Granitoids from the Äspö area, southeastern Sweden ‐ geochemical and geochronological data

Abstract

The bedrock on and around Äspö island, north of Oskarshamn is predominated by Småland granitoids belonging to the Trans‐scandinavian Igneous Belt (TIB). A second magmatic event was the formation of anorogenic granites (e.g. the Götemar granite) 1.4 Ga ago, represented by massifs of coarse‐grained granite cut by fine‐grained granitic dikes. The Småland granitoids constitute a suite of medium‐grained quartz monzodiorites (Äspö diorite) to granites (Ävrö granite) penetrated by fine‐grained granites. They are classified as alkalic to alkali‐calcic, metaluminous to peraluminous I‐granites. A U‐Pb dating on zircon and titanite of the Äspö diorite yielded an age of 1804±3 Ma. Two darings of the fine‐grained Småland granite gave ages of 1794⁺¹⁶ _‐12 and 1808⁺³³ _‐30 Ma. The fine‐grained, felsic Småland granites are distinguished chemically from the similar looking fine‐grained anorogenic granites through, e.g., differing Fe/Mg, alkali contents and HREE‐pat‐terns.

Kornfält, K.‐A., Persson, P.‐O. & Wikman, H., 1997: Granitoids from the Äspö area, southeastern Sweden ‐ geochemical and geochronological data. GFF, Vol. 119 (Pt. 2, June), pp. 109–114. Stockholm. ISSN 1103–5897.

Keywords:

• Radiometric dating
• U‐Pb
• zircon
• titanite
• geochemistry
• REE
• TIB
• Småland granite
• anorogenic granite
• Äspö
• SE Sweden