Apatite Fission Track Thermochronology of Khibina Massif (Kola Peninsula, Russia): Implications for post-Devonian Tectonics of the NE Fennoscandia

Veselovskiy, R.V.; Thomson, S.N.; Arzamastsev, A.A.; Zakharov, V.S.

Авторы: Veselovskiy Roman V., Thomson Stuart N., Arzamastsev Andrey A., Zakharov Vladimir S.
Журнал: Tectonophysics
Том: 665
Год издания: 2015
Издательство: Elsevier BV
Местоположение издательства: Netherlands
Первая страница: 157
Последняя страница: 163
DOI: 10.1016/j.tecto.2015.10.003
Аннотация: The thermal history of the Kola Peninsula area of NE Fennoscandia remains almost fully unknown because of absence of any thermochronological data such as apatite and/or zircon fission track or (U-Th)/He ages. In order to fill this gap and to constrain the post-Devonian erosion and exhumation history of this region, we present the results of apatite fission track (AFT) dating of eleven samples selected from the cores taken from different depths of the northern part of the Khibina intrusive massif. This alkaline magmatic complex is located at the center of Kola Peninsula and formed at about 370 Ma (Kramm and Kogarko, 1994). Samples were analyzed from depths between +520 to -950 meters and yielded AFT ages between 290-268 Ma with an average age uncertainty (1σ) of ±30 Ma. Mean track lengths (MTL) lie between 12.5-14.4 μm. We used the most reliable AFT ages and distribution of MTL in two samples, corresponding to depths of +280 and -920 m, to conduct inverse time-temperature modelling of the Khibina massif. Thermal histories that best predict the measured data show three stages: (1) 290-250 Ma – rapid cooling from >110°C to 70°C/50°C for lower/upper sample correspondingly; (2) 250-50 Ma – a stable temperature stage; (3) 50-0 Ma – slightly increased cooling rates down to modern temperatures. We propose that the first cooling stage is related to late-Hercynian orogenesis; the second cooling stage may be associated with tectonics accompanying with opening of Arctic oceanic basin. The obtained data show that geothermal gradient at the center of Kola Peninsula has remained close to the modern value of 20°C/km for at least the last 250 Myr. AFT data show that the Khibina massif has been exhumed not more then 5-6 km in the last 290 Myr.
Добавил в систему: Веселовский Роман Витальевич

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Apatite Fission Track Thermochronology of Khibina Massif (Kola Peninsula, Russia): Implications for post-Devonian Tectonics of the NE Fennoscandiaстатья

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