Crustal-derived versus mantle-derived carbonatites

Abstract

Mantle-derived carbonatites are an important type of igneous carbonate rock found in diverse tectonic settings. They are commonly associated with alkaline rocks and can contain various mineralization. In contrast, crustal-derived carbonatites form from the direct melting of limestones or marbles at depths within the Earth's crust. These crustal-derived carbonatites are exclusively found in orogenic belts, alongside metamorphic silicate rocks and marbles, and generally do not develop mineralization. Both types of carbonatites exhibit distinct differences in their sources, as well as their elemental and isotopic geochemistry. They can be classified as ortho‑carbonatite (mantle-derived) and para‑carbonatite (crustal-derived). The radiogenic SrNd isotope compositions of both types of carbonatites, along with additional stable CO isotopes and radiogenic Hf isotopes in para‑carbonatites, show correlations with geological time. These temporal variations could provide valuable insights into the Earth's evolutionary history.