TY - JOUR

T1 - Pyroxenite as a Product of Mafic-Carbonate Melt Interaction (Tazheran Massif, West Baikal Area, Russia)

AU - Sklyarov, Eugene V.

AU - Lavrenchuk, Andrey V.

AU - Doroshkevich, Anna G.

AU - Starikova, Anastasia E.

AU - Kanakin, Sergei V.

N1 - Funding Information: The study was carried out on government assignments to Institute of the Earth?s Crust (Irkutsk) and Institute of Geology and Mineralogy (Novosibirsk). Geological and geochemical investigations were supported by the Russian Foundation for Basic Research (Project 20-05-00005). Mineral chemistry was analyzed under the support of the government of the Russian Federation (Project 075-15-2019-1883). Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021/6

Y1 - 2021/6

N2 - Pyroxenite and nepheline-pyroxene rocks coexist with dolomite-bearing calcite marbles in Tazheran Massif in the area of Lake Baikal, Siberia, Russia. Pyroxenites occur in a continuous elongate zone between marbles and beerbachites (metamorphosed gabbro dolerites) and in 5 cm to 20 m fragments among the marbles. Pyroxene in pyroxenite is rich in calcium and alumina (5–12 wt% Al2O3) and has a fassaite composition. The Tazheran pyroxenite may originate from a mafic subvolcanic source indicated by the presence of remnant dolerite found in one pyroxenite body. This origin can be explained in terms of interaction between mafic and crust-derived carbonatitic melts, judging by the mineralogy of pyroxenite bodies and their geological relations with marbles. According to this model, the intrusion of mantle mafic melts into thick lower crust saturated with fluids caused partial melting of silicate-carbonate material and produced carbonate and carbonate-silicate melts. The fassaite-bearing pyroxenite crystallized from a silicate-carbonate melt mixture which was produced by roughly synchronous injections of mafic, pyroxenitic, and carbonate melt batches. The ascending hydrous carbonate melts entrained fragments of pyroxenite that crystallized previously at a temperature exceeding the crystallization point of carbonates. Subsequently, while the whole magmatic system was cooling down, pyroxenite became metasomatized by circulating fluids, which led to the formation of assemblages with garnet, melilite, and scapolite.

AB - Pyroxenite and nepheline-pyroxene rocks coexist with dolomite-bearing calcite marbles in Tazheran Massif in the area of Lake Baikal, Siberia, Russia. Pyroxenites occur in a continuous elongate zone between marbles and beerbachites (metamorphosed gabbro dolerites) and in 5 cm to 20 m fragments among the marbles. Pyroxene in pyroxenite is rich in calcium and alumina (5–12 wt% Al2O3) and has a fassaite composition. The Tazheran pyroxenite may originate from a mafic subvolcanic source indicated by the presence of remnant dolerite found in one pyroxenite body. This origin can be explained in terms of interaction between mafic and crust-derived carbonatitic melts, judging by the mineralogy of pyroxenite bodies and their geological relations with marbles. According to this model, the intrusion of mantle mafic melts into thick lower crust saturated with fluids caused partial melting of silicate-carbonate material and produced carbonate and carbonate-silicate melts. The fassaite-bearing pyroxenite crystallized from a silicate-carbonate melt mixture which was produced by roughly synchronous injections of mafic, pyroxenitic, and carbonate melt batches. The ascending hydrous carbonate melts entrained fragments of pyroxenite that crystallized previously at a temperature exceeding the crystallization point of carbonates. Subsequently, while the whole magmatic system was cooling down, pyroxenite became metasomatized by circulating fluids, which led to the formation of assemblages with garnet, melilite, and scapolite.

KW - Carbonate melt

KW - Early Paleozoic orogeny

KW - Fluids

KW - Gabbro dolerite

KW - Mafic melt

KW - Marble

KW - Metasomatism

KW - Pyroxenite

KW - Silicate-carbonate melt interaction

KW - Tazheran Massif

UR - http://www.scopus.com/inward/record.url?scp=85108160981&partnerID=8YFLogxK

U2 - 10.3390/min11060654

DO - 10.3390/min11060654

M3 - Article

AN - SCOPUS:85108160981

VL - 11

JO - Minerals

JF - Minerals

SN - 2075-163X

IS - 6

M1 - 654

ER -