Metadata: Identification_Information: Citation: Citation_Information: Originator: U.S. Geological Survey Publication_Date: 2016 Title: Igneous Rock Geochemistry Geospatial_Data_Presentation_Form: vector digital data Larger_Work_Citation: Citation_Information: Originator: Susan M. Karl (ed.) Originator: James V. Jones, III (ed.) Originator: Timothy S. Hayes (ed.) Publication_Date: 2016 Title: GIS-based identification of areas that have resource potential for critical minerals in six selected groups of deposit types in Alaska Series_Information: Series_Name: U.S. Geological Survey Open-File Report Issue_Identification: 2016-1191 Other_Citation_Details: The larger work includes data sets for mineral resource data, geochemistry (stream sediment, rock, soil, mineral, and heavy mineral concentrate), igneous rock geochemical indices, lithology, aeroradiometric data, and hydrologic units analyzed for select deposit types. Online_Linkage: http://dx.doi.org/10.3133/ofr20161191 Description: Abstract: This geodatabase contains a point data set of over 50,000 records of geochemical indices of igneous rocks in Alaska. Major and trace element data were compiled from Alaska Geochemical Database version 2 (AGDB2), Alaska Division of Geological and Geophysical Surveys (ADGGS), peer-reviewed literature, and unpublished USGS data. Data was screened to included only high-resolution analyses. This data set contains calculations of various ratios and displacements from established boundaries on x-y plots to help classify igneous rocks. The point data set is also provided as a shapefile. Purpose: Feature class all_igneous_ratios is used to identify permissive rock types for REE deposits and Sn-W-Mo deposits. The ratios for the aluminum saturation index, ASI, (Al/[Ca-1.67xP)+Na+K], and ANK, Al/[Na+K], allow for the differentiation between peraluminous, metaluminous, and peralkaline rocks. Trace element concentration ratios Nb/Y and Ga/Al can distinguish alkaline and subalkaline igneous rocks. Also, the modified alkali-lime index, MALI, (Na2O+K2O-CaO), and Fe_no, FeO/[FeO+MgO], can used to distinguish alkaline vs calcic, and ferroan vs magnesian rocks. Supplemental_Information: The method for screening high-resolution analyses is as follows. All the elements used to calculate the geochemical index need to be of similarly high precision. In general, major-element data were used only for samples where all major rock forming element oxides were measured by x-ray fluorescence (XRF) methods. For trace elements such as Y and Nb, only XRF and inductively coupled plasma mass spectrometry (ICP-MS) analyses were used. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2014 Currentness_Reference: compilation date Status: Progress: In work Maintenance_and_Update_Frequency: Irregular Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: 173.11667 East_Bounding_Coordinate: -130.01306 North_Bounding_Coordinate: 70.20583 South_Bounding_Coordinate: 51.25 Keywords: Theme: Theme_Keyword_Thesaurus: None Theme_Keyword: igneous rock Theme_Keyword: peraluminous Theme_Keyword: metaluminous Theme_Keyword: peralkaline Theme_Keyword: alkaline Theme_Keyword: subalkaline Theme_Keyword: calcic Theme_Keyword: ferroan Theme_Keyword: magnesian Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation, 008 Access_Constraints: None Use_Constraints: None. Users are advised to read the publication text and metadata to understand the appropriate use and data limitations. Data_Set_Credit: Erin Todd and Nora Shew, USGS Native_Data_Set_Environment: Dataset was created using ESRI ArcGIS, version 10.2 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The samples in this data set were collected by several agencies for various projects with differing needs. In addition, the analyses were performed over a long period of time during which analytical methods have changed. Therefore the degree of accuracy is varied and difficult to assess. Logical_Consistency_Report: Analytical data included in this data set were screened for being high-resolution analyses. Elements used to calculate geochemical indices need to be of similar high precision. In general, major-element data were only used for samples where all major rock forming element oxides were measured by x-ray fluorescence (XRF) methods. For trace elements, such as Y and Nb, only XRF and inductively coupled plasma mass spectrometry (ICP-MS) analyses were used. Completeness_Report: The original data set includes many more fields than are presented here. The fields in this subset are those that are used in the analyses for REE-Th-Y-Nb and Sn-W-Mo deposits. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Users must be aware that the locational accuracy is an unknown factor because of the background of each contributing dataset. Resolution is variable. Samples with obvious spurious locations (such as quadrangle corners) in the contributing source datasets were not included in this dataset. Lineage: Process_Step: Process_Description: All indices were calculated using Matlab. Indices using major elements were calculated using values normalized to anhydrous compositions, assuming that the sum of oxides equalling less than 100% were due to the presence of water or other volatile species. Thus each major element used in the index calculation was divided by the sum of major element oxides. (SumMajors = SiO2+TiO2+Al2O3+FeOt_calc+MnO+MgO_CaO+Na2O+K2O+P2O5). If any of these major element oxides were not measured, or if measured values were below detection limits, they were assumed to equal zero. No major element indices were calculated if SiO2 was not measured, if SiO2 was below detection limits, or if SiO2 was analyzed by a method not associated with robust analysis. Analytical methods for SiO2 considered robust within the context of this study were: AES_Fuse, CM_Fuse, EDX, WDX_Fuse, XRF (DGGS data only), and XRF_Slab (DGGS data only). Data for trace elements Y and Nb were also filtered to include only data measured by robust methods. Nb data included only measurement by AES_HF, EDX, MS_Fuse, MS_ST, and WDX_Fuse. Y data included only measurement by AES_HF, EDX, MS_Fuse, MS_Fuse_REE, NA, and WDX_Fuse. No filter was used for Ga data. Process_Date: 2014 Process_Contact: Contact_Information: Contact_Person_Primary: Contact_Person: Erin Todd Contact_Organization: U.S. Geological Survey Contact_Position: Research Geologist Contact_Address: Address_Type: mailing and physical Address: 4210 University Drive City: Anchorage State_or_Province: AK Postal_Code: 99508-4626 Country: USA Contact_Voice_Telephone: 907-786-7441 Contact_Electronic_Mail_Address: etodd@usgs.gov Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: Point Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Map_Projection: Map_Projection_Name: NAD 1983 Alaska Albers Albers_Conical_Equal_Area: Standard_Parallel: 55.0 Standard_Parallel: 65.0 Longitude_of_Central_Meridian: -154.0 Latitude_of_Projection_Origin: 50.0 False_Easting: 0.0 False_Northing: 0.0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: 0.001 Ordinate_Resolution: 0.001 Planar_Distance_Units: meters Geodetic_Model: Horizontal_Datum_Name: North American Datum of 1983 Ellipsoid_Name: GRS_1980 Semi-major_Axis: 6378137.0 Denominator_of_Flattening_Ratio: 298.257222101 Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: all_igneous_ratios Entity_Type_Definition: Point feature class, found in rock_igneous.gdb, contains geochemical indices of igneous rocks in Alaska. Entity_Type_Definition_Source: this data set Attribute: Attribute_Label: LAB_ID Attribute_Definition: A character field where null values may be present. For SOURCE = 'USGS', LAB_ID is a unique identifier assigned to each submitted sample by the Sample Control Officer of the USGS analytical laboratory. For SOURCE = 'DGGS', LAB_ID is a unique identifier that is a concatenation of 'AK' and field SAMPLE_ID from the ADGGS data base. For SOURCE = 'PR_LIT', LAB_ID is either free text or null. Attribute_Definition_Source: this data set Attribute_Domain_Values: Unrepresentable_Domain: free text Attribute: Attribute_Label: FIELD_ID Attribute_Definition: FIELD_ID is the field identifier assigned by the sample collector. The values in FIELD_ID are not unique and null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Unrepresentable_Domain: free text Attribute: Attribute_Label: SAMPLE_ID Attribute_Definition: SAMPLE_ID is a numeric field and is the key field for the ADGGS data. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 1906 Range_Domain_Maximum: 100799 Attribute: Attribute_Label: SOURCE Attribute_Definition: SOURCE identifies where the geochemical data was obtained. Attribute_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: DGGS Enumerated_Domain_Value_Definition: Data from Alaska Division of Geological and Geophysical Surveys (ADGGS) geochemical database, located http://www.dggs.alaska.gov/webgeochem. Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: PR_LIT Enumerated_Domain_Value_Definition: Data was obtained from either peer-reviewed literature or is unpublished USGS data. Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: USGS Enumerated_Domain_Value_Definition: Data was obtained from the U.S. Geological Survey Alaska Geochemical Database, version 2.0. Data is available at http://mrdata.usgs.gov/agdb/ Enumerated_Domain_Value_Definition_Source: this data set Attribute: Attribute_Label: LATITUDE Attribute_Definition: Latitude coordinate of sample site reported in decimal degrees, usually with NAD27 datum and Clark 1866 spheroid. Resolution is variable. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 51.25 Range_Domain_Maximum: 70.20583 Attribute_Units_of_Measure: degrees Attribute: Attribute_Label: LONGITUDE Attribute_Definition: Longitude coordinate of sample site reported in decimal degrees, usually with NAD27 datum and Clark 1866 spheroid. Resolution is variable. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -179.11667 Range_Domain_Maximum: 179.45 Attribute_Units_of_Measure: degrees Attribute: Attribute_Label: SiO2_pct Attribute_Definition: Silicon, as silicon dioxide, in weight percent. A null or empty cell means not analyzed. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -21.4 Range_Domain_Maximum: 99.11111 Attribute_Units_of_Measure: weight percent Attribute: Attribute_Label: ASI_calc Attribute_Definition: Aluminum saturation index; ASI = [Al/(Ca - 1.67P + Na + K)]. The aluminum saturation index is used to subdivide granitic rocks into peraluminous, metaluminous or peralkaline. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 715.97213 Attribute: Attribute_Label: ANK Attribute_Definition: ANK = Al/[Na + K]; geochemical index for determining if granitic rock is metaluminous or peralkaline. Null values present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 715.97213 Attribute: Attribute_Label: Fe_no Attribute_Definition: Fe_no, sometimes written Fe#, is the ratio FeO/(FeO + MgO), which is used to differentiate if a rock is ferroan or magnesian (Frost and others, 2001). Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 0.99919 Attribute: Attribute_Label: Fe_no_displ Attribute_Definition: Displacement along the y-axis from the ferroan-magnesian boundary line on the SiO2 vs Fe_no plot. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -0.87373 Range_Domain_Maximum: 0.38882 Attribute: Attribute_Label: MALI_displ Attribute_Definition: MALI_displ is the displacement along the y-axis from the alkali-calcic and calc-alkalic boundary on the SiO2 vs MALI plot. MALI is the modified alkali-lime index; MALI = Na2O + K2O - CaO. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: -48.78075 Range_Domain_Maximum: 30.40781 Attribute: Attribute_Label: Ga_Al Attribute_Definition: Trace element concentration ratio 10,000 x Ga/Al; can be used to distinguish alkaline and subalkaline igneous rocks. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 68.32067 Attribute: Attribute_Label: Nb_Y Attribute_Definition: Trace element concentration ratio Nb/Y; can be used to distinguish alkaline and subalkaline igneous rocks. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Range_Domain: Range_Domain_Minimum: 0 Range_Domain_Maximum: 40 Attribute: Attribute_Label: class_Fe_no Attribute_Definition: Classification ferroan or magnesian. Null values are present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Enumerated_Domain_Value_Definition: Not determined Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Ferroan Enumerated_Domain_Value_Definition: Fe_no_displ > 0. There are also samples in which Fe_no_displ is null included in Ferroan, because MgO was extremely low (extremely fractionated), that Fe_no could not be calculated. These samples are judged to be ferroan because Fe would be about 1.0. Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Magnesian Enumerated_Domain_Value_Definition: Fe_no_displ <= 0 Enumerated_Domain_Value_Definition_Source: this data set Attribute: Attribute_Label: class_MALI Attribute_Definition: Classification of alkali-calcic or calcic-alkalic based on MALI_displ. Null values present. Attribute_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Enumerated_Domain_Value_Definition: insufficient data to determine Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: calcic Enumerated_Domain_Value_Definition: MALI_displ < -2.5 Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: alk-calc Enumerated_Domain_Value_Definition: -2.5 < MALI_displ < 0 Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: calc-alk Enumerated_Domain_Value_Definition: 0 < MALI_displ < 1.5 Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: alkalic Enumerated_Domain_Value_Definition: MALI_displ > 1.5 Enumerated_Domain_Value_Definition_Source: this data set Attribute: Attribute_Label: class_ASI Attribute_Definition: Classification metaluminous, peralkaline, or peraluminous. Attribute_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: Enumerated_Domain_Value_Definition: insufficient data to determine Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: peraluminous Enumerated_Domain_Value_Definition: ANK > 1.2 and ASI >= 1.1 Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: metaluminous Enumerated_Domain_Value_Definition: ANK > 1.2 and ASI < 1.1 Enumerated_Domain_Value_Definition_Source: this data set Attribute_Domain_Values: Enumerated_Domain: Enumerated_Domain_Value: peralkaline Enumerated_Domain_Value_Definition: ANK <= 1.2 Enumerated_Domain_Value_Definition_Source: this data set Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Address: Address_Type: mailing address Address: MS902 Box 25286 Denver Federal Center City: Lakewood State_or_Province: CO Postal_Code: 80225 Country: USA Contact_Voice_Telephone: 1-888-ASK-USGS Resource_Description: USGS Open-File Report 2016-1191 Distribution_Liability: This publication was prepared by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, expressed or implied, or assumes any legal liability or responsibility for the accuracy, product, or process disclosed in this report, or represents that its use would not infringe privately owned rights. Reference therein 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. Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: ArcGIS geodatabase Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://dx.doi.org/10.3133/ofr20161191 Fees: none Metadata_Reference_Information: Metadata_Date: 20151210 Metadata_Review_Date: 20160906 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: U.S. Geological Survey Contact_Person: Nora Shew Contact_Address: Address_Type: mailing and physical Address: 4210 University Drive City: Anchorage State_or_Province: AK Postal_Code: 99508-4626 Country: U.S.A. Contact_Voice_Telephone: 907-786-7445 Contact_Electronic_Mail_Address: nshew@usgs.gov Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998