Wedges Research Articles

UHP GARNET ORTHOPYROXENITES (DABIE SHAN, CHINA) AS MONITORS OF PERCOLATION OF HYDROUS SI-RICH MELTS IN DEEP SUBDUCTION ENVIRONMENTS

UHP GARNET ORTHOPYROXENITES (DABIE SHAN, CHINA) AS MONITORS OF PERCOLATION OF HYDROUS SI-RICH MELTS IN DEEP SUBDUCTION ENVIRONMENTS

Wedges and Taxes

Wedges and Taxes

Analysis of the Ultrasonic Beam Profile Due to Variation of the Inter-Element Spacing for the Phased Array Transducer

The phased array transducer has two distinct advantages. One is rapid scanning comparing with the conventional mechanical or manual scanning system. Therefore, output image is represented in real-time. The other is the dynamic focusing and the dynamic steering of ultrasonic beam. Only the delay times that are controlled electrically are used to focus and to steer beam without any lenses or wedges. In this study, the profile of the ultrasonic beam for the phased array transducer has been simulated in the Huygens principle with varying the inter-element spacing of the linear phased array transducer. From the result of this study, it was found that the ultrasonic beam spread wider as the inter-element spacing was decreased. However, the focusing effect was improved, even when the number of the element was not big. In addition, there was grating lobes that are constructed when the inter-element spacing is more than half wavelength. However, this grating lobe has lower amplitude than the main lobe.

The basal complex stratigraphy of the Helminthoid Monte Cassio Flysch: A key to the eoalpine tectonics of the Northern Apennines

Below the Monte Cassio helminthoid Flysch of the type locality, a well exposed basal complex outcrops in which Cenomanian turbidites of up to 200 m thickness are recognized. The bulk of these turbidites, named here Case Baruzzo Sandstone (CBS), consists of thick-bedded silty marlstones with a fine arenaceous base and represents the oldest siliciclastic input within the succession of the Cassio tectonic unit. The Case Baruzzo Sandstone lies unconformably on the Palombini shale of Hauterivian-Aptian age and on stratified packets of Jurassic-Cretaceous formations with Austroalpine affinity (Radiolarites, Aptici Shale and Maiolica). The Cenomanian CBS are unconformably overlain by Varicoloured Clay of Santonian - Campanian age and affected by soft-sediment deformations. The petrography of the CBS shows two petrofacies indicating (1) a direct provenance from their substrate and (2) an extrabasinal source similar to the terrigenous framework of the tectonically independent Coniacian-Santonian Ostia Sandstone outcropping southwest of the Cassio Unit. Because of its Cenomanian age the CBS must be considered as a siliciclastic wedge distinct from the younger Ostia Sandstone belonging to the Media Val Taro Unit and time correlative to the Varicoloured Clay of the Cassio Unit. The initiation of the turbidite sandstones terrigenous supply is Cenomanian into the Cassio Basal Complex (CBS), Coniacian into the Media Val Taro Unit (Ostia Sandstone) and Campanian into the more internal Gottero Unit (fine-grained turbidites interbedded within the Val Lavagna Formation). It is proposed that the relative positions of the highest tectonic units outcropping in the Emilian Apennines (i.e. Gottero, Media Val Taro and Cassio Units) during Late Cretaceous were not very different to the present setting, and that their tectono-stratigraphic evolution was related to Alpine-vergent accretionary wedges. The Alpine tectonic polarity should have controlled the westwards migration of the basinal depocentres and the evolution from the Adriatic-margin supply of the Cenomanian turbidites to the European-margin supply of the Maastrichtian turbidites. During the middle Eocene tectonic phase, before the counterclockwise apenninic rotation, the ophiolite-free Cretaceous Ligurian Units (i.e. Gottero, Media Val Taro, Cassio) overthrusted the Ligurian Units characterized by late Cretaceous ophiolitic detritus, known as Ottone and Caio Units, along a significant lithospheric discontinuity which acted as a transpressive fracture zone.

PROVENANCE FROM OPHIOLITES AND OCEANIC ALLOCHTONS: MODERN BEACH AND RIVER SANDS FROM LIGURIA AND THE NORTHERN APENNINES (ITALY)

The Northern Apennine arc consists of allochtonous oceanic units (Ligurids) and synorogenic terrigenous wedges, and includes both alpine (Voltri Massif) and apenninic (Bracco Unit) ophiolitic complexes and isolated slabs of oceanic lithosphere (Casanova Complex). Detritus transported by streams in this vast region, comprised between Bologna and Alessandria, and sand of Liguria beaches from Savona to La Spezia can be distinguished - through analysis of framework composition and transparent heavy mineral suites - in four provinces, further subdivided in sub-provinces and variants. The Apennine Province and the Antola Province are carbonaticlastic and characterized by recycling of Ligurid flysches, whereas the Voltri Province and the Bracco Province are dominated by ophioliticlastic detritus. Along the boundaries of major ophiolitic complexes various sub-provinces with mixed provenances characerized by significant ophioliticlastic detritus are recognized (Bormida di Spigno and Polcevera river sands, and Celle-Varazze beach sands for the Voltri Massif; Vara, Lavagna and Ghiaiaro river sands for the Bracco Unit). Ophiolite-derived material dominates the heavy mineral fraction also in the sand transported by major streams draining the Emilia Apennines (Trebbia, Nure, Taro). Framework composition and heavy mineral suites clearly differentiate the serpentineschist- and amphibole-rich (glaucophane, actinolite) detritus derived from alpine ophiolites involved in thick-skinned deformation and high-pressure metamorphism (Voltri Massif), from the serpentinite- and pyroxene-rich (diallage) detritus derived from oceanic lithosphere involved in thin-skinned deformation within the Apennine belt (Bracco Unit; Casanova Complex). In the study of ancient perisutural-basin clastic wedges, these criteria can help reconstructing subduction style and paleogeodynamic evolution of associated suture belts.

A new approach to study the architectural arrangement of spermatogenic stages revealed little evidence of a partial wave along the length of human seminiferous tubules.

Although evidence of the spermatogenic wave in humans has been reported, little is known about the architectural arrangement of stages along the length of tubules in men with varied rates of sperm production. To conduct these studies, methodology is needed to stage relatively long lengths of straight portions of tubules in several men. Testes obtained at autopsy were glutaraldehyde perfused. Six men representing a range of daily sperm production were selected for this study. Wedges composed of groups of seminiferous tubules attached to the rete testis and separated by testicular septa were teased apart from the remaining testicular tissue, fixed in osmium, and oriented during Epon embedding. This orientation allowed for sections to be cut perpendicular to the length of the group of tubules, beginning at the end near where the tubules had been attached to the rete testis. Also, a tubule isolated away from the rete testis was oriented for perpendicular sectioning for one of the men. Several serial sections were cut at a setting of 22 microns, and each was optically sectioned approximately at 7 microns and photographed using Nomarski optics. Because many cytoplasmic and nuclear features of spermatogonia, spermatocytes, and spermatids were distinguished in photomicrographs produced by Nomarski optics, this optical system facilitated the identification of stages of the spermatogenic cycle in human seminiferous tubules.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanics of extensional wedges

Mechanics of extensional wedges

Activities: Understanding Angles: Wedges to Degrees

Activities: Understanding Angles: Wedges to Degrees

Edges and Wedges

Edges and Wedges

Deviation drilling without wedges : Kaspersen, P; Oden, A Proc Drillex 87, Stoneleigh, 7–10 April 1987P75–82. Publ London: IMM, 1987

Deviation drilling without wedges : Kaspersen, P; Oden, A Proc Drillex 87, Stoneleigh, 7–10 April 1987P75–82. Publ London: IMM, 1987

Wedges I

Wedges I

Physical and numerical experiments with granular wedges

This Paper describes the development of a numerical model for discontinua, the discrete stiffness model, Comparison with physical observations on granular wedges indicates that the simple form in which the model reduces to a lattice analogue with nodes connected by discrete elements is adequate for granular media. The resulting solutions are shown to approach closely the previously derived clastic solutions. Examinations of the associated displacement patterns emphasizes the need for careful interpretation of displacement monitoring of earth and rock structures for stability purposes. L'article décrit la mise au point d'un modèle numérique pour discontinua, le Modèle de Rigidité Discrète. Par comparaison avec des observations physiques de prismes granulaires, on peut voir que la forme simple du modèle qui se réduit à une représentation analogique sous forme de réseau dont les noeuds sont reliés par des éléments discrets, convient bien aux milieux granulaires. L'article montre que les solutions qui en resulter sont très proches des solutions clasiques qui avaient été trouvées précédemment. L'examen des chemins de déplacement associés met en évidence la nécessité d'une interprétation minutieuse du contrôle du déplacement de structures en terre et en roche effectué à des fins de stabilité.

Interpretation of Merged Layer Behavior for Wedges

Interpretation of Merged Layer Behavior for Wedges

The first report on “till wedges” in Europe — a reply

(1973). The first report on “till wedges” in Europe — a reply. Geologiska Foreningen i Stockholm Forhandlingar: Vol. 95, No. 1, pp. 156-157.

Ground-ice wedges interpreted by A. von Bunge (1884) in Siberia

Ground-ice wedges interpreted by A. von Bunge (1884) in Siberia

Apparatus for measuring pH by colour wedges

Apparatus for measuring <i>p</i>H by colour wedges