USGS CMG C-1-88-SP Metadata

The main focus of RC2901 was a geophysical study of the interaction
between the Chilean ridge and trench.  The inner trench slope accretionary
processes and the extent of the continental crust were of particular interest.
Multichannel seismic surveys were conducted in four areas:  35  -40  S
were surveyed as a subcontract for the Chilean oil company, ENAP;  three
areas at 44  30'S, 46  S, and 48 S were surveyed as possible ODP drilling
sites.  Magnetics, gravity and Sea Beam were run at all times during these
surveys.  An intensive seven day Sea Beam survey was conducted from
45  30'S to 47  S in the area where the Chile trench is actively subducting
a segment of the Chilean ridge.  Single channel seismic, magnetics and
gravity data were also collected during the survey.

Lamont-Doherty Geological Observatory

! Converted to time format with year at start.
!
DATA COLLECTION OVERVIEW  (use NGDC GEODAS CD to retrieve data)

MCG Data Collection ID ---         C188SP
Institution Data Collection ID --- C2901
NGDC ID ---                        01010288
Funding ---                        (unspecified)
Project, Cruise & Leg ---          (unspecified)
Study region ---                   -32.00000,-54.00000, -77.00000, -70.00000
Chief Scientist(s) ---             STEVEN CANDE, STEPHEN LEWIS
Name of vessel ---                 R/V Robert D. Conrad (surface ship)
Date field data collection started --- 01/07/88     VALPARAISO, CHILE
Date field data collection ended ---   02/10/88     PUNTA ARENAS, CHILE
Parameters surveyed ---
   Bathymetry:                     surveyed, contained in data file
   Magnetics:                      surveyed, contained in data file
   Gravity:                        surveyed, contained in data file
   High-resolution seismics:       not surveyed
   Deep penetration seismics:      surveyed, but not contained in data file
Format --- 

(I1,A8,F5.2,4I2,F5.3,F8.5,F9.5,I1,F6.4,F6.1,I2,i1,3F6.1,I1,F5.1,F6.0,F7.1,F6.1,F5.1,A8,4I1)
Date of data input to NGDC ---     02/18/90
Contributing institution ---       Lamont-Doherty Geological Observatory
Country ---                        United States of A

Navigation instrumentation ---     FURUNO,TRANSIT SAT,GPS
Position determination method ---  FURUNO DR BETWEEN SAT FIXES

Bathymetry instrumentation ---            GENERL INSTRMNTS SEABEAM CENTER BEAM
Additional forms of bathymetric data ---  SWATH ALSO COLLECTED BY URI
General rate of bathymetry in file ---    1.0 minutes
General collection rate of bathymetry --- 1 each 6 sec
Assumed sound velocity ---                1500.0 m/sec
Bathymetric datum code ---                No correction applied (sea level)
Bathmetry interpolation scheme ---        LOGGED ALL CNTR BEAM,CLOSEST TO 0 
SECS. INTERP

Magnetics instrumentation ---            VARIAN V75 MAGNETOMETER
Additional forms of magnetics data ---   (unspecified)
General rate of magnetics in file ---    1.0 minutes
General collection rate of magnetics --- 20 seconds
Magnetic sensor tow distance ---         (unspecified)
Magnetic sensor depth ---                (unspecified)
Two sensor horizontal separation ---     (unspecified)
Residual magnetics reference field ---   IGRF-85
Method of applying residual field ---    BILINEAR INTERP IN 1 DEG SQUARE

Gravity instrumentation ---            BELL AEROSPACE BGM-3 GRAVITY METER
Additional forms of gravity data ---   (unspecified)
General rate of gravity in file ---    1.0 minutes
General collection rate of gravity --- (unspecified)
Theoretical gravity formula ---        INTERNATIONAL 80
Reference system ---                   Potsdam system
Corrections applied ---                +.0328 MGAL/DAY, DC +.57 MGAL
Starting land tie ---                  978030.0  NOAA SHIP BASE 
NO.2,MIAMI,1/7/87
Ending land tie   ---                  981326.2  PORT ADMIN BLDG,P. ARENAS,2/13/S

Seismic instrumentation --- DIGICON DSS-240
Formats of seismic data --- (unspecified)

Notes ---
THEORETICAL GRAVITY FORMULA: Yo = 978.0327 * ( 1 + a - b ) where
b = .0000058 * sin( 2 * theta ) * sin( 2 * theta ) .
NGDC has multibeam bathymetric data for this cruise, however the tracklines
found here in GEODAS may not exactly correspond to the multibeam data.