Yaxley G M, Berry A J, Rosenthal A, Woodland A B, Paterson D
Research School of Earth Sciences, The Australian National University, Canberra, ACT, 2601, Australia.
Bayerisches Geoinstitut, Universität Bayreuth, 95440, Bayreuth, Germany.
Sci Rep. 2017 Feb 14;7(1):30. doi: 10.1038/s41598-017-00049-3.
We present the first oxygen fugacity (fO) 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 fO, 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 SiO-undersaturated magmas.
我们展示了加拿大北部斯拉维克拉通中部拉克德格拉斯金伯利岩田熊猫金伯利岩（埃卡蒂钻石矿）下方克拉通岩石圈地幔的首个氧逸度（fO）剖面。将这些数据与来自附近戴维克钻石矿几乎同期的金伯利岩（A154 - N）中石榴石橄榄岩捕虏体的新数据和现有数据相结合，表明斯拉维克拉通地幔的氧逸度随深度和短距离横向变化几个数量级。含钻石的斯拉维岩石圈下部（深度大于120 - 130千米）的fO已被氧化高达4个对数单位，这显然与交代富集作用有关。这种耦合的富集和氧化作用可能是由含碳酸盐、含水的硅酸盐熔体在钻石存在的情况下渗透造成的，这一过程被认为对“预处理”深部岩石圈地幔并使其适合后来金伯利岩和其他SiO不饱和岩浆的生成至关重要。
