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                                       Details van artikel 13 van 23 gevonden artikelen
 
 
  Mafic dyke swarms of the Baltica-Iapetus transition, Seve Nappe Complex of the Sarek Mts., Swedish Caledonides
 
 
Titel: Mafic dyke swarms of the Baltica-Iapetus transition, Seve Nappe Complex of the Sarek Mts., Swedish Caledonides
Auteur: Andreasson, Per-Gunnar
Svenningsen, Olaf
Johansson, Ingrid
Solyom, Zoltan
Xiaodan, Tan
Verschenen in: GFF
Paginering: Jaargang 114 (1992) nr. 1 pagina's 31-45
Jaar: 1992-03-10
Inhoud: Mafic dyke swarms of the Baltica-Iapetus transition, Seve Nappe Complex of the Sarek Mts., Swedish Caledonides With respect to petrography and chemistry, the Sarek dolerites compare excellently to T-MORB as far as REE abundance patterns and some trace element ratios are concerned: chondrite normalized (La/Sm) = 0.77-1.04 and (La/Yb) = 1.2-2.9; Zr/Nb = 8.3-11.6; Zr/Y = 2.8-4.8; Y/Nb = 1.9-4.3. However, high abundances of LIL elements and straddling of boundaries to fields of destructive margins in Nb-Y-Zr and Hf-Ta-Th discrimination diagrams indicate a mixed magmatectonic signature. In this respect, the Sarek dolerites compare to basalts of ensialic back-arc basins e.g. the Gulf of California. However, such a setting is incompatible with our present knowledge about the Baltoscandian scenario 500-600 Ma ago, unless the Sarek sheeted dyke complex was part of the Laurentian passive margin. The favoured interpretation is a situation similar to the present-day opening of the South Atlantic Ocean, where T-MORB of similar characteristics occur in a passive margin context and where magma variation is due to both mantle heterogeneity and crustal contamination. In harmony with their geological setting, the Sarek dolerites are generally more oceanic in character than the tholeiites of the BDS dolerites. Both the Sarek and the BDS dolerites differ distinctly from those North American dyke swarms which have been considered to represent the opening of the Iapetus Ocean.
Uitgever: Taylor & Francis
Bronbestand: Elektronische Wetenschappelijke Tijdschriften
 
 

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