Burns, L.E.
Fugro Airborne Surveys Corp.
Fugro GeoServices, Inc.
2011
LADUE SURVEY AREA: Magnetic and Electromagnetic Line, Grid, and Vector Data and Maps, Fortymile mining district, Tanacross Quadrangle, eastern Alaska (DIGHEM [V] SURVEY)
raster digital data, tabular digital data, and vector digital data
Geophysical Report
GPR 2011-1
Fairbanks, AK, USA
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS)
1 DVD
http://dx.doi.org/10.14509/22562
http://dggs.alaska.gov/pubs/gpdata/135
This digital publication, GPR 2011-1, contains data produced from airborne geophysical surveys conducted in 2010 for the Ladue survey area in the Fortymile mining district, Tanacross quadrangle, eastern Alaska. Aeromagnetic and electromagnetic (EM) data were acquired by helicopter for about 742 sq miles. Fugro Airborne Survey's frequency-domain DIGHEM V system was used for the EM data. GPR 2011-1 includes (1) raw and processed linedata; (2) gridded, Google Earth, and Geotiff formats of the calculated linedata; (3) maps of the data; and (4) vector files of data contours and flight lines.
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.
The airborne data were acquired and processed under contract between the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS), and Fugro GeoServices, Inc. Fugro Airborne Surveys, the subcontractor, acquired and processed the data in 2010 and 2011. A future publication will include the technical project report, interpretation map, and EM anomalies, as well as other files.
File 'gpr2011-001_readme.PDF' contains file names and definitions, map numbers and grid correlations, projection information, location figures, and much general information. In case the text version of 'gpr2011-001_readme.txt' needs to be used, the location figures are provided as jpegs in the main directory. Some detailed information about the data is given in the 'Entity_and_Attribute_Information' section of this metadata file. 'Ladue_linedata.txt' gives information on the linedata in an easy-to-read format. All data are provided in NAD27, UTM zone 7N, except for Google Earth KMZ files, which are in Geographic Coordinate System (Simple Cylindrical projection) with a WGS84 datum. Besides NAD27, UTM zone 7N easting and northing coordinates, the linedata files also include latitude and longitude (Geographic Coordinate System with a WGS84 datum).
This publication, GPR2011-1, contains the data types or files given below.
>***********************************************************
LINEDATA Geosoft binary GDB and Geosoft ASCII XYZ format
>***********************************************************
GRIDS, GEOTIFFS, GOOGLE EARTH FILES, VECTORS
File names and general definitions for the raster and vector files are given below. Not all files listed below are included in each format listed above. Grid files are provided in Geosoft binary GRD and ER Mapper ERS formats. Vector files are provided in an ESRI shape file format.
All file names listed below start with 'Lad_'.
> NAME GENERAL DEFINITION
>
> mag_diu Pre-final total magnetic field (without leveling
> and before IGRF removal)
> mag_rmi Residual magnetic field with IGRF removed (nT)
> magigrf Total magnetic field with IGRF removed (nT)
> 1vd First vertical derivative (calculated vertical gradient)
> of the total magnetic field with IGRF removed (nT/m)
> asig Analytic signal calculated from the total magnetic
> field with IGRF removed (nT/m)
> tiltder Tilt derivative of total magnetic field with
> IGRF removed (degrees)
> res56k Apparent coplanar resistivity for 56,000 Hz (56 kHz; ohm-m)
> res7200 Apparent coplanar resistivity for 7200 Hz (ohm-m)
> res900 Apparent coplanar resistivity for 900 Hz (ohm-m)
> dtm Digital terrain or elevation model (m)
> SecGrid Alaska PLSS Section Grid for map sheets (vector only)
> UTMGrid NAD27, UTM zone 7N grid (vector only)
> fp Flight path (vector only)
>
>**********************************************************
MAPS PDF and HPGL/2 formats
The thirteen maps at 1:63,360-scale need two sheets to cover the survey area. Maps are generally produced in two versions, one with data contours and no topography and one with topography and no data contours. Not all images are provided as maps. File 'gpr2011-001_readme.PDF' contains a table linking the map numbers with the data and map version. This information is also in the 'Detailed_Description' section for the maps.
201008
201106
publication date
None
-142.58
-141.00
64.48
63.27
ISO 19115 Topic Category
geoscientificInformation
none
Aeromagnetic Data
Aeromagnetic Map
Airborne Geophysical Survey
Apparent Resistivity Data
Apparent Resistivity Map
Digital Elevation Model
DIGHEM V EM System
Electromagnetic Data
First Vertical Derivative
Geophysics
HEM Survey
none
Alaska, State of
Fortymile Mining District
Tanacross Quadrangle
This report, map and/or dataset are available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).
Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way the user is obligated to describe the types of modifications the user has made. User specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS).
Alaska Division of Geological & Geophysical Surveys
Geophysicist
mailing address
3354 College Rd
Fairbanks
AK
99709-3707
USA
(907) 451-5020
Funding was provided by the Alaska State Legislature as part of the DGGS Airborne Geophysical/Geological Mineral Inventory (AGGMI) program.
Microsoft Windows XP Professional Version 2002 Service Pack 2; Geosoft Oasis Montaj Version 7.0; Autocad Version 2000; ESRI Shape file format; MapInfo Professional file format; ER Mapper; Adobe Acrobat Distiller v9.0; Adobe Acrobat Professional v9.0; Fugro Airborne Survey proprietary software
Burns, L.E.
Fugro Airborne Surveys Corp.
Stevens Exploration Management Corp.
2006
Line, grid, and vector data and plot files for the airborne geophysical survey of parts of the Alaska Highway corridor, east-central Alaska
raster digital data, tabular digital data, vector digital data
Geophysical Report
GPR 2006-6
Fairbanks, AK, USA
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS)
1 DVD
http://dx.doi.org/10.14509/14864
http://dggs.alaska.gov/pubs/gpdata/33
DGGS Staff
Geoterrex-Dighem Corp.
Stevens Exploration Management Corp.
1999
CD-ROM containing profile and gridded data and section lines of the 1998 geophysical survey data for part of the Fortymile mining district, Alaska, southern Eagle and northern Tanacross quadrangle
Public Data File
DGGS PDF 99-9
Fairbanks, AK, USA
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS)
1 DVD
http://dx.doi.org/10.14509/1886
http://dggs.alaska.gov/pubs/gpdata/13
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.
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).
The file 'LADUE.GDB' contains 1,521,961 records with 50 channels each. Channel names and definitions of all 50 channels are included in 'Ladue_linedata' in .TXT and .PDF format, and the 'Entity_and_Attribute_Information' section of this metadata.
Almost all items were sampled at 0.1 sec. intervals. Five of the following six channels were sampled at intervals larger than 0.1 sec. and contain interpolated data. The diurnal_cor channel conTAINS
CHANNELS CONTAINING INTERPOLATED VALUES
>***************************************
> X_NAD27z7n (location information; interp. from 0.5 sec.)
> Y_NAD27z7n (location information; interp. from 0.5 sec.)
> lat_WGS84 (location information; interp. from 0.5 sec.)
> lon_WGS84 (location information; interp. from 0.5 sec.)
> diurnal_filt (diurnal filter; interp. from 1.0 second-sampled 'diurnal_filt')
> diurnal_cor (the correction applied based on the interpolated 'diurnal_filt' channel)
Few values are missing from the databases.
CHANNELS WITH MISSING VALUES IN 'LADUE.GDB'
Channel Data Null
Values Values
>*****************************************
> mag_raw 1521958 3
> cpsp 1521956 5
> cxsp 1521954 7
> difi 1521954 7
> difq 1521954 7
> diurnal_filt 1521943 18
> cppl 1521928 33
> mag_lag 1521881 80
> mag_diu 1521881 80
> mag_rmi 1521881 80
> magigrf 1521881 80
> res56K 1521860 101
> res7200 1521860 101
> res900 1521860 101
> dep56k 1518636 3325
> dep7200 1441221 80740
> dep900 760902 761059
Missing magnetic values occur in the database for the Ladue survey area because of the lagging process, at the beginning of some lines, and due to despiking. 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.
The helicopter position was derived every 0.5 seconds using post-flight differential positioning to an accuracy of better than 1 m.
The laser altimeter ('ALTLAS_BIRD'), located in the bird (EM equipment and magnetometer housing), had a stated resolution of 0.10 meter. The ALTLAS_BIRD value may be unreliable over bodies of water where the laser returns are scattered.
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
None
paper
1970
1970
Akima, 1970
Fugro Airborne Surveys used a modification of this method while making grids.
Alaska Department of Natural Resources - Land Records Information Section
1995
Alaska PLSS Section Grid
vector digital data
http://mapper.landrecords.info/ (Anchorage, Alaska)
State of Alaska, Department of Natural Resources, Division, Land Records Information Section (LRIS)
ESRI shape file format
<ftp://ftp.dnr.state.ak.us/asgdc/adnr/pls_section.zip>
http://dnr.alaska.gov/SpatialUtility/SUC?cmd=vmd&layerid=45 (metadata)
online
1950
1998
2008
ADNR-LRIS, 1995
The downloaded section grid file, built from original protraction diagram data, was used as a starting point for the section grid digital file included in GPR 2011-1. Minor formatting modifications were made to the file. The section grid is used on the maps without topography and is provided in digital format in this publication. The publication date given above reflects the current metadata file for the Alaska PLSS Section Grid.
The airborne geophysical data were acquired with a DIGHEM (V) Electromagnetic (EM) system and a Fugro D1344 cesium magnetometer with a Scintrex CS3 cesium sensor from August 5 to August 24, 2010. The EM and magnetic sensors were flown at a height of 100 feet. In addition, the survey recorded data from radar and laser altimeters, GPS navigation system, 50/60 Hz monitors, and video camera.
>
Flights were performed with an Aerospatiale AS-350-B3 helicopter at a mean terrain clearance of 200 feet (61 m) along N10W (350 degrees) survey flight lines with one-quarter mile (402.3 m) line spacing. Tie lines were flown perpendicular to the flight lines at intervals of approximately 3 miles (4,828 m). Traverse line coverage was 3,003.8 mi (4,834.2 km) and tie line coverage 395.8 mi (637.0 km) for a total of 3,399.6 km (5,471.2 km) of data. This distance includes overlapping reflight segments but not any rejected portions of lines.
>
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 five meters. The positional xy data are interpolated from 2 Hz to 10 Hz. Flight path positions were projected onto the Clarke 1866 (UTM zone 7N) spheroid, 1927 North American datum using a central meridian (CM) of 141 degrees, a north constant of 0, and an east constant of 500,000.
2010
The total magnetic field data were acquired with a sampling interval of 0.1 seconds, and were (1) corrected for measured system lag (resulting in channel 'mag_lag' in file 'Ladue.gdb'), (2) corrected for diurnal variations by subtraction of the digitally recorded base station magnetic data (resulting in channel 'mag_diu' in file 'Ladue.gdb'), (3) adjusted for regional variations (by subtracting IGRF model 2010, updated for date of flight and elevation variations), (4) leveled to the tie line data resulting in the final residual magnetic intensity (resulting in channel 'mag_rmi' in file 'Ladue.gdb'), and (5) increased by a constant IGRF average value to restore the mag_rmi values to a total magnetic field channel (resulting in channel 'magigrf' in 'Ladue.gdb'). 'Mag_Diu', 'Mag_RMI', and 'MagIGRF' were then interpolated onto a regular 80-m grid using a modified Akima (1970) technique.
Akima, 1970
2010
Three different algorithms were applied to the total magnetic field 80 m grid, resulting in three magnetic derivative grids. The analytic signal grid (Lad_ASig) 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 grid (Lad_TiltDer) is the angle between the horizontal gradient and the total vertical gradient, and 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 has the added advantage of responding 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.
>
The first vertical derivative grid was calculated using a fast Fourier transform (FFT) based frequency-domain filtering algorithm. 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 ('Lad_1VD') provides better definition and resolution of near-surface magnetic units and helps to identify weak magnetic features that may not be evident in the total field data.
>
All magnetic and derivative derivative 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.
Akima, 1970
2010
The DIGHEM (V) EM system measured inphase and quadrature components at five frequencies. Two vertical coaxial-coil pairs operated at 1113 (1000) and 5491 (5500) Hz while three horizontal coplanar-coil pairs operated at 923 (900), 7090 (7200), and 55,590 (56,000) Hz. EM data were sampled at 0.1 second intervals. The EM system responds to bedrock conductors, conductive overburden, and cultural sources. The EM inphase and quadrature data were drift corrected using base level data collected at high altitude (areas of no signal). Along-line filters are applied to the data to remove spheric spikes. The data were inspected for variations in phase, and a phase correction was applied to the data if necessary. Apparent resistivities were then calculated from the inphase and quadrature data for all coplanar frequencies based on a pseudo-layer half-space model. Manual leveling of the inphase and quadrature of each coil pair, based on the resistivity data and comparisons to the data from the other frequencies, was performed. Automated micro-leveling is carried out in areas of low signal. The EM data were interpolated onto a regular 80-m grid using a modified Akima (1970) technique. The resulting grids were subjected to a 3x3 Hanning filter and resampled to a 25-m cell size before contouring and map production.
Akima, 1970
2010
The digital elevation/terrain model was produced from the differentially corrected GPS-Z data (channel 'GPSZ' in file 'Ladue.gdb') and the laser altimeter data measured in the bird (channel 'ALTLAS_BIRD' in file 'Ladue.gdb'). Both the GPSZ and ALTLAS_BIRD data were checked for spikes, which were removed manually. The ALTLAS_BIRD data were despiked and then filtered using a 13 median filter, followed by a 13 Hanning filter. The corrected altimeter was then subtracted from the GPSZ data to produce profiles of the height above mean sea level along the survey lines. The data were manually leveled to remove any errors between lines. After all leveling, the data were DC shifted to match the local maps, in this case, NAD27. The 80-m DTM grid was then resampled to a 25-m cell size to produce the DTM grid contained in this publication.
2010
DGGS downloaded the Alaska PLSS Section Grid shapefile in fall 2010 and cut the file to roughly fit the map sheets for this publication using MapInfo Professional. Fugro Airborne Surveys modified the formatting of the file using AutoCad, changing township and range line widths and colors, and added township and range labels. The modified file was then used as overlays on maps without topography.
ADNR-LRIS, 1995
2010
The HPGL/2 files were created with HP Designjet 5000 printer driver v5.32 and plot on some plotters, but not all plotters correctly. The Adobe Acrobat format files were created with Adobe Acrobat Distiller v9.0 from Postscript files.
2011
Universal Transverse Mercator
7
0.9996
-141
0
500000
0
row and column
25
25
meters
Grids
North American Datum of 1927
Clarke 1866
6378206.4
294.978698
The linedata file ('Ladue') is provided in both Geosoft binary GDB and Geosoft ASCII XYZ formats. A file ('Ladue_linedata') contains some of the linedata information included in this metadata document, but in normal ASCII text format. 'Ladue_linedata' is provided in txt and PDF formats on the DVD publication; these are also included with each downloadable zipped database file.
Each linedata file contains raw and processed linedata, and related calculated fields. Missing data are represented with the dummy variable '*'. Each of the 197 flight lines or partial flight lines (e.g., Line 10701, referred to as 'LINE' attribute) is associated with a 'DATE' (e.g., 2010/08/13), a 'FLIGHT (number)' (e.g., 19023), and a particular multi-record set of data. Each record represents data acquisition from one spatial location in the flight line. A total of 1,521,961 records are present in each data file.
L.E. Burns, Division of Geological & Geophysical Surveys and Fugro Airborne Surveys
LINEDATA
Ladue.GDB and Ladue.XYZ
The file 'Ladue' contains raw and processed linedata and related calculated fields for locational, magnetic, and electromagnetic data. The file is provided in Geosoft binary grid (GRD) and Geosoft ASCII XYZ (XYZ) formats; formatting varies slightly between these. Except for the 'LINE' attribute, all attributes, including 'DATE' and 'FLIGHT', are represented by one of the 50 data columns on each record. The 'LINE' and 'FLIGHT' attributes are discussed further in the attribute 'ID Cell'.
L.E. Burns & Fugro Airborne Surveys
ID_CELL
The 'ID CELL' occurs in the GDB file only; the contents of the 'ID CELL' are also present in the XYZ file. In the 'ID CELL' for this project, the 'LINE' attribute is followed by a colon followed by the 'FLIGHT' attribute (e.g., 'L10010:19003' and 'T19030:19009'). More than one line is typically flown on a particular date and flight; more than one flight may be flown on a particular date. Each ID-cell value will have an associated spreadsheet view consisting of a column for each of the 50 attributes. In the XYZ file, the 'LINE' and 'FLIGHT' attributes and the 'DATE' are present as header lines, one attribute per line, before each set of associated data, for example:
> //Flight 19003
> //Date 2010/08/05
> 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.
L.E. Burns & Fugro Airborne Surveys
Definitions of the 'LINE' and 'FLIGHT' attributes are listed below.
> LINE TYPES and SYMBOLS:
> Traverse lines - oriented nominally N10W (350 degrees);
> Tie lines - oriented nominally N80E (80 degrees); and
> Border lines - present inside and parallel to 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
> Planned flight lines increase by 10 in a consistent fashion.
> For this project, traverse line numbers increase from SW to
> NE; tie line numbers increase from north to south; and
> border line numbers increase in a clockwise direction.
>
> When more than one uninterrupted flight traverse was needed
> to complete a planned flight line, the fifth digit of the line
> number is increased by '1' for each new flight segment/version.
> MAIN LINE NUMBERS:
> Lowest Traverse Lines: L10010 (southwest)
> Highest Traverse Lines: L11670 (northeast)
> Lowest Tie Lines: T19010 (north)
> Highest Tie Lines: T19140 (south)
> Lowest Border Lines: T19150 (long northwestern edge near
> middle of map,increasing in clockwise direction
> Highest Border Lines: T19230 (southwest)
>------------------------------------------------------------
> 'FLIGHT' DESIGNATORS
> The 5 digit flight designator consists of a two digit Fugro
> Dighem (V) system number (19 for this project) and a three
> digit flight identification number, e.g., '003'.
x_NAD27z7N
easting NAD 27 (UTM Zone 7)
Fugro Airborne Surveys
443032.79
500104.81
m
y_NAD27z7N
northing NAD 27 (UTM Zone 7)
Fugro Airborne Surveys
7015944.02
7086091.42
m
fid
Fiducial increment; the time in tenths of seconds from the start to the end of the particular flight. Sampling typically occurred at each fiducial for almost all items in the database.
Fugro Airborne Surveys
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.
lat_WGS84
latitude WGS 84
Fugro Airborne Surveys
63.2705237
63.9026360
degrees
lon_WGS84
longitude WGS 84
Fugro Airborne Surveys
-142.1398096
-141.0000640
degrees
flight
First two digits are Fugro's EM bird identification number for the bird used for this job, i.e., '19'. The last three digits represent the flight numbers associated with this project. A flight number is the number of the helicopter flight from home base to home base associated with this project. The flights are numbered from the beginning of the project to the end. Only those flight numbers containing acquisition of final data measurements are included in the database.
Fugro Airborne Surveys
19003
19031
flight
date
range of flight dates (yyyy/mm/dd) for production flights
Fugro Airborne Surveys
2010/08/05
2010/08/22
day
altrad_calcbird
calculated bird height above surface to simulate location of radar altimeter in the bird; radar altimeter measurement was recorded in the helicopter. Altrad_calcbird was calculated by subtracting a constant representing the height difference from the helicopter to the bird when towing and recording data.
Fugro Airborne Surveys
18.26
151.50
m
altlas_bird
bird height above surface, measured by laser altimeter in the EM bird
Fugro Airborne Surveys
15.28
173.10
m
gpsz
bird height above spheroid. The GPSZ (or GPS-Z) value is primarily dependent on the number of available satellites. Although post-processing of GPS data will yield X and Y accuracies on the order of 1 meter, the accuracy of the Z value is usually much less, sometimes in the +/-20 meter range.
Fugro Airborne Surveys
549.08
1592.67
m
dtm
digital terrain model (NAD27 UTM zone 7); calculated from channel 'GPS-Z' and the laser altimeter data (channel 'ALTLAS_BIRD') measured in the bird
Fugro Airborne Surveys
521.96
1562.32
m
diurnal_filt
interpolated diurnal ground magnetic intensity; measured every 1.0 sec.
Fugro Airborne Surveys
57269.86
57374.94
nT
diurnal_cor
diurnal correction - base removed; interpolated from 1.0 second 'diurnal_filt' measurements
Fugro Airborne Surveys
-61.54
43.54
nT
mag_raw
total magnetic field - spike rejected
Fugro Airborne Surveys
53878.68
61530.04
nT
mag_lag
total magnetic field - corrected for lag
Fugro Airborne Surveys
53878.68
61530.04
nT
mag_diu
total magnetic field - diurnal variation removed
Fugro Airborne Surveys
53887.40
61526.71
nT
igrf
international geomagnetic reference field model 2010, updated for date of flight and elevation variations
Fugro Airborne Surveys
57090.90
57302.59
nT
mag_rmi
residual magnetic intensity (nT) - final; IGRF model 2010, updated for date of flight and elevation variations, was subtracted from Mag_Diu, then the data were leveled.
Fugro Airborne Surveys
-3325.10
4307.60
nT
magigrf
total magnetic field with IGRF removed - final; mag_rmi with constant added back
Fugro Airborne Surveys
53881.38
61514.08
nT
cpi900_FILT
coplanar inphase 900 Hz - unlevelled
Fugro Airborne Surveys
-378.19
320.98
ppm
cpq900_FILT
coplanar quadrature 900 Hz - unlevelled
Fugro Airborne Surveys
-20.26
381.16
ppm
cxi1000_FILT
coaxial inphase 1000 Hz - unlevelled
Fugro Airborne Surveys
-80.90
88.45
ppm
cxq1000_FILT
coaxial quadrature 1000 Hz - unlevelled
Fugro Airborne Surveys
-29.45
113.52
ppm
cxi5500_FILT
coaxial inphase 5500 Hz - unlevelled
Fugro Airborne Surveys
-73.62
223.17
ppm
cxq5500_FILT
coaxial quadrature 5500 Hz -unlevelled
Fugro Airborne Surveys
-32.99
230.20
ppm
cpi7200_FILT
coplanar inphase 7200 Hz - unlevelled
Fugro Airborne Surveys
-274.88
803.47
ppm
cpq7200_FILT
coplanar quadrature 7200 Hz -unlevelled
Fugro Airborne Surveys
-71.20
865.84
ppm
cpi56K_FILT
coplanar inphase 56 kHz - unlevelled
Fugro Airborne Surveys
-117.77
1803.49
ppm
cpq56K_FILT
coplanar quadrature 56 kHz - unlevelled
Fugro Airborne Surveys
-67.61
1764.63
ppm
cpi900
coplanar inphase 900 Hz
Fugro Airborne Surveys
-382.31
322.51
ppm
cpq900
coplanar quadrature 900 Hz
Fugro Airborne Surveys
-0.76
381.11
ppm
cxi1000
coaxial inphase 1000 Hz
Fugro Airborne Surveys
-78.55
85.25
ppm
cxq1000
coaxial quadrature 1000 Hz
Fugro Airborne Surveys
-0.30
114.69
ppm
cxi5500
coaxial inphase 5500 Hz
Fugro Airborne Surveys
-72.50
221.74
ppm
cxq5500
coaxial quadrature 5500 Hz
Fugro Airborne Surveys
-2.83
229.07
ppm
cpi7200
coplanar inphase 7200 Hz
Fugro Airborne Surveys
-274.87
803.45
ppm
cpq7200
coplanar quadrature 7200 Hz
Fugro Airborne Surveys
3.44
865.91
ppm
cpi56k
coplanar inphase 56 kHz
Fugro Airborne Surveys
-107.83
1803.54
ppm
cpq56K
coplanar quadrature 56 kHz
Fugro Airborne Surveys
7.83
1764.63
ppm
res900
900 Hz coplanar apparent resistivity; calculated using a psuedo-layer half-space model
Fugro Airborne Surveys
3.50
1325.00
ohm·m
res7200
7200 Hz coplanar apparent resistivity; calculated using a psuedo-layer half-space model
Fugro Airborne Surveys
7.83
10418.24
ohm·m
res56K
56,000 Hz coplanar apparent resistivity; calculated using a psuedo-layer half-space model
Fugro Airborne Surveys
6.98
18992.55
ohm·m
dep900
apparent depth 900 Hz
Fugro Airborne Surveys
-83.04
294.39
m
dep7200
apparent depth 7200 Hz
Fugro Airborne Surveys
-72.13
86.89
m
dep56K
apparent depth 56 kHz
Fugro Airborne Surveys
-69.42
24.82
m
difi
difference channel based on cxi5500 & cpi7200
Fugro Airborne Surveys
-42.99
84.49
unitless
difq
difference channel based on cxq5500 & cpq7200
Fugro Airborne Surveys
-36.05
45.41
unitless
cppl
coplanar powerline monitor
Fugro Airborne Surveys
0.00
0.00
unitless
cxsp
coaxial spherics monitor
Fugro Airborne Surveys
0.00
0.00
unitless
cpsp
coplanar spherics monitor
Fugro Airborne Surveys
0.00
0.00
unitless
GRIDS
GPR2011-1GridsAsGRD.zip and GPR2011-1GridsAsERS.zip
The zip files contain the 11 grids and supporting files for this publication in either Geosoft binary float (GRD) format or ER Mapper (ERS) format. Each grid is in NAD27 datum, UTM Zone 7N, and has a 25m cell size with x and y in meters. An image from each of the grids is provided as Geotiffs and KMZ files. Grid files are listed below as attributes.
>
Two supporting files, a Geosoft projection file (GI) and a Geosoft-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.
Fugro Airborne Surveys
Lad_MagDiu
Partially processed total magnetic field (nT); processing included removal of magnetic spikes, correction for lag, and removal of diurnal variations. Not shown as a map.
Fugro Airborne Surveys
Grid file
Lad_MagRMI
Residual magnetic field (nT) - final; IGRF model 2010, updated for date of flight and elevation variations, was subtracted from Mag_Diu, then the data were leveled. Shown in map numbers GPR2011-1-1A, 1B, 2A, 2B, 7A, and 7B.
Fugro Airborne Surveys
Grid file
Lad_MagIGRF
Total magnetic field (nT) - final, with IGRF removed; residual magnetic field (Mag_RMI) with constant added back in. Not produced as a map. However Lad_RMI (also produced as maps) is directly the same as Lad_MagIGRF except off by a constant.
Fugro Airborne Surveys
Grid file
Lad_1VD
First vertical derivative 'dz' ( nT/m) of the total magnetic field with IGRF removed; also referred to as 'calculated vertical gradient' (cvg). Shown in map numbers GPR2011-1-3A and 3B.
Fugro Airborne Surveys
Grid file
Lad_ASig
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
Grid file
Lad_TiltDer
Tilt derivative (degrees) of the total magnetic field with IGRF removed. Shown in map numbers GPR2011-1-6A and 6B. Contours from the tilt derivative are shown upon a color shadows residual magnetic field (Lad_MagRMI) in maps GPR2011-1-7A and 7B.
Fugro Airborne Surveys
Grid file
Lad_Res56k
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
Grid file
Lad_Res7200
Apparent coplanar resistivity (ohm-m) for 7200 Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
Grid file
Lad_Res900
Apparent coplanar resistivity (ohm-m) for 900 Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
Grid file
Lad_DTM
Digital terrain or elevation model (m). Not shown as a map.
Fugro Airborne Surveys
Grid file
Lad_AltLasBird
EM bird height (m) above surface, measured by Laser altimeter in EM bird. Not shown as a map.
Fugro Airborne Surveys
Grid file
GEOTIFFS
GPR2011-1GEOTIFFS_NAD27_z7N.zip
The zip file 'GPR2011-1_TIFS_NAD27_z7N.zip' contains Geotiffs in NAD27, UTM Zone 7N. Each of the 11 grids is represented in Geotiff (TIF) format. The images shown in 7 of the Geotiffs are the same images used on the maps in this publication; no maps were made of the other 4 images. Map numbers are given below for the appropriate Geotiff attribute definition; the correlation between Geotiff image and map number is also given in 'gpr2011_001_readme.pdf'.
Fugro Airborne Surveys
Lad_MagDiu
Partially processed total magnetic field (nT); processing included removal of magnetic spikes, correction for lag, and removal of diurnal variations. Not shown as a map.
Fugro Airborne Surveys
Geotiff file
Lad_MagRMI
Residual magnetic field (nT) - final; IGRF model 2010, updated for date of flight and elevation variations, was subtracted from Mag_Diu, then the data were leveled. Shown in map numbers GPR2011-1-1A, 1B, 2A, 2B, 7A, and 7B.
Fugro Airborne Surveys
Geotiff file
Lad_MagIGRF
Total magnetic field (nT) - final, with IGRF removed; residual magnetic field (Mag_RMI) with constant added back in. Not produced as a map. However Lad_RMI (also produced as maps) is directly the same as Lad_MagIGRF except off by a constant.
Fugro Airborne Surveys
Geotiff file
Lad_1VD
First vertical derivative 'dz' ( nT/m) of the total magnetic field with IGRF removed; also referred to as 'calculated vertical gradient' (cvg). Shown in map numbers GPR2011-1-3A and 3B.
Fugro Airborne Surveys
Geotiff file
Lad_ASig
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
Geotiff file
Lad_TiltDer
Tilt derivative (degrees) of the total magnetic field with IGRF removed. Shown in map numbers GPR2011-1-6A and 6B. Contours from the tilt derivative are shown upon a color shadows residual magnetic field (Lad_MagRMI) in maps GPR2011-1-7A and 7B.
Fugro Airborne Surveys
Geotiff file
Lad_Res56k
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
Geotiff file
Lad_Res7200
Apparent coplanar resistivity (ohm-m) for 7200 Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
Geotiff file
Lad_Res900
Apparent coplanar resistivity (ohm-m) for 900 Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
Geotiff file
Lad_DTM
Digital terrain or elevation model (m). Not shown as a map.
Fugro Airborne Surveys
Geotiff file
Lad_AltLasBird
EM bird height (m) above surface, measured by Laser altimeter in EM bird. Not shown as a map.
Fugro Airborne Surveys
Geotiff file
KMZs
GPR2011-1KMZS_WGS84.zip
The zip file 'GPR2011-1KMZS_WGS84.zip' contains Google Earth KMZ files in Geographic Coordinate System (Simple Cylindrical projection) with a WGS84 datum. Each of the 11 grids is included. The images shown in 7 of the KMZ files are the same images used on the maps in this publication; no maps were made of the other 4 images. Map numbers are given below for the appropriate KMZ attribute definition; the correlation between KMZ image and map number is also given in 'gpr2011_001_readme.pdf'.
Fugro Airborne Surveys
Lad_MagDiu
Partially processed total magnetic field (nT); processing included removal of magnetic spikes, correction for lag, and removal of diurnal variations. Not shown as a map.
Fugro Airborne Surveys
KMZ file
Lad_MagRMI
Residual magnetic field (nT) - final; IGRF model 2010, updated for date of flight and elevation variations, was subtracted from Mag_Diu, then the data were leveled. Shown in map numbers GPR2011-1-1A, 1B, 2A, 2B, 7A, and 7B.
Fugro Airborne Surveys
KMZ file
Lad_MagIGRF
Total magnetic field (nT) - final, with IGRF removed; residual magnetic field (Mag_RMI) with constant added back in. Not produced as a map. However Lad_RMI (also produced as maps) is directly the same as Lad_MagIGRF except off by a constant.
Fugro Airborne Surveys
KMZ file
Lad_1VD
First vertical derivative 'dz' ( nT/m) of the total magnetic field with IGRF removed; also referred to as 'calculated vertical gradient' (cvg). Shown in map numbers GPR2011-1-3A and 3B.
Fugro Airborne Surveys
KMZ file
Lad_ASig
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
KMZ file
Lad_TiltDer
Tilt derivative (degrees) of the total magnetic field with IGRF removed. Shown in map numbers GPR2011-1-6A and 6B. Contours from the tilt derivative are shown upon a color shadows residual magnetic field (Lad_MagRMI) in maps GPR2011-1-7A and 7B.
Fugro Airborne Surveys
KMZ file
Lad_Res56k
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
KMZ file
Lad_Res7200
Apparent coplanar resistivity (ohm-m) for 7200 Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
KMZ file
Lad_Res900
Apparent coplanar resistivity (ohm-m) for 900 Hz.; calculated using a pseudo-layer half-space model. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
KMZ file
Lad_DTM
Digital terrain or elevation model (m). Not shown as a map.
Fugro Airborne Surveys
KMZ file
Lad_AltLasBird
EM bird height (m) above surface, measured by Laser altimeter in EM bird. Not shown as a map.
Fugro Airborne Surveys
KMZ file
VECTORS
GPR2011-1_VECTORS.zip
Data contours produced for the maps are provided in ESRI shape file format. Except for maps GPR2011-1-6 and GPR2011-1-7, the vector files are shown on the maps without topography. Additional vector files included are the flight path, and the Alaska Section Grid and a UTM grid for the map area.
Fugro Airborne Surveys
Lad_magRMI_1
One of four ESRI shape files containing information for the residual magnetic field data contours. This file contains contours for 5 and 10 nT. These lines are the thinnest on the residual magnetic field maps. The 10 nT line is solid, and the 5 nT line is dashed. Shown in map numbers GPR2011-1-1A, 1B, 2A, and 2B.
Fugro Airborne Surveys
vector file
Lad_magRMI_2
One of four ESRI shape files containing information for the residual magnetic field data contours. This file contains contours for 50 nT. These lines are the middle thickness on the residual magnetic field maps and are solid. Shown in map numbers GPR2011-1-1A, 1B, 2A, and 2B.
Fugro Airborne Surveys
vector file
Lad_magRMI_3
One of four ESRI shape files containing information for the residual magnetic field data contours. This file contains contours for 250 nT. These lines are the thickest on the residual magnetic field maps and are solid. Shown in map numbers GPR2011-1-1A, 1B, 2A, and 2B.
Fugro Airborne Surveys
vector file
Lad_magRMI_4
One of four ESRI shape files containing information for the residual magnetic field data contours. This file contains labels for the contours. The labels are made of vector lines, not alphanumeric characters. Shown in map numbers GPR2011-1-1A, 1B, 2A, and 2B.
Fugro Airborne Surveys
vector file
Lad_ASig_1
One of four ESRI shape files containing information for the analytic signal contours. This file contains contours for 0.1 and 0.2 nT/meter. These lines are the thinnest on the analytic signal maps. The 0.1 nT/meter line is dashed; the 0.2 nT/meter line is solid. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
vector file
Lad_ASig_2
One of four ESRI shape files containing information for the analytic signal contours. This file contains contours for 1.0 nT/meter. These lines are the middle thickness on the analytic signal maps and are solid. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
vector file
Lad_ASig_3
One of four ESRI shape files containing information for the analytic signal contours. This file contains contours for 5.0 nT/meter. These lines are the thickest on the analytic signal maps and are solid. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
vector file
Lad_ASig_4
One of four ESRI shape files containing information for the analytic signal contours. This file contains labels for the contours. The labels are made of vector lines, not alphanumeric characters. Shown in map numbers GPR2011-1-4A, 4B, 5A, and 5B.
Fugro Airborne Surveys
vector file
Lad_TILTDER_p45
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for positive 45 (+45) degrees; the contours are thick and cyan. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys
vector file
Lad_TiltDer_p30
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for positive 30 (+30) degrees; the contours are thin and black. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys
vector file
Lad_TiltDer_p15
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for positive 15 (+15) degrees; the contours are thin and black. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys and Laurel Burns
vector file
Lad_TiltDer_0
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for 0 degrees; the contours are thick and black. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys and Laurel Burns
vector file
Lad_TiltDer_n15
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for negative 15 (-15) degrees; the contours are thin and black. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys
vector file
Lad_TiltDer_n30
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for negative 30 (-30) degrees; the contours are thin and black. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys
vector file
Lad_TiltDer_n45
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. Two line weights are used in the tilt derivative contours; all are solid. This file contains contours for negative 45 (-45) degrees; the contours are thick and red. numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys
vector file
Lad_TiltDer_Labels
One of eight ESRI shape files containing information for the magnetic tilt derivative contours. This file contains labels for the contours. The labels are made of vector lines, not alphanumeric characters. Tilt derivative contours are shown in map numbers GPR2011-1-6A, 6B, 7A, and 7B.
Fugro Airborne Surveys
vector file
Lad_Res56k_1
One of five ESRI shape files containing information for the 56,000 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the minor intervals (i.e., 125, 200, 300, 500, 800, 1,250, 2,000, 3,000, 5,000, 8,000, and 12,500 ohm-m) between the decades of 100, 1,000, 10,000, and 100,000. These lines are the thinnest on the 56,000 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
vector file
Lad_Res56k_2
One of five ESRI shape files containing information for the 56,000 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the major intervals (i.e., 150, 250, 400, 600, 1,500, 2,500, 4,000, 6,000, and 15,000 ohm-m) between the decades of 100, 1,000, 10,000, and 100,000. These lines are the middle thickness on the 56,000 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
vector file
Lad_Res56k_3
One of five ESRI shape files containing information for the 56,000 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the decades 100, 1,000, and 10,000 ohm-m. These lines are the thickest on the 56,000 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
vector file
Lad_Res56k_4
One of five ESRI shape files containing information for the 56,000 Hz coplanar apparent resistivity contours. This file contains labels for the contours. The labels are made of vector lines, not alphanumeric characters. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
vector file
Lad_Res56k_5
One of five ESRI shape files containing information for the 56,000 Hz coplanar apparent resistivity contours. This file contains 'triangles' that are used to indicate the lowest contours in an area. The 'triangles' (composed of scribbled infill) are attached to the lowest contour and point in the direction of the low. Shown in map numbers GPR2011-1-8A, 8B, 9A, and 9B.
Fugro Airborne Surveys
vector file
Lad_Res7200_1
One of five ESRI shape files containing information for the 7200 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the minor intervals (i.e., 125, 200, 300, 500, 800, 1,250, 2,000, 3,000, 5,000, and 8,000 ohm-m) between the decades of 100, 1,000, and 10,000. These lines are the thinnest on the 7200 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
vector file
Lad_Res7200_2
One of five ESRI shape files containing information for the 7200 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the major intervals (i.e., 150, 250, 400, 600, 1,500, 2,500, 4,000, and 6,000 ohm-m) between the decades of 100, 1,000, and 10,000. These lines are the middle thickness on the 7200 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
vector file
Lad_Res7200_3
One of five ESRI shape files containing information for the 7200 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the decades 100, 1,000, and 10,000 ohm-m. These lines are the thickest on the 7200 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
vector file
Lad_Res7200_4
One of five ESRI shape files containing information for the 7200 Hz coplanar apparent resistivity contours. This file contains labels for the contours. The labels are made of vector lines, not alphanumeric characters. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
vector file
Lad_Res7200_5
One of five ESRI shape files containing information for the 7200 Hz coplanar apparent resistivity contours. This file contains 'triangles' that are used to indicate the lowest contours in an area. The 'triangles' (composed of scribbled infill) are attached to the lowest contour and point in the direction of the low. Shown in map numbers GPR2011-1-10A, 10B, 11A, and 11B.
Fugro Airborne Surveys
vector file
Lad_Res900_1
One of five ESRI shape files containing information for the 900 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the minor intervals (i.e., 125, 200, 300, 500, 800, and 1,250 ohm-m) between the decades of 100, 1,000, and 10,000. These lines are the thinnest on the 900 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
vector file
Lad_Res900_2
One of five ESRI shape files containing information for the 900 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the major intervals (i.e., 150, 250, 400, and 600 ohm-m) between the decades of 100, 1,000, and 10,000. These lines are the middle thickness on the 900 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
vector file
Lad_Res900_3
One of five ESRI shape files containing information for the 900 Hz coplanar apparent resistivity contours. The apparent resistivity maps use a logarithmic scale for the contours. This file contains contours for the decades 100 and 1,000 ohm-m. These lines are the thickest on the 900 Hz coplanar apparent resistivity maps and are solid. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
vector file
Lad_Res900_4
One of five ESRI shape files containing information for the 900 Hz coplanar apparent resistivity contours. This file contains labels for the contours. The labels are made of vector lines, not alphanumeric characters. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
vector file
Lad_Res900_5
One of five ESRI shape files containing information for the 900 Hz coplanar apparent resistivity contours. This file contains 'triangles' that are used to indicate the lowest contours in an area. The 'triangles' (composed of scribbled infill) are attached to the lowest contour and point in the direction of the low. Shown in map numbers GPR2011-1-12A, 12B, 13A, and 13B.
Fugro Airborne Surveys
vector file
Lad_FP_1
One of four ESRI shape files containing information about the flight path. This file contains all flight lines.
Fugro Airborne Surveys
vector file containing lines for all flight lines
Lad_FP_3
One of four ESRI shape files containing information about the flight path. This file contains tic marks and associated alphanumeric numbers, for fiducial marks (FIDs) ending in '00' and '50' as well as tic marks for beginning and ending FIDs regardless of the FID value. Lyn Vanderstarren of Fugro Airborne surveys manually corrected the placement of the text.
Fugro Airborne Surveys
vector file containing lines and numbers for major FIDs and beginning and ending FIDs
Lad_FP_2
One of four ESRI shape files containing information about the flight path. This file contains tic marks for fiducial marks (FIDs) ending in '10', '20', '30', '40', '60', '70', '80', and '90'. These fiducial tics are not labeled with any numbers.
Fugro Airborne Surveys
vector file containing lines for minor FIDs
Lad_FP_1001
One of four ESRI shape files containing information about the flight path. This file contains individual alphanumeric characters that form the line numbers and flight numbers. Between each line number and associated flight number, a '<' or '>' points in the direction of flight.
Fugro Airborne Surveys
vector file containing lines for alphanumeric characters
Lad_SecGrid
Alaska PLSS Section Grid (original file name 'pls_section') for the map areas. Modified by Fugro Airborne Surveys for line width, color, township and range numbers to use on the maps.
Alaska Department of Natural Resources - Land Records Information Section; L.E. Burns, Division of Geological & Geophysical Surveys; and Fugro Airborne Surveys
vector file containing alphanumeric characters
LAD_UTMGrid
A UTM grid for the maps areas produced by Fugro Airborne Surveys. Contains non-alphanumeric labels around the edges of the map sheets.
Fugro Airborne Surveys
file containing alphanumeric characters
Maps are provided in PDF and HPGL/2 format, and are downloadable in zip files by data format. The HPGL/2 maps are divided into three files with the range of map numbers included at the end of the file name. The HPGL/2 files have brighter and more gradational colors, and sharper topography than the Adobe Acrobat files. See 'Technical_Prerequisites' section for more information on printing HPGL/2 maps.
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). Thirteen different maps (26 map sheets) are included in this publication. Bounding coordinates for the sheets are given immediately below.
** 'A' maps - northern part of area ******
> West, -141.83
> East, -141.00
> North, 63.93
> South, 63.58
** 'B' maps - southern part of area *******
> West, -142.17
> East, -141.00
> North, 63.58
> South, 65.25
Authors and titles of the maps are like the example given below:
Burns, L.E., Fugro Airborne Surveys Corp., and Fugro GeoServices, Inc., 2011, Residual magnetic field of the Ladue Survey Area, Fortymile mining district, eastern Alaska, part of Tanacross quadrangle: Alaska Division of Geological & Geophysical Surveys Geophysical Report 2011-1-1A, 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 'gpr2011_001_readme.pdf' included with this publication.
L.E. Burns, Division of Geological & Geophysical Surveys, and Fugro Airborne Surveys
MAPS
GPR2011-1_MapsAsPDFS.zip, GPR2011-1_MapsAsHPGL2_1-5.zip, GPR2011-1_MapsAsHPGL2_6-8.zip, and GPR2011-1_MapsAsHPGL2_9-13.zip
Zip file names indicate the map numbers and format included in the zip file.
Fugro Airborne Surveys
GPR2011-1-1A
Residual magnetic field (nT) with IGRF removed (includes topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-1B
Residual magnetic field (nT) with IGRF removed (includes topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-2A
Residual magnetic field (nT) with IGRF removed (includes data contours); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-2B
Residual magnetic field (nT) with IGRF removed (includes data contours); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-3A
First vertical derivative (nT/m) of the total magnetic field with IGRF removed (includes topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-3B
First vertical derivative (nT/m) of the total magnetic field with IGRF removed (includes topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-4A
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed (includes topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-4B
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed. (includes topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-5A
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed (includes data contours); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-5B
Analytic signal (nT/m) calculated from the total magnetic field with IGRF removed (includes data contours); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_1-5.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-6A
Tilt derivative (degrees) of the total magnetic field with IGRF removed (includes data contours and topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_6-8.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-6B
Tilt derivative (degrees) of the total magnetic field with IGRF removed (includes data contours and topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_6-8.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-7A
Shadowed residual magnetic field (nT with IGRF removed with tilt derivative contours (includes data contours); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_6-8.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-7B
Shadowed residual magnetic field (nT with IGRF removed with tilt derivative contours (includes data contours); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_6-8.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-8A
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz. (includes topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_6-8.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-8B
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz. (includes topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_6-8.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-9A
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz. (includes data contours); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-9B
Apparent coplanar resistivity (ohm-m) for 56,000 (56k) Hz. (includes data contours); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-10A
Apparent coplanar resistivity (ohm-m) for 7200 Hz. (includes topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-10B
Apparent coplanar resistivity (ohm-m) for 7200 Hz. (includes topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-11A
Apparent coplanar resistivity (ohm-m) for 7200 Hz. (includes data contours); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-11B
Apparent coplanar resistivity (ohm-m) for 7200 Hz. (includes data contours); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-12A
Apparent coplanar resistivity (ohm-m) for 900 Hz. (includes topography); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-12B
Apparent coplanar resistivity (ohm-m) for 900 Hz. (includes topography); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-13A
Apparent coplanar resistivity (ohm-m) for 900 Hz. (includes data contours); northern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
GPR2011-1-13B
Apparent coplanar resistivity (ohm-m) for 900 Hz. (includes data contours); southern sheet. Map contained in GPR2011-1_MapsAsPDF.zip and GPR2011-1_MapsAsHPGL2_9-13.zip.
Fugro Airborne Surveys
map in PDF and HPGL/2 format
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS)
Natural Resource Technician
mailing and physical address
3354 College Road
Fairbanks
AK
99709-3707
USA
907-451-5020
None available
907-451-5050
dggspubs@alaska.gov
8 am to 4:30 pm, Monday through Friday, except State holidays
Please view our website (http://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address above whenever possible.
Geophysical Report 2011-1
The State of Alaska makes no express or implied warranties (including warranties of merchantability and fitness) with respect to the character, function, or capabilities of the electronic services or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products, any failure thereof, or otherwise, and in no event will the State of Alaska's liability to the requester or anyone else exceed the fee paid for the electronic service or product.
Maps from current publications are available on paper or Mylar. Please ask for the maps to be printed from HPGL/2 files to ensure the best quality image. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turn around time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount.
Variable
Geosoft binary float (GRD)
Unknown
DVD
Unspecified
ER Mapper (ERS)
Unknown
DVD
Unspecified
Geosoft binary database (GDB)
Unknown
DVD
Unspecified
Geosoft ASCII (XYZ)
Unknown
DVD
Unspecified
ESRI Shape (SHP)
Unknown
DVD
Unspecified
MapInfo Professional Tab (TAB)
Unknown
DVD
Unspecified
PDF
1.5
DVD
Unspecified
HPGL/2
unknown
DVD
Unspecified
http://dx.doi.org/10.14509/22562
Digital files on DVD are available for $10 plus shipping and are available for no charge when downloaded.
Order by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: cash, check, money order, VISA, or MasterCard. The geophysics page of the DGGS website (http://www.dggs.alaska.gov/pubs/geophysics) has geophysical order forms for this project and others.
Digital downloads: less than 30 minutes for most files. Free FTP access is available upon request for files not available on the web. Offline CD/DVD-ROMs: 1-2 weeks unless special arrangements are made and an express fee is paid.
Custom views or processing may be requested. Please contact Laurel Burns by phone (907-451-5021), e-mail (laurel.burns@alaska.gov), or fax (907-451-5050) to discuss custom processing availability, fees, and turnaround time.
Software with ability to use, import, or convert Geosoft float GRD, Geosoft binary GDB or ASCII XYZ files, Autocad DXF files, ESRI Shape files, MapInfo Professional TAB files, Adobe Acrobat PDF, Google Earth files, and text files. Free downloadable interfaces to view or convert the gridded and dxf files are available at the Geosoft website (http://www.geosoft.com; Oasis Montaj viewer). The KMZ files can be dragged and dropped into the 'My Places' folder of the free downloadable 'Google Earth' software. Freeware software 'printfile' (http://www.lerup.com/printfile) prints HPGL/2 files easily on compatible printers. The HPGL/2 files have brighter colors and sharper topography than the PDF maps and should be used for printing when possible. The PDF format maps are the only maps digitally viewable in this publication.
20111116
20111117
20140621
State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (DGGS)
Geophysicist (Laurel Burns)
mailing and physical address
3354 College Road
Fairbanks
AK
99709-3707
USA
907-451-5021
None available
907-451-5050
dggspubs@alaska.gov
8 am to 4:30 pm, Monday through Friday, except State holidays.
Please contact us through the e-mail address above whenever possible.
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time
none
If the user has modified the data in any way the user is obligated to describe the types of modifications the user has made in the supporting metadata file. User specifically agrees not to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys.
http://www.dggs.alaska.gov/metadata/dggs.ext
dggs metadata extensions