Identification_Information: Citation: Citation_Information: Originator: U.S. Geological Survey Publication_Date: 2014 Title: Airborne geophysical survey: Ugashik North Online_Linkage: https://mrdata.usgs.gov/magnetic/show-survey.php?id=AK_204 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: Single_Date/Time: Calendar_Date: 195505 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: none planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -157.62217712402 East_Bounding_Coordinate: -156.25791931152 North_Bounding_Coordinate: 59.008636474609 South_Bounding_Coordinate: 57.992809295654 Keywords: Theme: Theme_Keyword_Thesaurus: USGS Metadata Identifier Theme_Keyword: USGS:bbd93a06-53aa-4029-9076-95b0b739d489 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: f02060 = Bristol Bay Place_Keyword: f02070 = Dillingham Place_Keyword: f02164 = Lake and Peninsula Access_Constraints: none Use_Constraints: none Browse_Graphic: Browse_Graphic_File_Name: http://mrdata.usgs.gov/geophysics/surveys/geophysics2/AK/AK_204.jpg Browse_Graphic_File_Description: Reduced-size image depicting the data, 1104 x 868 pixels, 116,017 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: Andreasen, G.E., Dempsey, W.J., Vargo, J.L. Publication_Date: 1963 Title: Aeromagnetic map of part of the Naknek quadrangle, Alaska Series_Information: Series_Name: Geophysical Investigation Map Issue_Identification: 353 Type_of_Source_Media: paper Source_Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 1963 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 USGS in the time period 05/55 direction N-S at altitude 1000-1300 B with spacing 2 miles for a total of 700 line miles Process_Date: 195505 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: 195505 Process_Step: Process_Description: Added keywords section with USGS persistent identifier as theme keyword. Process_Date: 20201110 Process_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: VeeAnn A. Cross Contact_Position: Marine Geologist Contact_Address: Address_Type: Mailing and Physical Address: 384 Woods Hole Road City: Woods Hole State_or_Province: MA Postal_Code: 02543-1598 Contact_Voice_Telephone: 508-548-8700 x2251 Contact_Facsimile_Telephone: 508-457-2310 Contact_Electronic_Mail_Address: vatnipp@usgs.gov 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_204.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: 0.12802600860596 Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://mrdata.usgs.gov/geophysics/surveys/geophysics2/AK/AK_204.zip Fees: none Metadata_Reference_Information: Metadata_Date: 20201110 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