Ancient coastlines of Eastern Kildin

Abstract

Relict Lake Mogilnoe, which is a unique object on the Murmansk coast, is located in the southeastern part of Kildin Island. Despite a history of almost a century and a half of geomorphological research of the island, the beginning of which should be related to 1860 when A. Middendorf [1] published a description of the three main terraces of Kildin Island, the genesis of the lake basin remains disputable. B.I. Koshechkin et al. presented the most detailed description of the ancient coastlines of Kildin Island [2]. He investigated five geomorphological profiles, and the main Holocene terrace levels were distinguished on the basis of the results of these investigations. All later researchers of Lake Mogilnoe cited this publication [2]. In 2007, geomorphological investigations were carried out in the eastern part of Kildin Island, which made it possible to get more exact data and supplement the results of the previous studies. During the works on geological routes, hypsometric marks of the coastal ridges and terrace levels were determined to an accuracy of 1 m. Description of loose sediments and collection of mollusk shells to determine the dates were carried out on the terraces around Lake Mogilnoe. Determination of radiocarbon age was carried out at the Laboratory of 14 C Dating of Lund University in Sweden. Radiocarbon years were transformed to calendar years on the basis of the standard calibration procedure. The value of δ 13 e was not measured but was accepted on the basis of the mean value +1‰ for marine carbonates. Neotectonic analysis was performed using standard methods [3, 4]. PECULIARITIES OF NEOTECTONIC STRUCTURE OF THE EASTERN PART OF KILDIN ISLAND The eastern part of Kildin Island is an independent neotectonic block limited from the south and north by the Karpinskii Fracture zones and from the west and east by the Fiordo-Ozernyi Fracture zones. The block of Eastern Kildin is characterized by independent neotectonic motions, which are fixed by altitude marks of the postglacier coastlines. Disjunctive structures within the block are poorly pronounced. The sublatitudinal zone dividing the block into two regions, northern and southern, is traced best of all. The northern region has a structural topography with a flat slope to the north, where it descends abruptly to the Barents Sea along the Karpinskii Fracture zone. Therefore, terrace levels within this region are developed locally. The surface of the southern region descends steeply to the south and then abruptly descends to Kildinskaya Salma as a series of cliffs divided by subhorizontal surfaces, part of which are terraces.