1,720,965 research outputs found
Does a detachment level exist beneath the Ceraunius Fossae? Insights from graben mapping and lost-area balancing analysis
No full textWe took advantage of the close relationship between graben width and rheology of the involved materials (e.g., number, thickness and spacing of rheological layers, presence of mechanical discontinuities of different nature) and attempted to obtain information about the mechanical stratigraphy of the Ceraunius Fossae area (Northern Tharsis Region). The possible existence of detachment levels beneath the Ceraunius Fossae area were investigated using the lost-area balancing method and a topographic profile derived from Mars Orbiter Laser Altimeter (MOLA) data. Results suggest a marked difference in structural style between the western and eastern sectors of the study area, which is interpreted as a result of different mechanical stratigraphies. On the western sector the maximum depth reached by grabens is well localized within 1000 m from the topographic surface suggesting the existence of a detachment level, which we interpret as a weak horizon at the base of the Late Hesperian-Early Amazonian units. The ductile behaviour of this horizon could be favoured by the presence of volatile reservoir or ice. In the eastern sector of the profile (HNf and Hf units) the maximum depth reached by the grabens is scattered and does not support the existence of clearly defined detachment horizons suggesting that Noachian Fractured Rocks are mechanically homogeneous. A maximum depth, however, could be established
Sheet 280 – Fossombrone 3D: a study project for the new geological map of Italy at the scale of 1:50,000 in three dimensions.
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3D Structure of the northern Marche Region and implications for the active tectonics of the outer northern Apennines (Italy).
No full text3D Model of the active extensional fault system of the high Agri River valley, Southern Apennines, Italy
No full textThe high Agri River valley (southern Apennines, Italy) hosts an active fault system, and a severe earthquake struck the area in 1857 (equivalent magnitude Me = 6.98; Imax = XI). In this study, we integrated surface geology with available subsurface data in order to propose a new 3D structural model for the high Agri River valley fault system. The model presented here is based on a series of published deep geological sections across the study area, using the software 2D Move and 3D Move (Midland Valley Exploration Ltd.). It displays the active extensional fault system dissecting the pre-existing southern Apennines fold and thrust belt. This region is characterised by the tectonic superposition of carbonate platform and pelagic basin allochthonous units onto a several km-thick carbonate platform succession representing the underthrusting foreland sequence. The detachment between the allochthon and the buried carbonate platform succession is marked by a several hundreds of metres thick mélange zone which consists mainly of intensely deformed and overpressured deepwater mudstones and siltstones. The 3D model shows that, at surface, the valley is asymmetric, with the most relevant normal faults, as well the maximum thickness of Quaternary alluvial deposits, located along its northeastern side. Locally, minor antithetic faults generate secondary grabens. All these faults occur only in the shallow brittle layer. At depth, a normal fault cuts the top of the deeper unit just below the central part of the Quaternary plain, and does not continue in the tectonic units above. This SW-dipping feature, extending for about 20 km into a WNW-ESE direction, appears to be the most probable deep structure responsible for the development of the active fault system. Therefore, it is also likely to be the source of strong earthquakes such as the 1857 event. The 3D model outlines the mechanically fundamental role played by the ductile mélange zone, which controls the modes of fault propagation from the deep brittle layer to the shallow (allochthonous) one
Il Foglio 280 – Fossombrone 3D: un progetto pilota per la cartografia geologica nazionale in tre dimensioni
No full textUnderstanding the geometry of structures and relationships among stratigraphic and tectonic units at the depth is one of the main challenges faced by geologists. This aim is traditionally pursued through interpreting geological and geophysical data in one or two dimensions (logs of deep wells, stratigraphic columns, cross-sections, structural maps) and performing structural analysis (cut-off lines maps, branch lines maps, restoration and balancing of crosssections). The recent development of software devoted to geological modelling in three-dimensions represents a significant resource for geologists for reconstructing and visualizing geological bodies at depth (SLAT et alii, 1996; DE DONATIS, 2001). Geological models in three-dimensions integrate different kinds of data (cross-sections, seismic profiles, logs of deep wells) more easily than traditional techniques and allow a more coherent and exhaustive representation of the reality. Furthermore, progressive insertion of data in the model makes the geologist able to verify step by step the quality of his previous interpretations and to reach better results through iterative corrections. The aim of this prototype study project is to define and test a methodology for building three-dimensional geological models based on maps on the scale of 1:50000, from the new Italian geological mapping program. Another target of this work is to test the suitability of the national geological data base for 3D reconstruction purpose (DE DONATIS et alii, 2002). The recently developed three-dimensional visualization technique is used to build a structural model of sheet 280-Fossombrone, an external area of northern Apennines, central Italy. This area is characterized by faulted anticlines and broad synclines, involving a Triassic-Paleogene succession that is detached from the underlying basement. The exhaustive knowledge of the regional and local geology together whith the availability of subsurface (well and seismic) data makes this area a good test to define a methodology for building a 3D geological map. This model has been built in two main steps. In the first step, a 2.5 dimensional geological model has been built using a digital elevation model and the new geological map of the study area at the scale of 1:50000. This 2.5 model better shows the relationships among topography, geology and main structures better than traditional 2D geological maps. During the second phase a deep model was built, integrating a large amount of sub-surface data, as commercial seismic profiles (arising from hydrocarbon explorations made by Eni - div. Agip during past decades) and deep well logs, with field data resulting from the recent mapping project. The whole 3D geological model of Sheet 280-Fossombrone allowed a better understanding of the geometry of the deep structures and the kinematics of this external part of northern Apennines. Structural and geomorphological analysis are performed on the model to improve the knowledge of several aspects of the study area
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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