Field Activity 1985-028-FA

Identifier 1985-028-FA
Alternate names 85 Leg 2; FRNL 85-2, F285GM
Purpose The purpose of the cruise was to map the sea floor between the shelf edge and the seaward limit of the EEZ, using the GLORIA system owned and operated by IOS. Leg 2 focused in the central Gulf of Mexico on the Mississippi Fan seaward of Louisiana, Mississippi, Alabama, and Florida.
Location central Gulf of Mexico, Mississippi fan area, Louisiana, Mississippi, Alabama, Florida, United States, North America, North Atlantic;
Summary This cruise was very successful. Equipment down time was minimal. The warm surface water temperature continued to limit the GLORIA range necessitating closer line spacing than planned. The presence of the loop current for the last half of the cruise not only provided warm surface water temperatures but also a strong current often approaching 4 knots. The current shear prevented the GLORIA fish from towing parallel to the ship's track, introducing some distortion in the mosaic. In the northeast portion of the Gulf near Desoto Canyon fishing boats with lines set across our proposed track caused a problem requiring several lines to be terminated early. Leg 3A will collect data to cover these data gaps. An additional 8 days will be necessary on Leg 3 to complete the coverage of the Mississippi Fan. The objective of this leg was to map the surface features in the Mississippi Fan area. Although the channel of the Mississippi could be identified on the mid-fan, over much of the fan the channel was obscured by a major submarine slide or slides. Flow patterns were well displayed on the surface and the slide could be mapped to the base of the West Florida Escarpment. Another submarine slide was also present in the Desoto Canyon area. The meandering channel from Desoto Canyon was traced from this slide seaward parallel to the escarpment. Mass wasting appears to be an important process in distributing sediments in the deep water of the central Gulf. The Sigsbee Escarpment was mapped to the east as far as the Mississippi Canyon. Isolated salt diapirs were present to the east of the Mississippi Canyon.
Info derived As part of a cooperative program between the U.S. Geological Survey and the Institute of Oceanographic Sciences (IOS), U.K., a survey of the Exclusive Economic Zone (EEZ) in the Gulf of Mexico was conducted aboard the M/V FARNELLA. The purpose of the cruise was to map the sea floor between approximately the shelf edge and the seaward limit of the EEZ, using the GLORIA (Geologic LOng-Range Inclined Asdic) system owned and operated by IOS. Additional geophysical data collected simultaneously with the sidescan data include: 10 kHz, 3.5 kHz, air gun (160 cubic-inch chamber) with two-channel hydrophone, and magnetometer. Navigation was principally based on Loran-C, although transit satellite and Global Positioning System (GPS) data were also logged for comparison. All geophysical data were recorded digitally on magnetic tape and the airgun data were recorded on analog magnetic tape. A preliminary mosaic of the sidescan data was constructed at sea at a scale of 1:375,000, using an anamorphic camera to adjust the images to the ship's track. Post-cruise image processing and enhancement of the data are planned before construction of the final mosaic.
Comments image2segy data at PCMSC on FAD PI's Bonnie McGregor, Neil Kenyon Platform Farnella Original Center People field contained: Ronald Circe; John Schlee - geologist; Dave Twichell - Data curator. Project = GLORIA Gulf of Mexico Survey 1985, GLORIA Gulf of Mexico Survey 1985
Projects
Platform
Farnella
230 feet
Itinerary
Start New Orleans, LA 1985-09-05
End Tampa, FL 1985-09-29
Days in the field 24
Bounds
West -91
East -85
North 29.25
South 25

Personnel

Organization
384 Woods Hole Road
Quissett Campus
Woods Hole, MA02543-1598
(508) 548-8700
Principal investigators McGregor, Bonnie
Crew members
David C Twichell
Scientist, Staff
Ronald C. Circe
Scientist, Staff
John Schlee
Scientist, Staff
Information specialist(s)
(not identified)
Specialist, Information
Affiliate principal Neil Kenyon - IOS
Affiliate staff Bonnie McGregor - co-Ch. Sci., USGS-Miami; Neil Kenyon - co-Ch. Sci., IOS; Martin Beney - Shipboard computing, RVS; Eric Darlington - GLORIA engineer, IOS; Malcolm Harris - GLORIA engineer, IOS; Colin Jacobs - geologist, IOS; Ross Walker - GLORIA engineer, IOS; Robert Wallace - airgun tech, IOS; Stephen Willams - geologist, IOS; John Wagner - geologist, LSU

Data types and categories

Data category: Electro-Magnetic, Location-Elevation, Seismics, Sonar
Data type: Magnetics, Navigation, Air Gun / Water Gun, Sub Bottom Profiler, Sidescan, Single Beam

Documents: Notes and log books

Name Description
Cruise report Chief Scientist's cruise report includes personnel and a summary for each leg of the operation (covers 2 cruises - 85027 and 85028) as well as trackmaps.
Contractor's report Contract Report (pdf file) Institute of Oceanographic Sciences contract report. Includes personnel, program description, cruise narrative, scientific results and trackmaps. The report specified 4 legs of operation.

Equipment used

Equipment Usage description Data types Datasets
10 kHz Bathymetry Single Beam 3
GLORIA sidescan Sidescan 3
Marine magnetometer Magnetics 1
Loran-C Navigation 2
Single channel hydrophone Air Gun / Water Gun, Boomer, Bubble Gun, Sparker, Sub Bottom Profiler 4
ABC navigation system Navigation (no data reported)
Other Unknown, Multichannel, Boomer, Sub Bottom Profiler, Sparker, Bubble Gun, Air Gun / Water Gun, Ocean Bottom Seismometer, Sonobuoy (no data reported)
3.5 kHz Sub Bottom Profiler (no data reported)
Air gun Air Gun / Water Gun (no data reported)

Datasets

Datasets produced in this activity

Dataset name Equipment Description Dataset contact
1985-028-FA-BA-001 10 kHz Bathymetry Digital tape(s) of GLORIA, NV,BT, PROCESSED GLORIA, Nancy K. Soderberg
1985-028-FA-BA-002 10 kHz Bathymetry CD ROM disk of GLORIA ATLANTIC GEOTIFF, GLORIA GULF MEXICO GEOTIFF, GLORIA IMAGES, GLORIA/MOSAIC 1-16, Nancy K. Soderberg
NGDC MGD77 data 10 kHz Bathymetry Linda P McCarthy
1985-028-FA-SO-001 GLORIA sidescan Digital tape(s) of GLORIA, NV,BT, PROCESSED GLORIA, Nancy K. Soderberg
1985-028-FA-SO-002 GLORIA sidescan CD ROM disk of GLORIA ATLANTIC GEOTIFF, GLORIA GULF MEXICO GEOTIFF, GLORIA IMAGES, GLORIA/MOSAIC 1-16, Nancy K. Soderberg
GLORIA sidescan data GLORIA sidescan Linda P McCarthy
NGDC MGD77 data Marine magnetometer Linda P McCarthy
1985-028-FA-LN-001-01 Loran-C Trackline map for R/V FARNELLA cruise FRNL85-2 Nancy K. Soderberg
Nav data Loran-C Linda P McCarthy
1985-028-FA-SE-001 Single channel hydrophone microfilm of Nancy K. Soderberg
1985-028-FA-SE-002 Single channel hydrophone analog tape of seismic data Nancy K. Soderberg
1985-028-FA-SE-003 Single channel hydrophone Collection of single-channel high-resolution seismic paper profiles including 3.5kHz (22 folders FD#1981-2000,4001-4002); airgun 5-sec sweep (5 folders #FD4003-4007; airgun 8-sec sweep (5 folders FD #4008-4012); airgun 2-sec sweep (1 folder FD #4026); airgun 4-sec sweep (2 folders FD #4027-4028); 10kHz (9 folders FD #4013-4021) Alice M. Orton
1985-028-FA-SE-003-01 Single channel hydrophone Electronic scans of some paper seismic profiles. Alice M. Orton

Publications

Samples collected during this field activity