TY - JOUR

T1 - The role of magmatic heat sources in the formation of regional and contact metamorphic areas in West Sangilen (Tuva, Russia)

AU - Polyansky, O. P.

AU - Kargopolov, S. A.

AU - Izokh, A. E.

AU - Semenov, A. N.

AU - Babichev, A. V.

AU - Vasilevsky, A. N.

PY - 2019/2

Y1 - 2019/2

N2 - The tectonomagmatic evolution of the Sangilen massif has been described in detail in numerous publications, but little attention was given to heat sources related to the HT/LP metamorphism. Modeling of the magma transport to the upper-crust levels in West Sangilen shows that the NT/LP metamorphism is related to gabbromonodiorite intrusions. This article is focused on the thermo-mechanical modeling of melting and lifting of melts in the crust, taking into account the density interfaces. The model of the Erzin granitoid massif shows that in case of fractional melting, the magma ascent mechanism is fundamentally different, as opposed to diapir upwelling – percolation take place along a magmatic channel or a system of channels. An estimated rate of diapiric rise in the crust amounts to 0.8 cm/yr, which is more than an order of magnitude lower than the rate of melt migration in case of fractional melting (25 cm/yr). In our models, a metamorphic thermal ‘anticline’ develops in stages that differ, probably, due to the modes of crust melting: batch melting occurs at the first stage, and fractional melting takes place at the second stage. It is probable that the change of melting modes from melting conditions in a ‘closed’ system to fractional melting conditions in ‘open’ systems is determined by tectonic factors. For the Sangilen massif, we have estimated the degrees of melting in the granulite, granite, and sedimentary-metamorphic layers of the crust (6, 15, and 5 vol. %, respectively).

AB - The tectonomagmatic evolution of the Sangilen massif has been described in detail in numerous publications, but little attention was given to heat sources related to the HT/LP metamorphism. Modeling of the magma transport to the upper-crust levels in West Sangilen shows that the NT/LP metamorphism is related to gabbromonodiorite intrusions. This article is focused on the thermo-mechanical modeling of melting and lifting of melts in the crust, taking into account the density interfaces. The model of the Erzin granitoid massif shows that in case of fractional melting, the magma ascent mechanism is fundamentally different, as opposed to diapir upwelling – percolation take place along a magmatic channel or a system of channels. An estimated rate of diapiric rise in the crust amounts to 0.8 cm/yr, which is more than an order of magnitude lower than the rate of melt migration in case of fractional melting (25 cm/yr). In our models, a metamorphic thermal ‘anticline’ develops in stages that differ, probably, due to the modes of crust melting: batch melting occurs at the first stage, and fractional melting takes place at the second stage. It is probable that the change of melting modes from melting conditions in a ‘closed’ system to fractional melting conditions in ‘open’ systems is determined by tectonic factors. For the Sangilen massif, we have estimated the degrees of melting in the granulite, granite, and sedimentary-metamorphic layers of the crust (6, 15, and 5 vol. %, respectively).

KW - Contact metamorphism

KW - Crust

KW - Heat transfer

KW - Magmatic chamber

KW - Melt

KW - Melting

KW - Modeling

KW - Sangilen

KW - Zoning

KW - modeling

KW - MELT

KW - MINGLING DYKES

KW - GEODYNAMICS

KW - contact metamorphism

KW - SIBERIA

KW - melting

KW - MANTLE

KW - melt

KW - zoning

KW - LITHOSPHERE

KW - DIAPIRISM

KW - COMPLEX

KW - EARTHS CRUST

KW - crust

KW - SOUTH-EAST TUVA

KW - magmatic chamber

KW - heat transfer

UR - http://www.scopus.com/inward/record.url?scp=85076601927&partnerID=8YFLogxK

U2 - 10.5800/GT-2019-10-2-0416

DO - 10.5800/GT-2019-10-2-0416

M3 - Article

AN - SCOPUS:85076601927

VL - 10

SP - 309

EP - 323

JO - Geodynamics and Tectonophysics

JF - Geodynamics and Tectonophysics

SN - 2078-502X

IS - 2

ER -