The 1160 ma hidderskog meta-charnockite - implications of this a-type pluton for the sveconorwegian belt in vest agder (sw norway)
Zhou, Xq × Bingen, B Demaiffe, D Liegeois, Jp Hertogen, Jan Weis, D Michot, J #
Elsevier science bv
Lithos vol:36 issue:1 pages:51-66
The Hidderskog massif is a chamockitic intrusion located in the Rogaland-Vest Agder segment of the Sveconorwegian province of SW Norway. The U-Pb zircon age (1159 +/- 5 Ma) and the Rb-Sr whole-rock isochron age (1153 +/- 39 Ma) of this pluton are concordant. This age is interpreted as the magmatic emplacement age. The Hidderskog charnockitic intrusion is deformed and at a large scale concordant with amphibolite facies gneisses. It has been partially transformed to amphibole-biotite gneiss during the main Sveconorwegian orogeny (1040-980 Ma in Rogaland). Major and trace element composition as well as isotopic systems have been only weakly disturbed during this event. The Hidderskog intrusion displays A-type geochemical features. Most samples could correspond to mixing of a granitic liquid with feldspar crystals. It may be correlated in age with the Gloppurdi and Botnavatnet intrusions of Rogaland and tentatively to the Hovdefjell and Gjeving charnockites of the Bamble sector. This group of charnockitic intrusions defines an intraplate anorogenic geodynamic environment prior to the main Sveconorwegian orogenic phase. These anorogenic charnockites are distinct from the chamockitic magmas spatially related to the Rogaland anorthosite complex, which intruded after the main Sveconorwegian orogeny within a short period of time, from around 950 to 930 Ma.