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Application to Neogene Bimodal Igneous Rocks and Mineral Resources in the Great Basin

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Application to Neogene Bimodal Igneous Rocks and Mineral Resources in the Great Basin Development of an igneous rock database with geologic functions: Application to Neogene bimodal igneous rocks and mineral resources in the Great Basin Douglas B. Yager1*, Albert H. Hofstra1*, Katheryn Fifarek2*, and Ank Webbers3* 1Central Mineral and Environmental Resources Science Center, U.S. Geological Survey, Denver Federal Center, Box 25046, MS 973, Denver, Colorado 80225, USA 2Department of Geology, Mailcode 4324, Southern Illinois University, Carbondale, Illinois 62901, USA 3516 Orchard Way, Louisville, Colorado 80027, USA ABSTRACT and various subsamples. Absolute radiomet- INTRODUCTION ric age determinations on samples from geo- Geologists routinely use sample data logic features and expert interpretations of Now that GIS is fully implemented for (descriptive, qualitative, quantitative) to relative age relationships between different Windows-based software platforms on personal characterize a hierarchy of larger geologic features may be captured and used together computers and has interoperability with rela- features that each have their own indepen- to constrain the ages of undated features. tional databases, a new realm for data investiga- dent attributes, use physical relationships Such age information is linked to features tion, display, and analysis is available to earth between geologic features to establish their of various scales in the hierarchy. Common scientists. GIS enables data to be input, man- relative ages, combine this information with attributes that are shared between the rela- aged (in a database management system), ana- dated features to understand evolutionary tional database and geographic informa- lyzed, and output as derivative maps and tables. histories of study areas at various scales, tion system (GIS) features include feature- The relational database enables data retrieval and produce maps to display such informa- identifi cation or sample-identifi cation, and between logically designed tables that are linked tion in space and time relative to other fea- they permit linking of geographic entities through a common relational join item such tures of interest. This paper demonstrates and tabular data for query, analysis, and dis- as a unique sample-identifi cation or feature- how we integrated such routine geologic play in GIS or derivative tables. identifi cation. Relational database functional- functions into an existing igneous rock Relational database keys merge analyti- ity permits users to construct Structured Query relational database designed to store, orga- cal, map, and image data across this geologic Language (SQL) queries that retrieve data from nize, update, query, and retrieve sample hierarchy-age-location schema to facilitate linked tables in organized ways for analysis and data that have well-defi ned locations. The queries that address geologic problems. Data display in GIS software. resulting igneous rock database is utilized acquired at the sample scale of observation User-friendly relational databases that store to capture information on Neogene bimodal is linked to increasingly larger features that information specifi c to igneous rocks are rela- igneous rocks in northern Nevada and the have their own independent attributes using tively new. Web-based portals can now access eastern Great Basin Province. The database GIS. This schema enables users to retrieve solid earth geochemical data and visualization is a useful tool that facilitates queries to information on one or more hierarchical tools for igneous rocks (Walker et al., 2004; generate geographical information system features for input into external software Lehnert et al., 2003). GEOROC, PetDB, and displays and petrologic plots that elucidate for various GIS, statistical, petrologic, and NAVDAT that are part of the EarthChem web- the time-space-composition relationships of other display, analysis, or comparison pur- based portal (Lehnert et al., 2003), in particular, volcanic centers to one another and to geo- poses. Fundamental interpretations result- utilize a relational database schema that facili- physical anomalies, structural features, and ing from such analyses or displays, e.g., rock tates query and retrieval of geochemical data mineral deposits. classifi cation, may be used to populate addi- on samples. Lehnert et al.’s (2000) database Database information is parsed into the tional fi elds in the database. The database is structure is very robust for managing geochemi- following data tables: physical hierarchy of designed for fl exibility and can accommodate cal sample level data; therefore we build upon scale, absolute and relative age, chemistry, information resulting from both detailed and much of their schema in our database. As earth paleomagnetic, rock mode, image, cross sec- reconnaissance studies. The geologic func- scientists continue to link GIS systems and other tion, X-ray diffraction, and igneous-related tions that were developed and that we added applications to igneous rock or other geologic structure. Information is organized in a tele- to an existing igneous rock database (Lehnert databases, either directly from individual PC’s or scoping geologic hierarchy schema: igneous et al., 2000) for this study have wide appli- via internet resources such as the western North province, volcanic fi eld, volcanic system or cability and could readily be integrated into American volcanic rock database NAVDAT, caldera, extrusive fl ow or intrusion, sample, other geoscience databases. http://navdat.kgs.ku.edu/ (Walker et al., 2004) or *Emails: Yager: [email protected]; Hofstra: [email protected]; Fifarek: kfi [email protected]; Webbers: [email protected]. Geosphere; October 2010; v. 6; no. 5; p. 691–730; doi: 10.1130/GES00516.1; 35 fi gures; 3 tables; 1 appendix fi gure; 1 appendix table. For permission to copy, contact [email protected] 691 © 2010 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/6/5/691/5070789/691.pdf by guest on 25 September 2021 Yager et al. the EARTHCHEM portal, http://www.earthchem graphic areas of interest (geo-hierarchy of Yager 1992; Wallace, 1993; Ludington et al., 1996; .org/ (Lehnert et al., 2003), there is a need to and Hofstra, 2004). John, 2001; John et al., 2003; Wallace, 2003). implement data structures that permit geologists Our database is able to store and manipulate Great Basin bimodal igneous rocks are broadly to use these resources in an effi cient and logical the multiple data types discussed above such as characterized by basaltic and rhyolitic end- manner to address a geologic question or prob- physical hierarchy-of-scale, relative and absolute member compositions. Ages and compositions lem that utilizes fundamental geologic principles. ages, geochemical analyses, rock modes, scanned of the bimodal suite, however, vary in age and Geologists commonly approach a geologic cross sections, maps, and images from the prov- composition across the Great Basin Province. problem from multiple scales of observation ince to inclusion level of observation. To manage They include ages and compositions of 22 Ma using all available data sources pertaining to the physical hierarchy of scale, our schema uses a to Holocene high-silica and high fl uorine topaz features having various ages, composition, and nested set approach similar to Celko (2004), where rhyolites (Christiansen et al., 1986), 14–17 Ma geographic distribution. In order to investigate the largest size features can have multiple, nested, peralkaline to tholeiitic volcanics and intru- a geologic question, Earth scientists commonly smaller size features in the hierarchy (Fig. 1). In sions, and Neogene alkali basalts. The younger require ready access to (a) the total number and addition, we provide database placeholders to eruptives (3–11 Ma) are mostly alkali-olivine types of geochemical information available for a capture expert knowledge regarding fundamental basalts (Leeman and Rogers, 1970). magmatic center or unit, aiding in the identifi ca- geologic fi eld relationships and interpretations Information on bimodal igneous rocks was tion of data-rich areas and areas that have data useful for determining relative ages of features retrieved and organized from legacy U.S. Geo- gaps, (b) isotopic and relative age information, when absolute ages are unknown or uncertain. logical Survey geochemistry data archives as well as the best or highest precision ages avail- The resulting GIS-linked relational database (Granitto et al., 2005) and from published pro- able, (c) geochemical data on major-, trace-, and is used to compile and organize information fessional and academic sources. Most of the rare-earth-element concentrations for analysis for the bimodal (basalt-rhyolite) igneous suite information compiled is from bimodal igneous in petrologic discrimination and classifi cation of rocks in a large area of northern Nevada that rocks along the Northern Nevada Rift (NNR). diagrams, (d) isotopic data that can be used for also contains broadly coeval low sulfi dation In the latter part of the paper, we demonstrate interpreting magma genesis, crustal assimila- Au-Ag deposits (Fig. 2) (John, 2001; Leavitt et and use the geologic functions of the database tion, and differentiation processes, among other al., 2004). We have also imported geochemical to query, retrieve, and display important time- petrologic issues, and (e) a map, or GIS, that can data for the eastern Great Basin Province that space-composition relationships between dif- be used to place geologic features of multiple
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