Swedish granitoids of S- and I-type and their lithophile element distribution

Abstract

Three groups of Swedish granitoids, early, late and postorogenic, have been studied with respect to how S- or I-type granite models might be useful in the classification of these rocks. An attempt has also been made to determine which relationships, reflected in the distribution of lithophile ore elements, best characterize S- and I-types. The model is presented as a probability diagram based on two variables, the mole fraction Al₂O₃/(Na₂O + K₂O + CaO) and the degree of oxidation Fe³⁺/Fe_tot. It is shown that most of the postorogenic granites are I-type granites. These include the Karlshamn, Småland, Dala, Rätan, Sorsele, Lina and Åland granites. The primorogenic granites of central Sweden, as well as the serorogenic Fellingsbro granite, are also I-type granites. The primorogenic granites of southern Sweden are of S-type character. Some granites, e.g. the serorogenic Revsund granite, cannot be classified using the above model. The intensity of I-type characteristics increases from primorogenic to postorogenic granitoids. With respect to Na and K no clear difference can be demonstrated between the three intrusion types. No systematic relation between the metallic elements studied (Sn, W, Mo and Li) and the two parameters studied has been established with respect to the S- or I-type character.

Key Words:

• Granitoids
• S- and I-type granite
• lithogeochemistry
• lithophile ore elements
• Sn
• W
• Mo
• Li
• statistical grouping
• probability calculation
• Proterozoic
• Sweden