Magma reservoir evolution at a slow-spreading mid-ocean ridge

Lead Research Organisation: CARDIFF UNIVERSITY
Department Name: Sch of Earth and Environmental Sciences

Abstract

Mid-ocean ridges form the largest magmatic system on Earth. Oceanic crust is formed when the upper mantle wells up and partially melts in response to plate separation. The melts thus formed rise upwards, forming the magma reservoirs of the lower oceanic crust, and erupt to form mid-ocean ridge basalts.

The nature of magma reservoirs at mid-ocean ridges remains poorly constrained. Traditional models hold that they are bodies of pure melt in which magma evolution is controlled by fractional crystallisation. This model is increasingly challenged, and a new paradigm in which magma reservoirs are comprised of crystal mush - a mixture of melt and crystals - has now emerged. Melt transport and evolution in mush reservoirs may be controlled by porous flow, which has fundamental implications for the eruption dynamics and geochemical signatures of mid-ocean ridge basalts.

This project will reconstruct the architecture and evolution of magma reservoirs at the Mid-Atlantic Ridge. It will capitalise on core that will be recovered from Hole U1309D (30 degrees N) by scientific ocean drilling. Previous drilling at this location has shown that this section contains an excellent record of fossilised magma reservoirs beneath a slow-spreading mid-ocean ridge.

This project will integrate core observations with state-of-the-art element mapping and measurements of mineral major- and trace elements to address three challenges:

1) The size of magma reservoirs;
2) The melt composition and evolution within these reservoirs;
3) The thermal histories of the reservoirs.

Together, these different components will enable a test of the different end member models for reservoir architecture and melt transport. The outcome is a rigorous assessment of the nature and evolution of magma reservoirs beneath the Mid-Atlantic Ridge, with implications for magma evolution of oceanic basalts, which may serve as a template for mafic igneous systems generally.

Publications

10 25 50
 
Description Montpellier 
Organisation University of Montpellier
Department Geosciences Montpellier
Country France 
Sector Academic/University 
PI Contribution Isotopic data collection to underpin joint research into the composition of the mantle
Collaborator Contribution Major- and trace element data collection to underpin joint research into the composition of the mantle
Impact None to date
Start Year 2023
 
Description University of Leeds 
Organisation University of Leeds
Country United Kingdom 
Sector Academic/University 
PI Contribution Nd isotopic data collection to underpin joint research on the interaction of seawater with peridotite
Collaborator Contribution B and Sr isotopic data collection to underpin joint research on the interaction of seawater with peridotite
Impact None to date
Start Year 2023
 
Description IODP outreach 
Form Of Engagement Activity Participation in an open day or visit at my research institution
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact IODP Expedition 399 had a team of two Onboard Outreach Officers (OOO) on board the ship. The team provided ship-to-shore broadcasts, organized interviews, conducted interviews, and managed the ship social media and blog. Using a direct satellite link, the team was able to connect with classrooms and community groups across 17 countries. This amounted to a total of 60 ship-to-shore tours, reaching over 3 million participants. The age ranges were a complete spectrum from kindergarten classrooms to nursing homes. As Shipboard scientist, I
actively participated in Q&A sessions following the tours, thus contributing to the outreach.
Year(s) Of Engagement Activity 2023
 
Description IODP press 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Media (as a channel to the public)
Results and Impact Interview with Science magazine
Year(s) Of Engagement Activity 2023
URL https://www.science.org/content/article/long-last-ocean-drillers-exhume-bounty-rocks-earth-s-mantle