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Abstract

The Dovyren Intrusive Complex (DIC, Northern Baikal region, 728 Ma) includes the layered dunite-troctolite-gabbronorite Yoko-Dovyren massif (YDM), associated mafic-ultramafic sills, and dykes of olivine-rich to olivine-free gabbronorite. Major rock types of the DIC are presented, including a diversity of olivine orthocumulates to olivine-plagioclase and gabbroic adcumulates, carbonate-contaminated ultramafics and Cu-Ni-PGE mineralisation. Detailed comparisons of complete cross-sections of the YDM in its centre and at the NE and SW margins demonstrate differences in the cumulate succession, mineral chemistry, and geochemical structure that likely reflect variations in parental magma compositions. Combining petrochemical reconstructions for most primitive rocks and calculations using the COMAGMAT-5 model, it is shown that the central and peripheral parts of the intrusion formed by olivine-laden parental magmas ranged in their temperatures by 100 °C, approximately from 1290 °C (∼11 wt% MgO, olivine Fo88) to 1190 °C (∼8 wt% MgO, olivine Fo86). Thermodynamic modelling suggests that the most primitive high-Mg magma was S-undersaturated, whereas its derivatives became S-saturated at T 2, K2O, P2O5, and incompatible trace elements, which are 3-5 fold depleted in the cumulate rocks from the inner horizons of the intrusion with respect to the relatively thin lower and upper contact zones. In addition, a marked misbalance between estimates of the average composition of the YDM and that of the proposed olivine-laden parental magmas is established. This misbalance reflects a significant deficit of the YDM in incompatible elements, which argues that 60-70% of basaltic melts had to have been expelled from the Dovyren magma chamber during its consolidation. A possible scenario of the evolution of the open magma chamber is proposed.

Item Type:	Article
Authors/Creators:	Ariskin, A and Danyushevsky, L and Nikolaev, G and Kislov, E and Fiorentini, M and McNeill, A and Kostitsyn, Y and Goemann, K and Feig, ST and Malyshev, A
Keywords:	Yoko-Dovyren, layered intrusion, Cu-Ni-PGE mineralisation, COMAGMAT-5, parental magma, sulphide immiscibility, open magma chamber, anomalous mantle source, thermodynamic modelling
Journal or Publication Title:	Lithos
Publisher:	Elsevier Science Bv
ISSN:	0024-4937
DOI / ID Number:	10.1016/j.lithos.2018.01.001
Copyright Information:	Copyright 2018 Elsevier B.V.
Related URLs:	Google Scholar: Danyushevsky, L UTAS Profile: Danyushevsky, L UTAS Profile: Feig, ST
Item Statistics:	View statistics for this item

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