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RRS Discovery D208
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | RRS Discovery (74E3) |
| Cruise identifier | D208 |
| Cruise period | 1994-04-19 — 1994-05-20 |
| Status | Completed |
| Port of departure | Port Louis, Mauritius |
| Port of return | Port Louis, Mauritius |
| Purpose | Research |
| Objectives | To study the crustal structure of the Southwest Indian Ridge |
| Chief scientist | Tim A Minshull (University of Cambridge Department of Earth Sciences) |
| Ocean/sea areas | |
| General | Indian Ocean |
| Specific | Southwest Indian Ocean, Atlantis II fracture zone, SW Indian Ridge at 66E |
| Measurements | |
| Physical oceanography | |
| Bathythermograph | Quantity: number of profiles = 11 Description: XBT drops to 750m depth |
| Geology and geophysics | |
| Dredge | Quantity: number of hauls = 16 Description: rock dredges in SW Indian ridge rift valley, fresh and altered basalts and mud |
| Geophysical measurements made at depth | Quantity: number of profiles = 2 Description: velocimeter dips, to 3000m at 32 45S, 57 4E and to 3950m at 25 28S, 66 25E |
| Single-beam echosounding | Quantity: track kilometres = 6000 Description: Simrad EA500 10kHz narrow beam echo sounder, automatically picked |
| Multichannel seismic reflection | Quantity: track kilometres = 1700 Description: 8-channel data, 100m receiver/shot spacing,to 12s 2-way time, 10 gun |
| Seismic refraction | Quantity: number of deployments = 20 Description: Free floating Spartan AN/SSQ-57B sonobuoys, depl. during reflection profiling |
| Gravity measurements | Quantity: track kilometres = 6000 Description: Lacoste and Romberg shipboard gravimeter, sampled at 30s intervals |
| Magnetic measurements | Quantity: track kilometres = 4000 Description: Barringer Research M123 total field proton magnetometer, with fish |
| Moorings, landers, buoys | |
| Geology and geophysics | |
| Seismic refraction | 32° 45' 0" S 57° 16' 59" E — 1st depl. Julian days 112-113; recovered days 118-120 |
| Seismic refraction | 27° 49' 0" S 65° 58' 59" E — also at 27 41.0S, 065 59.0E |
| Seismic refraction | 32° 43' 59" S 57° 37' 59" E — |
| Seismic refraction | 27° 34' 59" S 65° 46' 59" E — |
| Seismic refraction | 27° 34' 0" S 66° 10' 0" E — |
| Seismic refraction | 27° 40' 59" S 65° 46' 0" E — |
| Seismic refraction | 32° 40' 59" S 57° 16' 59" E — 2nd depl. Julian days 127-128; recovered days 133-134 |
| Seismic refraction | 32° 55' 59" S 57° 16' 59" E — Ocean bottom seismometers, depl. and recovered. |
| Seismic refraction | 32° 43' 59" S 56° 51' 0" E — |
| Seismic refraction | 32° 45' 0" S 57° 27' 0" E — |
| Seismic refraction | 32° 45' 0" S 57° 4' 0" E — |
| Seismic refraction | 27° 34' 59" S 65° 58' 0" E — |
| Seismic refraction | 27° 33' 0" S 66° 22' 59" E — |
| Seismic refraction | 27° 25' 59" S 66° 57' 0" E — |
| Seismic refraction | 32° 31' 59" S 57° 16' 59" E — Sample rate 128Hz, recording air gun shots |
