Аннотация:Here we present new data from a systematic Sr, Nd, O, C isotope and geochemical study of kimberlites of Devonian age Mirny
field that are located in the southernmost part of the Siberian diamondiferous province. Major and trace element compositions of
the Mirny field kimberlites show a significant compositional variability both between pipes and within one diatreme. They are
enriched in incompatible trace elements with La/Yb ratios in the range of (65–300). Initial Nd isotope ratios calculated back to the
time of the Mirny field kimberlite emplacement (t = 360 ma) are depleted relative to the chondritic uniform reservoir (CHUR)
model being 4 up to 6 ɛNd(t) units, suggesting an asthenospheric source for incompatible elements in kimberlites. Initial Sr
isotope ratios are significantly variable, being in the range 0.70387–0.70845, indicating a complex source history and a strong
influence of post-magmatic alteration. Four samples have almost identical initial Nd and Sr isotope compositions that are similar
to the prevalent mantle (PREMA) reservoir.We propose that the source of the proto-kimberlite melt of the Mirny field kimberlites
is the same as that for the majority of ocean island basalts (OIB). The source of the Mirny field kimberlites must possess three
main features: It should be enriched with incompatible elements, be depleted in the major elements (Si, Al, Fe and Ti) and heavy
rare earth elements (REE) and it should retain the asthenospheric Nd isotope composition. A two-stage model of kimberlite melt
formation can fulfil those requirements. The intrusion of small bodies of this proto-kimberlite melt into lithosphericmantle forms
a veined heterogeneously enriched source through fractional crystallization and metasomatism of adjacent peridotites. Remelting
of this source shortly after it was metasomatically enriched produced the kimberlite melt. The chemistry, mineralogy
and diamond grade of each particular kimberlite are strongly dependent on the character of the heterogeneous source part from
which they melted and ascended.