caa a22 4500 465790917 CHVBK 20180323112024.0 cr unu---uuuuu 170327e19900301xx s 000 0 eng 10.1007/BF00321485 doi (NATIONALLICENCE)springer-10.1007/BF00321485 Magmatic evolution of the Karmøy Ophiolite Complex, SW Norway: relationships between MORB-IAT-boninitic-calc-alkaline and alkaline magmatism [Elektronische Daten] [Rolf Pedersen, Jan Hertogen] The polyphasal magmatic evolution of the Caledonian Karmøy Ophiolite Complex includes: (1) formation of an axis sequence from island-arc tholeiitic (IAT) and more MORB-like magmas (493+7/-4 Ma); (2) intrusion of magmas of boninitic affinity (485±2 Ma); (3) intrusion of MORB- and IAT-like magmas; (4) intrusion and extrusion of calc-alkaline magmas (470+9/-5 Ma); (5) intrusion and extrusion of basalts with alkaline trace-element affinity. Repeated intrusion of MORB and IAT-like magmas may be explained by intermittent magmatism involving magma-chamber solidification and remelting of a source characterized by initial ɛNd of approximately +6.5. The boninitic rocks may have formed from two LREE-depleted sources: the primary source of the axis-sequence magmas and the residual source left after extraction of these magmas. These sources have been enriched in LREE, Th and Zr from subducted material exhibiting a continental Nd-isotope signature with initial ɛNd less than-8. Covariation between ɛNd and Th, Zr, Nd, Y and Yb may be explained by metasomatic enrichment of a LREE-depleted mantle source by a LREE-enriched subduction component, followed by partial melting during which the degree of melting of the metasomatized mantle source increased linearly with the amount of subduction component added to the mantle source. The calc-alkaline magmas may have formed by remelting of a highly depleted source, which became enriched in some trace elements derived from the source of the subsequent alkaline magmatism. The geology and geochemistry of the Karmøy Ophiolite Complex suggest growth of an island-arc upon newly-formed oceanic crust, followed by arc-splitting and the development of a new basin. Springer-Verlag, 1990 Pedersen Rolf Institute of Geology, University of Bergen, Allegt. 41, N-5007, Bergen, Norway aut Hertogen Jan Department of Physicochemical Geology, University of Leuven, Celestijnenlaan 200C, B-3030, Leuven, Belgium aut Contributions to Mineralogy and Petrology Springer-Verlag 104/3(1990-03-01), 277-293 0010-7999 104:3<277 1990 104 410 https://doi.org/10.1007/BF00321485 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00321485 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Pedersen Rolf Institute of Geology, University of Bergen, Allegt. 41, N-5007, Bergen, Norway aut NATIONALLICENCE 700 1- Hertogen Jan Department of Physicochemical Geology, University of Leuven, Celestijnenlaan 200C, B-3030, Leuven, Belgium aut NATIONALLICENCE 773 0- Contributions to Mineralogy and Petrology Springer-Verlag 104/3(1990-03-01), 277-293 0010-7999 104:3<277 1990 104 410 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer