The tinguaite boulder fan in northern Dalarna, Sweden, and the Permo‐Carboniferous rifting of Scandinavia

Abstract

Boulders of the tinguaites connected with the alkaline Siksjöberget‐Ekorråsen massif near Särna, northern Dalarna, have been distributed southward by the inland ice as an erratic fan. The fan and the different tinguaite types indicate that spreading has taken place from two or possibly three different centres. Theoretically, these may correspond to protuberances from a plume of alkaline mantle materia in the extension of the Permo‐Carboniferous rift in the Oslo region, Norway, a model that must be checked using geophysical measurements. A plume may also account for the updoming of porphyry which emerges through the overlying Jotnian sandstone. Two of the tinguaite centres are situated within this dome.

Lundqvist, J., 1997: The tinguaite boulder fan in northern Dalarna, Sweden, and the Permo‐Carboniferous rifting of Scandinavia. GFF, Vol. 119 (Pt. 2, June), pp. 123–126. ISSN 1103–5897.

Keywords:

• Quaternary
• glacial transport
• Permo‐Carboniferous rifting
• tinguaite dykes
• alkaline mantle plumes