Granitoids and associated volcanics, postorogenic in relation to the Svecokarelian orogeny ending at ca. 1800-1750 Ma, constitute a belt in central Sweden. Evidence presented in this thesis suggests that the individual batholiths in this belt (the Småland, Värmland, Dala and Rätan granites) were formed during repeated orogenic episodes in an Andinotype environment. These episodes were characterized by fracture-controlled high-level emplacement of batholiths in an ensialic setting. Voluminous venting of ignimbrites and formation of grabens through cauldron subsidence accompained the recurrent intrusive activity. Block movements and episodes of burial metamorphism appear to have been prominent features, even after the emplacement of the batholiths.

Metamorphic assemblages and mineral compositions in intermediate to basic volcanics of two Post-Svecokarelian units in the Data region reveal a history comprising two metamorphic episodes. The sub-Jotnian rocks of the older unit were metamorphosed during a first episode: the metamorphic grade ranges from prehnite-pumpellyite facies (in a displaced block with sub-Jotnian (?) lava near a major impact structure), to pumpellyite-actinolite facies, and to greenschist facies in the lower part of the unit. The Jotnian rocks of the unconformably overlying unit were metamorphosed to prehnite-pumpellyite facies during the subsequent episode, which also left its imprint in the sub-Jotnian basement. Two other Jotnian sequences in central Sweden are in the same facies.

Pumpellyite composition is partly controlled by the extent of alteration in its host rock. There seems to be a clear trend for the compositional field of pumpellyite to shrink and be shifted towards the Fe* corner of the Al-Fe*-Mg triangle with increasing extent of host rock alteration. This trend is most evident in the Jotnian rocks. Since the fields in the Al-Fe*-Mg triangle given in the literature as representative of pumpellyites from different facies are partly based on analyses of samples containing relicts, these fields should be adjusted if future tests show that the above-mentioned trend is of general validity.

Most epidotes in Jotnian rocks are remarkably Fe-rich. There is a continuous replacement of Al by Fe³⁺ up to 1.5 atom per formula unit (Ps₅₀), exceeding the maximum pistacite content of PS₃₃ usually accepted in the literature.