Strontium isotope ratios and REE geochemistry in the Suwałki anorthosites, NE Poland

Abstract

Strontium isotopic ratios for 14 samples of anorthositic rocks in the Suwałki Anorthosite Massif (SAM) range from 0.704875 to 0.705772. The same isotopic ratios calculated for 1.5 Ga (the U-Pb zircon age of the rapakivi-like granites from adjacent Mazury Complex) range from 0.704583. to 0.705483. The corresponding eSr₁₅₀₀ values for the same rocks range from 25.5 to 39.0. The pronounced Eu anomaly which characterises the REB distribution in the anorthosite plagioclase is consistent with early crystallization from basic magma.