Geologic map of Unga Island and the northwestern part of Popof Island, Alaska

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator: James R. Riehle
Originator: Frederic H. Wilson
Originator: Nora Shew
Originator: Willis H. White
Publication_Date: 1999
Title:
Geologic map of Unga Island and the northwestern part of Popof Island, Alaska
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: 99-136
Other_Citation_Details:
Riehle, J.R., Wilson, F.H., Shew, Nora, White, W.H., 1999, Geologic map of Unga Island and the northwestern part of Popof Island, Alaska: U.S. Geological Survey Open-File Report 99-136, scale 1:63,360.
Larger_Work_Citation:
Citation_Information:
Originator: Riehle, J.R. (ed.)
Publication_Date: 1999
Title:
Geological and geophysical setting of the gold-silver vein systems of Unga Island, southwestern Alaska
Geospatial_Data_Presentation_Form: map
Series_Information:
Series_Name: U.S. Geological Survey Open-File Report
Issue_Identification: 99-136
Other_Citation_Details:
Riehle, J.R., ed., Geological and geophysical setting of the gold-silver vein systems of Unga Island, southwestern Alaska: U.S. Geological Survey Open-File Report 99-136, CD-ROM.

The CD-ROM contains seven chapters, including shaded- relief images of Unga Island showing topographic lineaments that are the physiographic expression of mineralized faults, geologic map, airborne magnetic and resistivity data, rock- and stream- sediment geochemical data, and a statistical analysis of the probable gold-deposit type.

Description:
Abstract:
This dataset is a geologic map units created as annotated polygons of an ARC/Info coverage. The geologic polygons together with five other coverages compose a geologic map at 1:63,360 scale. Both the plotfile and a graphic version of the map as a viewable image are presented on the CD-ROM publication. The other coverages, which are not described in separate metadata files, are as follows: topographic contours as a line coverage, faults and physographic lineaments as a line coverage, areas of alteration as a polygon coverage, bedding orientations (strike and dips) as a point coverage, and symbols such as mines and drill holes as a point coverage.

Purpose:
This geologic map was developed as part of a study of the nature and origin of the gold-silver vein systems on Unga Island. Previously published mapping was at 1:250,000 scale, too small a scale to support the vein study.
Supplemental_Information:
All six ARC/Info coverages relating to the geologic map are available on the CD-ROM as export files. The airborne magnetic and resistivity survey datasets are also provided as ascii line-data files and as grids; the geophysical contractor's report and image files from the interpretive geophysics chapter of the CD-ROM are included as well. The geophysical survey extends over only the southeastern one-sixth of Unga Island, whereas the geologic map coverages include the entire island. A USGS-formatted DEM (30-m cellsize) of the study area is provided, which is the basis of the shaded-relief images and the topographic line coverage.
Time_Period_of_Content:
Time_Period_Information:
Single_Date/Time:
Calendar_Date: 1999
Currentness_Reference: publication date
Status:
Progress: Complete
Maintenance_and_Update_Frequency: Unknown
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate: -160.89
East_Bounding_Coordinate: -160.27
North_Bounding_Coordinate: 55.43
South_Bounding_Coordinate: 55.11
Keywords:
Theme:
Theme_Keyword_Thesaurus: None
Theme_Keyword: geology
Theme_Keyword: bedrock
Theme_Keyword: gold
Theme_Keyword: volcanic
Place:
Place_Keyword_Thesaurus: None
Place_Keyword: Unga Island
Place_Keyword: Popof Island
Place_Keyword: Shumagin Islands
Place_Keyword: Alaska
Access_Constraints: None
Use_Constraints: None
Point_of_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
U.S. Geological Survey Mineral Resource Program - Alaska Section
Contact_Person: James R. Riehle
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 4200 University Drive
City: Anchorage
State_or_Province: AK
Postal_Code: 99508-4667
Country: USA
Contact_Voice_Telephone: 907-561-1181
Contact_Electronic_Mail_Address: jriehle@usgs.gov
Browse_Graphic:
Browse_Graphic_File_Name: *** add name of file to be on CD
Browse_Graphic_File_Description: *** enter browse graphic description
Browse_Graphic_File_Type: *** enter browse graphic file name
Data_Set_Credit: J.R. Riehle, and J.D. Hall, Raytheon STX Contractor
Native_Data_Set_Environment:
This coverage was created using ESRI ARC/Info version 7 on a Unix platform
Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
This geologic map was compiled from hand-drawn field maps on 1:63,360 scale paper topographic maps. Polygons were hand-digitized by visual reference to topographic contours on a back-coverage. DEM and derivative products like shaded-relief images and topographic line coverage created by scanning 1:63,360 paper topographic maps at 300 dpi, importing the scanned images as TIF file, registering them to Albers coordinates, rectifying, and converting to a vector coverage. Contours were then edited and cleaned by removing extraneous lines such as cultural features and were assigned the appropriate elevations to the item "elev". Lastly, the coverage was converted to a lattice and the lattice to a DEM. (Assistance in scanning and importing the topographic maps from Bo Wilmer, ECO Cooperative Agreement 1434-96-A-01453.)
Logical_Consistency_Report:
This coverage is a net coverage containing arcs and polygons. Each polygon has a class attribute classifying bedrock, surficial deposit, or water body. Faults and stratigraphic contacts are represented as arcs. When a fault is also a stratigraphic contact, only a single arc is present. Dangling arcs may be present (faults, dikes, etc.)
Completeness_Report:
In addition to this polygon coverage of geologic units, the geologic map is built from (i) a polygon coverage of alteration areas, (ii) a line coverage of structural fold axes, physiographic lineaments, faults, dikes, and veins, (iii) a point coverage of strike and dip measurements, (iv) a point coverage of annotation symbols such as mines, drill holes, and exploration trenches, and (v) a line coverage of topographic elevation contours. The graphics plotfile includes a considerable amount of text and collar information, such as abbreviated descriptions of geologic units, a correlation chart that shows geologic ages of the units, explanation of map symbols, scale bar, and latitude and longitude ticmarks. The Open-File publication also includes descriptive and interpretive text and a structural cross-section through the middle of the map area.
Positional_Accuracy:
Horizontal_Positional_Accuracy:
Horizontal_Positional_Accuracy_Report:
Users of this digital geologic map should respect the intentions of the original mappers and the limitations of the map. The Unga geologic map is intended to be used at a scale of 1:63,360; it is not intended to be used at a more detailed scale.
Lineage:
Process_Step:
Process_Description:
Geologic map compiled from hand-drawn field maps on 1:63,360 scale paper topographic maps, then hand digitized by visual reference to topographic contours on a back coverage. The linework was edited and cleaned in ARC/Info, then attributed for labels and built for polygon topology. The CD/ROM publication includes both the graphics plotfile and export files of each of the constituent coverages created using the ARC/Info "export" command.
Process_Date: 1998
Process_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: U.S. Geological Survey
Contact_Person: James R. Riehle
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 4200 University Drive
City: Anchorage
State_or_Province: AK
Postal_Code: 99508-4667
Country: USA
Contact_Voice_Telephone: 907-561-1181
Contact_Electronic_Mail_Address: jriehle@usgs.gov
Spatial_Data_Organization_Information:
Direct_Spatial_Reference_Method: Vector
Spatial_Reference_Information:
Horizontal_Coordinate_System_Definition:
Planar:
Grid_Coordinate_System:
Grid_Coordinate_System_Name: Universal Transverse Mercator
Universal_Transverse_Mercator:
UTM_Zone_Number: 4
Transverse_Mercator:
Scale_Factor_at_Central_Meridian: 0.9996
Longitude_of_Central_Meridian: -159
Latitude_of_Projection_Origin: 0.0
False_Easting: 500000
False_Northing: 0.0
Planar_Coordinate_Information:
Planar_Coordinate_Encoding_Method: coordinate pair
Coordinate_Representation:
Abscissa_Resolution: 150.
Ordinate_Resolution: 150.
Planar_Distance_Units: meters
Entity_and_Attribute_Information:
Detailed_Description:
Entity_Type:
Entity_Type_Label: arc-code
Entity_Type_Definition:
Arc-code is a positive integer value (3 3 I) item in the arc attribute table. Values range from 1-6. It identifies the line type. The values in this data set are:

1 stratigraphic contact, certain; or shoreline 2 annotation leaders 6 stratigraphic contact, inferred or approximately located

Entity_Type_Definition_Source: Riehle and others, 1999
Entity_Type:
Entity_Type_Label: class
Entity_Type_Definition:
Class is a positive integer value (4 5 B) item in the polygon attribute table. Values range from 0-8000. It identifies the geologic unit (rock type and geologic age). A lookup table, unga.lut, located in the INFO directory keys the class value with the label of the geologic unit. The values in this data set are:

0 unmapped areas 100 Qs - Colluvium, alluvium and beach deposits (Holocene) 110 Qls - Landslide and talus deposits (Holocene) 125 Qm - Glacial deposits (Pleistocene) 200 Tu - Unga Fm. (Miocene and Oligocene) 210 Tpu - Undifferentiated Popof volcanics (late Eocene to Oligocene). Subdivided into: class 220-250. 220 Tpdu - Domes, undifferentiated (Oligocene) 221 Tpda - Andesitic domes 222 Tpdb - Basaltic andesite domes 223 Tpdd - Dacitic domes 224 Tpdr - Rhyolitic domes 230 Tpth - Hornblende tuff (Oligocene) 240 Tps - Volcaniclastic rocks (late Eocene to Oligocene) 250 Tptb - Biotite tuff (Oligocene) 300 Tmv - Volcanic rocks (Miocene) 310 Tmb - Basalt flows (Miocene) 400 Ts - Stepovak Fm (Eocene and Oligocene) 410 Tpz - Lavas of Zachary Bay (Tertiary) 500 s - areas of thorough replacement by silica 8000 water

Entity_Type_Definition_Source: Riehle and others, 1999
Distribution_Information:
Distributor:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USGS Information Services
Contact_Address:
Address_Type: mailing address
Address:
Box 25286 Denver Federal Center
City: Denver
State_or_Province: CO
Postal_Code: 80225-0046
Country: USA
Contact_Voice_Telephone: 303-202-4200 or 1-800-USA-MAPS
Contact_Facsimile_Telephone: 303-202-4695
Resource_Description:
This geologic map coverage is chapter 2 in U.S.G.S. Open-File Report 99-136, CD-ROM publication.
Distribution_Liability:
This Compact Disc-Read Only Memory (CD-ROM) publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their emmployees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed in this report, or represents that its used would not infringe privately owned rights. Reference therin to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof.

Although all data and software published on this CD-ROM 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 and (or) the functioning of the software. The act of distribution shall not constitute any such warranty, and no responsibility is assumed by the USGS in the use of this data, software, or related materials.

Metadata_Reference_Information:
Metadata_Date: 19990308
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization: USGS Mineral Resources Program - Alaska Section
Contact_Person: Nora B. Shew
Contact_Position: Geologist
Contact_Address:
Address_Type: mailing and physical address
Address: 4200 University Drive
City: Anchorage
State_or_Province: AK
Postal_Code: 99508-4667
Country: USA
Contact_Voice_Telephone: 907-561-1181
Contact_Electronic_Mail_Address: nshew@usgs.gov
Metadata_Standard_Name: FGDC Content Standards for Digital Geospatial Metadata
Metadata_Standard_Version: June 8, 1994
Generated by mp on Mon Mar 8 15:33:53 1999