Sr isotopes and the structural state of feldspars as indicators of post-magmatic hydrothermal activity in continental dolerites

摘要: Late-crystallised interstitial alkali feldspars and a single epidote from selected Proterozoic dolerites in Sweden have higher initital 87Sr/86Sr ratios, (e.g., 0.709) than the early-crystallised minerals of same rocks (∼ 0.704); anomalies Rb Sr concentrations are also noted. This radiogenically-enriched must originate older host intrusions. As contaminated phases often occupy <1 % dolerite, only an aqueous fluid would been capable transporting contamination through 99% solid Textural association late with hydrous alteration products supports this interpretation. Feldspar structural data suggest that most affected by subsolidus fluids, causing extensive re-equilibration K-feldspars, as well occasional metasomatic effects. Anomalies 87Sr developed where fluids interacted rocks.