Reactive melt migration in the lower oceanic crust and its implications for the evolution of mid-ocean ridge basalt
Lead Research Organisation:
CARDIFF UNIVERSITY
Department Name: School of Earth and Ocean Sciences
Abstract
Mid-ocean ridge basalt (MORB) is the most abundant magma on Earth. It is generated beneath mid-ocean ridges by decompression melting of upwelling mantle, and, following processing in lower crustal magma chambers, erupted onto the seafloor. For more then four decades igneous petrologists and geochemists have relied upon MORB as their major window into the mantle, deriving its composition, melting processes and melt migration mechanisms from the erupted lavas. However, this approach assumes that modification of melts in crustal magma chambers occurs exclusively by fractional crystallisation, and can thus be easily corrected for. Within the last decade evidence has emerged that melt may react extensively with existing cumulus crystals as it migrates through mid-ocean ridge magma chambers. This process can strongly modify both the major and trace element compositions of the melt, leading to significant deviations from fractional crystallisation trends. In a recent paper, I was the first to reconstruct the potential effect of reactive melt migration in the lower crust on magma compositions, arguing that the process may impart strong chemical signals on MORB. If so, this requires a fundamental reassessment of MORB petrogenesis and its use as a messenger from the mantle. Thus, in order to understand MORB petrogenesis, and its implications for mantle studies, a robust model that fully characterises the nature and extent of reactive flow in oceanic magma chambers is required. However, no systematic study of reactive melt migration has been done to date, with data limited to a small number of samples from only two locations. As a result, no data exist to robustly assess the extent, nature and spatial distribution of reactive melt migration, hampering an understanding of MORB petrogenesis and its use for studying the mantle. This proposal seeks to determine the nature and extent of reactive melt migration in mid-ocean ridge magma chambers, and test the hypothesis that it plays an important role in MORB petrogenesis. This will be achieved by conducting a systematic, high-resolution study of what has previously been shown to represent a complete, discrete intrusion within an ancient mid-ocean ridge magma chamber (ODP Hole 735B, Southwest Indian Ridge). I will obtain extensive textural and mineral chemical analyses, acquiring the first systematic dataset on reactive melt migration in the lower oceanic crust. The melt-rock reaction history as deduced from the rock record will then be modelled, allowing its role in MORB evolution to be quantified. Combined, the data and models will provide an unprecedented view of reactive melt migration through mid-ocean ridge magma chambers and its role in the evolution of MORB. Ultimately, this will determine the fidelity of MORB as recorders of mantle properties and processes.
Organisations
People |
ORCID iD |
Cornelis Lissenberg (Principal Investigator) |
Publications
Boulanger M
(2020)
Magma Reservoir Formation and Evolution at a Slow-Spreading Center (Atlantis Bank, Southwest Indian Ridge)
in Frontiers in Earth Science
Gleeson M
(2023)
Porosity evolution of mafic crystal mush during reactive flow
in Nature Communications
Leuthold J
(2018)
Partial Melting of Lower Oceanic Crust Gabbro: Constraints From Poikilitic Clinopyroxene Primocrysts
in Frontiers in Earth Science
Lissenberg C
(2016)
A Reactive Porous Flow Control on Mid-ocean Ridge Magmatic Evolution
in Journal of Petrology
Lissenberg CJ
(2019)
Consequences of a crystal mush-dominated magma plumbing system: a mid-ocean ridge perspective.
in Philosophical transactions. Series A, Mathematical, physical, and engineering sciences
Sun C
(2018)
Formation of fast-spreading lower oceanic crust as revealed by a new Mg-REE coupled geospeedometer
in Earth and Planetary Science Letters
Sun C
(2018)
Caveats and challenges in geospeedometry: A reply to Faak et al.'s critique of the Mg-REE coupled geospeedometry
in Earth and Planetary Science Letters
Description | The ocean floor is paved with basaltic rocks erupted from subsurface volcanoes. Research funded by this grant discovered that the compositions of these rocks is in part controlled by chemical reactions between the magma and minerals in the earth's crust. |
Exploitation Route | Results have established a new mode of igneous differentiation, which would be expected to occur in basaltic magma chambers worldwide. On-land counterparts to oceanic magma chambers host the majority of the Earth's Ni, Cr and PGE, and the reactive flow mechanism may control the distributions of these elements. |
Sectors | Other |
Description | Findings have inspired a workshop to secondary school students focusing on the geology of the ocean basins. Feedback was very positive, and two students in attendance went on to apply to study Geology at university. |
First Year Of Impact | 2013 |
Sector | Education |
Impact Types | Societal |
Description | Ocean floor outreach |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | Talk provided students with a perspective of Geosciences Numerous pupils expressed interest in studying Geosciences. |
Year(s) Of Engagement Activity | 2013 |
Description | Outreach to primary schools JR |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Schools |
Results and Impact | Live Q&A broadcasts to primary schools while aboard RV JOIDES Resolution during IODP Expedition 335 Stimulated interest in Geosciences |
Year(s) Of Engagement Activity | 2011 |
Description | Schools petro prac |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | Regional |
Primary Audience | Schools |
Results and Impact | Workshop provided students with a perspective of Geosciences Stimulated interest in Geosciences |
Year(s) Of Engagement Activity | 2013,2014 |