Porphyritic syenite at Lake Mykle, the Oslo Rift - a possible derivative of larvikite.
Abstract
New Rb-Sr and Sm-Nd isotope data on porphyritic syenite from lake Mykle in the southern part of the Oslo Rift confirm a close compositional and genetic relationship and genetic relationship between this rock and the associated larvikite. The porphyritic syenite has initial 87Sr\/86Sr at 280 Ma between 0.7044 and 0.748, and End between + 1.56 and + 2.52. This pattern of variation is compatible with with contamination of a mantle-derived parent magma with small amounts of Precambrian calc-alkaline gneisses in the deep crust.