Volatile Recycling at the Lesser Antilles Arc: Processes and Consequences
Lead Research Organisation:
Imperial College London
Department Name: Earth Science and Engineering
Abstract
The Earth is unique in our solar system in having abundant liquid water, plate tectonics and life. These properties are not unconnected; The evolution of life has depended heavily on water, and water is pumped around the planet by the plate tectonic cycle. Plate tectonics in turn, and its capacity to generate the very continents on which we live, also depends on the existence of water.
Subduction zones are the most important "valve" in the plate tectonic system. They form where tectonic plates sink back into the mantle. Here water, along with other volatiles such as carbon dioxide and sulphur, are returned to the deep interior. However, the return is not wholesale. As the sinking plate is subjected to heat and pressure, a large fraction of the incoming volatiles is "sweated off" and added to the overlying mantle where it causes melting. These melts feed volcanoes at subduction zones which are characteristically dangerously explosive. When considered with the earthquakes triggered by the plates scraping past each other and the consequent tsunamis and landslides, it is clear that subduction zones are the most hazardous places on Earth. Yet, these regions also have benefits: the cocktail of fluids travelling with magmas at subduction zones is responsible for transporting and emplacing valuable metal deposits into the crust, and the fine ash distributed by the explosive volcanoes produces nutrient-rich, fertile soils.
The importance of cycling volatiles through subduction zones is self-evident. However we still don't really know how it works and what the budgets are of volatiles delivered to the subduction zone, versus those recycled into the lithosphere, hydrosphere and atmosphere compared with those sequestered back into the deep mantle.
We propose an innovative multidisciplinary experiment to track volatiles at a subduction zone. Questions to be answered include: How do volatiles influence the types and amounts of magmas generated? How do they control where volcanoes, such as Mt Pinatubo and Montserrat are located and how explosive they are? How do volatiles dictate where ore deposits are formed? How do volatiles mediate the seismogenic behaviour of subduction zones - whether there are large "megathrust" earthquakes like Japan and Sumatra or whether slip is less violent?
Our focus area is the Lesser Antilles Arc, which is a special case, because it is one of only two Atlantic subduction zones. Plate formation processes at the slowly-spreading mid-Atlantic ridge produce a much more pervasively hydrated plate than those in the extensively studied Pacific. Furthermore, a laterally varying capacity to carry water in the plate and sediments subducting below the Antillean arc are a likely culprit for the arc's highly variable style and intensity of seismic and volcanic activity. By mapping structural differences along the arc we will be able to pinpoint the effects of variable water input.
We plan to use novel seismic approaches complemented by geochemical analyses and integrated using numerical models to identify and quantify where volatiles are in the downgoing plate, where they are released at depth, and how they are transported from the subducting plate through the mantle wedge to the arc. We will use a unique suite of rocks from deep in the crust which have been carried up in volcanoes to help us understand how magmas evolve, and what allows them to concentrate ore metals. Mapped water pathways will be compared with seismic and volcanic activity, as well as with those inferred at other subduction zones.
This large research project will be "bookended' on the one hand by an enormous amount of resource; data, samples, expertise and results from previous studies that will provide excellent value for money, and on the other hand a special focus on the societal benefits; informing natural hazard planning, and a better appreciation of how and where economic deposits form.
Subduction zones are the most important "valve" in the plate tectonic system. They form where tectonic plates sink back into the mantle. Here water, along with other volatiles such as carbon dioxide and sulphur, are returned to the deep interior. However, the return is not wholesale. As the sinking plate is subjected to heat and pressure, a large fraction of the incoming volatiles is "sweated off" and added to the overlying mantle where it causes melting. These melts feed volcanoes at subduction zones which are characteristically dangerously explosive. When considered with the earthquakes triggered by the plates scraping past each other and the consequent tsunamis and landslides, it is clear that subduction zones are the most hazardous places on Earth. Yet, these regions also have benefits: the cocktail of fluids travelling with magmas at subduction zones is responsible for transporting and emplacing valuable metal deposits into the crust, and the fine ash distributed by the explosive volcanoes produces nutrient-rich, fertile soils.
The importance of cycling volatiles through subduction zones is self-evident. However we still don't really know how it works and what the budgets are of volatiles delivered to the subduction zone, versus those recycled into the lithosphere, hydrosphere and atmosphere compared with those sequestered back into the deep mantle.
We propose an innovative multidisciplinary experiment to track volatiles at a subduction zone. Questions to be answered include: How do volatiles influence the types and amounts of magmas generated? How do they control where volcanoes, such as Mt Pinatubo and Montserrat are located and how explosive they are? How do volatiles dictate where ore deposits are formed? How do volatiles mediate the seismogenic behaviour of subduction zones - whether there are large "megathrust" earthquakes like Japan and Sumatra or whether slip is less violent?
Our focus area is the Lesser Antilles Arc, which is a special case, because it is one of only two Atlantic subduction zones. Plate formation processes at the slowly-spreading mid-Atlantic ridge produce a much more pervasively hydrated plate than those in the extensively studied Pacific. Furthermore, a laterally varying capacity to carry water in the plate and sediments subducting below the Antillean arc are a likely culprit for the arc's highly variable style and intensity of seismic and volcanic activity. By mapping structural differences along the arc we will be able to pinpoint the effects of variable water input.
We plan to use novel seismic approaches complemented by geochemical analyses and integrated using numerical models to identify and quantify where volatiles are in the downgoing plate, where they are released at depth, and how they are transported from the subducting plate through the mantle wedge to the arc. We will use a unique suite of rocks from deep in the crust which have been carried up in volcanoes to help us understand how magmas evolve, and what allows them to concentrate ore metals. Mapped water pathways will be compared with seismic and volcanic activity, as well as with those inferred at other subduction zones.
This large research project will be "bookended' on the one hand by an enormous amount of resource; data, samples, expertise and results from previous studies that will provide excellent value for money, and on the other hand a special focus on the societal benefits; informing natural hazard planning, and a better appreciation of how and where economic deposits form.
Planned Impact
The proposed research is fundamental, and will deepen our understanding of plate tectonics, and the water cycle. Non-academic beneficiaries will include: [1] regional (Caribbean) agencies responsible for mitigating potential hazards such as earthquakes, volcanoes and tsunami. [2] Mining companies interested in understanding the genesis and distribution of subduction-related ore deposits; [3] Agencies, including government, involved in the development of policies on securing the future resource base and the sustainability of resource exploitation; [4] Host nation capacity building through education and training [5] The general public, specifically individuals and groups focused on geology and lay science, and school children.
To achieve this impact the project has set up partnerships with the Seismological Research Centre of the University of West Indies, who will use our new data and seismic velocity structures to improve their hazard maps, and with the NERC-funded STREVA project that focuses on volcanic hazard in the Antilles, and includes ties with the Montserrat Volcano Observatory and regional government agencies. A student from the University of West Indies will undertake a six-month study visit to the UK to receive training in seismological methods that will allow them to be involved in the analysis of the new data.
Co-I Wilkinson has various projects with mineral exploration companies and hosts an annual symposium to communicate new scientific results to representatives from UK industry. To further engage potential industrial users, we will publish our results in academic journals and present our work at both academically focused conferences such as the American Geophysical Union Fall Meeting, and also at industry focused conferences such as the Society of Exploration Geophysicists Meeting.
We will communicate to the wider public via several routes. We will set up a project web site with specialist as well as outreach components. In addition, all involved universities participate in outreach programs to schools as well as specialist-interest adult groups and the general public, including the Seismology-in-Schools effort (Imperial), the Discover Oceanography Program (Southampton), Nature Live at the London Natural History Museum (Imperial), Science Weeks of Imperial College and Royal Society, and the "Beacons of Engagement" public outreach project (Bristol, Durham). Several of us have experience with interviewing and presenting in the media and to public audiences.
The project will be wrapped up with a workshop in the Antilles to which international scientists as well as potential non-academic beneficiaries will be invited.
To achieve this impact the project has set up partnerships with the Seismological Research Centre of the University of West Indies, who will use our new data and seismic velocity structures to improve their hazard maps, and with the NERC-funded STREVA project that focuses on volcanic hazard in the Antilles, and includes ties with the Montserrat Volcano Observatory and regional government agencies. A student from the University of West Indies will undertake a six-month study visit to the UK to receive training in seismological methods that will allow them to be involved in the analysis of the new data.
Co-I Wilkinson has various projects with mineral exploration companies and hosts an annual symposium to communicate new scientific results to representatives from UK industry. To further engage potential industrial users, we will publish our results in academic journals and present our work at both academically focused conferences such as the American Geophysical Union Fall Meeting, and also at industry focused conferences such as the Society of Exploration Geophysicists Meeting.
We will communicate to the wider public via several routes. We will set up a project web site with specialist as well as outreach components. In addition, all involved universities participate in outreach programs to schools as well as specialist-interest adult groups and the general public, including the Seismology-in-Schools effort (Imperial), the Discover Oceanography Program (Southampton), Nature Live at the London Natural History Museum (Imperial), Science Weeks of Imperial College and Royal Society, and the "Beacons of Engagement" public outreach project (Bristol, Durham). Several of us have experience with interviewing and presenting in the media and to public audiences.
The project will be wrapped up with a workshop in the Antilles to which international scientists as well as potential non-academic beneficiaries will be invited.
Publications
Perrin A
(2018)
Mantle wedge temperatures and their potential relation to volcanic arc location
in Earth and Planetary Science Letters
Altoe I
(2020)
Thermo-compositional structure of the north-eastern Canadian Shield from Rayleigh wave dispersion analysis as a record of its tectonic history
in Earth and Planetary Science Letters
Chen Y
(2024)
Lesser Antilles slab reconstruction reveals lateral slab transport under the Caribbean since 50 Ma
in Earth and Planetary Science Letters
Bie L
(2022)
Imaging slab-transported fluids and their deep dehydration from seismic velocity tomography in the Lesser Antilles subduction zone
in Earth and Planetary Science Letters
Eeken T
(2018)
Seismic evidence for depth-dependent metasomatism in cratons
in Earth and Planetary Science Letters
Goes S
(2019)
Project VoiLA: Volatile Recycling in the Lesser Antilles
in Eos
Harmon N
(2021)
Widespread Hydration of the Back Arc and the Link to Variable Hydration of the Incoming Plate in the Lesser Antilles From Rayleigh Wave Imaging
in Geochemistry, Geophysics, Geosystems
Allen R
(2018)
30 Years in the Life of an Active Submarine Volcano: A Time-Lapse Bathymetry Study of the Kick-'em-Jenny Volcano, Lesser Antilles
in Geochemistry, Geophysics, Geosystems
Kounoudis R
(2020)
Seismic Tomographic Imaging of the Eastern Mediterranean Mantle: Implications for Terminal-Stage Subduction, the Uplift of Anatolia, and the Development of the North Anatolian Fault
in Geochemistry, Geophysics, Geosystems
Chen F
(2022)
How Slab Age and Width Combine to Dictate the Dynamics and Evolution of Subduction Systems: A 3-D Spherical Study
in Geochemistry, Geophysics, Geosystems
Description | Volatiles, such as water, CO2, and sulphur, not only make Earth a unique, life-supporting planet but also lubricate the dynamics of plate tectonics. At subduction zones, where they are transported into the planet's interior in oceanic plates, volatiles contribute to violent volcanism and earthquakes but also help build both new continental material and valuable metal deposits. This transport is not well understood and what we do know comes mainly from studying subduction of the Pacific Plate, while we expect the Atlantic plates to be different in where and how much water they carry because they formed differently, by slow-spreading. In this project, we performed the first integrated analysis of an Atlantic subduction zone to identify and quantify where volatiles are held in the subducting plate, where they are released from that plate, and how they are transported from there through the mantle wedge to the volcanic arc. The new geophysical datasets we collected, complemented by novel geochemical and petrological analyses, and integrated using numerical models allow us to trace volatile pathways through the Lesser Antilles subduction zone and indeed reveal a strongly variable distribution of volatiles in the incoming plate. An old boundary between two plate domains appears particularly volatile-rich and responsible for higher magmatic productivity in the central islands and peaks in the number of earthquakes in the overriding and subducting plates. Our new images of deep mantle structure below the region shed light on the unusual evolution of this subduction system through time. Furthermore, our images show that fluids released from the downgoing plate and the melts induced by these fluids do not travel in a straight path from their source to the volcanic arc above. |
Exploitation Route | - The project produced insights in the distribution and style of earthquakes along the whole arc. Further work is ongoing to use these to update seismic hazard assessment. - Understanding of the endmember subduction zone adds to our overall understanding of dynamics and stresses due to subduction. - Understanding of the pathways of fluids and melts will help build understanding of this in other subduction zones and link to volcanic and mineralisation potential |
Sectors | Environment |
URL | http://www.voila.ac.uk |
Description | Our findings are contributing to more informed seismic and volcanic hazard assessment by Caribbean agency responsible for hazard monitoring in the region. We compiled a new earthquake catalogue with improved locations and a new local seismic velocity model for routine earthquake locations. Using newly collected data, we made a detailed reconstruction of 30 year evolution of Kick'em Jenny underwater volcano. We held a highly successful final workshop with strong engagement and attendance from local observatories, members of Antillean universities, regional partners as well as top international scientists. Throughout the project outreach activities were held including, general audience talks, school demonstrations, open days, twitter, and website. |
First Year Of Impact | 2017 |
Sector | Environment |
Impact Types | Societal |
Title | JC133 cruise report |
Description | Cruise report detailing ship activities |
Type Of Material | Database/Collection of data |
Year Produced | 2016 |
Provided To Others? | Yes |
Impact | Details of cruise activities |
URL | https://www.bodc.ac.uk/resources/inventories/cruise_inventory/report/16047/ |
Title | JC149 cruise report |
Description | Describes all ship data collection activity |
Type Of Material | Database/Collection of data |
Year Produced | 2018 |
Provided To Others? | Yes |
Impact | Cruise activity |
URL | https://www.bodc.ac.uk/resources/inventories/cruise_inventory/report/16391/ |
Description | SWAMMIS |
Organisation | University of Bergen |
Country | Norway |
Sector | Academic/University |
PI Contribution | Asked to be collaborator/contributor to SWAMMIS (https://swammis.w.uib.no) because of shared research interest between this network and VoiLA. Participated in workshops, collaborated on two papers (Halpaap et al 2019 led by SWAMMIS student and Perrin et al., 2018, led by VoiLA-associated student) |
Collaborator Contribution | Regular research discussions, collaboration on two papers (Halpaap et al., 2019, Perrin et al., 2018) |
Impact | two papers (Halpaap et al 2019 led by SWAMMIS student and Perrin et al., 2018, led by VoiLA-associated student) |
Start Year | 2015 |
Description | Ben Maunder Poster at Fall AGU Washington DC |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Poster by Project PDRA Ben Maunder DI23B-0030: The Decoupling Depth and Slab Thermal Structure |
Year(s) Of Engagement Activity | 2018 |
URL | https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/438049 |
Description | Invited presentation at international conference (American Geophysical Union, New Orleans, December 2017) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Keynote (invited) presentation in a special session of Caribbean subduction. Overview of VOILA project given. Title VoiLA: A multidisciplinary study of Volatile recycling in the Lesser Antilles Arc, given by J Collier. |
Year(s) Of Engagement Activity | 2017 |
URL | https://agu.confex.com/agu/fm17/preliminaryview.cgi/Paper239559.html |
Description | Poster Ben Chichester FAll AGU 2018 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Poster by VoiLA PhD student Ben Chichester at Fall meeting of American Geophysical Union Washington DC |
Year(s) Of Engagement Activity | 2018 |
URL | https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/431031 |
Description | Poster Lidong Bie at Fall AGU 2018 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Presentation at Fall meeting of American Geophysical Union Washington DC |
Year(s) Of Engagement Activity | 2018 |
URL | https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/430987 |
Description | Poster presentation at international conference (AGU 2017) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Poster presentation by NERC-DTP PhD student Rob Allen. 30 years in the life of an active submarine volcano: The evolution of Kick-'em-Jenny and implications for hazard in the southern Caribbean |
Year(s) Of Engagement Activity | 2017 |
URL | https://agu.confex.com/agu/fm17/preliminaryview.cgi/Paper234459.html |
Description | Presentation at International Workshop (GeoPRISMs) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Professional Practitioners |
Results and Impact | Presentation at a workshop from large US initiative which is also one of our partners |
Year(s) Of Engagement Activity | 2015 |
URL | http://geoprisms.org/tei-scd-2015/ |
Description | Talk Nick Harmon Fall AGU 2018 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Presentation at Fall meeting of American Geophysical Union Washington DC |
Year(s) Of Engagement Activity | 2018 |
URL | https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/409571 |
Description | Talk Steve Hicks Fall AGU 2018 |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | International |
Primary Audience | Other audiences |
Results and Impact | Presentation by VoiLA PDRA Steve Hicks at Fall meeting American Geophysical Union meeting Washington DC |
Year(s) Of Engagement Activity | 2018 |
URL | https://agu.confex.com/agu/fm18/meetingapp.cgi/Paper/427860 |
Description | participation in Imperial Festival April 2018 |
Form Of Engagement Activity | Participation in an activity, workshop or similar |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Other audiences |
Results and Impact | Our team made an exhibit to demonstrate the role of fluids in explosive volcanism. We had a volcano model where we injected fluids to cause eruptions as well as rocks and a game to find out where in the system these came from. We participated in the school day and the two subsequent general public days and attracted over 3000 visitors to our demonstrations. See also our project website www.voila.ac.uk. |
Year(s) Of Engagement Activity | 2018 |
URL | http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/eventssummary/event_17-8-2017-12-52-36 |