Rationalized Detailed Gravity Data                        Click here to return to Index Page
Southern Saskatchewan

This open file is a compilation of more than 150 separate gravity surveys acquired by the exploration industry and stored in map form by Saskatchewan Energy and Mines Geodata Branch.  These data have been levelled to a common datum.  The datum is represented by  the regional gravity data holdings of the National Gravity Anomaly Data Base maintained by the Geodetic Survey Division of Geomatics Canada.  The national data are tied to the International Gravity Standardization Network 1971 (IGSN71) and are included in this compilation.

The levelled data are presented here as a PC binary file of 230,312 records. Each record contains 31 fields.  The file is  \DATA\Binary\grav\SASKGRAV.BIN.  This is the file to be used as input to  RET_256.COM.  An ASCII version of the data is also  included as \DATA\Binary\grav\SASKGRAV.ASC.  This file's format is described in \DOC\SASKGRAV.FORMAT

The binary data may be manipulated using the program 'RET_256.COM'.  This program will run on any 386 or higher PC.  To run the program in Windows NT or Windows 95 or higher, open Explorer, go to the directory containing the program and click on the application 'RET_256'.   To run the program from an MSDOS window, go to the directory containing the program and type 'RET_256'.  The program can also be run by clicking here. (Note: this CD-ROM has been tested with Netscape Communicator v4.7 and Microsoft Internet Explorer v3.02).  A Windows Security Warning may appear and prompt you to Open or Save the program file.  Choose Open.

'RET_256' allows the user to extract subsets of the data based on area or survey.  Areas are defined by latitude and longitude ranges and surveys are defined by a range of project numbers.  The user may also recalculate Bouguer gravity anomalies using user-specified Bouguer densities (rock, water and ice) in order to better represent local crustal densities.  In addition,  the anomalies may be recalculated using the three most common geoid models: WGS84, GRS67 or Potsdam 1930.

The following is an example of a data retrieval.  Descriptive text is black, user prompts are  red and answers to the prompts are green:

 --------------------------------------------------------------
 RATIONALIZED DETAILED GRAVITY DATA, SOUTHERN SASKATCHEWAN
 --------------------------------------------------------------
 

 RET_256: Manipulates binary 256 character gravity files.

    This program extracts data from the rationalized
    Saskatchewan Digitized Gravity Archive by latitude
    and longitude bounded area and/or by project number.
    In addition, Bouguer anomalies can be recomputed with
    user-specified Bouguer densities and geoid models.

    See the file RET_256.TXT for a description of this program.

   Input: binary 256 character record (SASKGRAV.BIN)

  Output: ASCII user-specified records or
          binary 256 character record (can be used as
          input to this program).

          Summary file containing data retrieval
          specifications and statistics.
 ------------------------------------------------------

 ======================================================
 ENTER THE INPUT FILENAME (binary 256 CHARACTER RECORDS)
G:\DATA\BINARY\GRAV\SASKGRAV.BIN

 ======================================================
 ENTER THE OUTPUT FILE NAME (USER-SPECIFIED FORMAT)
SASKGRAV.TEST

 ======================================================
 ENTER THE SUMMARY FILE NAME
SASKGRAV.SUMMARY

 ======================================================
 STATIONS HAVE BEEN MARKED AS DELETED WHERE DATA ARE
 INCOMPLETE OR CONSIDERED IN ERROR

 DO YOU WISH TO RETRIEVE DELETED STATIONS (Y or N)?
y

 ======================================================
 SOME ANCILLARY FIELDS MAY NOT BE AVAILABLE AND HAVE
 BEEN MARKED WITH NULL VALUES

 DO YOU WISH TO RETRIEVE RECORDS WITH NULL VALUED FIELDS (Y or N)?
y

 ======================================================
 DO YOU WISH TO RECALCULATE ANOMALIES WITH USER-SPECIFIED
 BOUGUER DENSITIES AND GEOID MODEL (Y or N)?
y

 -----------------------------------------------------
 DENSITIES: STANDARD ROCK: 2.67 g/cc
           STANDARD WATER: 1.03 g/cc
             STANDARD ICE: 0.90 g/cc

   ENTER ROCK DENSITY:
2.0
  ENTER WATER DENSITY:
1.03
    ENTER ICE DENSITY:
.9

 -----------------------------------------------------
  Rock Density:   2.000
 Water Density:   1.030
   Ice Density:   0.900
  ----------------------------------------------------
  CHANGE ANY OF THESE (Y or N)?
n
 -----------------------------------------------------
 ELLIPSOID: 1984 - WGS84
            1967 - GRS67 (GSC standard since 1974)
            1930 - POTSDAM (pre-1974 GSC standard)

  ENTER ELLIPSOID REFERENCE YEAR(1984, 1967, OR 1930)
1967
 -----------------------------------------------------
 
 
 
 

 ======================================================
 DATA MAY BE EXTRACTED WITHIN A SPECIFIC AREA BOUNDED BY
 USER SPECIFIED LATITUDE AND LONGITUDE RANGES.

 DO YOU WISH TO EXTRACT DATA FROM A SPECIFIC AREA (Y OR N)?
y
 ENTER THE MINIMUM AND MAXIMUM LATITUDES (DECIMAL DEGREES)
48 57
 ENTER THE MINIMUM AND MAXIMUM LONGITUDE (DECIMAL DEGREES-NEGATIVE WEST)
-112 -99
 ======================================================
 THE DATA HAVE BEEN ASSIGNED PROJECT NUMBERS TO IDENTIFY
 INDIVIDUAL, INTERNALLY CONSISTANT SURVEYS. A LIST OF ALL
 PROJECT NUMBERS CAN BE FOUND IN THE FILE SASKGRAV.SUMMARY
 AND A LIST OF THE PROJECTS IN THIS RETRIEVAL CAN BE
 FOUND IN THE SUMMARY FILE IT GENERATES.

 DO YOU WISH TO EXTRACT DATA BY PROJECT NUMBER (Y OR N)?
y
 Project Number Ranges
 1 - PRE-1994 DATA (NIMA)
     min project #8495
     max project #9567

 2 - 1994 DATA (MOBIL OIL)
     min project #19941
     min project #19942

 3 - 1995 DATA
     min project #94
     min project #2992

 4 - NATIONAL GRAVITY DATA BASE
     min project #46001
     min project #96115

 -----------------------------------
 Enter the range of project numbers to be retrieved
    -(enter the project number twice for a single project)

 Enter the minimum project number
0
 Enter the maximum project number
9999999
 -----------------------------------

 ======================================================
  The following fields are contained in each record:
  NOTE: Complete field descriptions can be found in the
        Open File report and in your summary file
 ------------------------------------------------------------------
  1 - PROJ    - project #        | 17 - BOUGUER - Bouguer anomaly
  2 - STN     - station #        | 18 - BAV     - Bouguer acc.
  3 - DECLAT  - latitude         | 19 - STATUS  - station status
  4 - DECLONG - longitude        | 20 - OSTN    - orig. stn.#
  5 - CAV     - coord. acc.      | 21 - OPROJ   - orig. proj.#
  6 - ELEV    - elevation        | 22 - OBOUG   - digitized Bouguer
  7 - EAV     - elev. acc.       | 23 - ECF     - elev. cor. factor
  8 - DEPTH   - depth            | 24 - OBSG    - gravity from OBOUG
  9 - DAV     - depth acc.       | 25 - OOBSG   - NIMA gravity value
 10 - DT      - depth type       | 26 - OFA     - NIMA free air
 11 - ADJG    - adjusted grav.   | 27 - OBA     - NIMA Bouguer
 12 - GAV     - gravity acc.     | 28 - RHOC    - Bouguer density
 13 - TCOR    - terrain cor.     | 29 - ELEVCOR - elev correction
 14 - TAV     - tcor acc.        | 30 - OBSGCOR - adjg correction
 15 - FREEAIR - free air anomaly | 31 - ESTATUS - elev. status
 16 - FAV     - free air acc.
 ------------------------------------------------------------------
 HOW MANY FIELDS DO YOU WISH TO EXTRACT (ENTER 0 FOR ALL FIELDS)?
31
ENTER THE NUMBER FOR EACH FIELD SEPARATED BY A SPACE (eg. 3 4 17)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30  31

 --------------------------------------------------------------
 Total projects retrieved:  174
 Total stations retrieved:  230312
 Total deletes retrieved :  10101
 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
 NUMBER OF READS....................  230312
 NUMBER OF WRITES...................  230312
 --------------------------------------------------------------
 For more retrieval statistics, see SASKGRAV.SUMMARY

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