Site Survey for IODP Proposal 646-Full:- Icelandic V-Shaped-Ridges

Lead Research Organisation: National Oceanography Centre
Department Name: Science and Technology

Abstract

This Urgency Grant Proposal aims to take advantage of a site survey opportunity in support of a UK-led IODP proposal to drill the North Atlantic basement. A bid made last October to the Science Foundation, Ireland and the Irish Marine Institute by Steve Jones (Trinity Colege, Dublin) and Bramley Murton (NOCS) resulted in 450,0000 euros of ship-time being awarded. The Celtic Explorer has been made available to Jones and Murton between mid-April and mid-May 2008. To support this expedition, funds are sought to mobalise and set-up a portable multibeam exchosounder (Reson 8160), and to hire several dredges from NMFD. The costs are modest, at about 2.5% of the ship-time. The scientific objectives are to map and sample along the strike of a V-shaped ridge that is exposed on the western flank of the Rejkanes Ridge, southwest of Iceland. This Urgency Grant Proposal is in support of a major, UK-led, IODP proposal (646-Full) that addresses fundamental questions about the causes of fluctuations in the activity of volcanic hotspots and their effects on the Earth's environment including climate. Does deep upwelling in the mantle, localized temperature and compositional anomalies, or shallow-mantle flow cause hotspot fluctuations? What are the time scales and rates involved? Where mantle flow is involved, what is its fate as it flows away from a hotspot? To address these issues, we propose to sample time-transgressive features that are common where hotspots interact with mid-ocean spreading ridges. These phenomena are exceptionally clearly developed for the Iceland-Reykjanes Ridge couplet where a series of diachronous V-shaped ridges (VSR's) preserve a record of changing hotspot activity, over the last 35Ma, on the floor of the North Atlantic. Linked to these fluctuations in the Iceland hotspot are variations in the flux of North Atlantic Component Water (NACW) that drives the 'global ocean conveyor' and whose return flow is manifest as the North-Atlantic Drift that moderates the climate of northwestern Europe. The significance of the Iceland VSR's as indicators of the processes of hotspot fluctuations has been recognised in the recent Large Igneous Province IODP Workshop (Colrain, 2007). Sampling the diachronous VSR's by drilling on the flanks of the Reykajnes Ridge in the North Atlantic is the only way to access this geological record. We propose to sample lavas from a transect along one of the youngest VSR's, exposed on the western flank of Reykjanes Ridge. The geochemistry of these lavas will yield insights into the genesis of the VSR's, and hence the causes and processes of hotspot fluctuation. The nature of the questions being addressed and our methodology have been informed from four separate, internationally sponsored workshops over the past 4 years. During the most recent, an UK-IODP workshop 'Rift2Ridge '07', Southampton, 2007, we identified an important link between this proposal and another IODP proposal by Wright et al, (in prep.) that aims to investigate the correlation between the initiation of VSR's on Iceland and fluctuations of NACW overflow strength.

Publications

10 25 50
 
Description The deep interior of the Earth beneath Iceland is hot and rising in the form of a plume of hot mantle. Our research has demonstrated that this plume is transient, with pulses every 2-4 million years that spread radially outward from Iceland over a distance of about 1000km. These pulses affect changes in the volcanic activity on Iceland and the adjacent mid-ocean ridge as well as deep-ocean circulation and Earth climate.
Exploitation Route The findings have led directly to a multinational collaborative proposal to the IODP for deep-ocean drilling of the geological record of the pulsating Iceland plume.
Sectors Environment,Other

 
Description IODP drilling proposal has been submitted and is now in a scheduling stage. This represents a multimillion pounds investment into the research questions posed by our findings, with global impact on planet evolution and climate.
First Year Of Impact 2018
Sector Education,Other
Impact Types Economic

 
Description Tectonic Ocean Spreading at the Charlie-Gibbs Fracture Zone (TOSCA)
Amount € 800,000 (EUR)
Organisation Marine Institute 
Sector Public
Country Ireland
Start 05/2018 
End 04/2019
 
Description Tectonic Oceanic Spreading (TOSCA) 
Organisation University College Dublin
Country Ireland 
Sector Academic/University 
PI Contribution We have collaborated in conceiving the original concept of the proposal and provided interpretation of the initial data.
Collaborator Contribution Partners have acquired Irish research vessel time and access to their Irish research ROV over a 4 week-long cruise for May-June 2018.
Impact Geology and geophysics.No outcomes as yet
Start Year 2016