The Central African Republic Diamond Database (2018) - Geomorphology

Metadata also available as - [Outline] - [Parseable text] - [XML]

Frequently anticipated questions:


What does this data set describe?

Title:
The Central African Republic Diamond Database (2018) - Geomorphology
Abstract:
This GIS raster dataset describes the spatial extent of geomorphic landforms in the Central African Republic (CAR). Although national-scale geologic data, published by Lescuyer and Milesi (2004), provides some geologic context for CAR, this dataset does not provide information regarding the quaternary surficial geology that hosts alluvial placer diamond deposits in CAR. The artisanal and small-scale mining (ASM) of diamonds that occurs in these alluvial and low colluvial landforms is of international interest, due to its potential links to conflict diamonds and illicit trade networks. The dataset published here indicates the geospatial extent of alluvium, terraces, and colluvial hillslopes throughout the country, and thus serves as the best-available data of areas potentially containing alluvial placer diamond deposits and associated ASM activity.
  1. How might this data set be cited?
    Chirico, Peter G., DeWitt, Jessica D., and Bergstresser, Sarah E., 2018, The Central African Republic Diamond Database (2018) - Geomorphology: U.S. Geological Survey, Reston, VA.

    Online Links:

    This is part of the following larger work.

    DeWitt, Jessica D., Chirico, Peter G., Bergstresser, Sarah E., and Clark, Inga E., 2018, The Central African Republic Diamond Database – A Geodatabase of Archival Diamond Occurrences and Areas of Recent Artisanal and Small-scale Diamond Mining: U.S. Geological Survey, Reston, VA.

  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: 14.150390620846
    East_Bounding_Coordinate: 27.861328120298
    North_Bounding_Coordinate: 11.048608926563
    South_Bounding_Coordinate: 2.8548257978541
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 2018
    Currentness_Reference:
    publication date
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: GIS data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a Raster data set.
    2. What coordinate system is used to represent geographic features?
      The map projection used is Transverse Mercator.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.9996
      Longitude_of_Central_Meridian: 15.0
      Latitude_of_Projection_Origin: 0.0
      False_Easting: 500000.0
      False_Northing: 0.0
      Planar coordinates are encoded using row and column
      Abscissae (x-coordinates) are specified to the nearest 30.0
      Ordinates (y-coordinates) are specified to the nearest 30.0
      Planar coordinates are specified in METERS
      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257223563.
  7. How does the data set describe geographic features?
    Table
    Values of the raster (Source: USGS Artisanal and Conflict Minerals Project)
    Value
    Numeric identifier for a unit of surficial geology or geomorphology (Source: Producer-defined)
    ValueDefinition
    1Alluvium - a geomorphic unit of negative or low relative elevation that typically exhibits comparatively deep unconsolidated surficial sediments and gravels deposited by hydrologic processes
    2Terrace - which are micro-relief features located in close proximity to the alluvium and the current or paleo channel; created through the deposition or erosion of sediments during flood conditions, and can provide evidence of previous channel locations
    3colluvial hillslope - the surficial weathered or weakened rock which is primarily affected by gravity-driven erosion and is underlain by undifferentiated bedrock

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    U.S. Department of State, U.S. Agency for International Development
  3. To whom should users address questions about the data?
    Peter G. Chirico
    U.S. Geological Survey
    12201 Sunrise Valley Dr.
    Reston, VA
    USA

    703-648-6950 (voice)
    pchirico@usgs.gov

Why was the data set created?

This GIS dataset was created to describe the spatial extent of geomorphology in the Central African Republic. The raster contains 3 values: 1 - alluvium, 2 - terrace, 3 - colluvial hillslope. All other areas have a value of 'no data'.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 2017 (process 1 of 1)
    The processing methods were adapted from the methods of Chirico and Malpeli (2013), and divided the quaternary-aged landscape into alluvium, terrace, colluvial hillslope. A 3-part process was used to model geomorphology: 1) geomorphic ‘zones’ are segmented from relative elevation; 2) a slope-based path distance analysis characterizes erosive and depositional environments; and 3) the geomorphic zones are combined with the path distance analysis to provide geomorphic detail in the surficial geology. For complete description of the methods used to create the Surficial Geology and Geomorphology model, see the OFR by DeWitt and others (2017). Person who carried out this activity:
    Peter G. Chirico
    U.S. Geological Survey
    12201 Sunrise Valley Dr.
    Reston, VA
    USA

    703-648-6950 (voice)
    pchirico@usgs.gov
  3. What similar or related data should the user be aware of?
    DeWitt, Jessica D., Chirico, Peter G., and Bergstresser, Sarah E., 2018, The Central African Republic Diamond Database (2018) - Hydrologically Corrected Digital Elevation Model (30 m): U.S. Geological Survey, Reston, VA.


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

  1. How well have the observations been checked?
    No formal attribute accuracy tests were conducted
  2. How accurate are the geographic locations?
    No formal positional accuracy tests were conducted
  3. How accurate are the heights or depths?
    No formal positional accuracy tests were conducted
  4. Where are the gaps in the data? What is missing?
    Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details.
  5. How consistent are the relationships among the observations, including topology?
    No formal logical accuracy tests were conducted

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:
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  1. Who distributes the data set? (Distributor 1 of 1)
    Peter G. Chirico
    U.S. Geological Survey
    12201 Sunrise Valley Dr.
    Reston, VA
    USA

    703-648-6950 (voice)
    pchirico@usgs.gov
  2. What's the catalog number I need to order this data set?
  3. What legal disclaimers am I supposed to read?
    Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    This dataset is formatted as a .tif raster. It requires the user to have geospatial software such as ESRI ArcGIS, Blue Marble Global Mapper, Que GIS, GRASS, or other GIS software.

Who wrote the metadata?

Dates:
Last modified: 09-Apr-2018
Metadata author:
Jessica DeWitt
U.S. Geological Survey
12201 Sunrise Valley Dr.
Reston, VA
USA

703-648-6926 (voice)
jdewitt@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.9.47 on Mon Apr 9 07:58:09 2018