Igneous Rock Geochemistry

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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version 2 (AGDB2), Alaska Division of Geological and Geophysical Surveys (ADGGS), peer-reviewed literature, and unpublished USGS data.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: <null>
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: <null>
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: <null>
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

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