Lena Coal Basin

located in the Yakut ASSR and partly in Krasnoiarsk Krai of the RSFSR. It lies predominantly within the Central Yakut Lowland in the basin of the Lena River and its tributaries (the Aldan and Viliui). In the north the basin extends along the Laptev Sea from the mouth of the Lena River to Khatanga Gulf. Area, approximately 750,000 sq km. Total geological reserves to depths of 600 m total 1,647 billion tons (1968). In terms of geological structure the basin is divided into two parts: the western, which occupies the Viliui syneclise of the Siberian Platform, and the eastern, which is part of the margin of the Verkhoiano-Chukotka folded region.

The coal-bearing stratum is composed of a complex of sedimentary rock from the Lower Jurassic to the Paleogene inclusive, with a predominance of this stratum in the Chechum series of the Upper Jurassic and the Sangar series of the Lower Cretaceous. In the western part of the coal basin the Chechum series is not thick (100–300 m) and dips at a low angle. As depths increase to the east and north, the thickness of the Chechum series increases to 1,000 m. A section reveals coal-bearing deposits of the Sangar series, whose thickness also increases to 1,000 m and more. Occurrences of coal-bearing rock in the central part of the Viliui syneclise are complicated by gently slanting uplifts and depressions. In the Verkhoiansk trough the coal-bearing stratum is crushed into folds complicated by ruptures; the thickness of the stratum is 1,000–2,500 m. The quantity and thickness of Mesozoic coal beds in various parts of the basin are not uniform. From one to ten beds with thicknesses of 1–20 m have been discovered in the western part and up to 30 beds with thicknesses of 1–2 m in the eastern.

The coals are brown coal and hard coal. The degree of metamorphism of the coal increases in a latitudinal direction. In the western platform section there are deposits of brown coal; in the more deeply submerged central section deposits are transitional from brown coal to hard and long-flame coal; and in the eastern section adjoining the Verkhoiansk trough there is hard and coking coal (ranks F, or fat coal, and C, or coking coal). Moisture content of Mesozoic brown coal is 15–30 percent (for working fuel), and the ash content is 10–25 percent (sometimes as much as 30 percent); in a combustible mass the heat of combustion is 27.2 megajoules per kg (6,600 kilocalories per kg), and the volatile-matter yield is 45–52 percent. The corresponding figures for hard coal are moisture content of 3–10 percent and ash content of 10–25 percent; in a combustible mass the heat of dry fuel combustion is 30.1–35.7 megajoules per kg (7,400–8,600 kilocalories per kg), and the volatile-matter yield is 18–45 percent; sulfur content generally does not exceed 1 percent.

Coal-bearing strata of the Paleogene have been located over a considerable area along the lower course of the Aldan River and the northern part of the basin. Brown coal beds are lenticular, with thicknesses ranging from 1–10 m to 30 m; the number of beds varies.

The geology of the Lena Coal Basin has not been extensively studied. Known deposits of brown coal include Ust’-Markha and Kempendiai in the western part; Sobo-Khaia, Kangalassy, and Kil’diamtsy in the central part; and Taimyrlyr, Chai-Tumus, Ogoner-Iuriakh, and Syndasko in the northern part. In the eastern part there are deposits of hard coal (Dzhebariki-Khaia, Sangar, Chechum).