File 'gpr2010-001_readme.PDF' contains location figures, a table indicating which formats are available for each data type and associated map numbers, and much general information. File 'gpr2010-001_readme.PDF' also contains more complete information than this metadata for the supplemental information and completeness of data. Some detailed information about the data is given in the 'Entity_and_Attribute_Information' section of this metadata file. 'Moran-linedata.txt' gives information on the linedata in an easy-to-read format. All data are provided in NAD27, UTM zone 5N, except for Google Earth KMZ files, which are in Geographic Coordinate System (Simple Cylindrical projection) with a WGS84 datum. Besides NAD27, UTM zone 5N x and y coordinates, the linedata files also include latitude and longitude (Geographic Coordinate System with a WGS84 datum).
This publication, GPR2010-1, contains the following data types or files: LINEDATA (Geosoft binary GDB and Geosoft ASCII XYZ format), GRIDS, GEOTIFFS, GOOGLE EARTH FILES, VECTORS, and MAPS (PDF and HPGL/2 formats).
Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2010, Line, grid, and vector data, and maps for the airborne geophysical survey of the Moran Survey Area, Melozitna and Tanana quadrangles, central Alaska: Geophysical Report GPR 2010-1, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS), Fairbanks, AK, USA.Online Links:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 25
Ordinates (y-coordinates) are specified to the nearest 25
Planar coordinates are specified in meters
The horizontal datum used is North American Datum of 1927.
The ellipsoid used is Clarke 1866.
The semi-major axis of the ellipsoid used is 6378206.4.
The flattening of the ellipsoid used is 1/294.978698.
Each linedata file contains raw and processed linedata, and related calculated fields. Missing data are represented with the dummy variable '*'. Each of the 173 flight lines or partial flight lines (e.g. Line 10371, referred to as 'LINE' attribute) is associated with a 'DATE' (e.g. 2009/08/18), a 'FLIGHT (number)' (e.g. 29009), and a particular multi-record set of data. Each record represents data acquisition from one spatial location in the flight line. A total of 1,485,841 records are present in each data file.
//Flight 29010 //Date 2009/08/12 Line 10010 (or 'Tie 10950', etc.) Followed by all records for points sampled along Line 10010. (Pattern is repeated for each line number).The 'ID CELL' content, particularly combined with the definitions below for this particular survey, provides information about the flight line layout. (Source: L.E. Burns & Fugro Airborne Surveys)
Definitions of the 'LINE' and 'FLIGHT' attributes are listed below.
LINE TYPES and SYMBOLS:
Traverse lines – oriented nominally N-S (0 degrees);
Tie lines - oriented nominally E-W (90 degrees); and
Border lines - present inside and parallel the survey
tract border where traverse or tie lines
are not parallel to the border.
Traverse lines – 'L' (GDB file); 'LINE' (XYZ file).
Tie and border lines - 'T' (GDB file); 'TIE' (XYZ file).
LINE NUMBERS
In general, the traverse lines increase by 10 from west to
east; the tie lines increase by 10 from north to south; and
the border lines increase by 10 starting for this project
in the south-central edge of the survey area and continuing in
a clockwise direction until reaching the southeastern part.
When more than one uninterrupted flight segment was needed
to complete a planned flight line, the fifth digit is
increased by '1' for each new flight version.
MAIN LINE NUMBERS:
Lowest Traverse Lines: L10010 (west)
Highest Traverse Lines: L11520 (east)
Lowest Tie Lines: T19010 (north)
Highest Tie Lines: T19080 (south)
Lowest Border Lines: T19090 (south-central, progressing)
in clockwise direction)
Highest Border Lines: T19130 (southeast)
------------------------------------------------------------
'FLIGHT' DESIGNATORS
The 5 digit flight designator consists of a two digit Fugro
Dighem V system number (29 for this project) and a three
digit flight identification number, e.g. '008'.
Range of values | |
---|---|
Minimum: | 458130.23 |
Maximum: | 519205.96 |
Units: | m |
Range of values | |
---|---|
Minimum: | 7225239.02 |
Maximum: | 7260818.41 |
Units: | m |
The attribute measurement resolution is 0.1 second. The values increase from the beginning of a flight to the end. Only FIDs during production flights are included in the database.
Range of values | |
---|---|
Minimum: | 65.1520411 |
Maximum: | 65.4713032 |
Units: | degrees |
Range of values | |
---|---|
Minimum: | -153.9005963 |
Maximum: | -152.5855291 |
Units: | degrees |
Range of values | |
---|---|
Minimum: | 29005 |
Maximum: | 29053 |
Units: | flight |
Range of values | |
---|---|
Minimum: | 2009/08/11 |
Maximum: | 2009/08/29 |
Units: | day |
Range of values | |
---|---|
Minimum: | 14.14 |
Maximum: | 203.63 |
Units: | m |
Range of values | |
---|---|
Minimum: | 96.00 |
Maximum: | 1146.00 |
Units: | m |
Range of values | |
---|---|
Minimum: | 60.69 |
Maximum: | 1108.24 |
Units: | m |
Range of values | |
---|---|
Minimum: | 56491.01 |
Maximum: | 56633.30 |
Units: | nT |
Range of values | |
---|---|
Minimum: | -53.49 |
Maximum: | 17.90 |
Units: | nT |
Range of values | |
---|---|
Minimum: | 55623.17 |
Maximum: | 58782.73 |
Units: | nT |
Range of values | |
---|---|
Minimum: | 55623.17 |
Maximum: | 58689.14 |
Units: | nT |
Range of values | |
---|---|
Minimum: | 55613.92 |
Maximum: | 58690.93 |
Units: | nT |
Range of values | |
---|---|
Minimum: | 56644.99 |
Maximum: | 56817.36 |
Units: | nT |
Range of values | |
---|---|
Minimum: | -1193.84 |
Maximum: | 1940.91 |
Units: | nT |
Range of values | |
---|---|
Minimum: | 55549.19 |
Maximum: | 58683.94 |
Units: | nT |
Range of values | |
---|---|
Minimum: | -151.83 |
Maximum: | 1018.13 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -3.44 |
Maximum: | 480.13 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -38.04 |
Maximum: | 284.24 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -5.49 |
Maximum: | 119.65 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -28.2 |
Maximum: | 367.05 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -12.79 |
Maximum: | 161.76 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -87.56 |
Maximum: | 1087.90 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | 1.17 |
Maximum: | 570.75 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -25.01 |
Maximum: | 1347.64 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -3.59 |
Maximum: | 1085.73 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -150.55 |
Maximum: | 1015.33 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -2.25 |
Maximum: | 480.05 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -35.36 |
Maximum: | 280.50 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -0.46 |
Maximum: | 119.57 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -27.40 |
Maximum: | 367.77 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -1.24 |
Maximum: | 170.25 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -87.44 |
Maximum: | 1087.83 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -0.21 |
Maximum: | 570.76 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -19.98 |
Maximum: | 1347.88 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | 0.35 |
Maximum: | 1085.97 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | 0.50 |
Maximum: | 1325.00 |
Units: | ohm·m |
Range of values | |
---|---|
Minimum: | 1.41 |
Maximum: | 10750.00 |
Units: | ohm·m |
Range of values | |
---|---|
Minimum: | 4.05 |
Maximum: | 60000.00 |
Units: | ohm·m |
Range of values | |
---|---|
Minimum: | -79.09 |
Maximum: | 270.15 |
Units: | m |
Range of values | |
---|---|
Minimum: | -85.12 |
Maximum: | 125.30 |
Units: | m |
Range of values | |
---|---|
Minimum: | -96.81 |
Maximum: | 40.61 |
Units: | m |
Range of values | |
---|---|
Minimum: | -28.84 |
Maximum: | 110.27 |
Units: | unitless |
Range of values | |
---|---|
Minimum: | -12.04 |
Maximum: | 57.01 |
Units: | unitless |
Range of values | |
---|---|
Minimum: | 0.00 |
Maximum: | 0.00 |
Units: | unitless |
Range of values | |
---|---|
Minimum: | 0.00 |
Maximum: | 0.00 |
Units: | unitless |
Range of values | |
---|---|
Minimum: | 0.00 |
Maximum: | 0.00 |
Units: | unitless |
//Flight 29010 //Date 2009/08/12 Line 10010 (or 'Tie 10950', etc.) Followed by all records for points sampled along Line 10010. (Pattern is repeated for each line number).The 'ID CELL' content, particularly combined with the definitions below for this particular survey, provides information about the flight line layout. (Source: L.E. Burns & Fugro Airborne Surveys)
Definitions of the 'LINE' and 'FLIGHT' attributes are listed below.
LINE TYPES and SYMBOLS:
Traverse lines – oriented nominally N-S (0 degrees);
Tie lines - oriented nominally E-W (90 degrees); and
Border lines - present inside and parallel the survey
tract border where traverse or tie lines
are not parallel to the border.
Traverse lines – 'L' (GDB file); 'LINE' (XYZ file).
Tie and border lines - 'T' (GDB file); 'TIE' (XYZ file).
LINE NUMBERS
In general, the traverse lines increase by 10 from west to
east; the tie lines increase by 10 from north to south; and
the border lines increase by 10 starting for this project
in the south-central edge of the survey area and continuing in
a clockwise direction until reaching the southeastern part.
When more than one uninterrupted flight segment was needed
to complete a planned flight line, the fifth digit is
increased by '1' for each new flight version.
MAIN LINE NUMBERS:
Lowest Traverse Lines: L10010 (west)
Highest Traverse Lines: L11520 (east)
Lowest Tie Lines: T19010 (north)
Highest Tie Lines: T19080 (south)
Lowest Border Lines: T19090 (south-central, progressing
in clockwise direction)
Highest Border Lines: T19130 (southeast)
------------------------------------------------------------
'FLIGHT' DESIGNATORS
The 5 digit flight designator consists of a two digit Fugro
Dighem V system number (29 for this project) and a three
digit flight identification number, e.g. '008'.
Range of values | |
---|---|
Minimum: | 458130.23 |
Maximum: | 519205.96 |
Units: | m |
Range of values | |
---|---|
Minimum: | 7225239.02 |
Maximum: | 7260818.41 |
Units: | m |
The attribute measurement resolution is 0.1 second. The values increase from the beginning of a flight to the end. Only FIDs during production flights are included in the database.
Range of values | |
---|---|
Minimum: | 65.1520411 |
Maximum: | 65.4713032 |
Units: | degrees |
Range of values | |
---|---|
Minimum: | -153.9005963 |
Maximum: | -152.5855291 |
Units: | degrees |
Range of values | |
---|---|
Minimum: | 29005 |
Maximum: | 29053 |
Units: | flight |
Range of values | |
---|---|
Minimum: | 2009/08/11 |
Maximum: | 2009/08/29 |
Units: | day |
Range of values | |
---|---|
Minimum: | 42.40 |
Maximum: | 202.60 |
Units: | m |
Range of values | |
---|---|
Minimum: | 60.69 |
Maximum: | 1108.24 |
Units: | m |
Range of values | |
---|---|
Minimum: | 123 |
Maximum: | 4448 |
Units: | counts |
Range of values | |
---|---|
Minimum: | 0 |
Maximum: | 190 |
Units: | counts |
Range of values | |
---|---|
Minimum: | 1 |
Maximum: | 150 |
Units: | counts |
Range of values | |
---|---|
Minimum: | 5 |
Maximum: | 369 |
Units: | counts |
Range of values | |
---|---|
Minimum: | 0 |
Maximum: | 21 |
Units: | counts |
Range of values | |
---|---|
Minimum: | 59.58 |
Maximum: | 116.76 |
Units: | cps (counts per second) |
Range of values | |
---|---|
Minimum: | 37.14 |
Maximum: | 202.92 |
Units: | m |
Range of values | |
---|---|
Minimum: | 999 |
Maximum: | 999 |
Units: | ms (millisecond) |
Range of values | |
---|---|
Minimum: | 87.28 |
Maximum: | 100.09 |
Units: | kPa (kilopascal) |
Range of values | |
---|---|
Minimum: | 2.0 |
Maximum: | 17.2 |
Units: | °C |
Range of values | |
---|---|
Minimum: | -58.82 |
Maximum: | 3917.05 |
Units: | cps (counts per second) |
Range of values | |
---|---|
Minimum: | -4.98 |
Maximum: | 175.32 |
Units: | cps (counts per second) |
Range of values | |
---|---|
Minimum: | -2.87 |
Maximum: | 18.64 |
Units: | cps (counts per second) |
Range of values | |
---|---|
Minimum: | -15.53 |
Maximum: | 255.51 |
Units: | cps (counts per second) |
Range of values | |
---|---|
Minimum: | -2.08 |
Maximum: | 19.49 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -1.32 |
Maximum: | 46.38 |
Units: | ppm |
Range of values | |
---|---|
Minimum: | -0.27 |
Maximum: | 4.39 |
Units: | % |
Range of values | |
---|---|
Minimum: | 0.01 |
Maximum: | 286.70 |
Units: | ppm/% |
Range of values | |
---|---|
Minimum: | 0.02 |
Maximum: | 396.92 |
Units: | ppm/% |
Range of values | |
---|---|
Minimum: | 0.00 |
Maximum: | 136.41 |
Units: | ppm/ppm |
Range of values | |
---|---|
Minimum: | -6.33 |
Maximum: | 193.22 |
Units: | nGy/h (nanogray / hour) |
The radiometric spectrum for each sample point is in the form of an array.
Two supporting files, a Geosoft projection file (GI) and a Geosoft v7-produced metadata file (XML), are included for each Geosoft grid file. The Geosoft grid is viewable (or importable into other software) without using these supported files. When using Geosoft, the GI file automatically sets the projection of the grid if the GI file is placed in the same directory as the grid file (GRD). Setting the projection can also be done manually in Geosoft without the GI file.
Each ER Mapper grid consists of two files, a header (projection) file (.ERS) and a data file (no extension). Both ER Mapper files are necessary to view a grid or to convert it to another software format. (Source: Fugro Airborne Surveys)
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Grid file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
Geotiff file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
KMZ file
All vector files are provided in Autocad DXF format, v2000, except for the flight path. All of the alphanumeric–appearing characters in the DXF files are alphanumeric characters, which are shifted when imported into any version of MapInfo Professional, Geosoft, and presumably other GIS programs. To provide alphanumeric characters in appropriate places for the critical flight path and Range labels in GIS programs besides Autocad, we are providing the flight path file (name starts with 'Moran_fp_') as an ESRI shape (SHP) file and the text part of the Alaska Section Grid file ('Moran_SecGrid.dxf') as a MapInfo Professional table (TAB) file. The text part of the section grid DXF file is also included. The alphanumeric numbers for the data contours for all the maps are shifted about 0.05 miles [80 m; 0.05 inches at map scale (1:63,360-scale)] to the right and up from where they should be when looked at with the number right-side-up. The files are understandable upon examination, and were not corrected.
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing lines for all flight lines
vector file containing lines and numbers for major FIDs and beginning and ending FIDs
vector file containing lines for minor FIDs
vector file containing alphanumeric characters
vector file containing alphanumeric characters shifted slightly to the left and down, and lines in the correct places
file containing alphanumeric characters
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
vector file containing numbers shifted slightly to the right and up, and lines in the correct places
Two map sheets, labeled 'A' and 'B', are needed to cover the survey area at a scale of 1:63,360 (inch-to-a-mile). Twenty-eight different maps (56 map sheets) are included in this publication. Bounding coordinates for the sheets are given immediately below.
** 'A' maps – Part of Melozitna Quadrangle ******
West, -154.00 East, -153.25 North, 65.50 South, 65.13** 'B' maps - Parts of Melozitna and Tanana quadrangles *******
West, --153.25 East, -152.50 North, 65.50 South, 65.13Authors and titles of the maps are like the example given below:
Burns, L.E., Fugro Airborne Surveys Corp., and Stevens Exploration Management Corp., 2010, Total magnetic field of the Moran Survey Area, south-central Melozitna mining district, central Alaska, parts of Melozitna and Tanana quadrangles: Alaska Division of Geological & Geophysical Surveys Geophysical Report 2010-1-1A, 1 sheet, scale 1:63,360.
Most geophysical images are placed on two maps; one with topography and one with data contours and no topography. A table clearly showing information about the maps (numbers, type of image, and whether topography or data contours are included) is located in 'gpr2010_001_readme.pdf' included with this publication.
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
map in PDF and HPGL/2 format
Funding was provided by the Alaska State Legislature as part of the DGGS Airborne Geophysical/Geological Mineral Inventory (AGGMI) program.
The survey was part of the Alaska Airborne Geophysical/Geological Mineral Inventory project funded by the Alaska State Legislature and managed by State of Alaska, Department of Natural Resources (DNR), Division of Geological & Geophysical Surveys (DGGS). The project seeks to catalyze private-sector mineral development investment. The project delineates mineral zones on Alaska state lands that: 1) have major economic value; 2) can be developed in the short term to provide high quality jobs for Alaska; and 3) will provide economic diversification to help offset the loss of Prudhoe Bay oil revenue.
Akima, H., 1970, A new method of interpolation and smooth curve fitting based on local procedures: Journal of the Association of Computing Machinery v. 7, no. 4.Online Links:
- None
International Atomic Energy Agency, 2003, Guidelines for radioelement mapping using gamma ray spectrometry data: IAEA-TECDOC (Technical document) 1363.Online Links:
Alaska Department of Natural Resources - Land Records Information Section, 1995, Alaska PLSS Section Grid: State of Alaska, Department of Natural Resources, Division, Land Records Information Section (LRIS), <http://mapper.landrecords.info/> (Anchorage, Alaska).Online Links:
- <ftp://ftp.dnr.state.ak.us/asgdc/adnr/pls_section.zip>
- <http://dnr.alaska.gov/SpatialUtility/SUC?cmd=vmd&layerid=45> (metadata)
Flights were performed with an AS350B-3 Squirrel helicopter at a mean terrain clearance of 200 feet along N-S (0 degrees) survey flight lines with one-quarter mile line spacing. Tie lines were flown perpendicular to the flight lines at intervals of approximately 3 miles.
A Novatel OEM4-G2L Global Positioning System was used for navigation and flight path recovery. The helicopter position was derived every 0.5 seconds (2 Hz); the ground GPS base station data were collected at 0.1 second (10 Hz) intervals. The use of the differentially-corrected base station data results in a positional accuracy of better than one meter. The positional xy data are interpolated from 2 Hz to 10 Hz. Flight path positions were projected onto the Clarke 1866 (UTM zone 5) spheroid, 1927 North American datum using a central meridian (CM) of 153 degrees, a north constant of 0, and an east constant of 500,000.
The total magnetic field data were subjected to three processing algorithms for producing derivative grids. The vertical gradient algorithm enhances the response of magnetic bodies in the upper 500 m and attenuates the response of deeper bodies. The resulting (calculated) vertical gradient grid ('Moran-cvg') provides better definition and resolution of near-surface magnetic units. It also identifies weak magnetic features that may not be evident in the total field data.
Analytic signal is the total amplitude of all directions of magnetic gradient calculated from the sum of the squares of the three orthogonal gradients. Mapped highs in the calculated analytic signal of the magnetic parameter locate the anomalous source body edges and corners (e.g., contacts, fault/shear zones, basement fault block boundaries or lithologic contacts, etc.). Analytic signal maxima are located directly over faults and contacts, regardless of structural dip, and independently of the direction of the induced and/or remanent body magnetizations.
The calculated magnetic tilt derivative is the angle between the horizontal gradient and the total vertical gradient, which is useful for identifying the depth and type of magnetic source. The tilt angle is positive over the source, crosses through zero at, or near, the edge of a vertical sided source, and is negative outside the source zone. It responds equally well to shallow and deep sources and is able to resolve deeper sources that may be masked by larger responses caused by shallower sources.
All magnetic grids were then resampled from the 80-m cell size down to a 25-m cell size using a modified Akima (1970) technique to produce the maps and final grids contained in this publication.
Data sources used in this process:
Data sources used in this process:
Data sources used in this process:
Data sources used in this process:
Survey contracts specified the conditions and specifications under which these data were collected. Altimeter, heading, lag, and frequent EM calibrations were done. More information will be available in the project report to be published in the future.
The helicopter position was derived every 0.5 seconds using post-flight differential positioning to an accuracy of better than 1 m.
The radar altimeter ('ALTRAD') had a stated resolution of 0.3 meter, and an accuracy better than 10% of the flying height, i.e. better or equal to 4 meters for this survey. The ALTRAD value may be unreliable in areas of heavy tree cover, where the altimeter reflects the distance to the tree canopy rather than the ground.
The linedata were distributed into two linedata files for ease of download. 'Moran_EM' contains magnetic and electromagnetic data; 'Moran_RAD' contains radiometric data. A maximum of 1,485,841 records (sampling points) were recorded for the magnetic and electromagnetic data, all of which were sampled at 0.1 second intervals. Most of the radiometric data were sampled every 1.0 seconds and hence have a maximum number of data points of 148,586. Few values are missing from the databases. The file 'gpr2010-001_readme.PDF' contains detailed information about how many dummy variables are present for each channel in the databases. A short summary is given here.
Missing mag values occur in three different places in the survey area; 2 near the end of a border line or end of an overlapping tie line, and the third gap (Line 11110) was due to despiking. The magnetic gap on Line 11110 occurred for lagged magnetic data between fiducial marks (FIDs) 6862.7 and 6868.0. The length of the gap is about 150 m long for the magnetic values, and is larger than the footprint of the system; hence the magnetic data was not splined. Missing values in the apparent resistivity (res56k, res7200, and res900) and associated calculated 'depth' (dep56k, dep7200, and dep900) are due to calculations being meaningless, generally caused by increase in altitude. Only 2 values were missing from a few of the radiometric channels. A little over 9,000 are missing from the radiometric ratios because these are not calculated where the data values are too small for the ratios to be meaningful.
Data for this survey were collected by a single subcontractor (Fugro Airborne Surveys) who was responsible for collecting and processing the data. All the data were collected with the same instruments (magnetometers, electromagnetic bird and sensors, gamma ray spectrometer, altimeters, and navigational system).
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Geophysical Report 2010-1
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