Quartz porphyries of the outer islands of the gulf of Finland ‒ volcanic comagmates of the Rapakivi granites

Terekhov, E.N.; Makeyev, A.B.; Skublov, S.G.; Okina, O.I.; Maximova, Y.A.

Авторы: Terekhov E.N., Makeyev A.B., Skublov S.G., Okina O.I., Maximova Yu A.
Журнал: Journal of Volcanology and Seismology
Номер: 6
Год издания: 2023
Издательство: Springer Verlag
Местоположение издательства: Germany
Первая страница: 530
Последняя страница: 549
Оригинальные версии: Кварцевые порфиры внешних островов Финского залива – комагматы гранитов рапакиви: петрогеохимия, структурное положение и генезис
DOI: 10.1134/S0742046323700318
Аннотация: This paper presents new petrogeochemical data concerning rocks sampled on the Outer Islands inthe Gulf of Finland. Earlier, quartz porphyries on Hogland Island were regarded as the standard for volcaniccomagmates of rapakivi granites in the Wyborg massif. Sommers Island was found to contain two effusiverock sequences. The “southern” sequence is composed of quartz porphyries whose isotopic age is 1.66 Ga,so they can be regarded as the earliest manifestations of Riphean magmatic activity in the area. The “northern”rock sequence contains, apart from quartz porphyries, also trachybasalts, basaltic andesites, and dacites;the sequence has an isotopic age is 1.59‒1.57 Ga, which is inconsistent with the figures for the adjacentWyborg massif (1.65‒1.63 Ga). For this reason, in spite of the fact that quartz porphyries and rapakivi graniteshave similar compositions, the volcanics did not result from differentiation of the magma that has producedthe granites, but were formed independently of these from a source of the same type which howeverwas in a slightly different structural setting that allowed their free supply onto the ground surface.
Добавил в систему: Макеев Александр Борисович

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Quartz porphyries of the outer islands of the gulf of Finland ‒ volcanic comagmates of the Rapakivi granitesстатья

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