Woods Hole Oceanographic Institution

Cruise Planning Synopsis


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AT39-04 Rio Grande Rise

Ship

R/V Atlantis

Cruise Party

Antonius Koppers: Chief Scientist, Principal Investigator
Oregon State University, CEOAS 104 CEOAS Admin Bldg Corvallis, Oregon United States 97331
+1 541 737 5425
akoppers@ceoas.oregonstate.edu

Departure: Dec 16, 2017

Montevideo, Uruguay

Arrival: Feb 3, 2018

Praia, Cape Verde Islands

Operations Area

Between 28-39°S in the South Atlantic
Lat/Lon: 23° 0.034′ S / 38° 0.737′ W
Depth Range: min / max (m)
Will the vessel be operating within 200 NM of a foreign country? no

Science Objectives

The Rio Grande Rise (RGR) in the South Atlantic is an oceanic plateau that formed on, or close to the Mid-Atlantic Ridge (MAR) along with Walvis Ridge (WR). Volumetrically RGR is about twice WR and the young end of the Tristan-Gough hotspot trail (Guyot Province) combined. RGR and WR connect to the once conjunct Paranà-Etendeka large igneous province (LIP) and together they feature ~130 Myr of intra-plate volcanism. It is a rare example of a well-preserved conjugate intra-plate system with volcanic records on two tectonic plates. Yet, RGR truly is terra incognita for which only one DSDP site into igneous basement and one basalt dredge are available. Based on these few samples, it appears that RGR formed roughly between 70 and 90 Ma whereas isotopic analyses tell us that RGR sampled similar mantle sources as WR. New plate reconstructions suggest that RGR and the older part of WR formed together along the edges of one or several microplates. In addition, the formation site of RGR-WR aligns with the projected edge of the African LLSVP and this relationship makes RGR-WR a globally unique, long-standing window to the core-mantle boundary. RGR thus provides a unique opportunity to address a wide range of questions relating to plate tectonics, plume dynamics and lower mantle characterization: If formed as two paired aseismic ridges, why is RGR’s morphology so different from WR? Did RGR form along the edges of micro-plates? Is RGR itself age-progressive or did it form as a single volcanic edifice? Is RGR geochemically triple-zoned in a similar fashion as the Guyot Province in the WR? What geochemical components dominate the RGR plume source related to the African LLSVP? What are the consequences of the answers to the above questions for plume zonation and plume dynamic models, our understanding of sources related to LLSVPs, the opening of the Atlantic basin, and global tectonic modeling?

Science Activities

program includes (i) 9.9 days of multibeam mapping around our dredge targets; (ii) 9.7 days of transit and mapping between targets, including mapping of the RGR rift zones; (iii) 10.8 days for 40 dredging operations; (vi) 2 bad weather days.
24/7 dredge operations, Towed magnetometer, Gravity measurements, EM122 multibeam mapping

Additional Info

Pre-cruise Planning Meeting: Teleconference
Meeting Notes: Pre-cruise meeting 8/25

Stations:

Supporting documentation:

»Dredge.Targets.US.Cruise.xlsx

Funding

Funding Agency: NSF
Grant or contract number: 1558681

Scientific Instrumentation for R/V Atlantis

Shipboard Equipment

Bathymetry System 12 kHz
Sippican XBT System (Mark 21)
Bathymetry System 3.5 kHz
12 kHz Pinger for Wire Use
Navigation - Heading
Multibeam
Navigation - Position
Gravimeter
Towed Magnetometer

Shipboard Communication

Basic Internet access via HiSeasNet
Is there a need to transfer data to shore on a regular basis?
Is there an expectation to use Skype or any other real-time video conference program?

Critical CTD Sensors

Storage Notes: 10 wire racks for storing dredge bags for shipment back to OSU Marine and Geology Repository

Navigation

Will you be using Long Base Line (LBL) navigation? no
How many nets? null
How many tansponders? null
Will you be using Ultra-short baseline (USBL) navigation?no

Navigation

GPS
Navigation Notes:
Winch Notes: Wire needed for dredging. We will be dredging deep, up to 5-6 km water depth. Having 10 km of wire available would be important.
Winch Notes: Dredging only up to 5-6 km water depth.

Standard Oceanographic Cables

Slip ring required? no
Non-standard wire required? no
Traction winch required? no

Specialized Deck Equipment

Mooring Deployment/Recovery Equipment Required: no Type: 
Cruise Specific Science Winch Required: no Type: 
Nets Required: no Type: 

Over the Side Equipment

Will you be bringing any equipment (winches, blocks, etc.) that lowers instruments over the side? no

Special Requirements

Elecrical Power: no Identify 
Equipment Handling: no Identify: 
Inter/intraship Communications: no Identify: 
Science Stowage: yes Identify: 10 wire racks for rocks; 3 palettes of equipment
Water: yes Identify: For cleaning rocks after sawing

Additional Cruise Items/Activities

Explosive Devices:no
Portable Air Compressors:no
Flammable Gases:no
Small Boat Operations:no
SCUBA Diving Operations:no

Hazardous Material

Will hazardous material be utilized?no
Describe deployment method and quantity:

Radioactive Material

Radioiosotopes:no

Additional Information

Is night time work anticipated on this cruise?yes
Specialized tech support (Seabeam, coring, other):
This is a dredging cruise with often 24 hour dredging operations. We therefore require 2 restechs so we can operate day and night in a continuous dredging mode, if so required.
Other required equipment and special needs:
Rock saw area.
Portable Sink
From STR:• 24/7 dredge operations with two experienced restechs
• At least 5 spare dredges
• Towed magnetometer
• Gravity measurements
• EM122 multibeam mapping

Checklist & Notes

Checklist

U.S. Customs Form: yes
Diplomatic Clearance: no
Date Submitted:
Date Approved:
Agent Information:
Countries:
Notes:
Isotope Use Approval: no
Isotope Notes:
SCUBA Diving: no

Checklist

SSSG Tech:
Some equipment will be loaded at WHOI before Oct 2nd 2017 including dredges and dredge gear. Magnetometer, cable, winch and spare will be shipped to Barbados.