Airborne geophysical survey: Northern Alaska

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Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: U.S. Geological Survey
Publication_Date: 2014
Title: Airborne geophysical survey: Northern Alaska
Online_Linkage: https://mrdata.usgs.gov/magnetic/show-survey.php?id=AK_6169
Larger_Work_Citation:
Citation_Information:
Originator: Connard, G.G.
Originator: Saltus, R.W.
Originator: Hill, P.L.
Originator: Carlson, L.
Originator: Milicevic, B.
Publication_Date: 1999
Title: Alaska digital aeromagnetic database description
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: 99-503
Online_Linkage: http://pubs.usgs.gov/of/1999/ofr-99-0503/
Description:
Abstract:
Aeromagnetic data were collected along flight lines by instruments in an aircraft that recorded magnetic-field intensity values and location. In surveys such as this one where the data were originally collected in digital form and not digitized from contour maps, the information we provide typically includes latitude, longitude, magnetic anomaly in nanoTeslas, and intermediate values used to derive the magnetic anomaly such as total magnetic field.
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. 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.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date: 198007
Ending_Date: 198008
Currentness_Reference: ground condition
Status:
Progress: complete
Maintenance_and_Update_Frequency: none planned
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -163.43501281738
East_Bounding_Coordinate: -161.99499511719
North_Bounding_Coordinate: 70.005004882812
South_Bounding_Coordinate: 68.994995117188
Keywords:
Theme:
Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: geophysics
Theme_Keyword: geospatial datasets
Theme_Keyword: magnetic field (earth)
Theme_Keyword: aeromagnetic surveying
Theme_Keyword: field monitoring stations
Place:
Place_Keyword_Thesaurus: Common Geographic Areas
Place_Keyword: f02185 = North Slope
Access_Constraints: none
Use_Constraints: none
Browse_Graphic:
Browse_Graphic_File_Name: Browse_Graphic_File_Description:
Reduced-size image depicting the data, 1104 x 868 pixels, 87,594 bytes
Browse_Graphic_File_Type: JPEG
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Recent aeromagnetic surveys such as this one have generally been carried out on contract by private-sector companies that specialize in these surveys. In some cases we will retain a report from the contractor detailing methods and survey parameters, which could be consulted in order to understand the likely accuracy of the measurements.
Logical_Consistency_Report:
In general each original survey was collected by a single contractor, who would be responsible for processing the field observations, and reflect industry standard practices and controls. Variation among surveys is possible, especially if they were carried out during very different time periods.
Completeness_Report:
Observations were made along flight lines, so these data may not extend into all parts of the geographic bounding extents.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Detailed positional information is determined by the contractor using navigational controls to specifications given in the contractor reports. Generally these are more precise and accurate for newer surveys than for older ones.
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.
Lineage:
Source_Information:
Source_Citation:
Citation_Information:
Originator:
Connard, G.G., Saltus, R.W., Hill, P.L., Carlson, L., Milicevic, B.
Publication_Date: 1999
Title: Alaska digital aeromagnetic database description
Series_Information:
Series_Name: Open-File Report
Issue_Identification: 99-503
Online_Linkage: http://pubs.usgs.gov/of/1999/ofr-99-0503/DBDESC.HTM
Type_of_Source_Media: paper
Source_Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1999
Source_Currentness_Reference: publication date
Source_Citation_Abbreviation: paper
Source_Contribution:
Digital information were drawn from (or are presented in) this report
Process_Step:
Process_Description:
Aeromagnetic survey flown by Aero in the time period 07/80-08/80 direction E-W at altitude 400 AG with spacing 6 miles for a total of 8835 line miles
Process_Date: 198007 to 198008
Process_Step:
Process_Description:
Northwest Geophysical Associates, Inc. (NGA) was contracted by the U.S. Geological Survey (USGS) to construct a database containing original aeromagnetic data (in digital form) from surveys, maps and grids for the State of Alaska from existing public-domain magnetic data. This database facilitates the detailed study and interpretation of aeromagnetic data along flightline profiles and allows construction of custom grids for selected regions of Alaska. The database is linked to and reflects the work from the statewide gridded compilation completed under a prior contract. The statewide gridded compilation is also described in Saltus and Simmons (1997) and in Saltus and others (1999a, 1999b). NGA subcontracted a significant portion of the work described in this report to Paterson, Grant, and Watson Limited (PGW). Processed data values were tied to the two statewide aeromagnetic grids reported in Saltus and Simmons (1997). The two grids are the Alaska Composite Grid (AKC) and the Alaska Merged Grid (AKM). The AKC is a one-kilometer grid consisting of all the individual surveys at original altitudes with datum shifts to minimize differences at the boundaries. For the AKM, all of the individual surveys were draped at a level of 1,000 feet above the terrain and fit together with seamless joins along the survey boundaries. Saltus and others (1999) presented updated versions of the AKC and the AKM with additional long-wave components removed. For this project, we used the updated versions. In addition, a new Digital Elevation Model (DEM) for the State of Alaska with a 300-meter cell spacing (Riehle and others, 1997) was used to calculate terrain separation or construct a plausible flight surface when measured values for terrain separation or flight surface were not available in the original survey data.
Process_Date: 1996
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey, Mineral Resources Program
Contact_Person: Richard W. Saltus
Contact_Address:
Address_Type: mailing address
Address:
Mail Stop 964 Building 20 Denver Federal Center, West 6th Avenue and Kipling Streets
City: Lakewood
State_or_Province: Colorado
Postal_Code: 80225-0046
Contact_Voice_Telephone: 303-236-1375
Contact_Facsimile_Telephone: 303-236-1425
Contact_Electronic_Mail_Address: saltus@usgs.gov
Process_Step:
Process_Description:
USGS rearranged contractor-supplied digital data to ASCII format points. USGS personnel used the software package Oasis Montaj by Geosoft, Inc., to read in the data and create raster JPEG images.
Process_Date: 198008
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Point
Point_and_Vector_Object_Information:
SDTS_Terms_Description:
SDTS_Point_and_Vector_Object_Type: Entity 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: 6378206.4
Denominator_of_Flattening_Ratio: 294.98
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
The majority of these surveys are available as digital flightline data (data for which digital records of original flightline data exist). We attempted to recover or construct the standard channels (fields) to be included in the final database for all digital flightline data. For some surveys, some of the standard channels (e.g., MAG_BASE ) were not available and were removed from the individual final database file. The standard channels are: Standard Database Channels For Digital Flightline Surveys
Channel Name  Contents
Line          Line number
FID           Fiducial
LAT           Latitude
LON           Longitude
X             X-coordinate (meters) in an Alaska Albers projection
Y             Y-coordinate (meters) in an Alaska Albers projection
HEIGHT        Elevation above ground (meters) if available
FLTSURF       Flight surface (meters above sea level) consistent with AKC
FLTSURF_M     Flight surface (meters above sea level) consistent with AKM
MAG_RAW       Raw magnetics (if available)
MAG_BASE      Basemag-corrected magnetics (if available)
MAG_DGRF      DGRF-corrected magnetics (if available)
MAG_COMP      Composite magnetic value (consistent with AKC)
MAG_MERGE     Merged magnetic value (consistent with AKM)
USE_FLAG      Used/not-used flag to signal use in AKC
Two additional channels were included in the database files for a few of the INTAK surveys:
MAG_IGRF      IGRF-corrected magnetics where DGRF-corrected magnetic were not available
MAG_DRAPE     1,000 ft. draped version of MAG_DGRF or MAG_IGRF
Entity_and_Attribute_Detail_Citation: http://pubs.usgs.gov/of/1999/ofr-99-0503/DBDESC.HTM
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey, Mineral Resources Program
Contact_Person: Peter N. Schweitzer
Contact_Address:
Address_Type: mailing address
Address: Mail Stop 954 USGS National Center, 12201 Sunrise Valley Drive
City: Reston
State_or_Province: Virginia
Postal_Code: 20192
Contact_Voice_Telephone: 703-648-6533
Contact_Facsimile_Telephone: 703-648-6252
Contact_Electronic_Mail_Address: pschweitzer@usgs.gov
Resource_Description: AK_6169.zip
Distribution_Liability:
Reference herein to any specific commercial product, process, or service by trade name,trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.
Standard_Order_Process:
Digital_Form:
Digital_Transfer_Information:
Format_Name: CSV
Format_Version_Number: 1.0
Format_Information_Content:
Flight-line airborne magnetic anomaly measurements, collected in digital form
File_Decompression_Technique: unzip
Transfer_Size: 0.3256254196167
Digital_Transfer_Option:
Online_Option:
Computer_Contact_Information:
Fees: none
Metadata_Reference_Information:
Metadata_Date: 20141205
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey, Mineral Resources Program
Contact_Person: Peter N. Schweitzer
Contact_Address:
Address_Type: mailing address
Address: Mail Stop 954 USGS National Center, 12201 Sunrise Valley Drive
City: Reston
State_or_Province: Virginia
Postal_Code: 20192
Contact_Voice_Telephone: 703-648-6533
Contact_Facsimile_Telephone: 703-648-6252
Contact_Electronic_Mail_Address: pschweitzer@usgs.gov
Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

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