1,720,972 research outputs found
3D model of a sector of the South Scotia Ridge (Antarctica).
No full textthree-dimensional geological model was built to show and analyse a northern sector of the Scotia-Antarctica transform plate boundary.
The South Scotia Ridge is a 400 kill long submerged continental structural high representing the eastern continuation of the Antarctic Peninsula. South Scotia Ridge runs approximately in the E-W direction, separating Scotia Sea Plate from Antarctica Plates. Structures, due to the transform plate margin, are considered to be concentrated inside this continental high. The three-dimensional model, built using seismic profiles and a digital elevation model, is a powerful tool to visualize and help to understand deep geological structures. Maps and profiles, on the contrary, only give a two-dimensional view, and do not show the structure of the continental-oceanic boundary at depth.
The model shows that the deformation style of the continental-oceanic boundary, and of the oceanic crust nearby, is related to the left-lateral movement of the main transform fault system. Furthermore, it seems to be connected to the orientation and geometry of the South Scotia Ridge with respect to the homogeneous deformation regime, which affects the entire Scotia Plate. Moving from west to cast, the NW-dipping main fault surface becomes almost vertical with a sinistral strike-slip movement in the central sector. To the east, a south-dipping plane decreases its inclination and changes orientation (from E-W to ESE-WNW): here shortening features are visible.
The three-dimensional geological model presents a western and central province wherein the continental-oceanic boundary involves the fragmented continental blocks, the continental slope, the oceanic basement and sediments. The sedimentary cover and the oceanic basement are not deformed in the eastern province
Sheet 280 – Fossombrone 3D: a study project for the new geological map of Italy at the scale of 1:50,000 in three dimensions.
No full text
Continent-ocean boundary along the western sector of the South Scotia Ridge
No full textThe South Scotia Ridge (SSR) is a submerged structural high located at the eastern continuation of the Antarctic Peninsula and representing the Scotia-Antarctica transform plate boundary. A three-dimensional geological model of a sector of the SSR was built using reflection seismic and sea-floor bathymetry. The model covers the boundary between the oceanic crust of the Scotia Sea and the continental crust of the South Scotia Ridge, where the orientation of the SSR structure changes from SW-NE to W-E.
Most of the active faults are located within the continental crust, however, deformation locally involves the oceanic crust and appears connected to the orientation and geometry of the fault system which defines the continent-ocean boundary.
The 3D geological model helps visualize a western and central province where the active boundary involves continental blocks, the continental slope, the oceanic basement and sediments, and an eastern province where the sedimentary cover is not deformed and the oceanic basement dips underneath the continent. Moving from west to east, the NW-dipping main transtensional fault system becomes almost vertical in the central sector with an almost pure sinistral strike-slip movement. To the east, a south-dipping plane is progressively less inclined and changes orientation: here evidence of shortening is visible
Melt migration in the upper mantle along the Romanche Fracture Zone (Equatorial Atlantic)
No full textTextural and petrological data of mantle peridotites sampled in the central and western parts of the Romanche Fracture Zone (Equatorial Atlantic) during the oceanographic expedition PRIMAR-96 (Russian R/V Gelendzhik) are presented. The studied rocks are mantle peridotites carrying patches, pockets and veins/dikes of magmatic origin, interpreted to be the product of various extents of magma impregnation on mantle partial melting residues. Estimated partial melting degrees based on clinopyroxene Ti/Zr ratios are in the ranges 5-13% and 18-20%. In highly impregnated samples, refertilization of residual peridotite minerals precludes a correct evaluation of the degree of melting. Magmatic products occur as pl±cpx±opx±ol±sp aggregates with various textural features. Interstitial pl-rich patches and gabbroic pockets are interpreted to derive from magma migration through the upper mantle by diffusive porous flow in the ductile part of the lithosphere and melt-rock reactions. Metasomatism of the host peridotites is testified by Ti and Cr increase in spinel and Ti, Sr, Zr, Y and LREE increase in clinopyroxene. Veins and dikes reflect channeled magma migration focused by brittle failures at shallower lithospheric levels. Minor or no chemical changes occurred in peridotites impregnated along fractures. The compositions of magmatic minerals in impregnated peridotites are consistent with derivation from variably fractionated melts of probably MORB type. Barometric estimates suggest that the Romanche peridotites were impregnated at minimum depths of ca. 9-12 km. Thermometric estimates for the peridotite hosts are in the range 750-1050 °C. The spread in temperature values is partly ascribed to localized heating by migrating melts of relatively cold peridotites. Our data and the occurrence of both fertile and depleted peridotites in a neighbouring area along the western Romanche FZ are in accord with the hypothesis of small-scale (<100 km) mantle heterogeneity along this fracture zone
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
- …
