Testing for the Pulse of the Iceland Plume: IODP EXP.395

Do mantle plumes have a pulse? Does intraplate volcanism fluctuate and is that determined by mantle dynamics deep-within the interior of the earth? How do these changes impact the inhabited surface of the planet, its climate and life support systems? These are some of the questions we aim to address in IODP Exp. 395.

Oceanic islands and plateaus provide strong evidence that significant fluxes of mass and energy are transferred from the Earth's interior to its surface by processes that are independent of the normal plate tectonic cycle. Whereas today, mid-ocean ridges account for ~95% of the mass and energy flux from the mantle, in the past, the contribution from hotspot volcanism has been as high as 50%.

Such pulses of magmatism are implemented in climate change, mass extinctions, geomagnetic field anomalies and higher rates of seafloor spreading, hydrothermal activity, and continental break-up. Yet these pulses of excessive volcanism are episodic across a range of time scales. Understanding these, their periodicity and processes, are essential if we are to gain an insight into mantle dynamics and Earth evolution.

In this proposal, we aim to test hypotheses for the origin and affects of the hotspot responsible for the formation of the Iceland plateau. Through its interaction with the adjacent, slow-spreading Reykjanes Ridge, we aim to recover a record of Icelandic hotspot volcanism and its variability over the past 35Ma. Specifically IODP Exp.395 will investigate whether hotspot mantle upwells beneath Iceland and advects laterally along the ridge.

Fluctuations in melt production from the Iceland hotspot are indicated by a nested suit of diachronous V-shaped ridges that form the flanks of the Reykjanes Ridge. By sampling across these V-shaped ridges, we will explore whether they are caused by fluctuations in the hotspot mantle flux, temperature or composition. In addition, we will investigate the chemical aging of oceanic crust as it is affected by an adjacent hotspot.

Study of the Iceland-Reykjanes Ridge couplet is widely recognised as a type example of hotspot-ridge interaction. The outcome of this study will be a greater understanding of mantle hotspot dynamics and their impact on ocean basin evolution, the surrounding land masses, climate and ocean circulation.