Was the Panzhihua Large Fe‐Ti Oxide Deposit (SW China) Formed by Silicate Immiscibility?

Abstract

AbstractThe Panzhihua mafic intrusion, which hosts a world‐class Fe‐Ti‐V ore deposit, is in the western Emeishan large igneous province, SW China. The formation age (∼260 Ma), Sr, and Nd isotopes indicate that the Panzhihua intrusion is part of the Emeishan large igneous province and has little crustal contamination. However, the ore genesis of the Panzhihua Fe‐Ti‐V ore deposit has been extensively debated. Two different models have been provided to explain the formation of the Panzhihua oxide deposit, namely silicate immiscibility and normal fractional crystallization. Silicate immiscibility occurrings around 1,000 °C at the late stage of basaltic magma evolution argues against the silicate immiscibility model. Apatite‐hosted melt inclusion research indicates that silicate immiscibility occurred at the late stage of Panzhihua magma evolution. However, this may have little potential to form large ore deposits like Panzhihua. However, the continuous compositional variations of the Panzhihua intrusion and the calculations by thermodynamic modelling software support the Panzhihua deposit being formed by normal fractional crystallization. The reciprocal trace element patterns of the Panzhihua intrusion and the nearby felsic rocks also coincide with the fractional crystallization model. Normal fractional crystallization of high‐Ti basaltic magma played a key role in the formation of the Panzhihua Fe‐Ti‐V ore deposit.