CONTENTS

Specifications and Variables
(description of the database fields, missing values etc.)

Tables:
     Table 1. List of variables describing the samples and major element analyses.
     Table 2. List of variables describing the trace element analyses.
     Table 3. Laboratory codes.
     Table 4. Analysis method codes.
     Table 5. Rock class codes.
     Table 6. Classification of rock classes.
     Table 7. Reference codes, Geofile numbers and full references.

This help file contains documentation for the volcanic rock lithogeochemical database of Newfoundland and Labrador for the Geoscience Atlas.

The original database, organized by Saunders (1995), comprises volcanic and subvolcanic rock samples collected from 1966 to 1994 by the Newfoundland and Labrador Geological Survey (published and unpublished data), from M.Sc. and Ph.D. theses completed at various universities and from select exploration companies (Bitech and Falconbridge). It contains all analyses for each sample, including replicates done by different methods as well as some standards and duplicate analyses for quality control purposes.

The original database was accessed through an R:base 4.0 relational database run-time module. Since this module no longer works on modern-day computers the information was reorganized into a Microsoft Access database. To provide easy access to most of the data it was restructured and simplified in format for viewing and downloading from the Geoscience Atlas in common formats such as ArcGIS shapefiles. To reduce its size and complexity only the most reliable results and elements with the largest number of analyses are included.

The simplified online database consists of 5081 rock samples: 1040 samples from Labrador and 4041 samples from Newfoundland. It still contains a large number of variables, including field descriptions and major and trace element analyses, so the data are presented in two layers in the Geochemistry group: one for the field information and major element analyses (Volcanic_Field_Majors layer) and another for the trace element analyses (Volcanic_Traces layer).

The original Volcanic Rock Geochemical Database (Open File NFLD/2414 v.2) includes volcanic and subvolcanic (hypabyssal) rocks. Many fields (e.g., rock type and geological unit names) have been removed from the online database to simplify the structure. Minor editing has been done to correct such things as inconsistencies in the analysis methods and inconsistencies in concentration unit values.

Note that the major element analyses presented in this database are predominantly reported as raw data without any normalization (e.g., to volatile-free compositions). The database consists of samples with major element totals between about 98 and 102 percent (Saunders, 1995). Loss-on-ignition data is not available for 157 samples; most of these samples have comments indicating that the "major elements were analyzed anhydrously". Null values (i.e., no analysis or data) are indicated by "-99" in the data columns and by blanks in the text columns. Major element values below a detection limit of 0.01 percent are coded as 0.005 percent. Trace element values below their detection limits are coded with a negative sign as a prefix on the value of the detection limit (e.g., a detection limit of 10 is represented as -10 and should be read as <10). Note that the largest detection limit is 58 ppm for some of the Ce analyses done by XRF; these are represented as -58. There are no values between -58 and -99 (the null value) and no value smaller than -99.

Table 1 lists the variables for the field information and major elements file (Volcanic_Field_Majors). Table 2 lists the corresponding variables for the volcanic trace elements file (Volcanic_Traces). These two files can be downloaded from the Resource Atlas OnLine and combined using the unique variable "LabNum" which is common to both files.

The rocks have been coded to facilitate the selection of subsets of volcanic rocks (variable "Rock_Class" in the file "Volcanic_Field_Majors": see Table 5). Rocks included in the database consist of basaltic to rhyolitic volcanic rocks as well as pyroclastic tuffs and hypabyssal rocks. Hypabyssal rocks include ultramafic, gabbro and diabase sills, ophiolitic dykes, and felsic aphanitic to porphyritic subvolcanic rocks.

The coding of the volcanic rocks is based on their anhydrous SiO2 content (Saunders, 1995; see Table 6). The coding of the hypabyssal rocks, such as gabbro and diorite, is based on the classification by the geologist. Schistose ultramafic rocks represent high level sills and related extrusive rocks and have a "Rock_Class" code of "UMFC". The remaining intrusive rocks are classified as diabase or felsite based on their SiO2 content (see Table 6).

The Reference code and Geofile numbers in Table 7 provide information on the original source of the data. The Geofile numbers can be entered on the NL Geological Survey's Geofiles webpage to review more information about the source document. Where the Geofile number is highlighted in blue in Table 7 it is hyperlinked to the downloadable pdf version of the report.

The Comments column includes information about the rock type, detection limits, if the sample is from diamond drill core (location coordinates are for the drill collar), general sample location, and other assorted information obtained from the original source or included by past compilers. This information has not been updated from the original database, even though some of it is no longer pertinent due to the simplification of the online database.

These data are from numerous laboratories ( Table 3), and analysed using various digestion and instrumental analysis techniques ( Table 4) spanning over 25 years (1966 to 1994). The specific digestion techniques are not provided but can be accessed through the original source document ( Table 7). Some of the methods are quite old (e.g., "Rapid Chemical Method") and full descriptions of some of the techniques are not available.

The major elements in the file "Volcanic_Field_Majors" consist of the standard set of major elements expressed as oxide values (i.e., SiO2, Al2O3, Fe2O3, FeO, MgO, CaO, Na2O, K2O, TiO2, MnO, P2O5, and Cr2O3: see Table 1). Most of these major elements were analysed by one of four methods (listed in column "MajorsMeth"): atomic absorption spectrometry (AAS), x-ray fluorescence (XRF), inductively-coupled plasma emission spectrometry (ICS) and direct current plasma emission spectrometry (DCP). Other major elements analyzed by more specialized techniques, such as titration (for Fe2O3 and FeO), colourimetry (for P2O5), and infrared-gas analysis (for CO2, H2O and S), are included as separate columns. For these latter major elements the method of analysis is indicated as a suffix on the field name (e.g., FeO_TTR). Na2O analysis by AAS is included as a separate column only for those samples where the other major elements were analysed by XRF. Therefore, the user can select the method of analysis of the main major elements (e.g., "MajorsMeth=XRF"), and this automatically includes the ancillary analyses by other methods (e.g., LOI or P2O5 by colourimetry) for those samples.

Values for iron exist in a number of data columns that reflect the oxidation state of iron. Unique values (representing total iron, for the most part) are those where there are no other iron analyses in adjacent iron columns. There are 2124 unique values for Fe2O3, 160 unique values for FeO, and 6 unique values for FeO_TTR. Fe2O3_TTR is always paired with FeO by XRF (119 analyses). All other analyses are pairs of Fe2O3 (by AAS, ICS or XRF) with FeO_TTR (2028 analyses), and Fe2O3 with FeO (642 analyses by five different methods). Only two samples have no Fe analyses.

The trace elements in the file "Volcanic_Traces" consist of 42 elements analysed by one or more of seven methods (see Table 2 for a list of the elements, their descriptions and the number of samples analysed). The trace element field names consist of the element followed by its unit of measure followed by the method of analysis (e.g., Au_ppb_DCP). There are 101 element-method columns presented in the file "Volcanic_Traces". The laboratory number and location (as latitude and longitude) are also included. As previously mentioned, the variable "LabNum" can be used to join the trace element file "Volcanic_Traces" with the field and major elements file "Volcanic_Field_Majors".

A limited number of analyses of standards and duplicate samples are available in the original volcanic database (Saunders, 1995). Due to the variety of labs and techniques used to analyse the data and the limited quality control, major and trace element values may vary in both accuracy and precision from the different sources. Caution is advised if the data is to be used in any modeling.

The Geological Survey, a division of the Mining and Mineral Development Branch, Government of Newfoundland and Labrador (the "authors and publishers"), retains the sole right to its original data. The authors and publishers assume no legal liability or responsibility for any alterations, changes or misrepresentations made by third parties with respect to these products or the original data. Furthermore, the Geological Survey assumes no liability with respect to digital reproductions or copies of original products or for derivative products made by third parties. Please consult with the Geological Survey in order to ensure originality and correctness of data and/or products.

(for downloaded database)

Newfoundland and Labrador Geological Survey. "Volcanic Database." Newfoundland and Labrador GeoScience Atlas OnLine. Last update: August 2009. https://geoatlas.gov.nl.ca . [fill in date downloaded].

Saunders, C.M., 1995: Volcanic rock geochemical database: User manual. Government of Newfoundland and Labrador, Department of Natural Resources, Geological Survey, Open File NFLD/2414 Version 2, 93p. (Geofile NFLD/2414 Version 2)

(from Saunders, 1995)
Tim van Nostrand compiled the data for Labrador (references 39-60). Jim Butler and Chris Finch assisted with assignment of laboratory numbers for external data. Scott Swinden provided guidance throughout the project and made suggestions for improvement of the application. This project was initiated by the Geological Survey of the Newfoundland Department of Natural Resources under contract to the Geological Survey of Canada, funded by the Canada-Newfoundland Cooperation Agreement on Mineral Development, 1990-1994.

Any comments, questions or suggestions regarding the online volcanic database can be directed to:

GeoscienceOnline@gov.nl.ca

(Help file updated May 2021)

(Database updated August, 2009)