TY - JOUR

T1 - The P-T path of metamorphism and age of migmatites from the northwestern Irkut block (Sharyzhalgai uplift of the Siberian Platform)

AU - Sukhorukov, V. P.

AU - Turkina, O. M.

PY - 2018/6/1

Y1 - 2018/6/1

N2 - We study migmatized aluminous gneisses in the northwest of the Irkut granulite complex in the southeastern Sharyzhalgai uplift of the Siberian Platform basement. Migmatized gneisses with the mineral assemblage Grt + Sil + Bt + Kfs + Pl + Qz (+ Crd + Opx + Spl) contain a leucosome and widespread cordierite-bearing (+ orthopyroxene, quartz, and spinel) symplectites developed after garnet and sillimanite. Study of the microstructural relationships of minerals and modeling using the PERPLEX 672 software have shown a retrograde P-T path of metamorphism for the metasedimentary gneisses, close to the isothermal decompression (ITD). The parameters of the peak of metamorphism are T = 850-870 °C and P > 7 kbar. The weighted average age of zircon from the metasedimentary gneisses (1856 ± 13 Ma, SHRIMP) corresponds to the time of metamorphism. The decompression type of retrograde metamorphism of the rocks in the northwest of the Irkut block indicates their formation in the crust extension and thinning setting. The presence of domal structures in the section of the Irkut block on the shore of Lake Baikal suggests that the dome tectogenesis was involved in the exhumation processes. The Paleoproterozoic metamorphism and granite formation were associated with the same stage of collision processes, when the compression setting was changed by an extension one (1.88-1.85 Ga).

AB - We study migmatized aluminous gneisses in the northwest of the Irkut granulite complex in the southeastern Sharyzhalgai uplift of the Siberian Platform basement. Migmatized gneisses with the mineral assemblage Grt + Sil + Bt + Kfs + Pl + Qz (+ Crd + Opx + Spl) contain a leucosome and widespread cordierite-bearing (+ orthopyroxene, quartz, and spinel) symplectites developed after garnet and sillimanite. Study of the microstructural relationships of minerals and modeling using the PERPLEX 672 software have shown a retrograde P-T path of metamorphism for the metasedimentary gneisses, close to the isothermal decompression (ITD). The parameters of the peak of metamorphism are T = 850-870 °C and P > 7 kbar. The weighted average age of zircon from the metasedimentary gneisses (1856 ± 13 Ma, SHRIMP) corresponds to the time of metamorphism. The decompression type of retrograde metamorphism of the rocks in the northwest of the Irkut block indicates their formation in the crust extension and thinning setting. The presence of domal structures in the section of the Irkut block on the shore of Lake Baikal suggests that the dome tectogenesis was involved in the exhumation processes. The Paleoproterozoic metamorphism and granite formation were associated with the same stage of collision processes, when the compression setting was changed by an extension one (1.88-1.85 Ga).

KW - ITD

KW - migmatites

KW - Paleoproterozoic

KW - PERPLEX

KW - PT path

KW - Sharyzhalgai uplift

KW - Siberian Platform basement

KW - symplectites

KW - UPb zircon age

KW - SOUTH HARRIS

KW - BUSHVELD COMPLEX

KW - HIGH-TEMPERATURE

KW - ORTHO-PYROXENE

KW - UPLIFT

KW - CHARNOCKITE-GRANITE COMPLEX

KW - LAKE BAIKAL

KW - METATERRIGENOUS ROCKS

KW - MT STAFFORD

KW - GRANULITE-GNEISS BLOCK

UR - http://www.scopus.com/inward/record.url?scp=85048066371&partnerID=8YFLogxK

U2 - 10.1016/j.rgg.2018.05.006

DO - 10.1016/j.rgg.2018.05.006

M3 - Article

AN - SCOPUS:85048066371

VL - 59

SP - 673

EP - 689

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 6

ER -