Search results for " ROC"
showing 10 items of 951 documents
Structural highs formation and their relationship to sedimentary basins in the north Sicily continental margin (southern Tyrrhenian Sea): implication…
2005
Two high-penetration seismic profiles across the continental margin of north Sicily (southern Tyrrhenian Sea) have been interpreted to construct a crustal section across the margin and to provide a three-dimensional perspective on the upper crustal setting of the Solunto High and its structural relationships with the adjacent Cefalù Basin. Crystalline rocks of the Kabilian-Calabrian Units (KCU) are recognized in the Solunto High region and farther to the north. The KCU body is tectonically superimposed onto sedimentary rocks pertaining to the Sicilian-Maghrebian Units (SMU) and the Solunto High corresponds to the thrust sheet culmination. Its occurrence in the Solunto High demonstrates that…
Post-collisional adakite-like magmatism in the Ağvanis Massif and implications for the evolution of the Eocene magmatism in the Eastern Pontides (NE …
2011
In the Anatolia, the Caucasus and northwest Iran, the Eocene epoch is characterized by widespread basic to acidic magmatism, whose temporal and spatial evolutions and origin are poorly understood. In this paper, we provide geochronological and geochemical data on a suite of Early Eocene intrusions from northeast Turkey and discuss their origin within a regional tectonic framework. Post to late-collisional, moderate to small bodies of quartz diorite and leucogranodiorite as well as later dacite porphyries intrude Permo-Triassic low-grade metamorphic rocks in the southern part of the Eastern Pontides very close to the Neo-Tethyan Izmir-Ankara-Erzincan suture. In places, the intrusives display…
Characterization of an early metamorphic stage through inclusions in zircon of a diamondiferous quartzofeldspathic rock from the Erzgebirge, Germany
2003
About 1000 zircon grains from a diamondiferous quartzofeldspathic rock of the Saxonian Erzgebirge were investigated for inclusions using optical microscopy and confocal laser-Raman spectroscopy. Cathodoluminescence imagery was applied to characterize the growth zone of zircon where the inclusions occurred. The most abundant inclusion minerals are microdiamonds. Coesite was not detected. However, garnet and jadeite occur as rare inclusions in zircon cores where diamonds are lacking. Jadeite was detected for the first time in quartzofeldspathic rocks from the crystalline complex of the Erzgebirge. The compositions of the pristine garnets in the zircons are similar to those of core areas of mi…
Internal Differentiation of the Archean Continental Crust: Fluid-Controlled Partial Melting of Granulites and TTG-Amphibolite Associations in Central…
2009
Fault bound blocks of granulite and enderbite occur within upper amphibolite-facies migmatitic tonalitic-trondhjemitic-granodioritic (TTG) gneisses of the Iisalmi block of Central Finland. These units record reworking and partial melting of different levels of the Archean crust during a major tectonothermal event at 2·6-2·7 Ga. Anhydrous mineral assemblages and tonalitic melts in the granulites formed as a result of hydrous phase breakdown melting reactions involving amphibole at peak metamorphic conditions of 8-11 kbar and 750-900°C. A nominally fluid-absent melting regime in the granulites is supported by the presence of carbonic fluid inclusions. The geochemical signature of light rare e…
Controllable Solid Rocket Motor Nozzle Operations in Conditions of Limited-Amplitude Fluctuations
2009
A nonlinear multi scale analysis of a controllable solid rocket motor operating in conditions ranging from high-amplitude fluctuations in combustion chamber to conditions lying in limit cycle is presented and the motor behavior subsequent to some relevant nozzle operations is investigated. Effects of acoustic-vorticity-entropy wave coupling, wave steepening, rotational/viscous flow losses, steep-fronted wave losses are taken into account and oscillatory energy losses in pintle-nozzle, unsteady combustion and chamber geometry changes resulting from grain regression are included. The analysis provides evidence that the unsteady energy balance and the motor wave amplitude evolution are influen…
Diagénesis, análisis de procedencia y ambiente tectónico de rocas siliciclásticas. Un caso de estudio en el Devónico Superior de la Cordillera Ibéric…
2022
This paper describes the petrography and infers the provenance of siliciclastic rocks from the Upper Devonian of the Iberian Chains (Tabuenca, NE Spain), and outlines the tectonic setting associated with the Ebro Massif. These Devonian deposits are constituted by four different siliciclastic units: the Rodanas, Bolloncillos, Hoya and Huechaseca Formations. The provenance and diagenesis of over 400 sedimentary rocks samples are studied with a combination of petrographic polarizing microscope, scanning electron microscopy, atomic absorption spectroscopy, X-ray fluorescence and X-ray diffraction. In this sense, AAS and XRF analysis were used to determine the content of Ca, Mg, Fe, Mn, Na, K an…
A strike-slip core complex from the Najd fault system, Arabian shield
2014
Metamorphic core complexes are usually thought to be associated with regional crustal extension and crustal thinning, where deep crustal material is exhumed along gently dipping normal shear zones oblique to the regional extension direction. We present a new mechanism whereby metamorphic core complexes can be exhumed along crustal-scale strike-slip fault systems that accommodated crustal shortening. The Qazaz metamorphic dome in Saudi Arabia was exhumed along a gently dipping jog in a crustal-scale vertical strike-slip fault zone that caused more than 25 km of exhumation of lower crustal rocks by 30 km of lateral motion. Subsequently, the complex was transected by a branch of the strike-sli…
Planktonic foraminifera in ODP Hole 160-963A
2006
New faunal and floral records from Ocean Drilling Project Hole 963A, resolved at ?80-year spacing, provide evidence of suborbital scale climate variability in the central Mediterranean Sea throughout Marine Isotope Stage (MIS) 5. Cold events in the central Mediterranean Sea, indicated by low abundances of warm species and high abundances of cold species, are also evident in a planktonic foraminifera paleoclimatic curve. They have been linked to NGRIP Greenland ice core “C” events and appear correlative with similar sub-millennial climate fluctuations identified in the North Atlantic region and in the Alboran Basin (Westernmost Mediterranean). Low-resolution benthic and planktonic Oxygen Iso…
Age and tectonic setting of Late Archean greenstone-gneiss terrain in Henan Province, China, as revealed by single-grain zircon dating
1988
The authors report precise U-Pb zircon ages for single grains of a metarhyodacite from the Late Archean Dengfeng greenstone belt in Henan Province, China, near the southern margin of the North China craton. Most grains belong to an igneous population whose U-Pb isotopic systematics define a straight line intersecting concordia at 2512 +/- 12 Ma, and this is interpreted as the time of crystallization of the original greenstone volcanics. Several grains are distinctly older, between 2576 +/- 9 and 2945 +/- 44 Ma, and the authors interpret the older grains as xenocrysts of pre-greenstone continental crust that provide evidence for crustal derivation or crustal contamination of the original rhy…
Automatic Extraction of Blood Vessels, Bifurcations and End Points in the Retinal Vascular Tree
2008
In this paper we present an effective algorithm for automated extraction of the vascular tree in retinal images, including bifurcations, crossovers and end-points detection. Correct identification of these features in the ocular fundus helps the diagnosis of important systematic diseases, such as diabetes and hypertension. The pre-processing consists in artefacts removal based on anisotropic diffusion filter. Then a matched filter is applied to enhance blood vessels. The filter uses a full adaptive kernel because each vessel has a proper orientation and thickness. The kernel of the filter needs to be rotated for all possible directions. As a consequence, a suitable kernel has been designed …