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ID 85034
Also Known As 85034
FRNL85LEG3A
F-3A-85-GM
Abstract United States Geological Survey, Woods Hole, Massachusetts. Chief Scientists: Dave Twichell, Lindsay Parson. Data (sidescansonar, airgun, 3dot5khz, 10khz, magnetics, loranc, transitsatellite, gps) of field activity 85034 (F-3A-85-GM) in Gulf Mexico from 10/02/1985 to 10/22/1985
Organization United States Geological Survey, Woods Hole, Massachusetts
Project/Theme Exclusive Economic Zones (EEZ)
Geological Long-Range Inclined Asdic (GLORIA)
Chief Scientist Dave Twichell
Lindsay Parson
Platform Farnella
Area of Operation Gulf Mexico, Gulf of Mexico
Bounding Coordinates
29.21060
-88.26970     -82.00210
23.87920
Ports leave Tampa, FL
arrive Key West, FL
Dates 10/02/1985 (JD 275) to 10/22/1985 (JD 295)
Analog Materials No analog holdings.
Crew
Roy Hadgraft Captain, J. Marr and Sons
Dave Twichell Chief Scientist, USGS Woods Hole
Robert Commeau Geologist, USGS Woods Hole
Steven Mateus Geologist, USGS Woods Hole
Page Valentine Geologist Data Curator, USGS Woods Hole
Charlie Paull Geologist, Scripps Institute of Oceanography
Kim Benjamin Engineer, Woods Hole Oceanographic Institution
Derek Bishop GLORIA Engineer, IOS (Institute of Oceanographic Sciences, U.K.)
Lindsay Parson Co-chief Scientist, IOS
Robin Bonner Airgun Tech, IOS
Jon Campbell GLORIA Engineer, IOS
Andrew Harris GLORIA Engineer, IOS
Colin Jacobs Geologist, IOS
Doriel Jones Shipboard Computing, RVS (Research Vessel Services, U.K.)
Derek Lewis Shipboard Computing, RVS
Equipment Used
sidescansonar
airgun
3dot5khz
10khz
magnetics
loranc
transitsatellite
gps
Purpose
As part of the program to study the Exclusive Economic Zone (EEZ) of
the Gulf of Mexico, the U.S. Geological Survey, in cooperation with the
Institute of Oceanographic Sciences of the U.K., undertook a long-range
side-scan sonar survey of the Gulf of Mexico.  The EEZ seaward of
approximately the 500 m isobath was mapped using GLORIA (Geologic LOng-
Range Inclined Asdic), a system owned and operated by IOS.  In addition
to the GLORIA data, airgun, 3.5 kHz, 10 kHz, and magnetometer data were
collected.  During leg 3A, the final leg of the program in the Gulf of
Mexico, the Florida Escarpment and the distal end of the Mississippi Fan
were surveyed.  The cruise was 20 days long, and data were collected along
6,741 km (3,640 nm) of ship's track.  The area mapped by GLORIA during this
leg was approximately 50,586 square kilometers (27,314 square nautical miles).
Notes
NARRATIVE:
  
	Leg 3A was very successful.  The weather was superb and imposed no
restrictions on the operation of the equipment.  The warm surface water
temperatures, which imposed such severe restrictions on the line spacing during
legs 1 and 2, were not as serious a problem during this leg because of the deep
water depths in which we were working most of the time.  The only area where
the surface water temperature affected the sonar's range was in the shallow
water east of the Florida Escarpment, but even here we were able to get
complete GLORIA coverage to depths of 400-1,000m.  The Loop Current in the
southeastern corner of the Gulf reached speeds of 7.4 km/hr (4 kts) and was
highly variable in its direction of flow.  This current made it difficult to
steer straight lines, and had an effect on the orientation of the GLORIA
vehicle.  The greatest challenge to operations, though, was fishing boats and
their long-line fishing gear.  The lines were as long as 65 km (35 nm) and
were 20 m below the surface; too shallow to go over with GLORIA.  The fishing
fleet was particularly abundant in the DeSoto Canyon area, but some were
also found near the edge of the Florida Escarpment at 25dN.  The long-line
gear is the reason for the peculiarities in the ship's track in these two
areas.
  
	After the first two days, equipment down time was minimal and operation
were very smooth.  There were some logging problems with the GLORIA system and
about 11 hours of data were lost at the beginning of the cruise.  Initially the
Muirhead camera (part of the system used to play back the data for building
the at-sea mosaic) was not working properly, but it was fixed and caused only
a slight delay in building the mosaic.  The preamplifier in the Northstar
Loran C antenna was damaged when we left Tampa and could not be fixed, but we
managed very well using a combination of Loran C fixes from the ship's
receiver, satellite fixes, and fixes from the Global Positioning System when
available (6-7 hours a day).  The seismic-reflection system was down for about
9 hours during the entire cruise.  A 160 cu in airgun was used for the first
three days, and after that we switched to an 80 cu in chamber.  The smaller
chamber resulted in much less wear on the airgun, yet still provided excellent
subbottom penetration.
  
	The data from leg 3A were full of surprises.  The Florida Escarpment
was spectacular, and showed a lot of unexpected changes in morphology along
its length.  Mass wasting on the slope above the escarpment was more extensive
than expected, especially south of about 26dN.  The slide or slides on the
Mississippi Fan that we started mapping on Leg 2 extend to the southeastern
corner of the Gulf (24dN).  The distal end of the Mississippi Channel was
found at about 25d30'N-86dW, but it was filled with slide deposits which
extended much further to the south.
  
TABULATED INFORMATION:
  
	A.  Days at sea:  20
  	
	B.  Amount of data collected:
  
	System			Time Spent		Km Data Collected
  
	GLORIA			424 hr 45 min		6,557
  
	10 kHz profiler		435 hr			6,734
  
	3.5 kHz profiler	435 hr 15 min		6,738
  
	Airgun			428 hr			6,578
  
	Magnetometer		433 hr 30 min		6,712
Publications
Paskevich, Valerie F.; Wong, Florence L.; O'Malley, John J.; Stevenson,
Andrew J.; Gutmacher, Christina E., 2010, GLORIA sidescan-sonar imagery
for parts of the U.S. Exclusive Economic Zone and adjacent areas: U.S.
Geological Survey Open-File Report 2010-1332,
http://pubs.er.usgs.gov/publication/ofr20101332.
  
Twichell, David C., and Paskevich, Valerie, 1996, GLORIA sidescan sonar
field data and navigation data collected in the Gulf of Mexico during
R/V Farnella cruises in 1982 and 1985: U.S. Geological Survey Open-File
Report 96-707,
http://woodshole.er.usgs.gov/publications/of96-707/OPR96_707/INTRO.HTM.
Got Help? For 85034, we would appreciate any information on -- activity type, analog materials, contract, days at sea, dive count, funding, information specialist, information to be derived, kms of navigation, national plan, NGDC Info, owner, project number, scanned materials, seismic description, station count, station description, submersible, summary, tabulated info.
Type Webpage KMZ Arc         Metadata         WHSC
Metadata data     txt  data  FAQ  xml data
Navigation data nav      
Times   060.times      

85034 location map of where navigation 

equipment operated
85034 location map of where navigation 

equipment operated

 
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