Latest Cretaceous and Cenozoic magmatic rocks of Alaska: polygon data

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Frequently anticipated questions:


What does this data set describe?

Title:
Latest Cretaceous and Cenozoic magmatic rocks of Alaska: polygon data
Abstract:
This map is a statewide summary of magmatic (igneous) rocks grouped into geologic units that can be portrayed cartographically at 1:2,500,000.

This dataset consists of a polygon coverage and associated attribute data derived from the 1994 map "Latest Cretaceous and Cenozoic magmatic rocks of Alaska" compiled by E.J. Moll-Stalcup, D.A. Brew, and T.L. Vallier. This map was originally published ( at 1:2,5000,0000) as Plate 5 in Volume G-1, "The Geology of Alaska", edited by G. Plafker and H.C. Berg, and published by the Geological Society of America (GSA). Volume G-1 (The Geology of Alaska) is one of a series published by GSA for the Decade of North American Geology (DNAG), and is often referred to as the DNAG-Alaska volume.

This digital dataset includes all 44 magmatic rock units from the original map, including dredged and outcrop sampled areas. It includes attributes for rock age (6 groups), composition (8 groupings), ranges and combinations of age and composition; and the location of hypabyssal or agglomeratic/tuffaceous units (TYPE = H or T)

This coverage is not intended to be a complete representation of the printed map. It does NOT include the following features: locations of calderas or volcanoes; inset maps of magmatic provinces; or explanatory text (introduction and references).
Supplemental_Information:
Procedures_Used: The linework was digitized in 1997 from a paper copy of the 1994 map at the U.S. Geological Survey's Alaska Section (Geologic Division) facilities in Anchorage, AK. The original Transverse Mercator projection of the map (Central Meridian: 100*W; Scale factor: 0.926; Reference ellipsoid:(6371204m, 63712004m)) was converted to an Albers equal-area coverage in ARC/INFO (version 7.1.2). The resulting coverage did not align exactly with an Albers equal-area coverage of the Alaskan coastline, so a rubber-sheeting operation was performed using points along the coastline and major rivers to match an Albers equal area projection. Map unit (polygon) locations and attributes were checked by the person responsible for the digitizing, and spot-checked by one reviewer, by comparing a printed copy of the coverage to the published map. Metadata were collected using document.aml v. 7.1.1, distributed by ESRI, Inc.
  1. How might this data set be cited?
    U.S. Geological Survey, 1997, Latest Cretaceous and Cenozoic magmatic rocks of Alaska: polygon data: U.S. Geological Survey, Anchorage, AK.

    Online Links:

    This is part of the following larger work.

    Moll-Stalcup, E.J. (compiler), Brew, D.A. (compiler), and Vallier, T.L. (compiler), 1994, Latest Cretaceous and Cenozoic magmatic rocks of Alaska: Decade of North American Geology G-1, Geological Society of America, Boulder, CO.

    Other_Citation_Details:
    Volume G-1 is titled "The Geology of Alaska"; this map is plate 5 of the volume.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 167.0
    East_Bounding_Coordinate: -130.0
    North_Bounding_Coordinate: 72.0
    South_Bounding_Coordinate: 51.0
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 1997
    Currentness_Reference:
    Year in which the coverage was produced from the published map
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: map
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Vector data set. It contains the following vector data types (SDTS terminology):
      • Point (1285)
      • String (2156)
      • GT-polygon composed of chains (1287)
    2. What coordinate system is used to represent geographic features?
      The map projection used is Albers Conical Equal Area.
      Projection parameters:
      Standard_Parallel: 55.0
      Standard_Parallel: 65.0
      Longitude_of_Central_Meridian: -154.0
      Latitude_of_Projection_Origin: 50.0
      False_Easting: 0.00000
      False_Northing: 0.00000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.0
      Ordinates (y-coordinates) are specified to the nearest 1.0
      Planar coordinates are specified in meters
      The horizontal datum used is Unknown.
      The ellipsoid used is Clarke 1866.
      The semi-major axis of the ellipsoid used is 6378206.4.
      The flattening of the ellipsoid used is 1/294.98.
  7. How does the data set describe geographic features?
    MAGMATIC.PAT
    Plutonic rock units
    A
    Location of feldspathoid basalt units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not feldspathoid basalt
    1Unit is feldspathoid basalt
    B
    Location of basalt units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not basalt
    1Unit is basalt
    C
    Location of Andesite units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not andesite
    1Unit is andesite
    D
    Location of Dacite units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not dacite
    1Unit is dacite
    E
    Location of rhyolite and dacite units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not rhyolite or dacite
    1Unit is rhyolite or dacite
    F
    Location of granitic (intermediate to felsic) units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not intermediate to felsic granitic rock
    1Unit is intermediate to felsic granitic rock
    G
    Location of Granitic (dominantly felsic) units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not dominantly felsic rock
    1Unit is dominantly felsic rock
    H
    Location of gabbro units (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not gabbro
    1Unit is gabbro
    AGE-1
    Location of rocks of age: 0-5 Ma (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not in the specified age range
    1Unit is in the specified age range
    AGE-2
    Location of rocks of age: 5-30 Ma (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not in the specified age range
    1Unit is in the specified age range
    AGE-3
    Location of rocks of age: 30-45 Ma (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not in the specified age range
    1Unit is in the specified age range
    AGE-4
    Location of rocks of age: 45-55 Ma (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not in the specified age range
    1Unit is in the specified age range
    AGE-5
    Locations of rocks of age: 55-65 Ma (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not in the specified age range
    1Unit is in the specified age range
    AGE-6
    Location of rocks of age: 65-76 Ma (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    0Unit is not in the specified age range
    1Unit is in the specified age range
    TYPE
    Type of rocks of hypabyssal or agglomeratic/tuffaceous character (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    ValueDefinition
    Hhypabyssal rocks
    Tchiefly tuff, breccia, and agglomerate
    FEATURE_NAME
    Name of geologic feature (e.g. Mt. Susitna Pluton), where applicable. (Source: Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska, 1994.)
    Entity_and_Attribute_Overview:
    MAGMATIC.PAT
    COLUMN    ITEM NAME       WIDTH OUTPUT  TYPE N.DEC  ALTERNATE NAME
     1    AREA                   4    12     F      3
     5    PERIMETER              4    12     F      3
     9    MAGMATIC#              4     5     B      -
    13    MAGMATIC-ID            4     5     B      -
    17    A                      2     2     B      -    FELDSPATHOID-BAS
    19    B                      2     2     B      -    BASALT
    21    C                      2     2     B      -    ANDESITE
    23    D                      2     2     B      -    DACITE
    25    E                      2     2     B      -    RHYOLITE-DACITE
    27    F                      2     2     B      -    GRANITIC(INT-FEL
    29    G                      2     2     B      -    GRANITIC(DOM-FEL
    31    H                      2     2     B      -    GABBRO
    33    AGE-1                  2     2     B      -    0-5(MA)
    35    AGE-2                  2     2     I      -    5-30(MA)
    37    AGE-3                  2     2     I      -    30-45(MA)
    39    AGE-4                  2     2     I      -    45-55(MA)
    41    AGE-5                  2     2     I      -    55-65(MA)
    43    AGE-6                  2     2     I      -    65-76(MA)
    45    TYPE                   2     2     C      -
    47    FEATURE_NAME          44    44     C      -
    
    In MAGMATIC.PAT, items A through H and AGE-1 through AGE-6, contain values of either "0" or "1". A value of "1" indicates that the polygon satisfies the criteria defined in the alternate names or in the Attribute_Definitions listed above. (For example; a value of"1" in the column named "D" indicates the presence of rocks of dacite composition; and a value "1" in the column labeled AGE-3 indicates the presence of rocks of 30-45 Ma age). A value of "0" means that the polygon does not satisfy the defined criteria. The item TYPE may contain the character "H" (indicating hypabyssal rocks) or the character "T" (indicating an area of chiefly tuff, breccia, and agglomerate).


Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • U.S. Geological Survey
  2. Who also contributed to the data set?
    D. C. Pray, J. M. Schmidt
  3. To whom should users address questions about the data?
    U.S. Geological Survey Alaska Section, Mineral Resource Surveys Program, Geologic Division
    GIS Support Staff
    4200 University Dr.
    Anchorage, AK

    (907)-786-7495 (voice)

Why was the data set created?

This coverage is intended to provide digital features (polygons) representing generalized magmatic rock units in Alaska for use in small-scale spatial analysis (statewide) with similar coverages such as other geologic units, vegetation types, soils, etc.

How was the data set created?

  1. From what previous works were the data drawn?
    Moll-Stalcup and others (1994) (source 1 of 1)
    Moll-Stalcup, E.J. (compiler), Brew, D.A. (compiler), and Vallier, T.L. (compiler), 1994, Latest Cretaceous and Cenozoic Magmatic Rocks of Alaska: Decade of North American Geology G-1, Geological Society of America, Boulder, CO.

    Type_of_Source_Media: paper
    Source_Scale_Denominator: 2500000
    Source_Contribution: Geologic units and attributes
  2. How were the data generated, processed, and modified?
    Date: 1997 (process 1 of 2)
    The linework was digitized in 1997 from a paper copy of the 1994 map at the U.S. Geological Survey's Alaska Section (Geologic Division) facilities in Anchorage, AK. The original Transverse Mercator projection of the map (Central Meridian: 100*W; Scale factor: 0.926; Reference ellipsoid:(6371204m, 63712004m)) was converted to an Albers equal-area coverage in ARC/INFO (version 7.1.2). The resulting coverage did not align exactly with an Albers equal-area coverage of the Alaskan coastline, so a rubber-sheeting operation was performed using points along the coastline and major rivers to match an Albers equal area projection. Map unit (polygon) locations and attributes were checked by the person responsible for the digitizing, and spot-checked by one reviewer, by comparing a printed copy of the coverage to the published map. Metadata were collected using document.aml v. 7.1.1, distributed by ESRI, Inc.
    Date: 22-May-2006 (process 2 of 2)
    Edited metadata, fixing problems due to DOCUMENT.aml and clarifying information where possible.
  3. What similar or related data should the user be aware of?

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    The quality of the geologic data in the digital coverage is that of the published 1994 map, which summarized data collected prior to that date (mainly since 1980). No recent data have been added. The geographic accuracy of the published map has been slightly degraded by the rubber-sheet operation.
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
    The following map features are not included in the digital representation: calderas, volcanoes, inset maps, introduction, references, and Table 1.
  5. How consistent are the relationships among the observations, including topology?

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints:
This coverage should not be copied or distributed without its associated metadata file. Intended use is at small scales (e.g. statewide, 1:2,500,000 etc.) only; enlargements of this data to scales greater than that at which they were originally compiled can lead to misinterpretation of data. The U.S. Geological Survey (Dept. of Interior) should be acknowledged as the data source in products derived from these data. Use of these data is not restricted; however, organizations, agencies, units of government or other users are responsible for its appropriate application.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey
    Attn: David Pray
    GIS Support Staff
    4200 University Drive
    Anchorage, AK

    (907)-786-7495 (voice)
  2. What's the catalog number I need to order this data set? MAGMATIC
  3. What legal disclaimers am I supposed to read?
    Although these data have been processed successfully on a computer system at the U.S. Geological Survey, U.S. Department of the Interior, no warranty expressed or implied is made by the Geological Survey regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. The U.S. Dept. of Interior, nor any of its agencies are liable for misuse of the data, nor for any damage, transmission of viruses or computer contamination caused through transmission of these data sets.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 07-Dec-2016
Last Reviewed: 22-May-2006
Metadata author:
Peter N Schweitzer
USGS Eastern Mineral and Environmental Resources Science Center
Geologist
12201 Sunrise Valley Drive
Reston, VA
USA

703-648-6533 (voice)
703-648-6252 (FAX)
pschweitzer@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://mrdata.usgs.gov/metadata/akmagmatic.faq.html>
Generated by mp version 2.9.47 on Mon Mar 26 17:20:46 2018