Magnetic Telechemistry of the Reykjanes Ridge

Abstract

The magnetic telechemistry hypothesis proposes that hotspot mantle contains elevated Fe and Ti leading to enhanced crustal magnetic anomaly strength. Ridge segmentation and other geologic factors also influence oceanic crustal magnetization, potentially complicating the identification of a hotspot signature. At the Reykjanes Ridge, distinct segmented (offset) and unsegmented (linear axis) crustal terrains formed at different times over the Iceland hotspot allow an examination of these effects as well as contrasting hotspot models. We use ship magnetic anomaly data to invert for basement magnetization and examine variations in its root-mean-square intensity. We find that the unsegmented “linear” terrains indeed have greater magnetization intensities than the “segmented” terrain, in agreement with some models in which mantle plume material advanced, retreated, and advanced again forming these terrains. However, we also resolve a magnetization intensity low centered along a flowline at 61°N that cuts across the basin and coincides on axis with a previously identified geochemical boundary. We conclude that crustal age, resolution effects, and ridge segmentation create the main magnetization variations among the various terrains of the Reykjanes Ridge. The coincidence of a major geochemical boundary with a basin-crossing magnetization low, however, indicates a stably zoned hotspot mantle anomaly rather than a rapidly upwelling and radially flowing mantle plume.