Identification_Information:
Citation:
Citation_Information:
Originator:
U.S. Department of Energy, U.S. Geological Survey, Department of
Interior and the National Geophysical Data Center, NOAA
Publication_Date: 2009
Title: Tonopah 1° x 2° Quadrangle
Geospatial_Data_Presentation_Form: tabular digital data
Larger_Work_Citation:
Citation_Information:
Originator:
U.S. Geological Survey, Department of the Interior, the
National Geophysical Data Center, U.S. Department of Energy
Publication_Date: 2009
Title:
Aeromagnetic and aeroradiometric data for the Conterminous
United States and Alaska from the National Uranium Resource
Evaluation (NURE) Program of U.S. Department of Energy
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: OFR 2009-1129
Publication_Information:
Publication_Place: Denver, CO
Publisher: U.S. Geological Survey
Description:
Abstract:
Aeromagnetic and aeroradiometric data were collected along flight lines by
instruments in an aircraft that recorded magnetic-field and radiometric
values and locations. The magnetic data set presents latitude, longitude,
altitude, and magnetic-field values. Geologic symbols or codes are also
included. The geologic symbols were picked from surficial geologic maps.
The radiometric data set presents latitude, longitude, altitude, geologic
symbols or codes, apparent Uranium (Bismuth 214), Thorium (Thallium 208),
and Potassium (K 40), the element ratios, and ancillary information.
Purpose:
Aeromagnetic surveys are used for geophysical prospecting. Some
variations in magnetic measurements are caused by rocks that contain
significant amounts of magnetic minerals (magnetite being the most common).
These anomalies reflect variations in the amount and type of magnetic
material and the shape and depth of the body of rock.
Aeromagnetic anomaly maps are important tools in mapping surficial and
buried igneous rocks. The features and patterns of aeromagnetic anomalies
can also be used to delineate details of subsurface geology including the
locations of buried faults and the thickness of surficial sedimentary rocks.
Aeroradiometric surveys measure the radiation emanating from the earth's
surface, which provides general estimates of the geographic distribution of
uranium, thorium, and potassium in surficial and some bedrock units.
Bismuth 214 and Thallium 208 are decay products of Uranium and Thorium.
Along with Potassium 40 they give identifiable peaks in the gamma-ray spectra
of naturally occurring radiation. The element data and the ratios of the
element data are used to help map surficial geology and to detect
concentrations of radioactive minerals.
Supplemental_Information:
The U.S. Department of Energy through Bendix Corp. contracted
numerous airborne surveys over a period from 1974 to 1981 covering most
of the conterminous United States and much of Alaska. The primary
purpose was to obtain airborne radiometric data in order to locate and
evaluate uranium resources. Aeromagnetic data were also acquired at
the same time. In the mid-1980's, all the NURE Program's data were
given to the U.S. Geological Survey. The aeromagnetic data were also
archived at the National Geophysical Data Center. With the improvement
in digital communication and the ability to store and transmit large
data sets, the USGS is now able to release the flight-line data in a
common format.
The U.S. Geological Survey has contracted or flown numerous airborne
surveys over a long period (1950's to present). Much of the digital
flight-line data have been released to the public through a companion
DVD and a web site. Reference is in the Cross-Reference section of
this metadata file.
A companion CD-ROM/web site has been released containing magnetic
data that were generated by digitizing analog maps. The original
analog flight-line profiles used to create the analog maps are
unavailable. Reference is in the Cross-Reference section of this
metadata file.
CD's have been released containing the original radiometric flight-line
data in various formats. Reference is in the Cross-Reference section
of this metadata file.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 19771007 and 19780815
Ending_Date: 19771101 and 19780815
Currentness_Reference:
Time period indicates dates of airborne survey
data collection. Time period is expressed in the
format YYYYMM or YYYYMMDD when further accuracy is available.
Status:
Progress: complete
Maintenance_and_Update_Frequency: none planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -118.00
East_Bounding_Coordinate: -116.00
North_Bounding_Coordinate: 39.00
South_Bounding_Coordinate: 38.00
Data_Set_G-Polygon:
Data_Set_G-Polygon_Outer_G-Ring:
G-Ring:
-118.00 38.00, -118.00 39.00, -116.00 39.00,
-116.00 38.00, -118.00 38.00
Keywords:
Theme:
Theme_Keyword_Thesaurus: none
Theme_Keyword: geophysical surveys
Theme_Keyword: aeromagnetic data
Theme_Keyword: airborne surveys
Theme_Keyword: magnetic surveys
Theme_Keyword: residual magnetic field
Theme_Keyword: total field
Theme_Keyword: magnetic
Theme_Keyword: aeroradiometric surveys
Theme_Keyword: radiometric surveys
Theme_Keyword: radiometric
Theme_Keyword: radioactivity
Theme_Keyword: uranium
Theme_Keyword: thorium
Theme_Keyword: potassium
Theme_Keyword: total count
Place:
Place_Keyword_Thesaurus: none
Place_Keyword: United States
Place_Keyword: Nevada
Place_Keyword: NV
Place_Keyword: Tonopah
Access_Constraints: none
Use_Constraints:
none. Acknowledgement of the U.S. Geological Survey, National
Geophysical Data Center, U.S. Department of Energy, and
Prof. Dhananjay Ravat would be appreciated in products derived
from these data.
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USGS Gravity and Magnetics Contact
Contact_Address:
Address_Type: mailing address
Address:
U.S. Geological Survey
Box 25046 Mail Stop 964
Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225
Contact_Voice_Telephone: 303-236-5652
Data_Set_Credit:
These USGS employees contributed to reformatting and archiving
these data:
Pat Hill, Bob Kucks, Rick Saltus, Ron Sweeney, Sarah Shearer
Cooperating contributors from the National Geophysical Data
Center are:
Ronald Buhmann, David Dater, Susan McLean, Stewart Racey
The Comphrensive Model data were supplied by:
Prof. Dhananjay Ravat, University of Kentucky
Native_Data_Set_Environment:
These data were originally recorded on 9-track
magnetic tapes and were transferred to CD-ROM.
Data processing took place on a Dell personal computer
running a Windows XP operating system. Data
were reformatted using the Geosoft, Inc., program
Oasis Montaj version 6.3.
Cross_Reference:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: 1999
Title:
Digitized Aeromagnetic Datasets of the Conterminous United
States, Hawaii, and Puerto Rico
Geospatial_Data_Presentation_Form: raster digital data
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: OFR 99-557
Publication_Information:
Publication_Place: Denver CO
Publisher: U.S. Geological Survey
Other_Citation_Details:
CD-ROM or online files
Complements this publication with analog data
Online_Linkage:
<URL:http://pubs.usgs.gov/of/1999/ofr-99-0557/html/mag_home.htm
Cross_Reference:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: 2002
Title:
Digital Aeromagnetic Datasets of the Conterminous United States
and Hawaii
Geospatial_Data_Presentation_Form: raster digital data
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: OFR 02-361
Publication_Information:
Publication_Place: Denver CO
Publisher: U.S. Geological Survey
Other_Citation_Details:
CD-ROM or online files
Complements this publication with digital data
Online_Linkage:
<URL:http://pubs.usgs.gov/of/2002/ofr-02-361/mag_home.htm
Cross_Reference:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: 1999
Title:
Aerial Gamma-Ray Surveys of the Conterminous United States and Alaska
Geospatial_Data_Presentation_Form: raster digital data
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: OFR 99-0562-A through -M
Publication_Information:
Publication_Place: Denver CO
Publisher: U.S. Geological Survey
Other_Citation_Details: Thirteen CD-ROMs
Cross_Reference:
Citation_Information:
Originator: U.S. Department of Energy (DOE) Grand Junction Office
Publication_Date: 1979
Title:
Aerial radiometric and magnetic survey, Tonopah
National Topographic Map, Nevada
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: Grand Junction Bendix Office Report (GJBX)
Issue_Identification: GJBX-104(79)
Publication_Information:
Publication_Place: Grand Junction, Colorado
Publisher: DOE Grand Junction Office
Other_Citation_Details: map scale 1:500,000
Author(s): GeoLife, Inc.
Cross_Reference:
Citation_Information:
Originator: U.S. Department of Energy (DOE) Grand Junction Office
Publication_Date: 1983
Title:
Tonopah Quadrangle, residual intensity magnetic anomaly
profile and contour maps
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: Grand Junction Map Open-file Report
Issue_Identification: GJM-453
Publication_Information:
Publication_Place: Grand Junction, Colorado
Publisher: DOE Grand Junction Office
Other_Citation_Details: 4 sheets, map scale 1:250,000
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
The data in this file have been processed using various formulas and
methods that are not usually documented but that represent
industry standard practices for airborne data reduction. For example,
position is listed as latitude and longitude, but these values
were derived from the raw navigation data depending on the system used.
(see notes under horizontal accuracy). Line numbers were added to
records, and unusable data at flight-line ends were discarded
(as aircraft slowed and turned around). Separate recordings were
correlated by time and assigned to the correct location.
The exact accuracies of these processing steps may not be known.
They are discussed in the sections on attribute or positional
accuracies.
Logical_Consistency_Report:
The data in this file were collected by a single contractor or group
who were responsible for collecting and processing the data.
The data from this survey were collected using the same instruments
(magnetometers, altimeters, radiometic crystal packages, navigational
systems) throughout the survey and were collected in a normal length of
time with no long delays between survey beginning and end.
Survey contracts specified the conditions and specifications under which
these data were collected. Standard industry practices of the time
were followed in data collection and processing.
Completeness_Report:
Loss of data due to poor transmission, channel dropout, obvious spiking,
missing channels, and other obvious errors were replaced with one of the
Following values: -9999.9, -999.9, -99, etc. Sometimes channels were
added and filled with dummy values (-9999.9, etc.) to comply with the
established format. Records that had no usable data were deleted.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Flight Path Recovery
The horizontal position of the survey aircraft used to collect
data was determined by reconciling down-looking photographs
(recorded on continuous-strip film) with topographic maps
and orthophotoquadrangle maps. Fiducial numbers and marks,
impressed on any paper strips that were recording data or
added to magnetic tape records, were included
as a function of time to further reconcile location with
instrumentation.
Vertical_Positional_Accuracy:
Vertical_Positional_Accuracy_Report:
The aircraft vertical position was determined using the
navigational positioning equipment on the aircraft, which
were radar altimeter and barometric altimeter. Barometric
altimeter data are not available for most of these data sets.
Radar altimeters are estimated to have an error
of 2-5% of the altitude (Richard Hansen, PRJ, Inc.,
written communication).
The magnetometer was carried in a bird towed on a
line about 100 feet below the aircraft.
The bird as it is towed is slightly behind the aircraft
and therefore the vertical distance between the
magnetometer and the aircraft is less than the length
of the line but remains constant for the survey.
Lineage:
Process_Step:
Process_Description:
Conversion of measured values to geographic position and
magnetic and radiometric values was performed by the contractor
using industry standard practices.
Details are found under Attribute Accuracy Report,
Horizontal_Position_Accuracy_Report, and
Vertical_Position_Accuracy_Report
Conversion processes, if reported, may be found in the
U.S. Department of Energy's published GJO- or GJBX- reports for the
quadrangle or group of quadrangles. Unpublished products generated
by the contractor included magnetic tapes and perhaps some
written documentation.
Process_Date: 1978
Process_Step:
Process_Description:
USGS reformatting of contractor data to standard format.
USGS personnel used the software package Oasis Montaj version 6.3 by
Geosoft, Inc., to read in the original contractor's data. Positioning
and magnetic values were checked for obvious errors or spikes. Values
of -9999.9,-999.9, -99.9, etc., were given where the value could not be
reasonably corrected or, in some cases, the whole record was removed.
Information that was missing from the data file but recorded elsewhere, such
as year flown, was added th the file. The radiometric data were not checked
for errors except for dummy values which were replaced with -99.9, -999.9, etc.
The reformatted data files were written in the format described in the section
on Entity_and_Attribute_Overview.
Process_Date: 2008
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: point
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Geographic:
Latitude_Resolution: 0.0001
Longitude_Resolution: 0.0001
Geographic_Coordinate_Units: decimal degrees
Geodetic_Model:
Horizontal_Datum_Name: North American Datum of 1927
Ellipsoid_Name: Clarke 1866
Semi-major_Axis: 6,378,206.4
Denominator_of_Flattening_Ratio: 294.98
Vertical_Coordinate_System_Definition:
Altitude_System_Definition:
Altitude_Datum_Name: National Geodetic Vertical Datum of 1929
Altitude_Resolution: 0.1
Altitude_Distance_Units: meters
Altitude_Encoding_Method:
Explicit elevation coordinate included with horizontal coordinates
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Airborne survey specifications
These items are constant for the entire survey
Project number: 6044A
Project name: Tonopah Quadrangle
Survey flown by: GeoLife, Inc.
Survey flown for: DOE Grand Junction Office
Approx. no. of line miles: 3019
Survey height: 400 ft
Altitude method: Draped over terrain
Flight-line spacing: 3 miles
Flight-line direction: East-West
Aircraft used: Sikorsky S58T Helicopter
Airport - arrival: unknown
Airport - departure: unknown
Magnetometer used: proton precession
Sensor tow distance: 100 feet
Radiometric crystal package volume: 2493 (down) & 415 (up) cu. in.
Entity_and_Attribute_Detail_Citation:
Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
Geologists and Seismologists: Society of Exploration Geophysicists
Monograph Series No. 1, p. 83-87.
Dobrin, M.B., 1976, Introduction to Geophysical
Prospecting: New York, McGraw-Hill Book Company,
p. 505-517.
Grasty, R.L., and Holman, P.B., 1974, Optimum Detector Sizes for
Airborne Gamma-ray Surveys: Geological Survey of Canada Paper
74-1, Part B, p. 72-74.
Entity_and_Attribute_Overview: Aeromagnetics
Each record contains the following 13 attributes:
No name contents
1 line flight line number
2 fid fiducial number (integer)
3 time time (hhmmss)
4 day Julian day flown (integer)
5 year year flown (integer)
6 latitude latitude (decimal degrees)
7 longitude longitude (decimal degrees)
8 radalt radar altimeter reading above ground (meters)
9 totmag corrected magnetic value (nT)
10 resmag residual magnetic value (nT)
11 diurnal ground magnetometer value (nT)
12 geology surficial geology beneath flight line (coded)
13 resmagCM4 resmag calculated using the comprehensive model (nT)
Entity_and_Attribute_Overview: Radiometrics
Each record contains the following 21 attributes:
No name contents
1 line flight line number
2 fid fiducial number (integer)
3 time time (hhmmss)
4 day Julian day flown (integer)
5 year year flown (integer)
6 latitude latitude (decimal degrees)
7 longitude longitude (decimal degrees)
8 radalt radar altimeter reading above ground (meters)
9 resmag residual magnetic value (nT)
10 geology surficial geology beneath flight line (coded)
11 qual quality flags of the radiometrics (integer)
12 app_K apparent Potassium as Potassium 40 (percent potassium)
13 app_U apparent Uranium as Bismuth 214 (parts per million
equivalent uranium)
14 app_Th apparent Thorium as Thallium 208 (parts per million
equivalent thorium)
15 U_Th_ratio ratio of Uranium and Thorium
16 U_K_ratio ratio of Uranium and Potassium
17 Th_K_ratio ratio of Thorium and Potassium
18 total_count total count of radioactivity (counts/second)
19 atmos_BI214 atmospheric Uranium as Bi214 (counts/second)
20 air_temp air temperature (degrees Celsius)
21 air_press air pressure (mmHg)
Entity_and_Attribute_Detail_Citation:
Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
Geologists and Seismologists: Society of Exploration Geophysicists
Monograph Series No. 1, p. 83-87.
Dobrin, M.B., 1976, Introduction to Geophysical
Prospecting: New York, McGraw-Hill Book Company,
p. 505-517.
Ravat, D., T. Sabaka, A. Elshayat, A.Aref, E. Elawadi, R.P. Kucks,
P. Hill, J.D. Phillips, C.A. Finn, C. Bouligand, R. Blakely, 2008,
A Preliminary Full Spectrum Magnetic Anomaly Database of the United
States With Improved Wavelengths for Studying Continental Dynamics,
Invited Paper, Eos Trans. AGU, 89(53), Fall Meet. Suppl.,
Abstract GP52A-02.
Sabaka, T.J., Olsen, N., and Langel, R.A., 2002, A Comprehensive
Model of the Quiet-Time Near-Earth Magnetic Field; Phase 3:
Geophysical Journal International, v 151, no. 1, p. 32-68.
Parasnis, D.S., 1975, Mining Geophysics: Elsevier Scientific
Publishing Company, Methods in Geochemistry and Geophysics vol. 3,
p. 298-307.
Detailed_Description:
Entity_Type:
Entity_Type_Label: record for one magnetic or radiometric data point
Entity_Type_Definition:
The set of all measurements reported for a magnetic or radiometric
data point having the same spatial location.
Entity_Type_Definition_Source:
Standard aeromagnetic and aeroradiometric data collection procedures
as written in the contract for survey collection.
Attribute:
Attribute_Label: line
Attribute_Definition: flight line number
Attribute_Definition_Source: often assigned by airborne survey crew
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 20
Range_Domain_Maximum: 5180
Attribute_Units_of_Measure: alphanumeric value
Attribute:
Attribute_Label: fid
Attribute_Definition:
A fiducial number is a mark which indicates points of
simultaneity. It is a user-defined integer used during
airborne operations to correlate recording devices (magnetometers)
with navigational records (altimeters, camera film, strip charts)
that were recorded at the same time.
Attribute_Definition_Source:
Sheriff, R.E., 1984, Encyclopedic dictionary of
exploration geophysics: Tulsa, OK, Society of
Exploration Geophysicists, p. 89.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 1
Range_Domain_Maximum: 8420
Attribute:
Attribute_Label: time
Attribute_Definition: time of data point collection. Time is given
in either local time or Greenwich Meridian Time.
Values of 999999 indicate missing data.
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Unrepresentable_Domain: a range of time of day values has no meaning
because the timeframe can span several days or weeks.
Attribute:
Attribute_Label: day
Attribute_Definition:
Julian day, where Jan. 1 = 1 and
Dec. 31 = 365 or 366 (leap year)
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 227
Range_Domain_Maximum: 305
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 1
Attribute_Value_Accuracy_Explanation:
Both beginning and end Julian dates were taken from dataset.
Attribute:
Attribute_Label: year
Attribute_Definition: year of data point collection
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 1977
Range_Domain_Maximum: 1978
Attribute:
Attribute_Label: latitude
Attribute_Definition: latitude - geographic coordinate
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 37.9446
Range_Domain_Maximum: 39.0566
Attribute_Units_of_Measure: decimal degrees
Attribute:
Attribute_Label: longitude
Attribute_Definition: longitude - geographic coordinate
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -118.0791
Range_Domain_Maximum: -115.9365
Attribute_Units_of_Measure: decimal degrees
Attribute:
Attribute_Label: radaralt
Attribute_Definition:
radar altimetry reading, in meters
An aircraft navigational system in which short electromagnetic waves
are transmitted, and the energy scattered back by reflection
is detected. From this measurement, the distance between the aircraft
and the ground is calculated and recorded as radar altimetry.
Values of -999.9 indicate missing data.
Attribute_Definition_Source:
Sheriff, R.E., 1984, Encyclopedic dictionary of exploration geophysics:
Tulsa, OK, Society of Exploration Geophysicists, p. 89.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 7.6
Range_Domain_Maximum: 555.0
Attribute_Units_of_Measure: meters
Attribute:
Attribute_Label: totmag
Attribute_Definition:
Raw magnetic value with base magnetometer corrections applied.
Because the magnetic field of the earth varies diurnally,
a stationary base magnetometer is maintained on the ground
during airborne surveying. The base magnetometer records
changes in the magnetic field (in nanoTeslas) as a function
of time. The magnetic changes may have an amplitude of 20
to 50 nanoTeslas. If changes are more severe, as would
occur from a magnetic storm, surveying is discontinued or
the data recorded are not used.
Diurnal variations are then removed from the airborne magnetic
data based on the common time.
Records containing missing data were usually deleted.
Attribute_Definition_Source:
see: Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
Geologists and Seismologists: Society of Exploration Geophysicists
Monograph Series No. 1, p. 83-87.
A description of magnetometers and how they measure
the total magnetic field can be found in:
Dobrin, M.B., 1976, Introduction to Geophysical
Prospecting: New York, McGraw-Hill Book Company,
p. 505-517.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 51357.4
Range_Domain_Maximum: 54687.5
Attribute_Units_of_Measure: nanoTeslas
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 2
Attribute_Value_Accuracy_Explanation:
The airborne magnetometer is accurate to about 1 nanoTesla,
and the base magnetometer has the same accuracy. The accuracy
of the base-corrected airborne value therefore is near 2 nanoTeslas
or better.
Attribute_Measurement_Frequency:
The magnetometer has a recharging interval of 0.5
seconds. The data were recorded at 1 second intervals.
Attribute:
Attribute_Label: resmag
Attribute_Definition:
residual magnetic value
The total magnetic value minus a geomagnetic reference field (GRF),
which is a long-wavelength regional magnetic field. The most commonly
used reference field is determined from a model developed by the
International Association of Geomagnetism and Aeronomy (IAGA). The
International Geomagnetic Reference Field (IGRF), is a predictive model
adopted at the beginning of a model period (e.g. in 1989 for 1990-1995).
After the model period, a revised definitive model is adopted, the DGRF.
This is the preferred model to use for removing regional magnetic fields
for epochs when CM models are not available.
For this survey, the field removed is IGRF 1965.
Some contractors add a constant to the residual value in order to
avoid negative values. This constant can vary from one data set to
another.
Values of -9999.9 indicate missing data.
Attribute_Definition_Source:
Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
Geologists and Seismologists: Society of Exploration Geophysicists
Monograph Series No. 1, p. 83-87.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -1896.9
Range_Domain_Maximum: 4728.3
Attribute_Units_of_Measure: nanoTeslas
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 2
Attribute_Value_Accuracy_Explanation:
The Geomagnetic Reference Field that was subtracted from
the total magnetic value is based on a model, which was
updated to the date of the survey. New models are
available at five year intervals. These models have
varying degrees of accuracy in determining the local
reference field.
Attribute:
Attribute_Label: diurnal
Attribute_Definition:
Base magnetometer values used to correct the total magnetic
value.
Because the magnetic field of the earth varies diurnally,
a stationary base magnetometer is maintained on the ground
during airborne surveying. The base magnetometer records
changes in the magnetic field (in nanoTeslas) as a function
of time called the diurnal. The magnetic changes may have an
amplitude of 20 to 50 nanoTeslas. The diurnal is monitored
during the survey and if changes are severe, as would
occur from a magnetic storm, surveying is discontinued or
the data recorded are not used.
Diurnal variations are then removed from the airborne magnetic
data based on the common time.
Values of -9999.9 indicate missing data.
Attribute_Definition_Source:
see: Nettleton, L.L., 1971, Elementary Gravity and Magnetics for
Geologists and Seismologists: Society of Exploration Geophysicists
Monograph Series No. 1, p. 83-87.
A description of magnetometers and how they measure
the total magnetic field can be found in:
Dobrin, M.B., 1976, Introduction to Geophysical
Prospecting: New York, McGraw-Hill Book Company,
p. 505-517.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -9999.9
Range_Domain_Maximum: -9999.9
Attribute_Units_of_Measure: nanoTeslas
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 2
Attribute_Value_Accuracy_Explanation:
The airborne magnetometer is accurate to about 1 nanoTesla,
and the base magnetometer has the same accuracy. The accuracy
of the base-corrected airborne value therefore is near 2 nanoTeslas
or better.
Attribute_Measurement_Frequency:
The base magnetometer has a recharging interval of 0.5
seconds. The data were recorded at 2-4 second intervals.
Attribute:
Attribute_Label: geology
Attribute_Definition:
Geologic identification codes or numeric codes indicating the rock
types immediately beneath the flight line. These codes were determined by
plotting the flight lines on a surficial geologic map. A description
of the codes can be found in the GJBX- or GJO- report for this
quadrangle listed in the Cross Reference section above.
Values of -99 indicate missing data.
Attribute_Definition_Source: original publication
Attribute_Domain_Values:
Unrepresentable_Domain: values are not quantified
Attribute:
Attribute_Label: resmagCM4
Attribute_Definition:
The total magnetic field value minus the core component of geomagnetic
field is known as the comprehensive model (CM). CM4 (the fourth generation
of CM) is the modern reference field determined from a long-wavelength
spatially and temporally continuous model of the geomagnetic field that
simultaneously considers the Earth’s core, lithospheric, and external
magnetic fields (external ionospheric and magnetospheric fields and the
components induced by them inside the Earth). Spherical harmonic degree 13
of CM4 is the preferred model to use for removing regional magnetic fields
for the time periods it is valid for (1960 to June 2002).
Values of -9999.9 indicate missing data.
Attribute_Definition_Source:
Ravat, D., T. Sabaka, A. Elshayat, A.Aref, E. Elawadi, R.P. Kucks,
P. Hill, J.D. Phillips, C.A. Finn, C. Bouligand, R. Blakely, 2008,
A Preliminary Full Spectrum Magnetic Anomaly Database of the United
States With Improved Wavelengths for Studying Continental Dynamics,
Invited Paper, Eos Trans. AGU, 89(53), Fall Meet. Suppl.,
Abstract GP52A-02.
Sabaka, T.J., Olsen, N., and Langel, R.A., 2002, A Comprehensive
Model of the Quiet-Time Near-Earth Magnetic Field; Phase 3:
Geophysical Journal International, v 151, no. 1, p. 32-68.
Attribute_Domain_Values:
Unrepresentable_Domain: range of values were not determined
Attribute:
Attribute_Label: apparent potassium
Attribute_Definition: the apparent content of potassium in the surface
rock and soil
Values of -99.9 indicate missing data.
Attribute_Definition_Source:
Duval, J. S., 1990, Modern aerial gamma-ray spectrometry and regional
potassium map of the conterminous United States: Journal of Geochemical
Exploration, vol. 39, no. 1-2, p. 249-253.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -0.6
Range_Domain_Maximum: 8.1
Attribute_Units_of_Measure: percent potassium
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 1
Attribute_Value_Accuracy_Explanation:
Additional information can be found in the original GJBX- or
GJO- report listed in the Cross_Reference section above.
Attribute_Measurement_Frequency:
The data were recorded at 1-2 second intervals.
Attribute:
Attribute_Label: apparent uranium
Attribute_Definition: the apparent content of uranium in the surface
rock and soil
Values of -99.9 indicate missing data.
Attribute_Definition_Source:
Duval, J. S., 1990, Modern aerial gamma-ray spectrometry and regional
potassium map of the conterminous United States: Journal of Geochemical
Exploration, vol. 39, no. 1-2, p. 249-253.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -11.8
Range_Domain_Maximum: 30.6
Attribute_Units_of_Measure: parts per million equivalent uranium (ppm eU)
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 1
Attribute_Value_Accuracy_Explanation:
Additional information can be found in the original GJBX- or
GJO- report listed in the Cross_Reference section above.
Attribute_Measurement_Frequency:
The data were recorded at 1-2 second intervals.
Attribute:
Attribute_Label: apparent thorium
Attribute_Definition: the apparent content of thorium in the surface
rock and soil
Values of -99.9 indicate missing data.
Attribute_Definition_Source:
Duval, J. S., 1990, Modern aerial gamma-ray spectrometry and regional
potassium map of the conterminous United States: Journal of Geochemical
Exploration, vol. 39, no. 1-2, p. 249-253.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -1.1
Range_Domain_Maximum: 39.8
Attribute_Units_of_Measure: parts per million equivalent thorium (ppm eTh)
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 1
Attribute_Value_Accuracy_Explanation:
Additional information can be found in the original GJBX- or
GJO- report listed in the Cross_Reference section above.
Attribute_Measurement_Frequency:
The data were recorded at 1-2 second intervals.
Attribute:
Attribute_Label: total count
Attribute_Definition: the gross effect of the content of uranium, thorium,
and potassium in the surface rock and soil
Values of -9999.9 indicate missing data.
Attribute_Definition_Source:
Pitkin, James A., 1968, Airborne measurements of terrestrial
radioactivity as an aid to geologic mapping: U.S. Geological Survey
Professional Paper 516-F, 29 p.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0.0
Range_Domain_Maximum: 36,596.0
Attribute_Units_of_Measure: counts per second
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 1
Attribute_Value_Accuracy_Explanation:
Additional information can be found in the original GJBX- or
GJO- report listed in the Cross_Reference section above.
Attribute_Measurement_Frequency:
The data were recorded at 1-2 second intervals.
Attribute:
Attribute_Label: atmospheric bismuth 214
Attribute_Definition: the atmospheric content of equivalent uranium
determined by measuring the amount of its decay product bismuth 214.
Values of -99.9 indicate missing data.
Attribute_Definition_Source:
Duval, J. S., 1990, Modern aerial gamma-ray spectrometry and regional
potassium map of the conterminous United States: Journal of Geochemical
Exploration, vol. 39, no. 1-2, p. 249-253.
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 0.3
Range_Domain_Maximum: 3.7
Attribute_Units_of_Measure: parts per million
Attribute_Value_Accuracy_Information:
Attribute_Value_Accuracy: 1
Attribute_Value_Accuracy_Explanation:
Additional information can be found in the original GJBX- or
GJO- report listed in the Cross_Reference section above.
Attribute_Measurement_Frequency:
The data were recorded at 1-2 second intervals.
Attribute:
Attribute_Label: air temperature
Attribute_Definition: temperature of the air in degrees Celsius
Values of -999.9 indicate missing data.
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: -2.3
Range_Domain_Maximum: 22.1
Attribute:
Attribute_Label: air pressure
Attribute_Definition: pressure of the air measured in millimeters
of mercury (mmHg)
Values of -999.9 indicate missing data.
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Range_Domain:
Range_Domain_Minimum: 565.9
Range_Domain_Maximum: 589.5
Attribute:
Attribute_Label: qual
Attribute_Definition: quality flags indicating the relative quality
of the radiometric data. A description of the codes can be found
in the GJBX- or GJO- report for this quadrangle listed in the
Cross Reference section above.
Values of -9999 indicate missing data.
Attribute_Definition_Source: original publication
Attribute_Domain_Values:
Unrepresentable_Domain: values are not quantified
Attribute:
Attribute_Label: U-Th ratio, U_K ratio, and Th_K ratio
Attribute_Definition: The calculated ratios of uranium, thorium, and
potassium.
Values of -99.9 indicate missing data.
Attribute_Definition_Source: self evident
Attribute_Domain_Values:
Unrepresentable_Domain: ranges of values were not determined
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
Web site administration: U.S Geological Survey
Central Publications Group
Contact_Address:
Address_Type: mailing address
Address:
Central Publications Group
USGS MS 902, Box 25046 DFC
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Contact_Voice_Telephone: 303-236-5486
Resource_Description: USGS Open-File Report OFR 2009-1129
Distribution_Liability:
Although all data published on this web site have been used by the USGS,
no warranty, expressed or implied, is made by the USGS as to the
accuracy of the data and related materials. The act of distribution
shall not constitute any such warranty, and no responsibility is
assumed by the USGS in the use of these data or related materials.
Any use of trade, product, or firm names is for descriptive purposes
only and does not imply endorsement by the U.S. Government.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: ASCII
Format_Specification:
Magnetic data file
Each line contains data in the following format,
beginning with line 1 (no header included):
line I6
fid I8
time I8
day I5
year I6
latitude F10.4
longitude F11.4
radalt F7.1
totmag F9.1
resmag F9.1
diurnal F9.1
geology A10
resmagCM4 F9.1
Radiometric data file
Each line contains data in the following format,
beginning with line 1 (no header included):
line I6
fid I8
time I8
day I5
year I6
latitude F10.4
longitude F11.4
radalt F7.1
resmag F9.1
geology A10
qual A8
app_K40 F9.1
app_U_BI214 F9.1
app_Th_TL208 F9.1
U_Th_ratio F7.1
U_K_ratio F7.1
Th_K_ratio F7.1
total_count F10.1
atmos_BI214 F7.1
air_temp F8.1
air_press F8.1
File_Decompression_Technique: gunzip
Format_Version_Number: 2.1
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Network_Address:
Network_Resource_Name:
http://pubs.usgs.gov/of/2009/1129
Fees: none
Metadata_Reference_Information:
Metadata_Date: 200810
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USGS Gravity and Magnetics contact
Contact_Address:
Address_Type: mailing address
Address:
U.S. Geological Survey
Box 25046 Mail Stop 964
Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Contact_Voice_Telephone: 303-236-5652
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998