Formation of Tarim Large Igneous Province and Strengthened Lithosphere Revealed Through Machine Learning.

Earth history is punctuated by voluminous magmatism and the formation of large igneous provinces (LIPs). Although anomalous mantle temperatures are known to be involved in many LIPs formation, the potentially critical role of fluids remains elusive. Here we apply machine learning methods (e.g., random forest, deep neural network, and support vector machines) to train models based on global datasets of basalts associated with different settings. The trained models predict that the basalts of Tarim LIP in northwestern China show a spatial decrease in their island arc affinity from northeast to southwest, which can be correlated to fluids released from earlier southward oceanic subduction. Temporally, the fluid activity declined from 290 Ma basalts to 270 Ma mafic dykes, suggesting that the fusible components in the mantle source were waning over time and ultimately a strengthened lithosphere was generated. Our study provides new insights into the crucial role of fluids in the generation of LIPs, particularly those related to ancient subducted slabs. Plain Language Summary: Large igneous provinces (LIPs) represent enormous volume of magmas (>0.1 MKm3) produced within a short duration (∼1–5 Ma). The involvement of fluids in generating LIPs remains equivocal. Some studies suggest that water plays an important role, whereas the others argue against this model, based on the typical anhydrous mineralogy and oceanic island basalt‐like geochemical signatures displayed by the basalts in LIPs. In this study, we apply machine learning methods to investigate how the LIP basalts were influenced by fluids. Training data were extracted from database to establish the predictive models. The trained models are in turn applied to examine the fluid influence on the Tarim LIP basalts in NW China. The results show that the Tarim LIP basalts have variable IAB‐affinity up to 37%, suggesting that the source domains of Tarim LIP were affected by fluids. Spatially, the fluid activity decreases from northeast to southwest, which we correlate to southward subduction events. Temporally, the fluid activity declined over time from 290 to 270 Ma, suggesting that the mantle was dehydrated during the plume‐lithosphere interaction, which may induce a strengthened lithosphere. These observations suggest that the fluids played a crucial role in the generation of Tarim LIP. Key Points: Machine learning methods were employed to evaluate the fluid activity in Tarim large igneous provinceA spatial decrease in the fluid activity from northeast to southwest is observedSubducted slab‐derived fluids play a crucial role in the generation of large igneous provinces [ABSTRACT FROM AUTHOR]