US EPA

7464547 

Journal Article 

Mantle xenoliths from the Zimnii bereg kimberlite deposits of rounded diamonds, Arkhangelsk diamondiferous province 

Sablukov, SM; Sablukova, LI; Shavyrina, MV 

2000 

1 

Petrology
ISSN: 0869-5911
EISSN: 1531-8540 

8 

5 

466-494 

English 

WOS:000089593600004 

Kimberlites from the Zimnii Bereg region contain mantle-derived xenoliths of spinel and pyrope peridotites of the spinel-pyroxene, graphite-pyrope, and diamond-pyrope facies; ilmenite-bearing ultramafic rocks; eclogites; and eclogite-like rocks. The xenoliths experienced weak dynamometamorphism, while typical deformed rocks are very rare. The mineral composition of mantle xenoliths in kimberlites of various types defines the geochemistry of the host kimberlite. Within the area, homogeneous "dunite" and heterogeneous "eclogite-peridotite" mantle lithologies were distinguished, which produced the Al-series kimberlites (isotopically transitional between group 1 and group 2 kimberlites of South Africa) and Fe-Ti series kimberlites (similar to group 1 kimberlites of South Africa), respectively. The intense hydrous alkaline (K-Na) infiltration metasomatism of mantle peridotites at depths of 20-110 km resulted in wide development of amphibole (pargasite) and phlogopite. Partial melting of the metasomatized mantle was responsible for kimberlite enrichment in Na and K and subsequent crystallization of melilite and nepheline in the most differentiated kimberlite rocks of both Al and Fe-Ti series. This process also caused partial dissolution of diamond and formation of rounded grains typical of the Zimnii Bereg kimberlite deposits. Copyright © 2000 by MAIK "Nauka/Interperiodica". 

Physical Sciences - Other Topics; equilibria, region, rocks