Ancient Agrolandscapes of the Darkhat Basin (Northern Mongolia)

Abstract

According to remote sensing (space image decoding), the Darkhat Basin of Northern Mongolia is a sparsely populated cattle-breeding territory, which was an area of developed agriculture in the past. Quite numerous land plots are recognized at the end spills of rivers flowing from its mountainous frame, lake and river terraces, floodplains, and deluvial–proluvial slopes, at absolute elevations from 1535 to 1700 meters a.s.l. or more. Among the wide soil range, here are fertile chernozems, chestnut, and dark chestnut soils. The geological position of the region and its confinement to the southwestern periphery of the Baikal rift contributed to both the formation of the basin and its modern seismic activity, manifestations of basaltoid volcanism, as well as the emergence of a “regional thermal anomaly” (Vilor et al., 2019). The basin also belongs to the Khubsugul Upper Riphean–Cambrian phosphorite-bearing basin, where deposits and numerous manifestations of phosphorites, the basis of mineral fertilizers, are known (Il’in, 1973). The long history of the formation of the relief of the Darkhat Basin led to the enrichment to a greater or lesser extent of its Quaternary deposits with phosphorus compounds useful for agricultural practices. Modern volcanism and continental rifting processes contributed to the emergence of thermal springs in this area; nitrogen baths, which are a kind of liquid nitrogen fertilizer, are known here (Mongol’skaya..., 1990). The combination of the following features: fertile soils, the thermal anomaly of the Baikal rift, and the presence of nitrogen thermal springs, as well as deposits and manifestations of phosphorites, products of their destruction, enriching the soil, contributed to the development of agriculture here. Manifestations of Cenozoic basaltoid volcanism, causing the presence of fertile volcanic ash, as well as processes of medieval volcanic activation (Arzhannikov et al., 2017), played a possible role in the development of agricultural practices on this territory. Social and political events are also important reasons. According to an earlier analysis of ancient agriculture in the arid territories of Central Asia (Prudnikova, 2020), its maximum development in the Darkhat Basin occurred in the early Middle Ages, a time attributed to the small climatic optimum.