Mineralogy and petrography of a kimberlite-picrite dike in the northwestern Urik-Iya Graben,the eastern Sayan region |
| |
| Authors: | Yu A Minaeva K N Egorov |
| |
| Institution: | (1) Department of Earth and Ocean Sciences, University of British Columbia, 6339 Stores Road, Vancouver, BC, Canada, V6T 1Z4;(2) Scott-Smith Petrology Inc, 2555 Edgemont Blvd., North Vancouver, BC, Canada, V7R 2 M9 |
| |
| Abstract: | Mica kimberlite and alkali picrite were identified in the northwestern Urik-Iya Graben of the eastern Sayan region. Typomorphism
of Cr-diopside and high-Cr (up to 55.22 wt % Cr2O3) spinel from kimberlite of the Bushkanai dike indicate that the melt was generated in the mantle, composed of spinel peridotite.
The high content of Cr-spinel (45–55 wt % Cr2O3) microlites in the groundmass of kimberlite and small amounts of ulvospinel and titanomagnetite in the absence of perovskite
testifies to the diamond potential of this kimberlite. Picroilmenite, manganoilmenite with an anomalously high MnO content
(11.37–17.78 wt %), and barium titanate with (wt %) 62.21 TiO2, 0.61 Cr2O3, 15.89 FeO, 4.05 MnO, 1.71 CaO, and 11.13 BaO close in composition to a new mineral species from the Murun pluton were identified
in the groundmass for the first time. Kimberlite from the Bushkanai dike belongs to the Zolotitsa low-Ti geochemical type
of kimberlites derived from the slightly enriched lithospheric mantle EM1. The distribution of trace elements, including REE,
in picrite from the same dike corresponds to the slightly depleted asthenospheric mantle. Different mantle sources of kimberlite
and picrite from the same dike indicate that these rocks are related to independent melts rather than to products of fractionation
of a common parental alkaline ultramafic magma. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
