| NSF Org: |
OCE Division Of Ocean Sciences |
| Recipient: |
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| Initial Amendment Date: | February 8, 2013 |
| Latest Amendment Date: | August 6, 2014 |
| Award Number: | 0961680 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Candace Major
OCE Division Of Ocean Sciences GEO Directorate for Geosciences |
| Start Date: | February 15, 2013 |
| End Date: | January 31, 2017 (Estimated) |
| Total Intended Award Amount: | $715,330.00 |
| Total Awarded Amount to Date: | $715,330.00 |
| Funds Obligated to Date: |
FY 2014 = $458,628.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
266 WOODS HOLE RD WOODS HOLE MA US 02543-1535 (508)289-3542 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
266 WOODS HOLE RD WOODS HOLE MA US 02543-1535 |
| 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): |
Marine Geology and Geophysics, OCE-Ocean Sciences Research |
| Primary Program Source: |
01001415DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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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
Among the most exciting and unexpected findings related to plate tectonics was the discovery of the hydrothermal vents that populate the earth?s mid-ocean ridge system. Not only do these deep hot springs support a variety of exotic life forms, they are now known to be a primary means by which heat is extracted from the earth?s interior and to be a primary means of chemical exchange between the seafloor and the oceans. But just how heat is supplied to these systems, and how they relate to the tectonic environment remains poorly understood. This project will employ a combination of 3D and 2D high resolution seismic tomography, 2D multichannel reflection and micro-earthquake modeling define the relationship between magmatism, faulting, substrate lithology (rock types) and hydrothermal circulation at the Rainbow Hydrothermal Field on the Mid Atlantic Ridge. This integrated approach is designed to test several hypotheses related to hydrothermal activity and its relationship to the geological environment. Broader impacts include a substantial contribution to international studies of the mid-ocean ridge system, support for two Ph.D. thesis projects and experience for undergraduate interns.
PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH
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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.
Intellectual Merit
High-temperature hydrothermal circulation at mid-ocean ridge volcanic segments extracts heat from crustal magma bodies. However, the heat source driving hydrothermal circulation in ultramafic outcrops, where mantle rocks are exhumed in low-magma supply environments, has remained enigmatic. This project has produced, for the first time, seismic images of the Rainbow massif at the Mid-Atlantic Ridge that reveal that the ultramafic rocks comprising the massif have been intruded by magmatic sills distributed throughout the massif at depths of ~2–10 km. These sills, which appear to be at varying stages of crystallization, can supply the heat needed to drive high-temperature hydrothermal circulation, and thus provide an explanation for the hydrothermal discharge observed in this ultramafic setting. The results of this project demonstrate that deep-sea high-temperature hydrothermal systems can be driven by heat from deep-sourced magma even in settings with very low magma supply where the Earth’s oceanic mantle is exposed.
Hypocenters of micro-seismic events detected during our 9-month-long monitoring of the Rainbow massif do not cluster along fault surfaces, do not exhibit mainshock/aftershock sequences, and are largely absent from the surrounding axial rift valleys. Instead, the hypocenters demarcate a diffuse zone of deformation at relatively shallow (< 5 km) depths beneath the massif, supporting the idea that the faulting associated with the exhumation of the massif is currently inactive. Most of the continuous, low-magnitude seismicity is located in mantle (ultramafic) host rock. These, and other geological constraints suggest that hydration of mantle rocks (serpentinization) plays an important role in microearthquake generation at the Rainbow massif.
Broader Impacts
This project has supported the education and training of a MIT-WHOI Joint Program Ph.D. student, who was trained in marine seismic acquisition and systems, and data processing. In addition, several undergraduate and graduate students participated in the data acquisition and were trained in all aspects of seismic data acquisition and initial quality control and pre-processing. The graduate and undergraduate training of students contributes to the development of a workforce with expertise in seismic data acquisition and analysis methods (routinely used in the oil and gas industry), and earthquake analysis, benefiting both the US academic research community, society at large in the form of training earthquake analysts, and the natural resources and energy industries.
The results of this project have inspired a number of scientists from other disciplines to conduct future research by sampling the sub-surface of the Rainbow massif with deep-sea drilling, with the main objectives of: (1) understanding the nature/conditions of fluid-rock reactions and associated bio-geochemical processes at ultramafic-hosted hydrothermal sites; (2) establish the nature of the basement units beneath the Rainbow hydrothermal field; (3) study the temporal evolution of hydrothermal activity, mineralization, and associated biodiversity.
Last Modified: 02/16/2017
Modified by: Juan Pablo Canales
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