Age and emplacement of late Sveconorwegian monzogabbroic dykes, SW Sweden

摘要: Abstract The monzogabbroic (jotunitic) Goteborg dykes in SW Sweden display igneous mineralogy and texture, with chilled margins that crosscut all ductile structures the wall rock. Morphological features suggest emplacement into brittle crust along a set of pre-existing WNW- to W-trending fractures. U–Pb dating baddeleyites from largest these dykes, Tuve dyke, yields late Sveconorwegian (Grenvillian) age 935±3 Ma, which is considered as crystallisation dyke swarm. Hakefjorden Norite–Anorthosite Complex on Swedish west coast show many similarities jotunitic rocks Rogaland Anorthosite south-western Norway, terms age, major element composition Fe–Ti oxide concentrations. Blekinge–Dalarna swarm east Protogine Zone south-eastern Sweden, Hunnedalen also record characteristic high Ti–P–K, evolved “jotunitic” character. A distinct feature mafic low content normative diopside (low Ca), but other aspects they resemble modern continental flood basalts. Ages around 930 Ma for intrusions correspond time latest phase extensional movements crustal-scale shear zones, suggesting this magmatism related collapse exhumation orogen.