Mineralogical-geochemical peculiarities in composition of initial melt and parameters of crystallization of gabbroids in Dzhidinsky massif (south-eastern margin of the North-Asiatic craton)

Rodionov A. A., Buchko I. V.

Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2019. V. 148. N 2. P. 12-27

https://doi.org/10.30695/zrmo/2019.1482.01

Full text is available on Journals.eco-vector.com

Language: Russian

Abstract

Dzhigda gabbroid massif is a typical representative of the Permo-Triassic ultramafic-mafic intrusions in the south-eastern framing of the Siberian Сraton. The article presents results of calculations of the composition and crystallization parameters of the melt that produced the gabbroids. It is has shown that crystallization of the melt occurred at the pressure of 4—6 kbar and initial temperature of 1125—1160 °С. Fractionation of the melt led to the formation of gabbro and gabbrodiorites, on the one hand, and to the formation of gabbro and gabbro-diorites enriched with sodium, on the other hand. Analysis of available data shows that the compositions of the initial melt and crystallization parameters for Permo-Triassic ultramafic-mafic intrusions in the south-eastern framing of the Siberian Craton are significantly differ. Perhaps this is a characteristic of this stage of magmatism. In addition, rocks from these intrusions have obvious features of geochemical duality, which is a combination of signature as intraplate and suprasubduction origin.

Key words: ultramafic-mafic intrusions, modeling, initial melt, gabbro, Dzhigda intrusion