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Melting Off-Axis
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2016
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Atlantis
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Project Title: |
Melting in the Off-Axis Environment - Field and Modeling Studies of the 8° 20'N Seamount Chain and EPR Axis- Alvin Diving |
Project Status: |
Submitted |
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Principal Investigator: |
Patricia Gregg, UIUC |
Project Institution: |
UIUC |
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Project ID: |
104033 |
Version #: |
4 |
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Date Submitted: |
8/8/2013 8:04:00 AM |
Created By: |
Daniel J. Fornari |
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Date Last Modified: |
2/5/2015 8:37:00 PM |
URI Serial #: |
None |
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Funding Agencies: |
NSF/OCE/MGG - 1356610 - Funded |
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Summary of Field Work: |
The 8°20’N Seamount chain, located west of the East Pacific Rise (EPR) Siqueiros transform fault ridge-transform intersection (RTI), is an ideal location to test models of melt production and transport because it consists of a ridge-perpendicular volcanic chain extending ~200 km (to ~ 3.6 My seafloor) away from the ridge axis. We propose that melts delivered through the crust to build these seamounts provide geochemical ‘probes’ into the upper mantle adjacent to a fast-spreading MOR axis. This investigation will provide critical constraints to study the formation of off-axis oceanic crust and the development of near-axis seamount chains, and to test models of melt distribution and extraction, all of which are fundamental first-order processes associated with the formation of oceanic lithosphere and the evolution of the upper mantle.
Our 2-yr interdisciplinary investigation includes: (1) a seagoing expedition to collect geophysical data, conduct 15 (fifteen) Alvin dives to systematically make observations and collect in situ lava samples, and also dredge the 8°20’N Seamount Chain; (2) analytical geochemistry to collect major and trace element data; (3) geophysical data analyses; and (4) petrologic-geodynamic modeling of mantle melting and melt extraction.
Our acquisition plan for the bathymetric, gravity and magnetics survey data covering the 8°20’N Seamount chain includes first conducting shipboard underway surveying using the RV Atlantis’ EM2112 multibeam system, a BGM-3 gravimeter, and a Marine Magnetics SeaSpy towed magnetometer. Our proposed survey includes ~4 days of E-W oriented survey lines spaced ~9 km apart to provide reasonable overlap in bathymetric and derived-sidescan coverage, which should be nominally ~3.5x water depth over most of the survey area. We will spend an additional 4 days collecting N-S oriented tie lines at lengths over specific seamounts, which are critical for addressing seamount formation using magnetics data. The 60-km long tie lines will be collected during the geophysical survey, while the shorter 15 and 30 km N-S lines will be collected at night during the Alvin diving portion of the program.
The second phase of the field effort will be devoted to site-specific Alvin diving along the seamount chain and collecting observations and in situ samples, and at night conducting both dredging and TowCam surveys as reconnaissance of ~30 volcanoes in the 8°20’N chain focusing on sampling the largest seamounts farthest away, at the midpoint, and the ones closest to the EPR axis. The Alvin diving and dredge plan will be dictated by the findings of our multibeam and derived-sidescan surveys, as well as reconnaissance using TowCam, but we expect that we will devote approximately 2-3 Alvin dives to each of at least 5-7 of the largest volcanoes at distal, middle and proximal locations with respect to the EPR axis in order to better constrain whether magmas feeding them were of similar compositions throughout their construction (i.e., sampling summit and basal edifice lavas, or on flank-scarps that may expose older flows). We will also dredge as many additional volcanoes of various sizes distributed evenly along the 8°20’N chain as we can during nights when Alvin is charging batteries.
Based on extensive experience by Fornari and Perfit with Alvin diving and dredging both seamounts and the EPR axis, we are confident that we can accomplish at least 2 dredges each night when Alvin is charging its batteries and that we can collect ~20 well located samples with Alvin on each dive. |
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Summary of Facility Requirements: |
RV Atlantis with Alvin submersible and USBL navigation, and near-bottom sonar mapping system with DVL navigation and compartmentalized baskets for rock collecting. Atlantis geophysical survey systems must include EM2112 multibeam system, BGM3 gravimeter, towed SeaSpy magnetometer. The science party will provide the WHOI-MISO TowCam deep sea camera system which requires the stbd CTD winch and hydroboom, with 3 conductor 0.322" CTD wire with winch controls and tension/wire out readouts in the main lab.
At least 6 fully rigged SIO style dredges should be available with SIO weak link system and spares calibrated bolts for weak links. Extra net bags, chain bags, burlap, and dredging supplies should be available through the operator.
2 functioning deep sea pingers (12 kHz) should be available.
Extra USBL beacons for the TowCam and dredge wire should also be available |
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Summary of other requirements and comments: |
NOTE THAT THIS SHIP/VEHICLE REQUEST IS A REVISION BASED ON PI DISCUSSIONS WITH THE NSF OCE MGG PROGRAM MANAGER, B. RANSOM AND HER APPROVAL OF SWITCHING THIS FIELD PROGRAM TO BE AN ALVIN DIVING CRUISE
The PI P. Gregg has moved to U. Illinois as of Summer 2014 |
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Type of Request: |
Primary Ship Use |
Request Status: |
Submitted |
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Request ID: |
1006450 |
Created By: |
Daniel J. Fornari |
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Date Last Modified: |
2/5/2015 8:37:00 PM |
Date Submitted: |
8/8/2013 8:04:00 AM |
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Year: |
2016
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Ship/Facility: |
Atlantis
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Optimum Start Date:
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2/1/2016 |
Dates to Avoid: |
DO NOT SCHEDULE FOR PERIOD BETWEEN JUNE AND OCTOBER BECAUSE OF BAD WEATHER IN THE AREA |
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Earliest Start Date: |
1/1/2016 |
Multi-Ship Op: |
No |
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Latest Start Date: |
4/1/2016 |
Other Ship(s): |
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Operating Days Needed: |
Science Days |
Mob Days |
De-Mob Days |
Estimated Transit Days |
Total Days |
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23 |
3 |
3 |
7 |
36 |
Repeating Cruise?
(within same year) |
No |
Interval: |
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# of Cruises: |
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Description of Repeating cruise requirements: |
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Justification/Explanation for ship choice, dates,
conflicts, number of days & multi-ship operations: |
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Short Description of Op Area
for use in schedules: |
8 20N EPR |
| Description of Op Area: |
East Pacific Rise flank west of Siqueiros Transform between 8N and 8 30'N and 104W and 107W |
| Op Area Size/Dia.: |
10800 |
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Lat/Long |
Marsden Grid |
Navy Op Area |
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Beginning
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Ending
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Show Degrees Minutes |
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Foreign Clearance Required? |
No |
Coastal States:
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 Important Info on Foreign Research Clearances
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Are you or any member in your science party bringing in any science equipment items which are regulated for export by the International Traffic in Arms Regulations (ITAR) and/or the Export Administration Regulations (EAR)?
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No |
If yes, have you applied for the necessary permits through your export control office?
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No |
| Questions about ITAR/EAR regulations?
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Comments about foreign clearance requirements or
description of any other special permitting requirements
(e.g., MMPA, ESA, IHA, Marine Sanctuaries, etc.) |
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Requested Start Port |
Intermediate Port(s) |
Requested End Port |
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Manzanillo, Mexico |
None |
Manzanillo, Mexico |
Explanation/justification for requested
ports and dates of intermediate stops
or to list additional port stops |
start/end port could also be Pt. Caldera (Puntarenas) Costa Rica depending on ship movement/logistics |
Important Info on Working in Foreign Ports
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Chief Scientist: |
Patricia Gregg, UIUC |
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# in Science Party |
20 |
# of different science teams |
3 |
# Marine Technicians to be
provided by ship operator:
(include in science party total)
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2 |
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Explanation of Science Party Requirements and Technician Requirements |
multibeam and dredging shipboard techs required
Alvin near-bottom mapping is required, data processor from NDSF requested for near-bottom multibeam
TowCam will have its own engineer provided by the science party |
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 Dynamic Positioning |  ADCP | Multibeam | Seismic |
| Dredging/Coring/Large Dia. Trawl Wire | Stern A-frame | Fiber Optic (.681) | 0.680 Coax Wire |
| SCUBA Diving | Radioisotope use - briefly describe | NO Radioisotope use/Natural level work | Other Operator Provided Inst. - Describe |
| 0 PI-Provided Vans - briefly describe | MOCNESS | | |
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Explain Instrumentation or Capability
requirements that could affect choice
of ship in scheduling. |
EM2112 multibeam
BGM3 gravimeter
SeaSpy towed magnetometer for geophysical surveying
6 SIO style dredges and weak links with spare net bags
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Explain Major Ancillary Facilities
Requirements and list description
and provider for "other" systems. |
WHOI MISO TowCam system
http://www.whoi.edu/page.do?pid=17619 |
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