Search results for "Tectonics"

Backthrusts and passive roof duplexes in fold-and-thrust belts

2012

Abstract Seismic reflection profiles crossing the area bounded by the M. Kumeta Ridge and the M. Maranfusa-M. Galiello-Rocca Busambra morphostructural feature (central-western Sicily) were used to constrain the deep structural setting of the Sicilian–Maghrebian fold-and-thrust belt (FTB). By integrating seismic, field and well data, we attempted to correlate outcropping and deep-seated contractional structures, shedding light on the internal geometries of the thrust system. Results of the new seismostratigraphic analysis presented in this paper reveal structural variations along the tectonic edifice. This suggests dividing the study area into two sectors: the western sector is characterized…

Numerical investigation of deformation mechanics in fold-and-thrust belts: Influence of rheology of single and multiple décollements

2012

[1] Thin-skinned fold-and-thrust belts related to convergence tectonics develop by scraping off a rock sequence along a weaker basal decollement often formed by water-saturated shale layers or low-viscosity salt horizons. A two-dimensional finite element model with a viscoelastoplastic rheology is used to investigate the structural evolution of fold-and-thrust belts overlying different types of decollements. In addition, the influence of multiple weak layers in the stratigraphic column is studied. Model shale decollements are frictional, with lower friction angles as the cover sequence. Model salt layers behave linear viscous, due to a lower viscosity as the cover sequence, or with a power …

2021

Abstract. Foreland fold-and-thrust belts (FTBs) record long-lived tectono-sedimentary activity, from passive margin sedimentation, flexuring, and further evolution into wedge accretion ahead of an advancing orogen. Therefore, dating fault activity is fundamental for plate movement reconstruction, resource exploration, and earthquake hazard assessment. Here, we report U–Pb ages of syn-tectonic calcite mineralizations from four thrusts and three tear faults sampled at the regional scale across the Jura fold-and-thrust belt in the northwestern Alpine foreland (eastern France). Three regional tectonic phases are recognized in the middle Eocene–Pliocene interval: (1) pre-orogenic faulting at 48.…

Tectonic transport directions of the Lycian nappes in southwest Turkey constrained by kinematic indicators

2013

The orientation, asymmetry and cross-cutting relationships of the structures along the contact zone between the Lycian nappes and the Menderes Massif suggest the presence of three deformation phases in the Milas region of southwest Turkey. The first deformation phase (D1) is characterized by a ductile deformation with top-to-the-NE sense of shear. Structural data of the first deformation measured along the uppermost part of the Menderes Massif and the base of the Lycian nappes suggest that the lowermost unit of the Lycian nappes was emplaced initially from southwest to northeast onto the Menderes Massif during the Early Eocene. The second deformation phase (D2) is also ductile in nature and…

Fluid geochemistry and CO2 output in the southern Apennine (Italy): Preliminary results from the study of cold and thermal waters

2019

Waveforms clustering and single-station location of microearthquake multiplets recorded in the northern Sicilian offshore region

2013

In 2009 December, the OBSLab-INGV (Istituto Nazionale di Geofisica e Vulcanologia) deployed an Ocean Bottom Seismometer with Hydrophone (OBS/H) near the epicentral area of the main shock of the Palermo seismic sequence of 2002. The monitoring activity had a total duration of about 8 months. During this experiment, the OBS/H recorded 247 very local microearthquakes, whose local magnitude is between -0.5 and 2.5 and TS - TP delay time between 0.2 and 5 s, almost all ofwhichwere undetected by the Italian National Seismic Network. This local microseismicity has been analysed using an innovative clustering technique that exploits the similarity between the waveforms generated by different events…

A multidisciplinary approach to the evaluation of the mechanism that triggered the Cerda landslide (Sicily, Italy).

2005

Abstract The present paper describes a multidisciplinary approach to the evaluation of a seismically triggered landslide that occurred in the Cerda area (Italy) on September 6, 2002, about 1 h after an earthquake took place in the south Tyrrhenian Sea. The study was focused on an analysis of the role of the seismic input in triggering the landslide, in view of the evidence that no other mass movement was recorded in the adjacent areas despite geological and geomorphological spatial homogeneity. The studied area is located on a slope of the western flank of the Fiume Imera Settentrionale (Northern Sicily), which is made up of clayey–arenitic rocks. The slope inclines gently but is not unifor…

Present-day uplift of the European Alps: Evaluating mechanisms and models of their relative contributions

2019

Abstract Recent measurements of surface vertical displacements of the European Alps show a correlation between vertical velocities and topographic features, with widespread uplift at rates of up to ~2–2.5 mm/a in the North-Western and Central Alps, and ~1 mm/a across a continuous region from the Eastern to the South-Western Alps. Such a rock uplift rate pattern is at odds with the horizontal velocity field, characterized by shortening and crustal thickening in the Eastern Alps and very limited deformation in the Central and Western Alps. Proposed mechanisms of rock uplift rate include isostatic response to the last deglaciation, long-term erosion, detachment of the Western Alpine slab, as w…

Depositional environment and biofacies characterisation of the Triassic (Carnian to Rhaetian) carbonate succession of Punta Bassano (Marettimo Island…

2007

AThe aims of this study are to reconstruct the geological setting of the Punta Bassano series (Marettimo Island, Egadi Archipelago, western Sicily) and its palaeogeographic evolution. The reference section for the Upper Triassic of Marettimo shows an alternation of marl and limestone beds together with brecciated levels. The limestones are both homogeneous mudstones with evaporite pseudomorphs and laminated with fenestrae. Foraminiferal, palynomorph, and ostracod associations constrain the Punta Bassano sequence to the Carnian-Rhaetian interval. The Punta Bassano succession represents a shallow inner ramp, ranging from open-marine environment with good water circulation to lagoonal and peri…

The Palermo (Sicily) seismic cluster of September 2002, in the seismotectonic framework of the Tyrrhenian Sea-Sicily border area

2009

The northern coast of Sicily and its offshore area represent a hinge zone between a sector of the Tyrrhenian
 Basin, characterized by the strongest crustal thinning, and the sector of the Sicilian belt which has emerged. This
 hinge zone is part of a wider W-E trending right-lateral shear zone, which has been affecting the Maghrebian
 Chain units since the Pliocene. Seismological and structural data have been used to evaluate the seismotectonic
 behavior of the area investigated here. Seismological analysis was performed on a data set of about 2100 seismic
 events which occurred between January 1988 and October 2002 in the Southern Tyrrhenian Sea. This paper
 focuses…