Redox preconditioning deep cratonic lithosphere for kimberlite genesis - evidence from the central Slave Craton.
We present the first oxygen fugacity (fO2) profile through the cratonic lithospheric mantle under the Panda kimberlite (Ekati Diamond Mine) in the Lac de Gras kimberlite field, central Slave Craton, northern Canada. Combining this data with new and existing data from garnet peridotite xenoliths from an almost coeval kimberlite (A154-N) at the nearby Diavik Diamond Mine demonstrates that the oxygen fugacity of the Slave cratonic mantle varies by several orders of magnitude as a function of depth and over short lateral distances. The lower part of the diamond-bearing Slave lithosphere (>120-130 km deep) has been oxidized by up to 4 log units in fO2, and this is clearly linked to metasomatic enrichment. Such coupled enrichment and oxidation was likely caused by infiltrating carbonate-bearing, hydrous, silicate melts in the presence of diamond, a process proposed to be critical for "pre-conditioning" deep lithospheric mantle and rendering it suitable for later generation of kimberlites and other SiO2-undersaturated magmas.
Research School of Earth Sciences, The Australian National University, Canberra, ACT, 2601, Australia. greg.yaxley@anu.edu.au.
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0000-0003-0445-8812
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Yaxley
Research School of Earth Sciences, The Australian National University, Canberra, ACT, 2601, Australia.
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Berry
Bayerisches Geoinstitut, Universität Bayreuth, 95440, Bayreuth, Germany.|Institute of Petrology and Structural Geology, Charles University in Prague, Albertov 6, 128 43, Praha 2, Czech Republic.|Laboratoire Magmas et Volcans, Université Blaise Pascal, CNRS IRD-OPGC, Campus Universitaire des Cézeaux, 6 Avenue Blaise Pascal, 63178, Aubière Cedex, France.
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0000-0003-3912-4046
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Rosenthal
Institut für Geowissenschaften, Goethe Universität, 60438, Frankfurt am Main, Germany.
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Woodland
Australian Synchrotron, Clayton, Victoria, 3168, Australia.
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Paterson