| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | March 14, 2019 |
| Latest Amendment Date: | March 14, 2019 |
| Award Number: | 1836032 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Jennifer Wade
jwade@nsf.gov (703)292-4739 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | April 1, 2019 |
| End Date: | March 31, 2022 (Estimated) |
| Total Intended Award Amount: | $139,795.00 |
| Total Awarded Amount to Date: | $139,795.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
615 W 131ST ST NEW YORK NY US 10027-7922 (212)854-6851 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
61 Route 9W Palisades NY US 10964-1707 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | Petrology and Geochemistry |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
'Convergent plate margins' are major interfaces of the solid Earth geochemical cycle that are fundamental to the formation and maintenance of habitable Earth. At convergent plate margins, a kilometer-thick lithospheric plate consisting of the Earth's crust and uppermost mantle is drawn - or subducted - beneath another lithospheric plate. At around 80-140 kilometers depth, the subducted plate releases volatile-rich material and 'recycles' it back to the Earth's surface via highly explosive, volatile-rich volcanism that forms chains of volcanoes aligned in arcs. On human time scales, eruptions of such single arc volcanoes have caused deadly climate perturbations (e.g. Tambora in 1815) and tsunamis (e.g. Krakatoa in 1883). Hence, understanding how arc volcanism is related to the material transfer from slab remains at the core of geoscience research. In such studies, the cosmogenic isotope 10Be, plays a pivotal role, because it is a unique, geochemical tracer that unambiguously identifies material recycled from slab material. In addition to the important scientific impact of this work, this work impacts society by fostering international collaboration between the U.S. and Mexico, and it also supports students at Columbia. Results from this project will also be incorporated into course curricula.
Recent analytical advances have much improved the detection limit of 10Be in arc volcanic rocks, now allowing for integrating critical volcanic rock series from convergent margins that could not be studied previously. In this project, the 10Be tracer will be further explored and tested through a study in the Transmexican Volcanic Belt (TMVB). The TMVB is a major convergent margin which is well-known for historic eruptions that produced an unusually broad spectrum of volcanic rocks in close temporal and spatial association. While previous geochemical studies showed that these volcanic rocks have direct bearing on the material recycling from slab, crucial details of material transfer (how? how much? how fast?) remain contested. A selected set of well-studied samples from the central (Popocatepetl volcano and surrounding) and western (Colima volcano and surrounding) TMVB will be analysed for 10Be in order to test current hypotheses of subduction recycling. Overall, the project will provide new constraints on the connectivity between slab subduction and arc volcanism and its role in regulating the longterm evolution and maintenance of habitable Earth.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Among all active volcanoes on Earth, the subgroup of ‘arc volcanoes’ are special since they are not only fueled by hot molten material from the Earth’s interior, but also by material that is recycled from the Earth’s surface. The material from the Earth’s surface is returned back into the mantle in so-called ‘subduction zones’. Here, a lithospheric plate (a >10-30 km thick section consisting of crust and upper mantle) is dragged (or ‘subducted’) beneath another ‘overriding’ plate. As the plate sinks back deep into the mantle it also loses material to the mantle, causing it to melt at comparatively shallow depth of ~100 to ~200 km. This ‘recycled’ material, together with hot molten mantle, re-emerges in zones of arc volcanoes which are located at ~100 to ~200 km above the descending plate.
The ‘recycling’ of material in volcanic arcs engenders much interest among Earth’s scientists, owing to the special composition of the arc magmas produced. This composition resembles the composition of the continental crust that is the basis for subaerial life of Earth. Thus, understanding how arc magmas obtain their special composition can help to understand why Earth formed a continental crust in the first place. To this purpose, scientists need to know how much and how fast material is recycled in volcanic arcs.
Scientists approach this question with the help of ‘geochemical tracers’. Like dye is used to track the course of subterranean rivers, geochemical tracers allow to track to pathway of the material recycled in arcs. Among the wide range of tracers used, the cosmogenic 10Be isotope stands out by its ability to unambiguously trace recycling. The 10Be as tracer was introduced more than 30 years ago, but despite its potential, it fell into disuse because it is difficult and expensive to analyze.
This project aimed to revive the use of 10Be as tracer in arc volcanic rocks, building on recent analytical advances and >30 year of knowledge in tracking recycled material by other (less powerful) geochemical tracers. We successfully repeated 10Be data from splits of samples previously analyzed for 10Be, and further tested the method obtaining new 10Be data in the Transmexican Volcanic arc where 10Be abundances are very low. Despite these successes, the new data confirm all the that 10Be tracer remains capricious, because it does not correlate with any of the other geochemical tracers used to constrain material recycling in arcs.
The project provided training opportunities for a high-school student and a college undergraduate student. The undergraduate student became a Fullbright Scholar in Earth Sciences in Germany after graduation. In collaboration with a retired high-school teacher, two lectures were presented in the Earth2Class (E2C) outreach program that aims at K-12 teachers and students with the goal to integrate cutting edge research in to the K-12 classroom. A poster was presented at the 2021 meeting of the Geological Society of America that presents the concept of the Earth2Class (E2C) outreach program with material from this project.
The project enabled fostering of exchange with national and international (Mexican) researchers. For example, with the help of this network, we were able to obtain the samples analyzed for 10Be about 30 year ago, and to –re-analyze them at Lamont with advanced methods. Lastly, the projects contributed to the career development of the PI, a female career researcher with a disability.
Last Modified: 07/14/2022
Modified by: Susanne M Straub
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