TY - JOUR

T1 - Early Proterozoic Polymigmatites in a Zone of Granulite Metamorphism: P–T–X Conditions, Age, and Duration of Migmatization (Northern Ladoga Area, Russia)

AU - Baltybaev, S.K.

AU - Yurchenko, A.V.

AU - Rizvanova, N.G.

AU - Vivdich, E.S.

AU - Galankina, O.L.

AU - Borisova, E.B.

N1 - Export Date: 21 October 2024 Адрес для корреспонденции: Baltybaev, S.K.; Institute of Precambrian Geology and Geochronology, nab. Makarova 2, Russian Federation; эл. почта: shauket@mail.ru Сведения о финансировании: Siberian Branch, Russian Academy of Sciences, SB RAS Сведения о финансировании: Russian Science Foundation, RSF, 23-27-00106 Текст о финансировании 1: The manuscript profited from thoughtful constructive criticism by I.I. Likhanov (IGM SB RAS, Novosibirsk) and an anonymous reviewer. The studies were supported by the Russian Science Foundation (grant No. 23-27-00106).

PY - 2024/7/1

Y1 - 2024/7/1

N2 - Polymigmatites in the Early Proterozoic metamorphic complex of the Northern Ladoga area trace the evolution of thermodynamic conditions during anatexis. The P–T conditions inferred for anatectic leucosome correspond to the onset of partial melting under granulite facies conditions of 5.5–6.2 kbar and 720–810 °C. After the peak of metamorphism, pressure and temperature show a coupled decrease to 4 kbar and ~550 °C, respectively. The latest granitic veins were intruded into metamorphic rocks during an event of brittle deformation. The P–T trend correlates with changes in migmatitic mineral assemblages and in chemistry of minerals. Newly formed leucocratic material changed from plagiogranitic to granitic composition when melting involved plagiogneiss but melt derived from Al-rich metapelite remained granitic. The analyzed leucosomes and granitic veins originated by multistage melting, under P–T conditions changing from granulite to amphibolite facies, between 1875 and 1865 Ma. Judging by their ages, the leucosome and granitic vein bodies from the Lakhdenpokhia and Priozersky zones of the area differed in the total duration of crystallization. Therefore, a single thermal event involving different lithologies can produce intrusions of different ages. © 2024, Novosibirsk State University.

AB - Polymigmatites in the Early Proterozoic metamorphic complex of the Northern Ladoga area trace the evolution of thermodynamic conditions during anatexis. The P–T conditions inferred for anatectic leucosome correspond to the onset of partial melting under granulite facies conditions of 5.5–6.2 kbar and 720–810 °C. After the peak of metamorphism, pressure and temperature show a coupled decrease to 4 kbar and ~550 °C, respectively. The latest granitic veins were intruded into metamorphic rocks during an event of brittle deformation. The P–T trend correlates with changes in migmatitic mineral assemblages and in chemistry of minerals. Newly formed leucocratic material changed from plagiogranitic to granitic composition when melting involved plagiogneiss but melt derived from Al-rich metapelite remained granitic. The analyzed leucosomes and granitic veins originated by multistage melting, under P–T conditions changing from granulite to amphibolite facies, between 1875 and 1865 Ma. Judging by their ages, the leucosome and granitic vein bodies from the Lakhdenpokhia and Priozersky zones of the area differed in the total duration of crystallization. Therefore, a single thermal event involving different lithologies can produce intrusions of different ages. © 2024, Novosibirsk State University.

KW - duration of migmatization

KW - leucosome

KW - migmatites

KW - Northern Ladoga

KW - svecofennides

KW - U–Pb dating

KW - amphibolite facies

KW - granulite facies

KW - migmatization

KW - P-T conditions

KW - partial melting

KW - Proterozoic

KW - Svecofennian orogeny

KW - uranium-lead dating

KW - Russian Federation

UR - https://www.mendeley.com/catalogue/419f0c27-22ae-303d-a818-0bd23245d920/

U2 - 10.2113/rgg20234600

DO - 10.2113/rgg20234600

M3 - статья

VL - 65

SP - 795

EP - 813

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 7

ER -