Kravchenko G.L.¹, Rusakov N.F.²
1 –M.P. Semenenko Institute of Geochemistry, Mineralogy and Ore Formation of the National Academy of Sciences of Ukraine
2 –DONBASGEOLOGIYA, Ukraine
Language: Russian
Geochemistry and ore formation 2016, 37: 22-42
https://doi.org/10.15407/gof.2016.37.022
For the first time Kamyshevatsky metaultrabasite massif on the NW extension of the Sorokinska tectonic zone (STS) is revealed and mapped. Rocks of this massif are presented by apodunite and apoperidotite serpentinites, peridotites, olivine-bearing and olivine-free pyroxenites and their metamorphosed varieties, i.e. hornblendites, aktinolitites, tremolitites and phlogopite (chlorite) -tremolite-anthophyllite rocks. The primary composition of the massif corresponds to dunites, harzburgites, lherzolites and olivine pyroxenites.The massif is slightly differentiated and in the peripheral parts consist of olivine pyroxenites, and in the center of serpentinites and peridotites. Absence of distinctly displayed contact alternations in ultrabasites can evidence on injection of porridge-like magma as a protrusion or on intensive display of regional metamorphism and granitization which fully shaded these alterations. Petrographic, petrochemical and geochemical features of rocks, their rock-forming and ore minerals are described in detail. The presence of TiO2, Al2O3, CaO and alkalis, increased total iron content and low ratio of M/F and Cr/Al indicate on belonging of the studied rocks to ultraferrobasites (gabbro-peridotite association). It is suggested that these rocks are predominantly metamorphosed at the expanse of serpentine dehydration during the granitoid intrusions. The data on internal structure of the massif, its relationship with STS and some similarities and differences concerning metaultrabasite with metakomatiites that have been recently identified in the southern part of STS are presented.The similarity between these rocks consists in availability porphyraceous texture with large crystals of olivine in them, as well as practically the same chemical composition of serpentinites and komatiites with the spinifextextures in metaultrabasiteKamyshevatsky massifwere not found. As the rocks of this region have been transformed by multiple dynamic and thermal influences, the primary structure in these rocks could hardly been preserved. It is probable that the metaultrabasiteand metakomatiiteshave a secondary (metamorphogeneuos) origin at which they could have crystallized in the processes of serpentine dehydration. The latter may have a place at high contact thermal influence of granitoids or at the regional metamorphism of the moderate and low degrees. It is established that metaultrabasites of Kamyshevatsky massif are genetically closely related to those ones in STS this massif represent direct NW-continuation of layering intrusions which are spread in edge parts of STS.
Keywords: massif, metaultrabasite, mineral, rock, intrusion.
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