SUBSOLIDUS TRANSFORMATIONS OF STRONTIUM-AND BARIUM-BEARING CARBONATOTE CALCITE

Abstract

Endogene calcite is a reliable indicator of postcrystallization transformations. The most important indicator of subsolidus transformations in high-temperature endogene calcite is the decomposition of its solid solutions, which, though highly diverse, are confined to very specific changes. This paper discusses a unique phenomenon - a still largely preserved example of step-by-step exsolution of carbonatite calcite, containing strontium and barium. This calcite is the principal mineral phase in pyroxene-K-spar-calcite carbonatite that forms small bodies in the Murun syenite pluton. Because of its anomalously high strontium and barium content, the calcite of these rocks has virtually no known analogs, even in carbonatite.