| Résumé | (disponible en anglais seulement)
SHRIMP labs generate large quantities of results for scientists both internal and external to their home organization. The storage, tracking and retrieval of
data, along with associated metadata is an ongoing challenge. Added to this, SHRIMP facilities in publically funded laboratories may have mandated requirements to manage data in a way that makes it accessible and open to a wide variety of
stakeholders (including the public).
In most cases, the scientific unit of interest in a SHRIMP analysis is the sample (commonly a specific lithology/unit from a unique location) however a single sample may have many sources of SHRIMP data. These
may include multiple minerals from the same unit, the same mineral on multiple SHRIMP mounts, or the same SHRIMP mount analysed during multiple sessions or with multiple calibrations. The retrieval and compilation of all the results for a single
sample for different minerals, mounts, sessions, or calibrations can be time consuming.
Many SHRIMP laboratories are using Ludwig¿s VBA-based Excel Add-In SQUID2 for their U-Pb geochronology data reduction (Ludwig, 2003). This incredibly
powerful, customizable and complex piece of programming has the added benefit that it integrates seamlessly with Ludwig¿s Isoplot Add-In to generate the necessary calculations and plots utilized to interpret isotopic results. SQUID parses individual
sample results on separate worksheets and preserves SHRIMP data reduction metadata such as analyses of standards, calibration error, specifics on the task and interpolation methods used on a separate sheet in the same workbook. However, each
¿SQUIDed¿ workbook contains only the data from a single analytical session and this poses challenges when data from a single sample straddles multiple sessions/workbooks.
While other data-reduction protocols are under-development by the wider
geochronology community, we anticipate ongoing reliance on Excel workbooks. In light of the need to store, track, organize, retrieve and disseminate results in a timely way, the Geological Survey of Canada (GSC) has developed a number of software
tools that help to integrate:
1) SQUID reduced U-Pb data from Excel spreadsheets
2) Data reduction metadata
3) Sample imagery (e.g. CL/BSE)
4) Post-analysis reflected light imagery and
5) SHRIMP instrument analytical
conditions
Analytical results from SQUID, instrument conditions, and file/folder locations are stored in an Oracle database permitting rapid retrieval and compilation of all U-Pb geochronology results and associated metadata for a given sample.
An Excel VBA Add-In and external stand-alone applications are used to transfer data to the Oracle database. Once the database is populated with the results and instrumental parameters, data for an individual sample can be extracted as an Excel
2010 file using a ¿ZinfoExporter¿ tool, a Windows application. The resulting Excel workbook, referred to as a ¿Zinfo¿ file (GSC samples are given a laboratory number called a Z-number) includes U-Pb results from all analytical
session/mounts/calibrations, regardless of mineral. Each SHRIMP analysis is linked to the original SQUID workbook, the Adobe PDF file containing the SEM images and to the reflected light screen snap taken immediately after analysis.
Analysis-specific analytical parameters including the primary beam intensity and sample stage coordinates, and session-specific parameters including the multiplier and discriminator settings, Kohler aperture, and calibration error are also reported
in the Zinfo file. This permits easy quality assurance/quality control checks of the data. Data interpretation (concordia plots/weighted mean calculations) can be carried out using Isoplot in the Zinfo file. A consistent set of columns is output
by the ZinfoExporter, thus simplifying the preparation of publication data tables that include more than one sample.
Part of the GSC¿s analytical protocol includes the analysis of secondary standards to independently verify the accuracy of the
Pb/U calibration and identify any requirements for intra-element mass fractionation corrections. Data validation tools were developed to track average 206Pb/238U and 207Pb/206Pb ages of the secondary standards, as well as user-defined analytical
parameters (e.g. average UO/U) for both the primary and secondary standards within the SQUID workbook. These too are uploaded to the Oracle database where they can be queried to track long term trends in instrumental performance.
The goal in
developing these tools was to meet the laboratory objectives of quality control/quality assurance plus facilitated dissemination of results. The implementation of these tools has permitted the GSC¿s SHRIMP laboratory to partially automate the
validation, storage, retrieval and compilation of laboratory results on the basis of sample, avoiding the need to cut/paste from multiple worksheets and the associated risk of error.
The GSC SHRIMP Tools provide a framework for more efficient
and consistent SHRIMP data management. This facilitates the population of public-facing databases which underpin web accessibility via sites like the Canadian Geochronology Knowledgebase (CGKB, http://atlas.gc.ca/geochron/en/). The CGKB is one of
many ways the GSC is fulfilling its Open Data mandate of providing accessible, high-quality geoscience data to Canada and the world.
Ludwig, K. R. (2003), User's manual for Isoplot/Ex rev. 3.00: a geochronological toolkit for Microsoft Excel. in
Special Publication 4, pp. 70, Berkeley, Berkeley Geochronology Centre. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Le présent résumé porte sur l'élaboration et la mise en 'uvre d'une trousse d'outils logiciels qui a permis au laboratoire de microsonde ionique
à haute résolution et à haut niveau de sensibilité (SHRIMP) de la CGC de partiellement automatiser la validation, le stockage, la récupération et la compilation des résultats de laboratoire sur la base d'un échantillonnage, évitant ainsi la nécessité
de couper et de coller des données de nombreuses feuilles de calcul et d'éliminer le risque d'erreur connexe. Ce cadre visant une gestion plus efficace et plus uniforme des données SHRIMP facilite l'alimentation des bases de données destinées au
public, ce qui soutient l'accessibilité Web par le biais de sites tels la Base de connaissances géochronologiques canadiennes (CGKB, http://atlas.gc.ca/geochron/fr/). La CGKB est l'une des nombreuses façons dont la CGC s'acquitte de son mandat en
matière de données ouvertes, c'est-à-dire de fournir des données géoscientifiques accessibles et de grande qualité à la population canadienne et au monde entier. |