Reconstructions of mantle structure beneath kimberlites of Anabar shield and surroundings – similarities and differences.

Comparative study of the mantle xenocrysts from Anabar region (Ary-Mastakh, Dyuken, Orto-Yargyn fields) and Boomerang kimberlites and pipe show essential differences with the mantle in surrounding area from Olenek (Chomurdakh field)

The PTX diagram show presence of the rare lherzolitic pyrope and abundant eclogitic almandines to 6 GPa. In suture zone of Daldyn and Magan terranes (Boomerang pipe) eclogitic omphacites and Cr less pyroxenites and Cr diopsides occurs mainly in the middle mantle part the pyroxenite layer possibly formed after eclogites due to plume melt interaction. Long ilmenite fractionation trend extends from the lithosphere base to the GPa 2.5, which is typical. Geochemistry of minerals vary from most depleted pyropes with V-U shaped REE patterns typical of arc mantle and Ba, U peaks and HFSE minima of subduction type. The fertilization produced the increase of the incompatible elements and sometimes LILE and The marginal parts of the SCLM of Anabar shield are extremely enriched in eclogitic deep-seated material located in lower SCLM part and demonstrating similar thermobarometric trends and features to the diamond inclusions from the Ebelyakh (Mayat) placers. Mantle column beneath several pipes (Losi, Universitetskaya, Kuranakh) contain Cr amphiboles distributes from lithosphere base to Moho. Comparison of reconstructed SCLM beneath Anabar and Chomurdakh field reveal more fertile compositions of the mantle rocks and simpler structure for later field. Abundance of eclogites in Kuranakh and Orto-Yargyn kimberlite in the lower mantle lithosphere part and their PTX trends are similar to the eclogitic diamond inclusions from the Ebelyakh placers. This increase the possibility of finding of diamonds deposits in Anabar shield kimberlites.

RNF grant No. 24-27-00411