65 research outputs found
Middle Pleistocene seismically induced clay diapirism in an intraplate zone, western Brittany, France
No full textInternational audienceThe Brittany region of France is located in a low seismicity intraplate zone. Most of the instrumented earthquakes are limited to a shallow crustal depth without surface rupture. A paleoseismological analysis was performed on deposits on the Crozon Peninsula and in the Elorn estuary. We highlight hydroplastic deformations induced by liquefaction leading to clay diapirism, which were likely triggered by past earthquakes. This diapirism seems to be frequent in continental nonconsolidated sediments and to develop on the inherited tectonic structures, when a shallow water table and confining layers exist. Timing of deformation is dated using paleoenvironmental data, and electron spin resonance and infrared-stimulated luminescence dating methods. Two seismic periods were identified in western Europe during early Marine Oxygen Isotope Stage (MIS) 10 (~380 ka) and early MIS 8 (~280-265 ka). The lack of similar deformations affecting the Holocene tidal deposits in the Bay of Brest suggests that the magnitude of the triggering paleoearthquakes is probably higher (M w ~ 6) than the recent events (M w 5.4). These unusual intraplate major paleoearthquakes need specific factors affecting the far-field crustal stress loading to be triggered, such as a brief acceleration of the Africa-Eurasia lithospheric plate convergence, glacio-isostatic stress perturbations associated with the onset of major glaciations in northern Europe, or other processes induced by orbital forcing
A study of intermittency in Hadronic Z Decays
No full textA study on the modifications of the relation between author and lector due to the translation from text to hypertex
MEASUREMENT OF THE MASS AND WIDTH OF THE Z0 PARTICLE FROM MULTI - HADRONIC FINAL STATES PRODUCED IN e+ e- ANNIHILATIONS
No full textFirst measurements of the mass and width of the Z0 performed at the newly commissioned LEP Collider by the DELPHI Collaboration are presented. The measuements are derived from the study of multihadronic final states produced in e+e- annihilations at several energies around the Z0 mass. The values found for the mass and width are M(Z0)=91.06±0.09 (stat) ±0.045 (syst.) GeV and Γ(Z0)=2.42±0.21 (stat.) GeV respectively, froma three-parameter fit to the line shape. A two-parameter fit in the framework of the standard model yields for the number of light neutrino species Nν=2.4±0.4 (stat.) ±0.5 (syst.)0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Limits on the production of scalar leptoquarks from Z0 decays at LEP
No full textA search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392 000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit abd its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling αλ is equal to the electromagnetic one. An upper limit is also given on the coupling αλ as a function of the leptoquark mass m
SEARCH FOR THE t AND b-prime QUARKS IN HADRONIC DECAYS OF THE Z0 BOSON
No full textWe present a search for the third generation up type quark t and a possible fourth down type quark b' in hadronic Z0 decays observed in DELPHI at the LEP collider. For any scenario with a decay through the charged current or into a charged Higgs with a mass at least 6 GeV/c2 below the t and 3 GeVc2 below the b' mass, we set a lower limit for the t quark mass at 44.0 GeV/c2 and for the b' mass at 44.5 GeV/c2. For specific scenarios the mass limits are slightly higher, e.g. for charged current decays the limits are 44.5 and 45.0 GeV/c2 respectively, where all limits are given at a 95% confidence level. © 1990.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Lower Ordovican acritarchs from successions in England and North Wales.
No full textOne hundred and thirty eight acritarch taxa are described from the organic residues of samples collected in North Wales, Shropshire, and the Lake District. The species occur in one or more of 16 microfloral assemblages, selected from 88 prepared samples. Three new genera and seven new species are proposed. Range charts are presented which show the occurrence and distribution of all the species described in detail. On the basis of these results, five microfloral zones and two subzones are proposed. Each zone or subzone is characterised by an assemblage of species, and equates to part of the established Lower Ordovician graptolite zonation. The proposed biostratigraphical scheme is applied to microfloral assemblages from several localities in the English Lake District, most of which were either previously undated or doubtfully dated. Comparisons are made with Arenigian and Llanvirnian assemblages described from the European area, by other authors. Tentative conclusions are drawn as to the possible continuity of the British province with other European areas during Arenigian and Llanvirnian times. Factors affecting the preservation of acritarchs are discussed and a visual classification scheme is presented which takes into account fragmentation, degree of corrosion, and colour
The 2010 Haiti earthquake : a complex fault pattern constrained by seismologic and tectonic observations
No full textAfter the January 12, 2010, Haiti earthquake, we deployed a mainly offshore temporary network of seismologic stations around the damaged area. The distribution of the recorded aftershocks, together with morphotectonic observations and mainshock analysis, allow us to constrain a complex fault pattern in the area. Almost all of the aftershocks have a N-S compressive mechanism, and not the expected left-lateral strike-slip mechanism. A first-order slip model of the mainshock shows a N264 degrees E north-dipping plane, with a major left-lateral component and a strong reverse component. As the aftershock distribution is sub-parallel and close to the Enriquillo fault, we assume that although the cause of the catastrophe was not a rupture along the Enriquillo fault, this fault had an important role as a mechanical boundary. The azimuth of the focal planes of the aftershocks are parallel to the north-dipping faults of the Transhaitian Belt, which suggests a triggering of failure on these discontinuities. In the western part, the aftershock distribution reflects the triggering of slip on similar faults, and/or, alternatively, of the south-dipping faults, such the Trois-Baies submarine fault. These observations are in agreement with a model of an oblique collision of an indenter of the oceanic crust of the Southern Peninsula and the sedimentary wedge of the Transhaitian Belt
Determination of alpha-s for b quarks at the Z0 resonance
No full textThe strong coupling constant for b quarks has been determined, and its flavour independence, as predicted by QCD, investigated. The analysis involved events with lepton candidates selected from approximately 356 000 hadronic decays of the Z0, collected by the DELPHI detector at LEP in 1990 and 1991 A method based on a direct comparison of the three-jet fraction in a b enriched sample, selected by requiring leptons with large momenta and transverse momenta, to that of the entire hadronic sample, illustrated the significant effect of the b quark mass on the multi-jet cross section, and verified the flavour independence of the strong coupling constant to an accuracy of ±6%. A second procedure based on a fit to the momentum and transverse momentum spectra of the lepton candidates in both two-jet and three (or more)-jet event samples simultaneously determined the b content in each, and, using second order QCD calculations, gave an absolute measurement of αs for b quarks of 0.118 ± 0.004 (stat.) ± 0.003 (syst.) ± 0.008 (scale). A comparison with αs for all quark flavours, as measured from the three-jet fraction in all hadronic events, further allowed the coupling strength for b quarks to be expressed in terms relative to that for udsc quarks, thereby cancelling certain common systematic uncertainties, and yielded αsb/αsudsc = 1.00 ± 0.04 (stat.) ± 0.03 (syst.)
Aspects of the relationship between the central and Gallic empires in the mid to late third century ad with special reference to coinage studies
No full textNot availabl
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