Variation of the Crustal Structure Along the Juan de Fuca Ridge from Gravity and Seismic Data

Variations in axial topography and crustal structure are observed along the Juan de Fuca Ridge (JdFR). They may reflect spatial variations in mantle melt supply and delivery of the melt to the crust together with temporal changes, possibly linked to interaction with nearby melt anomalies/hotspots. Here we analyze gravity and multi-channel seismic (MCS) data at the JdFR in order to gain a better understanding of the possible sources for the crustal structure variation in this area. Gravity models for the propagator’s wakes show presence of thinner and probably denser crust that we attribute to the presence of FeTi basalts. In difference, on the younger crust side of the wakes the models show presence of thicker crust at the extent of ~10 km from the wake. The anomalously greater twtt to Moho within the axial region is explained by the presence of thicker crust. Since thickening of the crust and gradual changes of densities within the layer 2b/3 due to the half plate thermal cooling account for less than 60% of the observed anomaly, the remaining ~40% of the anomaly we attribute to the presence of low density body below the crust.