Thread: Two berths available on upcoming cruise to Rainbow hydrothermal field in the Mid Atlantic Ridge

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From: Interridge <interridge<at>noc.ac.uk>
Subject: Two berths available on upcoming cruise to Rainbow hydrothermal field in the Mid Atlantic Ridge
Date: January 11, 2013 5:14:59 AM EST
To: " interridge-mail<at>noc.soton.ac.uk" < interridge-mail<at>noc.soton.ac.uk>

Dear Colleagues

Please forward to any interested parties.

There are 2 berths available for international collaborators interested in mid-ocean ridge research, with the support of InterRidge through its Cruise Bursary Scheme.
- one berth for a postdoc or early-career scientist, ideally with expertise in multichannel seismic reflection data acquisition and processing, and/or multibeam bathymetry mapping.
- one berth for a graduate student or post-doc.

The above cruise will be onboard the RV Marcus Langseth, from April 10th (departure St. George, Bermuda) through May 19th (arrival Ponta Delgada, Azores), 2013.

The expedition will conduct:

- 3D active-source wide-angle seismic tomography with an array of 46 ocean bottom seismometers (OBSs);
- 2D multichannel seismic reflection profiling using an 8-km-long, 640-channel hydrophone streamer;
- Deployment of 15 OBS for long-term monitoring (~6-8 months) of local microseismicity.
- Underway acquisition of multibeam bathymetry, gravity, and sea-surface magnetics.

For more information please contact any of the Co-Chief Scientists/PIs: Pablo Canales, Robert Dunn, Rob Sohn:
jpcanales<at>whoi.edu
dunn<at>hawaii.edu
rsohn<at>whoi.edu

If you wish to make an application, complete an application form ( http://www.interridge.org/cruisebursary) and send it to the InterRidge Office, together with your CV and support letter from your advisor.

Deadline for applications: 31 January 2013

Scientific Objectives:
Seismic Investigation of the Rainbow Hydrothermal Field and its Tectono/Magmatic Setting, Mid-Atlantic Ridge 36deg14'N

Heat extraction from the Earth via hydrothermal systems along mid-ocean ridges (MORs) is a fundamental process affecting the Earth: hydrothermal systems extract approximately one third of the global yearly heat loss through ridges and are a primary means of chemical exchange between the solid Earth and the oceans. It is generally believed that sections of MORs with greater magma supply host a greater abundance of hydrothermal systems. While this simple conceptual model provides a framework within which to understand hydrothermal heat generation, the relative roles of magmatic heat input, tectonic heat advection, and faulting in controlling ridge thermal structure and hydrothermal circulation are still poorly understood. This is particularly important for hydrothermal circulation at slow- and ultra-slow spreading ridges, where venting occurs in a variety of host-rock lithology and tectonic setting. The Rainbow hydrothermal field (RHF) is a methane-, hydrogen- and iron-rich !
system located on an ultramafic massif within a tectonized non-transform discontinuity (NTD) of the Mid-Atlantic Ridge, where current models predict that long-term magma supply should be very low. Yet Rainbow vents high-temperature fluids at high flow rates, which is difficult to explain without a magmatic heat source. This conundrum stands in the way of our ability to develop general models for the roles of magmatic heat input and tectonic faulting on controlling ridge thermal structure and hydrothermal circulation, particularly for hydrothermal systems located in regions dominated by ultramafic lithologies, which are common at slow and ultra-slow MORs.

This project consists of a three-part seismic study of the physical architecture of the crustal and upper mantle at Rainbow to address the following fundamental question: What is the relationship between magmatism, faulting, substrate lithology, and hydrothermal circulation at the Rainbow hydrothermal field? A combination of 3D and 2D high-resolution active-source seismic tomography, 2D multichannel seismic reflection, and passive microearthquake monitoring will allows to determine the tectonic and thermal structure, melt content, and microseismicity around and beneath the RHF to determine:

· The nature and location of the heat source driving hydrothermal circulation at RHF.
· The nature and origin of the Rainbow massif.
· The role of the local stress field on focusing hydrothermal discharge.

Sent by:
Debbie Milton

Interim InterRidge Coordinator
coordinator<at>interridge.org

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Danielle Sumy
National Science Foundation Postdoctoral Fellow
Seismology
U. S. Geological Survey
525 S. Wilson Ave.
Pasadena, CA 91106
Phone: 626-583-7814
E-mail: danielle.sumy<at>gmail.com