Journal
MINERALS
Volume 10, Issue 4, Pages -Publisher
MDPI
DOI: 10.3390/min10040383
Keywords
eclogite; lithospheric mantle; kimberlite; Udachnaya pipe; melting; metasomatism
Funding
- Russian Science Foundation [18-77-00041]
- state assignment of IGM SB RAS
- Deutsche Forschungsgemeinschaft [AU356/10]
- Wilhelm and Else Heraeus Foundation
- Deutsche Forschungsgemeinschaft (DFG) [INST 161/921-1 FUGG, INST 161/923-1 FUGG]
- Russian Science Foundation [18-77-00041] Funding Source: Russian Science Foundation
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A coesite-bearing diamondiferous eclogite from the Udachnaya kimberlite (Daldyn field, Siberian craton) has been studied to trace its complex evolution recorded in rock-forming and minor mineral constituents. The eclogite sample is composed of rock-forming omphacite (60 vol%), garnet (35 vol%) and quartz/coesite (5 vol%) and contains intergranular euhedral zoned olivine crystals, up to 200 mu m long, coexisting with phlogopite, orthopyroxene, clinopyroxene (secondary), K-feldspar, plagioclase, spinel, sodalite and djerfisherite. Garnet grains are zoned, with a relatively homogeneous core and a more magnesian overgrowth rim. The rim zones further differ from the core in having higher Zr/Y (6 times that in the cores), ascribed to interaction with, or precipitation from, a kimberlite-related melt. Judging by pressure-temperature estimates (similar to 1200 degrees C; 6.2 GPa), the xenolith originated at depths of similar to 180-200 km at the base of the continental lithosphere. The spatial coexistence of olivine, orthopyroxene and coesite/quartz with K-Na-Cl minerals in the xenolith indicates that eclogite reacted with a deep-seated kimberlite melt. However, Fe-rich olivine, orthopyroxene and low-pressure minerals (sodalite and djerfisherite) likely result from metasomatic reaction at shallower depths during transport of the eclogite by the erupting kimberlite melt. Our results demonstrate that a mixed eclogitic-peridotitic paragenesis, reported previously from inclusions in diamond, can form by interaction of eclogite and a kimberlite-related melt.
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