Open AccessTHE FIRST EVIDENCE OF LATE DEVONIAN GRANITOID MAGMATISM IN THE NORTHEASTERN FLANK OF THE SOUTH MONGOLIA–KHINGAN OROGENIC BELT
Author(s) -
Y.V. Smirnov,
A.A. Sorokin,
N.M. Kudryashov
Publication year - 2021
Publication title -
tihookeanskaâ geologiâ
Language(s) - English
Resource type - Journals
ISSN - 0207-4028
DOI - 10.30911/0207-4028-2021-40-1-65-76
Subject(s) - massif , geology , geochemistry , biotite , devonian , terrane , magmatism , partial melting , paleontology , tectonics , mantle (geology) , quartz
The results of geochemical, U-Pb geochronological, Sm-Nd isotopic-geochemical studies of granites of the Medvedka Massif in the northern part of the Nora–Sukhotino terrane are presented. It has been found that these granites are of 378 ± 3 Ma in age. It was shown that these granites are characterized by the presence of ferruginous silicates, high iron index (FeO*/(FeO*+MgO)), low concentrations of Al2O3, CaO, MgO, high contents of Nb, Ga, Y, deficiency of Sr, Eu, positive values of εNd(t) (+3.0...+4.1), and high values of the ratio Y/Nb. In total, this indicates that the granites of the Medvedka massif are related to A2-type granites. The Late Devonian hastingsite-biotite granites of the Medvedka Massif most likely reflect evidence of the transform continental margin setting in the history of the formation of the South Mongolian – Khingan orogenic belt.