AbstractAbstract
[en] The earliest Svecofennian magmatism in southern Finland has been dated at 1.90-1.88Ga. As an example of this, the Orijärvi (ca. 1.89Ga) and Enklinge (ca. 1.88Ga) volcanic centres comprise bimodal plutonic batholiths surrounded by volcanic rocks of comparable ages and chemical compositions. Here, we report geochemical and Sm-Nd isotope data from intrusive and extrusive samples, combined with zircon U-Pb and Lu-Hf isotopes for granodiorites from both study areas. The samples range from gabbros to granites and indicate a subduction-related continental margin setting. The zircons from the Orijärvi granodiorite define an age of 1892±4Ma whereas the Enklinge granodiorite yields an age of 1882±6Ma. Several inherited ages of 2.25-1.95Ga as well as younger ages of 1.86-1.80Ga were found in the Enklinge granodiorite. The initial εNd values from the mafic rocks from both locations fall in the range +1.1 to +2.9 whereas the felsic rocks exhibit initial εNd values of -0.4 to +1.2. The magmatic zircons from the Orijärvi and Enklinge granodiorites show average initial εHf values of -1.1 (at 1892Ma) and zero (at 1882Ma), respectively, each with a spread of about 7 ε-units. The initial εHf values for the inherited zircons from Enklinge range from +3.5 to +7.6 with increasing age. The Sm-Nd data indicate that the mafic rocks were derived from a “mildly depleted” mantle source while the felsic rocks show larger crustal contribution. Also, the variation in εHf values indicates minor mixing between mildly depleted mantle derived magmas and crustal sources. U-Pb ages and Hf isotopes for inherited zircons in the Enklinge granodiorite suggest the presence of juvenile Svecofennian “proto-crust” at depth.
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Available on-line: 10.1344/GeologicaActa2018.16.1.1
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Journal Article
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Geologica Acta (Online); ISSN 1696-5728; ; v. 16(1); p. 1-23
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Georgel, B.; Pons, F.
Proceedings of the 5. International conference on non destructive testing methods1985
Proceedings of the 5. International conference on non destructive testing methods1985
AbstractAbstract
[en] In order to speed up on site check-up of steam generator tubing by means of eddy currents we have to develop automatic procedures of detection, analysis and classification of defects signals. Our paper presents a review of the main digital signal processing methods available. The point is that we don't consider a ''priori'' defects classes and that we carefully estimate each parameter we will use for discrimination (particularly the phase angle of the Lissajous lobes). We give the preliminary results of an investigation of 70 different flaws. 4 refs
[fr]
L'inspection des tubes de generateurs de vapeur de centrales nucleaires fournit une quantite enorme de signaux. Une premiere evolution dans les controles a conduit a preferer l'enregistrement numerique. Puis, on a cherche a automatiser le reperage des defauts et a ameliorer le stockage des resultats, grace aux facilites de l'informatique. Si on veut aller plus loin dans l'automatisation de ces controles, il faut developper des procedures de detection des defauts, de classification et d'estimation. On s'interesse ici plus particulierement aux methodes d'analyse automatique des defauts et plus specialement des defauts de tubes de generateurs de vapeurOriginal Title
Analyse et classification de defauts par traitement numerique de signaux de courants de Foucault
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Source
446 p; 1985; p. 67-71; Editions SACER; Paris (France); 5. International conference on non destructive testing methods; Bordeaux (France); 30 May - 3 Jun 1983
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Book
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Conference
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