Research Article New age data from the Lesnaya Group: A key to understanding the timing of arc-continent collision, Kamchatka, Russia
Abstract The Lesnaya Group is part of a thick, poorly dated turbidite assemblage that sits in the footwall of a regionally extensive collision zone in which the Cretaceous–Pale-ocene Olutorsky island arc terrane was obducted onto continental margin basin strata. Nannoplankton from 18 samples from th...
| Main Authors: | , , , , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.618.4540 http://ftlab.ginras.ru/PDF/Soloviev_elal2002.pdf |
| Summary: | Abstract The Lesnaya Group is part of a thick, poorly dated turbidite assemblage that sits in the footwall of a regionally extensive collision zone in which the Cretaceous–Pale-ocene Olutorsky island arc terrane was obducted onto continental margin basin strata. Nannoplankton from 18 samples from the upper part of the Lesnaya Group yield Pale-ocene through Middle Eocene assemblages. Detrital zircons from nine sandstone samples have a young population of fission-track ages that range from 43.7 ± 3.4 to 55.5 ± 3.5 Ma (uppermost Paleocene to Middle Eocene). The deformed footwall rocks of the Lesnaya Group and the overlying thrusts of the Olutorsky arc terrane, are unconformably overlain by neoautochthonous deposits which are Lutetian (lower Middle Eocene) and younger. Together, these new data indicate that thrusting, which is inferred to have been driven by collision of the Cretaceous–Paleocene island arc with north-eastern Asia, took place in the mid-Lutetian, at about 45 Ma. Key words: collision, Eocene, fission-track dating, Kamchatka, nannoplankton, zircon. number of names that have appeared in published reports, but most common are the Olutorsky Arc |
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