The Central African Republic Diamond Database (2018)

Identification_Information:

Citation:

Citation_Information:

Originator: Peter G. Chirico
Originator: Jessica D. DeWitt
Originator: Sarah E. Bergstresser
Publication_Date: 2018
Title:

The Central African Republic Diamond Database (2018) - Geomorphology

Geospatial_Data_Presentation_Form: GIS data
Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Online_Linkage: https://doi.org/10.5066/F7P26X1D
Larger_Work_Citation:

Citation_Information:

Originator: DeWitt, Jessica D.
Originator: Chirico, Peter G.
Originator: Bergstresser, Sarah E.
Originator: Clark, Inga E.
Publication_Date: 2018
Title:

The Central African Republic Diamond Database – A Geodatabase of Archival Diamond Occurrences and Areas of Recent Artisanal and Small-scale Diamond Mining

Geospatial_Data_Presentation_Form: Open File Report
Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Description:

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.

Purpose:

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'.

Time_Period_of_Content:

Time_Period_Information:

Single_Date/Time:

Calendar_Date: 2018

Currentness_Reference: publication date

Status:

Progress: Complete
Maintenance_and_Update_Frequency: Unknown

Spatial_Domain:

Bounding_Coordinates:

West_Bounding_Coordinate: 14.150390620846
East_Bounding_Coordinate: 27.861328120298
North_Bounding_Coordinate: 11.048608926563
South_Bounding_Coordinate: 2.8548257978541

Keywords:

Theme:

Theme_Keyword_Thesaurus: USGS Thesaurus
Theme_Keyword: geomorphology
Theme_Keyword: unconsolidated deposits

Theme:

Theme_Keyword_Thesaurus: Lithologic classification of geologic map units
Theme_Keyword: alluvium
Theme_Keyword: alluvial terrace
Theme_Keyword: floodplain

Place:

Place_Keyword_Thesaurus: Geographic Names Information System (GNIS)
Place_Keyword: Central African Republic

Temporal:

Temporal_Keyword_Thesaurus: USGS Thesaurus
Temporal_Keyword: Quaternary

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.

Point_of_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Peter G. Chirico
Contact_Organization: U.S. Geological Survey

Contact_Address:

Address_Type: mailing and physical
Address: 12201 Sunrise Valley Dr.
City: Reston
State_or_Province: VA
Postal_Code: 20192
Country: USA

Contact_Voice_Telephone: 703-648-6950
Contact_Electronic_Mail_Address: pchirico@usgs.gov

Data_Set_Credit:

U.S. Department of State, U.S. Agency for International Development

Cross_Reference:

Citation_Information:

Originator: DeWitt, Jessica D.
Originator: Chirico, Peter G.
Originator: Bergstresser, Sarah E.
Publication_Date: 2018
Title:

The Central African Republic Diamond Database (2018) - Hydrologically Corrected Digital Elevation Model (30 m)

Publication_Information:

Publication_Place: Reston, VA
Publisher: U.S. Geological Survey

Data_Quality_Information:

Attribute_Accuracy:

Attribute_Accuracy_Report: No formal attribute accuracy tests were conducted

Logical_Consistency_Report: No formal logical accuracy tests were conducted
Completeness_Report:

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.

Positional_Accuracy:

Horizontal_Positional_Accuracy:

Horizontal_Positional_Accuracy_Report: No formal positional accuracy tests were conducted

Vertical_Positional_Accuracy:

Vertical_Positional_Accuracy_Report: No formal positional accuracy tests were conducted

Lineage:

Process_Step:

Process_Description:

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).

Process_Date: 2017
Process_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Peter G. Chirico
Contact_Organization: U.S. Geological Survey

Contact_Address:

Address_Type: mailing and physical
Address: 12201 Sunrise Valley Dr.
City: Reston
State_or_Province: VA
Postal_Code: 20192
Country: USA

Contact_Voice_Telephone: 703-648-6950
Contact_Electronic_Mail_Address: pchirico@usgs.gov

Spatial_Data_Organization_Information:

Direct_Spatial_Reference_Method: Raster

Spatial_Reference_Information:

Horizontal_Coordinate_System_Definition:

Planar:

Map_Projection:

Map_Projection_Name: Transverse Mercator
Transverse_Mercator:

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_Coordinate_Information:

Planar_Coordinate_Encoding_Method: row and column
Coordinate_Representation:

Abscissa_Resolution: 30.0
Ordinate_Resolution: 30.0

Planar_Distance_Units: METERS

Geodetic_Model:

Horizontal_Datum_Name: D_WGS_1984
Ellipsoid_Name: WGS_1984
Semi-major_Axis: 6378137.0
Denominator_of_Flattening_Ratio: 298.257223563

Entity_and_Attribute_Information:

Detailed_Description:

Entity_Type:

Entity_Type_Label: Table
Entity_Type_Definition: Values of the raster
Entity_Type_Definition_Source: USGS Artisanal and Conflict Minerals Project

Attribute:

Attribute_Label: Value
Attribute_Definition:

Numeric identifier for a unit of surficial geology or geomorphology

Attribute_Definition_Source: Producer-defined
Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 1
Enumerated_Domain_Value_Definition:

Alluvium - a geomorphic unit of negative or low relative elevation that typically exhibits comparatively deep unconsolidated surficial sediments and gravels deposited by hydrologic processes

Enumerated_Domain_Value_Definition_Source: Producer-defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 2
Enumerated_Domain_Value_Definition:

Terrace - 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

Enumerated_Domain_Value_Definition_Source: Producer-defined

Attribute_Domain_Values:

Enumerated_Domain:

Enumerated_Domain_Value: 3
Enumerated_Domain_Value_Definition:

colluvial hillslope - the surficial weathered or weakened rock which is primarily affected by gravity-driven erosion and is underlain by undifferentiated bedrock

Enumerated_Domain_Value_Definition_Source: Producer-defined

Distribution_Information:

Distributor:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Peter G. Chirico
Contact_Organization: U.S. Geological Survey

Contact_Address:

Address_Type: mailing and physical
Address: 12201 Sunrise Valley Dr.
City: Reston
State_or_Province: VA
Postal_Code: 20192
Country: USA

Contact_Voice_Telephone: 703-648-6950
Contact_Electronic_Mail_Address: pchirico@usgs.gov

Distribution_Liability:

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.

Technical_Prerequisites:

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.

Metadata_Reference_Information:

Metadata_Date: 20180409
Metadata_Contact:

Contact_Information:

Contact_Person_Primary:

Contact_Person: Jessica DeWitt
Contact_Organization: U.S. Geological Survey

Contact_Address:

Address_Type: mailing and physical
Address: 12201 Sunrise Valley Dr.
City: Reston
State_or_Province: VA
Postal_Code: 20192
Country: USA

Contact_Voice_Telephone: 703-648-6926
Contact_Electronic_Mail_Address: jdewitt@usgs.gov

Metadata_Standard_Name: Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version: FGDC-STD-001-1998

The Central African Republic Diamond Database (2018) - Geomorphology

Metadata: