Geological–Geomorphological Types of Islands in the Kandalaksha Gulf, White Sea N
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ISSN 01458752, Moscow University Geology Bulletin, 2015, Vol. 70, No. 4, pp. 318–326. © Allerton Press, Inc., 2015. Original Russian Text © N.I. Kosevich, 2015, published in Vestnik Moskovskogo Universiteta. Geologiya, 2015, No. 4, pp. 53–61. Geological–Geomorphological Types of Islands in the Kandalaksha Gulf, White Sea N. I. Kosevich Department of Geography, Moscow State University, Moscow, Russia email: [email protected] Received March 13, 2015 Abstract—Based on a detailed geological–geomorphological study of the islands in the Severnyi, Luven’ga, Kuzakotsky, and Keret’ archipelagoes, Kandalaksha Gulf of the White Sea, new original geological–geomor phological maps of each studied island and general maps of each archipelago were made. The geological– geomorphological genetic typing of the islands was developed and graphic visualization of this typing was per formed. An attempt was made to apply the developed typing to other White Sea islands. Keywords: relief, islands, archipelago, Kandalaksha Gulf, geological–geomorphological genetic typing DOI: 10.3103/S0145875215040079 INTRODUCTION while it is considered obsolete internationally; the The White Sea is characterized by coasts and time span of this period is 1650 to 570 Ma B.P.). This islands that are different in the geological–geomor graben system is called either Onega–Kandalaksha phological sense (Fig. 1); this is of interest to geolo (Baluev et al., 2009a) or Kandalaksha–Dvina (Ave gists and geomorphologists. Many researchers narius, 2004). (Lymarev, 2002; Bulochnikova et al., 2010) believe After the Karelian tectonomagmatic cycle, the that islands that result from interactions between entire region existed as a united cratonic structure. In endogenous and exogenous processes can be a model the Oligocene, the neotectonic stage started in the to study the regularities of the joint effects of these White Sea region (Baluev, 2006; Slabunov, 2009). Iso processes on reliefforming processes. The study of the static rising, which involved the entire Baltic Shield land within the islands is one of the major fields in after glacial melting, largely determines the present marine (island) geomorphology. However, the islands day tectonic evolution of the study area. of the White Sea have been poorly studied and their Two structural stages can be identified in the geo geological–geomorphological typing has not been logical structure of the Kandalaksha Gulf. The first performed. To obtain detailed data on the structure of structural stage is a crystalline basement that is com the White Sea islands, in particular, those of Kan posed of rocks of the White Sea complex (Archean). dalaksha Gulf, the author performed comprehensive Within the study area, this ancient complex is repre geological–geomorphological research at large and sented mostly by biotite, garnet–biotite, amphibole– detailed scales. biotite gneisses, amphibolites, granitic gneisses, alu mina schists, quartzites, and multiple intrusive bodies of different compositions and ages, which pierce the THE TECTONIC SETTING AND GEOLOGIC mentioned rocks. The total thickness of these deposits STRUCTURE OF THE STUDY AREA is 8–10 km. The second structural stage is the cratonic The White Sea is notable for its complex geological cover; it starts from red Riphean sandstones that fill evolution and great variety of natural processes. In the the aulacogens in the crystalline basement and are tectonic sense, the White Sea depression is located at overlain in the southeastern direction by Vendian the junction between the Baltic Shield and the East (approximately Ediacaran) terrigenous deposits. On European Craton. The Kandalaksha Gulf, which is the bottom of the Kandalaksha Gulf, these ancient located in the western White Sea (Fig. 1), coincides rocks are nearly completely covered by young Pleis with the White Sea mobile belt of the Mesoarchean– tocene and Holocene deposits. Paleoproterozoic. The main structural unit that has The presentday White Sea is a young (10–12 ka) determined the tectonic evolution and structure of basin that formed at the end of the Pleistocene. During study area from the Riphean until the present is the the last Valdai glaciation, the entire White Sea depres graben system founded in the Riphean (we note that sion was filled with ice. In the Alleroed, particular the name Riphean is still used by Russian geologists, freshwater lakes occurred on the periphery of the 318 GEOLOGICAL–GEOMORPHOLOGICAL TYPES OF ISLANDS 319 BARENTS SEA Voronka Bay Kanin coast Kandalaksha K an t da s t Mezen lak a ai sha co r K co t Bay a as y S r K t k o A e a rs l b li nd e r r a a Konusha coast an lak T o m sh o c a G st v o Gu a s a lf ki Mezen s o i t c co Kandalaksha as Murmansk oblast ny t im 1 WHITE SEA Z L Dv e ina B co tn ay O a i Arkhangelsk oblast Karelia n s i e t Severodvinsk ga O c P ne o om ga as Arkhangelsk B t or a sk y Omega 2 y c oa st 085170310 km 3 4 Karelia 02550 100 km Fig. 1. Schematic locations of the study area and sites (archipelagoes): 1—Luven’ga arch., 2—Severnyi arch., 3—Kuzakotsky arch., 4—Keret’ arch. depression. In the late Alleroed, ice sheet destruction of lithologic, genetic, and age composition. The isos started, ocean water penetrated from the side of the tatic rebound, which involved the entire Baltic Shield Barents Sea into the White Sea depression, and the after the melting of the ice sheet, is about 100 m in the subglacial sedimentation regime settled. Sedimenta White Sea region. After the complete loss of the ice tion took place under complex, often contrasting tec sheet, the marine sedimentation regime settled in the tonic movements, which are typical of the White Sea White Sea, with hydrodynamic and biologic factors region. being the lead ones for this regime (Nevesskii et al., Deglaciation of the White Sea depression began in 1977; Rybalko, 2009; Polyakova et al., 2010). Thus, the preBoreal and finished in the early Atlantic peri varying paleogeographic and paleotectonic conditions ods. Deglaciation led to the formation of a sedimen shaped the islands with different geological–geomor tary stratum, which was highly heterogeneous in terms phological characteristics. MOSCOW UNIVERSITY GEOLOGY BULLETIN Vol. 70 No. 4 2015 320 KOSEVICH N Lodeinyi Is. Ka n d a l a Korabl’ Luda k s h a G u l Greater and Lesser Demenikha Is. f Peschanka Luda Voronii Is. Ryashkov Is. Voronii islet Voronka Luda Greater Gal’muk (Gul’makha) Is. da Lu aya hn rec pe Kurichek Is. Po 1st Devich’ya Luda 2nd Poperechnaya Luda K ar el i 3rd Poperechnaya Luda an co as t Greater Lomnishnyi Is. Lesser Lomnishnyi Is. 350 07001050350 m Fig. 2. Geologicgeomorphologic map of the Severnyi archipelago. MATERIALS AND METHODS of Geomorphology and Paleogeography of the Department of Geography of Moscow State Univer The factual basis of this paper is the data that were sity at particular sites of the Kandalaksha and Karelian collected by the author during the expeditions carried coasts of the White Sea. These materials were also aug out over 5 years in the 2007–2013 period by the Chair mented with literature and archive data. Archipela MOSCOW UNIVERSITY GEOLOGY BULLETIN Vol. 70 No. 4 2015 GEOLOGICAL–GEOMORPHOLOGICAL TYPES OF ISLANDS 321 ARBITRARY NOTATIONS (1) Landforms of tidal and surging origin (4) Landforms of joint glacialtectonic, marine, lake, and biogenic origin Boulderpebble beach Lake depressions Sandy beach Swamped sites Silty littoral zone Boulderpebblesandy belt (5) Other notations Marsh Clear geomorphologic boundaries Boulder belt Unclear geomorphologic boundaries Seaward boundary of the littoral zone Coastline (2) Landforms of joint tectonicglacial Isolines of each 10 m and marine (wave action) origin Isolines of each 5 m Contemporary marine terrace (up to 1 m high) Absolute elevation Late Holocene terrace (4–6 m high) Points of the state geodetic network Middle Holocene terrace (14–18 m high) Points of the survey network, referred to the area with stations Information board of the (3) Landforms of joint tectonicglacial, Kandalaksha nature reserve marine, and gravity origin Anthropogenically altered area Subhorizontal and lowinclined bedrock surfaces covered in places with thin loose deposits Slopes inclined by <12° Slopes inclined by >12° Bottoms of depressions, kettles, and grabenlike topographic lows Structuraldenudation residual outcrops Blocky nanorelief (piles of blocks) Fig. 3. Legend to the geological–geomorphological map. goes that are located in three parts of the Kandalaksha tions and along the coastal zone (within the limits of Gulf that are characterized by different geomorpho tidal zone). The profiles reflected the relief character logic conditions were chosen as the reference sites. and composition of the deposits. The complex of geo The first site is located at the apex of the Kandalak morphologic observations included GPS location of sha Gulf and includes the islands of the Severnyi and the planned observation points and all of the observed Luven’ga archipelagoes. The islands of the Severnyi bends of relief (edges, inner margins, etc), geomor and Luven’ga archipelagoes are located in front of the phologic objects, and local and linear manifestations Kandalaksha and Karelian coasts of the White Sea, of the contemporary exogenous processes, which can respectively. The islands by the Karelian coast form sev not be shown at the scale of the map (tectonic cracks, 1 eral parallel ranges. The islands of the Luven’ga archi breakoff blocks, iskors , erosion furrows, etc). pelago form a line that follows the coastline of the mainland continent. The second site includes the islands In addition, to increase the accuracy of the loca of the Kuzakotsky archipelago, which are located near tion, the spatial positions of the reference line points the Pertsov White Sea Biological Station of Moscow (shorelines, paths, roads, cleared strips, lake levels, State University (WSBS MSU).