Deep magmatic processes of mafic layered intrusions in the Lala mining area, western Sichuan

ObjectivePrevious studies have shown that many layered intrusions are formed by multiple pulsations of magma. However, little research has been done on whether the magma involved in the pulsation process comes from a single magma chamber or multiple magma chambers. Minerals, as products of magmatism, record the properties of magma chambers and deep magmatism.

MethodsThrough the electron probe microanalysis technique (EPMA) on the hornblende and mica, combined with genetic analysis, mineral classification, and thermodynamic calculation, five different lithofacies zones of mafic layered intrusions in the western Sichuan LaLa mining area were studied.

ResultsIt shows that hornblende and mica of five different facies lithofacies zones formed in different stages of magmatism, with changes in the property of the magma chamber during crystallization.

ConclusionThere were at least two magma chambers with different properties in the deep layers during the formation of mafic layered intrusions. The layered intrusions were formed through multiple (4–5) magmatic pulsations, activated by fluid overpressure, which mobilized two magma chambers of differing compositions and depths.