Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.14/170611
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- Title
- High-Mg carbonatitic HDFs, kimberlites and the SCLM
- Related
- Goldschmidt Conference (21st : 2011) (14 - 19 August 2011 : Prague, Czech Republic)
- Related
- Mineralogical magazine, Vol. 75, No. 3, p.2143
- Related
- http://goldschmidt.info/2011/index.html
- Publisher
- London : Mineralogical Society
- Date
- 2011
- Author/Creator
- Weiss, Y
- Author/Creator
- Griffin, W. L
- Author/Creator
- Bell, D. R
- Author/Creator
- Navon, O
- Description
- Trace-element patterns of high-Mg carbonatitic high- density fluids (HDFs) trapped in Siberian fibrous diamonds are similar to those of Group I kimberlites, but are slightly more fractionated. The patterns of both are comparable in shape to the average pattern of peridotite xenoliths from the sub-continental lithospheric mantle (SCLM) [1]. Possible scenarios for explaining these similarities include mixing, fractionation and melting: Adding 2.5% of kimberlitic magma or 0.7% of the Siberian high-Mg HDFs to a highly depleted peridotite closely reproduces the SCLM pattern. The formation of the high-Mg HDFs through fractionation of kimberlitic magma calls for 70% crystallization of olivine, pyroxene garnet and carbonate. However, the alkalis and Ba of the calculated fluid are too low and the middle to heavy REE, Zr, Hf, Ti and Y are too high compared to the Siberian high-Mg HDFs. Simple batch melting of 0.5% of a source with average SCLM modal abundance and trace-element composition closely reproduces the trace-element pattern of the Siberian high-Mg HDFs. Higher degrees of melting ( approximately 2%) of the same source yield patterns similar to those of Group I kimberlite. High-Mg HDFs in diamonds from Kankan, Guinea have major-element compositions comparable to that of the Siberian high-Mg carbonatitic HDFs. However, they are depleted in K, Rb, Cs, Nb and Ta and enriched in Ba, Th, U and LREE relative to the Siberian ones. These differences closely correspond to those between the patterns of Group II and Group I kimberlites, respectively. Extending the melting scenario to the Kankan HDFs and Group II kimberlites, the two can be produced by 0.2 and 1% melting of SCLM that carries phlogopite (0.3% and 0.1%, respectively) and a trace of rutile. Whether it is mixing, melting or combination of both, the new constraints indicate a very close genetic relation between high-Mg carbonatitic HDFs, kimberlites and the average SCLM. [1] McDonough (1990) EPSL 101, 1-18.
- Description
- 1 page(s)
- Resource Type
- conference paper abstract
- Organisation
- Macquarie University. National Key Centre for Geochemical Evolution and Metallogeny of Continents (GEMOC)
- Identifier
- http://hdl.handle.net/1959.14/170611
- Identifier
- ISSN: 0026-461X
- Identifier
- mq_res-ext-pro885339702
- Language
- eng
