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:
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RATIONALIZED DETAILED GRAVITY DATA, SOUTHERN
SASKATCHEWAN
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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.
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======================================================
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
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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
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Rock Density: 2.000
Water Density: 1.030
Ice Density: 0.900
----------------------------------------------------
CHANGE ANY OF THESE
(Y or N)?
n
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ELLIPSOID: 1984 - WGS84
1967 - GRS67 (GSC standard since 1974)
1930 - POTSDAM (pre-1974 GSC standard)
ENTER ELLIPSOID REFERENCE
YEAR(1984, 1967, OR 1930)
1967
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======================================================
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
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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
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Total projects retrieved: 174
Total stations retrieved: 230312
Total deletes retrieved : 10101
- - - - - - - - - - - - - - - - - - - - - -
- - - - - - - - -
NUMBER OF READS.................... 230312
NUMBER OF WRITES................... 230312
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For more retrieval statistics, see SASKGRAV.SUMMARY