Paleomagnetic and Geochronological Studies of the Kola Devonian Alkaline Province (Kola Peninsula, Russia) and Their Geological Implication

Abstract:

This study represents the conclusions of a five-year paleomagnetic study of the Kola Alkaline Province. Most of our work has been concentrated on Devonian magmatic rocks – dykes and intrusive massifs – but at least two dozen Precambrian dykes and, occasionally, host rocks were also sampled. Our paleomagnetic results are based on more than 2000 samples from 130 dolerite and alkaline dykes of Devonian and Precambrian age. Rock magnetic studies were made on tens samples. We also present new geochronological (Ar/Ar) and microprobe data from the Devonian dykes. Moreover, we present new apatite fission track ages, obtained on eleven drill cores from different depths of the Khibina alkaline massif and compare them with our own thermal numerical model in order to estimate the rate and age of the post-magmatic exhumation process. All obtained results will be made available through an open access GIS project from the end of December, 2014 on the site http://paleomag-ifz.ru/en. Analysis of the obtained multidisciplinary data does not fully support the hypothesis of regional Fennoscandia remagnetization event in the Late Jurassic, discussed earlier in (Veselovskiy et al., 2013), and instead leads us to propose the existence of an interval of abnormal behavior of the main geomagnetic field in Devonian time.

This study was funded by grants RFBR # 12-05-00216, 13-05-12021, 13-05-12030 and the project of the Ministry of Education and Science of the Russian Federation (grant no. 14.Z50.31.0017).