GEOCHEMICAL EVOLUTION OF LATE EOCENE-OLIGOCENE MAGMATISM IN THE SCHMIDT PENINSULA ( Northern Sakhalin )
S.V. Rasskazov a , V.P. Simanenko b , A.I. Malinovskyb, T.A. Yasnygina a
a Institute of the Earth's Crust, Siberian Branch of the RAS, 128 ul. Lermontova, Irkutsk, 664033, Russia
b Far East Geological Institute, Far East Branch of the RAS, 159 prosp. Stoletiya Vladivostoka, Vladivostok, 690022, Russia
Keywords: Cenozoic; essexites; trachyandesites; andesites; latites; trace elements; Sakhalin
Pages: 247-256
Abstract
The Middle Cenozoic evolution of magmatism in the Schmidt Peninsula between 37 and 25 Ma began with eruptions of subalkaline and moderately alkaline andesite, latite, trachyandesite, and trachyrhyolite lavas and ended with subvolcanic intrusions of highly alkaline strongly undersaturated essexites. According to trace-element data, magmatism evolved from melting of a mantle source in the zone of ocean-continent plate convergence to small-degree partial melting in lithospheric mantle at the final stage. This succession is generally typical of Late Cenozoic continental-margin magmatism in southeastern Russia. The similarity in the Middle and Late Cenozoic stages of magmatism is evidence for their individual significance.
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