Eocene Granitoids of the Okhotsk Granodiorite Complex (South Sakhalin)

As a result of U–Pb dating by LA-ICP-MS, the age of zircons from granitoids was determined to be 42.1–44.3 Ma for the rocks of first phase and 42.4–42.7 Ma for rhyolites from dikes of the second phase. On the basis of the geochemical studies of rocks, it was found for the first time that granodiorit...

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Bibliographic Details
Published in:Doklady earth sciences 2018-12, Vol.483 (2), p.1499-1503
Main Authors: Alexandrov, I. A., Liao, J.-P., Jahn, B.-M., Golozoubov, V. V., Ivin, V. V., Stepnova, Yu. A.
Format: Article
Language:English
Subjects:
Deceleration
Dikes
Earth and Environmental Science
Earth Sciences
Embankments
Eocene
Geochemistry
Geology
Magma
Petrogenesis
Plates (tectonics)
Rhyolites
Rock
Rocks
Subduction
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Summary:As a result of U–Pb dating by LA-ICP-MS, the age of zircons from granitoids was determined to be 42.1–44.3 Ma for the rocks of first phase and 42.4–42.7 Ma for rhyolites from dikes of the second phase. On the basis of the geochemical studies of rocks, it was found for the first time that granodiorites of the Okhotsk massif (first phase) refer to A2-type granitoids. The most likely explanation of petrogenesis for A2-type granitoids of the Okhotsk complex is the gradual cessation of subduction as a result of deceleration of the Pacific Plate and the transition of the Ozerskii terrane to transform northward motion along the Merei suture zone with a certain role of syn-shear extension. Thus, the data obtained on the age and geochemistry of the Okhotsk complex granitoids suggest the possible time of geodynamic regime change in this area as about 43 Ma ago.
ISSN:1028-334X
1531-8354
DOI:10.1134/S1028334X18120103