TY - JOUR

T1 - Apatite fission track thermochronology of Khibina Massif (Kola Peninsula, Russia): Implications for post-Devonian Tectonics of the NE Fennoscandia

AU - Veselovskiy, R.V.

AU - Thomson, S.N.

AU - Arzamastsev, A.A.

AU - Zakharov, V.S.

PY - 2015

Y1 - 2015

N2 - The thermal history of the Kola Peninsula area of NE Fennoscandia remains almost fully unknown because of the absence of any thermochronological data such as apatite and/or zircon fission track or (UTh)/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. The RbSr isochron age of this alkaline magmatic complex which is located at the center of Kola Peninsula is 368 + 6 Ma (Kramm and Kogarko, 1994). Samples were analyzed from depths between + 520 and − 950 m and yielded AFT ages between 290 and 268 Ma with an age uncertainty (1σ) of between ± 19 Ma (7%) and ± 42 Ma (15%). Mean track lengths (MTL) lie between 12.5 and 14.4 μm. Inverse time–temperature modeling was conducted on the age and track length data from seven samples of the Khibina massif. Thermal histories that best predict the measured data from three samples with the most reliable 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.

AB - The thermal history of the Kola Peninsula area of NE Fennoscandia remains almost fully unknown because of the absence of any thermochronological data such as apatite and/or zircon fission track or (UTh)/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. The RbSr isochron age of this alkaline magmatic complex which is located at the center of Kola Peninsula is 368 + 6 Ma (Kramm and Kogarko, 1994). Samples were analyzed from depths between + 520 and − 950 m and yielded AFT ages between 290 and 268 Ma with an age uncertainty (1σ) of between ± 19 Ma (7%) and ± 42 Ma (15%). Mean track lengths (MTL) lie between 12.5 and 14.4 μm. Inverse time–temperature modeling was conducted on the age and track length data from seven samples of the Khibina massif. Thermal histories that best predict the measured data from three samples with the most reliable 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.

KW - Apatite fission track dating

KW - Fennoscandia

KW - Kola Devonian Alkaline Province

KW - Khibina massif

KW - Time–temperature modeling

KW - Thermochronology

U2 - 10.1016/j.tecto.2015.10.003

DO - 10.1016/j.tecto.2015.10.003

M3 - Article

VL - 665

SP - 157

EP - 163

JO - Tectonophysics

JF - Tectonophysics

SN - 0040-1951

ER -