Crusie Prospectus and Summary of Objectives
Antarctica 2006
The objectives for this expedition include a number of independent but scientifically related operations. Ideally the research team could lay these out in chronological order, as the cruise is expected to play out, but the season of our deployment to the NW Weddell Sea will likely dictate what we can accomplish and when.
(Click to enlarge)
Sketch map of operational area illustrating transit south to Larsen Basin (solid line), proposed regional seismic line NBP06-03-1.0 (dashed line), and existing mooring locations (red dots with designation following the LMG05-02 station log).
Transit from PA to Larsen B region
The ship's master will make the best course possible to the eastern end of the Bransfield Basin and at this point we will transit to Antarctic Sound and Erebus Terror Gulf in such a way as to expand existing swath map coverage across the Trinity Peninsula shelf and through Antarctic Sound (ice and bathymetry permitting). Our first station will include a CTD and kasten core located in the Prince Gustav Channel (Table 1). This will allow us to work through our system deployment, laboratory apparatus, and recover a core to detail diagenetic features (ikaite crystals) within the Vega Drift sediment system. A CTD will also be taken at this location.
Table 1:
Location of first station for NBP06-03
| Operations |
Lat |
Long |
Water Depth (m) |
| CTDT kasten core |
63 42.166 |
57 18.515 |
736 |
Seismic Survey NBP06-03 Line 1.0
We will exit Prince Gustav Channel and deploy the seismic gear to run a regional seismic reflection line across the Robertson Trough, first south to 65 30 Latitude then toward the SE to mooring location #1 (table 2; Figure 1). Icebergs and pack ice will dictate the exact way points in this survey but our objective is to lay a single regional seismic line across the Larsen shelf to evaluate the Mesozoic and Neogene glacial stratigraphy in the middle shelf. We will attempt to tie this line to the previous work completed in the region.
Mooring Recovery
Upon completion of the seismic line we will proceed to mooring location (see Station #1, Table 2). Here we will conduct a CTD and then proceed to recover the mooring by dragging a grapple hook for the ground line. The detailed mooring diagrams will be included in a revised version of this prospectus at the time we sail and the procedure for recovery will be outlined in our daily briefings. All gear will be serviced and brought on board and we will then proceed south to the Larsen Basin, a glacial trough off the Larsen C ice shelf at Latitude 68 S. A seismic line (continuation of line 1.0) will be run during our transit south which will follow the calving front of the Larsen C ice shelf.
Table 2: Locations and names of moorings deployed during LMG05-02 (station numbers) and to be recovered during NBP06-03
| Station # mooring reference |
Lat |
Long |
Water Depth (m) |
| 1, Larsen C |
66 22.733 |
60 19.877 |
486 |
| 7, Hektoria Glacier |
65 05.220 |
61 18.797 |
818 |
| 9, Crane Glacier |
65 14.591 |
61 59.065 |
683 |
| 17, SCAR Inlet |
65 42.535 |
61 15.010 |
692 |
| 22, Drygalski Glacier |
64 44.126 |
60 34.263 |
718 |
Larsen Basin
Upon arrival at the main axis of the Larsen Basin (Lat 68 6.5' S, Long. 60 40' W) we will conduct a localized multibeam survey to guide us in the location of bottom sampling stations. A series of stations (including CTD) will then be occupied in order to collect bottom grabs, benthic photographs, kasten cores. A mud scud video survey will be taken of the main axis of the trough. A mooring, including sediment traps, will be deployed using gear retrieved from the first recovery (see above).
Larsen C shelf seismic survey
Depending upon ice conditions and sea state we will conduct a mulitbeam and seismic survey (grid lines to be determined) on the shelf off the Larsen C system. An attempt will be made to tie this survey into a preexisting survey.
Larsen B survey and mooring recovery
Upon completion of the Larsen C survey we will return north in a manner to compliment our multibeam and seismic coverage. Time permitting; we may deploy the seismic gear. Upon rounding Cape Framnes (~Lat 66 S) we will deploy seismic gear to run a line to old LMG 05-02 station #17. Here we will conduct a CTD followed by recovery of mooring #17 (table 2). Upon recovery we will conduct swath mapping of the Larsen B embayment in such a way as to integrate our preexisting bathymetric data base. We will conduct the survey in progression from south to north and across the main axial troughs of the Crane and Hektoria/Evans Glaciers; Fig. 1, inset). On the way we will stop to recover moorings at LMG 05-02 station #'s 9 and 7 (table 2) in the Crane and Hektoria basins respectively. We will conduct multibeam and CTD casts, while the sediment traps and instruments are reconfigured. The plan is to return to LMG05-02 stations 17, 9, and 7 (in that order) and redeploy the mooring gear, all the while adding to our multibeam coverage.
Cold seep survey
Upon redeploying the above moorings we will relocate to the distal end of the Crane Glacier Trough. Here we will complete a detailed swath mapping survey to cover the presumed extent of the cold seep system. Upon completion of the multibeam survey we will conduct a CTD followed by deployment of the Data Sonics side scan sonar. Following this a detailed survey utilizing the MUDSCUD bottom video sled will be conducted.
Seismic and multibeam
When the above is completed we will lay out a single seismic line that will run east to, and intersect with line 1.0. Upon completion of this line we will survey into the Hektoria Basin running multibeam and seismic gear. Upon completion of the multibeam survey in the Hektoria Basin we will attempt a Jumbo kasten core followed by a JPC. Upon core recovery we will continue the multibeam survey within the inner reaches and across the Hektoria Glacier Trough and Crane Glacier Trough, eventually returning to the outer end of the Crane Glacier Trough in order to sample the cold seep system.
Cold seep sampling
We will then conduct a series of bottom sampling deployments including: benthos camera, Smith MacIntyre grabs, megacorer, and kasten core. Replicate Smith MacIntyre grabs will be attempted in specific locations in order to recover macro-invertebrates from the vent sites.
Backscatter survey and side scan Data Sonics
In order to resolve "moraine stripes" on the seafloor we will conduct a detailed multibeam and Datasonics survey in the middle region of the Larsen embayment. This will be followed by a MUDSCUD bottom video survey, benthos camera, and Smith MacIntyre grabs.
Multibeam and Seismic survey
At this stage of the program we should be in a position to lay out a reasonable grid for seismic survey of the entire Larsen embayment region. A significant amount of time will be spent conducting this survey and adding multibeam data to the regional bathymetry. Particular attention will be paid to a morainal bank feature along the southern slope of the Seal Nunatak edifice.
Kasten cores and Smith MacIntyre grabs
A number of kasten cores and Smith MacIntyre grabs will be collected in selected localities, based upon the multibeam survey in the inner reaches of the embayment between Crane and Evans Glaciers and on either side of the morainal bank (see previous paragraph).
CTD
Several CTDs will be collected in glacier proximal regions of the Crane, Evans, and Hektoria Glaciers and along the remaining front of the Larsen B and A Ice Shelves.
This will complete our work in the Larsen B region and the remaining time will be spent north, in the Larsen A "Greenpeace Trough."
Drygalski Glacier Mooring recovery
Upon exiting the Larsen B region we will conduct a seismic line again to intersect with line 1.0 toward the NE and returning the line back into the Greenpeace Trough. Here we will retrieve Drygalski Glacier mooring (Sta. LMG05-02 Sta. #22, table 2) after first completing a CTD. The mooring will be serviced and returned to the site.
If there is time remaining we will return to the Vega Drift region of the Erebus & Terror Gulf to conduct seismic and additional JPC operations.
On April 28
the team will end operations for G-096 and transit via the best possible route to the South Orkney Plateau (SOP) to support O-124-L. This departure date is based upon one day transit to SOP and three days of work across the Plateau. We also assume 4 day transit back to PA from the SOP.
