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Statistical approaches to the discrimination of mantle- and crust-derived low-Cr garnets using major and trace element data.
- Source :
-
Mineralogy & Petrology . Dec2018 Supplement2, Vol. 112, p697-706. 10p. - Publication Year :
- 2018
-
Abstract
- Diamond exploration focuses on geochemical analysis of indicator minerals that are more abundant than diamond itself. Among such indicators, low-Cr (Cr2O3 < 1 wt%) garnets from mantle eclogites are problematic since they overlap compositionally with many lower-crust-derived garnets also transported by kimberlite. Misclassification of these garnets may create "false positive" mantle signatures and possible misdirection of exploration efforts. Statistical solutions using major elements in low-Cr garnet (Hardman et al. in J Geochem Explor 186:24-35, 2018) provide improved error rates for the discrimination of low-Cr crustal and mantle garnets recovered from kimberlite. In this study we analysed a large suite of garnets (n = 571) from both crustal and mantle settings, already characterised for major elements, for a wide range of trace elements by laser ablation inductively-coupled plasma mass spectrometry and use these new data along with literature data (n = 169) to evaluate the effectiveness of adding trace elements to garnet-based diamond exploration programs. A new garnet classification scheme, initially using a major-element based filter, uses garnet Sr contents and Eu anomalies to help identify low-Cr garnets that are misclassified using major element methods. Combined with existing methods, our new trace element classifiers offer improvement in classification error rates for low-Cr, crustal and mantle garnets to as low as 4.7% for calibration data. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 09300708
- Volume :
- 112
- Database :
- Academic Search Index
- Journal :
- Mineralogy & Petrology
- Publication Type :
- Academic Journal
- Accession number :
- 135149104
- Full Text :
- https://doi.org/10.1007/s00710-018-0622-7