Formation of the world's largest REE deposit through protracted fluxing of carbonatite by subduction-derived fluids

Citations Over TimeTop 10% of 2013 papers

Abstract

Rare Earth Elements (REE) are essential to modern society but the origins of many large REE deposits remain unclear. The U-Th-Pb ages, chemical compositions and C, O and Mg isotopic compositions of Bayan Obo, the world's largest REE deposit, indicate a protracted mineralisation history with unusual chemical and isotopic features. Coexisting calcite and dolomite are in O isotope disequilibrium; some calcitic carbonatite samples show highly varied δ26Mg which increases with increasing Si and Mg; and ankerite crystals show decreases in Fe and REE from rim to centre, with highly varied REE patterns. These and many other observations are consistent with an unusual mineralisation process not previously considered; protracted fluxing of calcitic carbonatite by subduction-released high-Si fluids during the closure of the Palaeo-Asian Ocean. The fluids leached Fe and Mg from the mantle wedge and scavenged REE, Nb and Th from carbonatite, forming the deposit through metasomatism of overlying sedimentary carbonate.

Related Papers

• → Origin of REE-rich ferrocarbonatites in southern Siberia (Russia): implications based on melt and fluid inclusions(2016)63 cited
• → Hydrothermal rare earth mineralisation in carbonatites of the Tundulu complex, Malawi: Processes at the fluid/rock interface(1994)85 cited
• → Geochemistry and age of the complex of alkaline metasomatic rocks and carbonatites of the Gremyakha-Vyrmes massif, Kola Peninsula(2012)7 cited
• DOLOMITE-GROUP FERROAN CARBONATES FROM KREMIKOVTSI DEPOSIT(2002)
• → Effects of Metasomatism on the Country Rocks Around the Carbonatites of Kudangulam Area, Tamil Nadu(1995)