Variations in crustal magma volume flux along the Hawaii-Emperor seamount chain and their implications for plume–lithosphere interactions

Abstract

The magma volume flux is reduced by a fracture zone (FZ) crossing the Laccadives-Maldives-Chagos Bank-Mascarene Plateau chain in the Indian Ocean and is negatively correlated with the plate motion rate along the Ninetyeast Ridge (NER). Whether the FZs in the Pacific decrease the crustal magma volume flux and whether the flux along the Hawaii-Emperor seamount chain (HESC) is also negatively correlated with the plate motion rate are both unclear. Focusing on these two issues, we estimate the variations in crustal magma volume flux along the HESC and discussed plume–lithosphere interactions. The present-day crustal thickness is mapped via gravity inversion based on Earth interior density modeling. The accretionary thickness is isolated by filtering the present-day crustal thickness. Then, according to the seamount age variation trend inferred from ages by rock dating, the crustal magma volume flux along the whole HESC is derived. All the FZs correspond well to flux peaks because these weak lithospheric zones provided potential conduits for magma upwelling and promoted magma accretion. However, for the Indian Ocean case, the Reunion plume was captured by the mid-ocean ridge before and after reaching the low-flux transform fault, so the transform fault represented a relatively stronger lithosphere than the nearby mid-ocean ridge. The crustal magma volume flux along the HESC does not correlate with the motion rate of the Pacific Plate because the lithosphere was old during seamount loading, which contrasts with the inverse correlation between these two parameters along the NER, which had a young lithosphere during seamount loading.