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New carbonatite complex in the western Baikal area, southern Siberian craton: Mineralogy, age, geochemistry, and petrogenesis

Citation

Savelyeva, VB and Demonterova, EI and Danilova, YV and Bazarova, EP and Ivanov, AV and Kamenetsky, VS, New carbonatite complex in the western Baikal area, southern Siberian craton: Mineralogy, age, geochemistry, and petrogenesis, Petrology, 24, (3) pp. 271-302. ISSN 0869-5911 (2016) [Refereed Article]

Copyright Statement

Copyright 2016 Pleiades Publishing Ltd.

DOI: doi:10.1134/S0869591116030061

Abstract

A dike–vein complex of potassic type of alkalinity recently discovered in the Baikal ledge, western Baikal area, southern Siberian craton, includes calcite and dolomite–ankerite carbonatites, silicate-bearing carbonatite, phlogopite metapicrite, and phoscorite. The most reliable 40Ar–39Ar dating of the rocks on magnesioriebeckite from alkaline metasomatite at contact with carbonatite yields a statistically significant plateau age of 1017.4 ± 3.2 Ma. The carbonatite is characterized by elevated SiO2 concentrations and is rich in K2O (K2O/Na2O ratio is 21 on average for the calcite carbonatite and 2.5 for the dolomite–ankerite carbonatite), TiO2, P2O5 (up to 9 wt %), REE (up to 3300 ppm), Nb (up to 400 ppm), Zr (up to 800 ppm), Fe, Cr, V, Ni, and Co at relatively low Sr concentrations. Both the metapicrite and the carbonatite are hundreds of times or even more enriched in Ta, Nb, K, and LREE relative to the mantle and are tens of times richer in Rb, Ba, Zr, Hf, and Ti. The high (Gd/Yb)CN ratios of the metapicrite (4.5–11) and carbonatite (4.5–17) testify that their source contained residual garnet, and the high K2O/Na2O ratios of the metapicrite (9–15) and carbonatite suggest that the source also contained phlogopite. The Nd isotopic ratios of the carbonatite suggest that the mantle source of the carbonatite was mildly depleted and similar to an average OIB source. The carbonatites of various mineral composition are believed to be formed via the crystallization differentiation of ferrocarbonatite melt, which segregated from ultramafic alkaline melt.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Igneous and Metamorphic Petrology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Kamenetsky, VS (Professor Vadim Kamenetsky)
ID Code:109862
Year Published:2016
Funding Support:Australian Research Council (DP130100257)
Web of Science® Times Cited:1
Deposited By:Earth Sciences
Deposited On:2016-07-05
Last Modified:2017-10-30
Downloads:0

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