TY - JOUR

T1 - Compositional variations of spinels from ultramafic lamprophyres of the chadobets complex (Siberian craton, Russia)

AU - Nugumanova, Yazgul

AU - Doroshkevich, Anna

AU - Prokopyev, Ilya

AU - Starikova, Anastasiya

N1 - Funding Information: Funding: The investigations were supported by the Russian Science Foundation (RSF), project #19‐ 77‐10004. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.

PY - 2021

Y1 - 2021

N2 - Ultramafic lamprophyres (UMLs) are mantle rocks that provide important information about the composition of specific carbonate–silicate alkaline melts in the mantle as well as the processes contributing to their origin. Minerals of the spinel group typically occur in UMLs and have a unique “genetic memory.” Investigations of the spinel minerals from the UMLs of the Chadobets complex show the physicochemical and thermodynamic features of the alkaline rocks’ crystalliza-tion. The spinels of these UMLs have four stages of crystallization. The first spinel xenocrysts were found only in damtjernite pipes, formed from mantle peridotite, and were captured during the ris-ing of the primary melt to the surface. The next stages of the spinel composition evolution are related to the high‐chromium spinel crystallization, which changed to a high‐alumina composition. The composition then changed to magnesian ulvöspinel–magnetites with strong decreases in the Al and Cr amounts caused by the release of carbon dioxide, rapid temperature changes, and crystallization of the main primary groundmass minerals such as phlogopite and carbonates. Melt inclusion analyses showed the predominance of aluminosilicate (phlogopite, clinopyroxene, and/or albite) and carbonate (calcite and dolomite) daughter phases in the inclusions that are consistent with the chemical evolution of the Cr‐spinel trend. The further evolution of the spinels from magnesian ulvöspinel–magnetite to Ti‐magnetite is accompanied by the formation of atoll structures caused by resorption of the spinel minerals.

AB - Ultramafic lamprophyres (UMLs) are mantle rocks that provide important information about the composition of specific carbonate–silicate alkaline melts in the mantle as well as the processes contributing to their origin. Minerals of the spinel group typically occur in UMLs and have a unique “genetic memory.” Investigations of the spinel minerals from the UMLs of the Chadobets complex show the physicochemical and thermodynamic features of the alkaline rocks’ crystalliza-tion. The spinels of these UMLs have four stages of crystallization. The first spinel xenocrysts were found only in damtjernite pipes, formed from mantle peridotite, and were captured during the ris-ing of the primary melt to the surface. The next stages of the spinel composition evolution are related to the high‐chromium spinel crystallization, which changed to a high‐alumina composition. The composition then changed to magnesian ulvöspinel–magnetites with strong decreases in the Al and Cr amounts caused by the release of carbon dioxide, rapid temperature changes, and crystallization of the main primary groundmass minerals such as phlogopite and carbonates. Melt inclusion analyses showed the predominance of aluminosilicate (phlogopite, clinopyroxene, and/or albite) and carbonate (calcite and dolomite) daughter phases in the inclusions that are consistent with the chemical evolution of the Cr‐spinel trend. The further evolution of the spinels from magnesian ulvöspinel–magnetite to Ti‐magnetite is accompanied by the formation of atoll structures caused by resorption of the spinel minerals.

KW - Aillikite

KW - Atoll spinel

KW - Chadobets upland

KW - Damtjernite

KW - Minerals of the spinel group

KW - Siberian Craton

KW - Ultramafic lamprophyre

KW - Zoning

UR - http://www.scopus.com/inward/record.url?scp=85104605144&partnerID=8YFLogxK

U2 - 10.3390/min11050456

DO - 10.3390/min11050456

M3 - Article

AN - SCOPUS:85104605144

VL - 11

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 5

M1 - 456

ER -