downgoing Apulian slab and the allochthonous orogenic wedge. Slab break off and the migration of a tear in the southeastward Apulian slab occurred, producing a strong subsidence in the external sectors of the southern Apennines recorded by the development of the Ariano Basin. Subsequently out-of-sequence synsedimentary thrusting, related to thin-skinned tectonics, occurred in the allochthonous units and unconformably overlying wedge-top basin deposits, producing northeastward migration of the main depocenters in the Ariano Basin. Finally renewed thrusting, related to the inversion of pre-existing normal faults located in the buried Apulian Platform and enhanced by regional uplift, affected the whole tectonic and sedimentary pile, as recorded by deformation of the overlying Pliocene deposits
Ruolo dello strain hardening nell’evoluzione delle zone di taglio: da deformazione omogenea ad eterogenea
No full textStrain analysis of heterogeneous ductile shear zones based on the attitudes of planar markers
No full textQuesto lavoro descrive un nuovo metodo di analisi di shear zone eterogenee e fornisce l'applicazione di questa metodologia ad alcune wrench zones duttili presenti in un plutone granitoide nelle Alpi orientali
Finite strain analysis of a natural ductile shear zone in limestones: insights into 3-D coaxial vs. non-coaxial deformation partitioning
No full textIn order to obtain new insights into the process of strain localization, a ca. 50 m thick shear zone has been investigated. The shear zone, located in the footwall to a major thrust, involves limestones and pelites. Calc-mylonites are characterized by a stretching lineation orthogonal to the shear direction and a foliation at an angle of 45-10 degrees to the thrust fault. Strain analysis and mean foliation analysis have been carried Out on 42 samples. Strain gradients and ellipsoid shape across the shear zone indicate, respectively, an increase of strain intensity approaching the thrust surface and overall oblate strain. Apparent flattening increases significantly for intensely deformed rocks. Theoretical models are proposed to explain the recorded finite strain configuration with a main deformation characterized by simultaneous simple shear and localized pure shear involving lengthening normal to the shear direction. A model of asymmetric lateral extrusion is adopted, as is consistent with measured horizontal strain gradients. This model also takes into account regional geological constraints such as the occurrence of accommodation space along the present-day Tyrrhenian extensional margin to the SW, and of a massive body of platform carbonates-forming a rigid buttress-to the NE
Influence of object concentration on finite strain and effective viscosity contrast: insights from naturally deformed packstones
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