The Tectonic, Thermal, and Temporal Controls on the Production of Lithium‐Enriched Melts

Abstract

Abstract We present a new tectonically‐based method for understanding the mountain‐belt‐scale controls on the distribution of critical metals, applied to lithium ores. Lithium‐rich melts in collisional zones are produced by biotite‐breakdown reactions, so we analyze the tectonic “filters” that control whether underthrusting (meta‐)sediments reach sufficiently high temperatures for these reactions. Such conditions are most readily achieved with large crustal thicknesses, high radiogenic heating rates, and slow convergence. The first two factors indicate an important role for geological history, in terms of creating a strong foreland and assembling sufficiently radiogenic lithologies. Slow convergence is generally incompatible with uplift outpacing erosion to develop thick mountain belts, but this paradox is resolved by, and explains, most lithium deposits being formed late in the history of mountain belts, at times of slowing convergence rates. Our results explain why lithium deposits are more prevalent in preserved Precambrian mountain belts, formed during times of higher radiogenic heating.