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ID 85027
Also Known As FRNL85LEG1
F-1-85-GM
85027
Abstract United States Geological Survey, Reston, Virginia. Chief Scientists: Bonnie McGregor, Guy Rothwell. Data (sidescansonar, airgun, 3dot5khz, 10khz, magnetics, loranc, transitsatellite, gps) of field activity 85027 (F-1-85-GM) in Gulf Mexico from 08/07/1985 to 09/03/1985
Organization United States Geological Survey, Reston, Virginia
Project/Theme Exclusive Economic Zones (EEZ)
Geological Long-Range Inclined Asdic (GLORIA)
Chief Scientist Bonnie McGregor
Guy Rothwell
Platform Farnella
Area of Operation Gulf Mexico, Gulf of Mexico
Bounding Coordinates
27.96980
-95.66830     -81.62170
23.82450
Ports leave Miami, FL
arrive New Orleans, LA
Dates 08/07/1985 (JD 219) to 09/03/1985 (JD 246)
Analog Materials No analog holdings.
Crew
Bonnie McGregor Chief Scientist, USGS Miami
Dann Blackwood Photographer, USGS Woods Hole
Bob Mattick Geologist Data Curator, USGS Woods Hole
Bill Sweet Geologist, MMS (Minerals Management Service, U.S.A.)
Kim Benjamin Engineer, WHOI (Woods Hole Oceanographic Institution, U.S.A.)
Mike Somers GLORIA Engineer, IOS (Institute of Oceanographic Sciences, U.K.)
Guy Rothwell Chief Scientist, IOS
Alan Gray Airgun Tech, IOS
Quentin Huggett Geologist, IOS
Ross Walker GLORIA Engineer, IOS
Derek Bishop GLORIA Engineer, IOS (Institute of Oceanographic Sciences, U.K.)
Christopher Jackson Shipboard Computing, RVS (Research Vessel Services, U.K.)
E. Cooper RVS
Roy Hadgraft Captain, J. Marr and Sons
Equipment Used
sidescansonar
airgun
3dot5khz
10khz
magnetics
loranc
transitsatellite
gps
Purpose
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.
Notes
LEG 1:
  
	Leg 1 focused on the western half of the Gulf of Mexico, seaward of
Texas and Louisiana, and abutting GLORIA coverage from a 1982 survey.  This
portion of the Gulf is dominated by salt tectonics.  The area mapped with
GLORIA during this leg was 45,000 sq nautical miles.
  
Data Summary - Leg 1
  
At sea a total of 27 days
  
Mileage for each type of data collected:
  
GLORIA sidescan		4430 nm		8195 km
  
3.5 kHz			4594 nm		8504 km
  
10 kHz			4594 nm		8504 km
  
airgun			4430 nm		8195 km
  
magnetometer		4080 nm		7548 km
  
Comments - Leg 1:
  
	The weather during leg 1 was generally excellent except for two
hurricanes.  Hurricane Danny resulted in a loss of 13 hours of operation
on August 14, 1985, and Hurricane Elena delayed arrival in New Orleans one
day, from September 2 to September 3, 1985.
  
	The impact that the warm surface water and strong thermocline
present in the Gulf of Mexico in the summer would have on the range of the
GLORIA system was not realized.  Although GLORIA was run at a 30 sec.
repetition rate (45 km swath width) the maximum swath width actually obtained
was 8 km in approximately 1000 m of water.  This required reducing the
trackline spacing, adding additional tracklines, and thus limiting the effort
in water depths shallower than 1000 m.
  
	Initially, much time was spent getting all equipment operational.
The GLORIA system suffered from logging problems resulting in a loss of
approximately 24 hours of data during the cruise.  The longest continuous
down time period was 12 hours.  Dirt particles in the air being pulled across
the recording heads by the air conditioning system appears to have been the
major problem.  The airgun system was down a total of approximately 24 hours
due to compressor, streamer, and airgun problems.  The longest continuous
period of down time was 7 hours.  The magnetometer required 3 days to get
operational initially, but this was partly a result of its lowest priority.
A new computer system was installed for this cruise.  Most of the leg was
required to get the system operating properly.  Navigation had to be plotted
by hand for the duration of the cruise.  Summary data plots for the cruise,
however, track line plots were completed with the computer system at the end
of the cruise.
  
	The data in the western Gulf are very interesting geologically.  The
Sigsbee Escarpment can be identified on the sonographs with piles of debris
in places at its base.  A continuous channel can be traced from the shelf edge
through the diapir province of the slope, forming a reentrant in the Sigsbee
Escarpment, and then meandering seaward across the rise into the deep
water of the Gulf.  The fan of the Rio Grande has a braided channel system,
on which are features interpreted to be bedforms.  Similar bedforms are
present seaward of the Sigsbee Escarpment suggesting that strong bottom
currents are present in the region.
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 85027, 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      

85027 location map of where navigation 

equipment operated
85027 location map of where navigation 

equipment operated

 
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