Loess soil distribution and properties in Mongolia

Loess and loess-like soil formations are distributed in 3 regions across Mongolia. The lower part of the Orkhon Selenge river basin North Mongolia is main loess area another two located east Mongolia, Onon Ulz basins Khalka Gol area. Loess-like covers a total 109,000 sq.km or 6.95 per cent territory country. properties have been studied on basis 8 sections 83 samples. Fine sand fraction predominant granulometric composition its mean value 51.3 cent, silt content about 34.9 cent. A typical non-stony fine sand, but there also gravel loess. average stone sediments 8.1 sandy doesn’t contain any stone, coarse fragment high (20.5 cent) There higher (57.0 as compared to (47.4 cent). Mongolian calcium carbonate 2.9 Organic Matter (0.93 than Chinese (0.41 Using 14C isotope data analysis sediment we tried define stratigraphy. Lower base section silty 1-3 meter thick layers were mostly formed during mid-Holocene (7.5-3.0 ka) period. Upper parts 1.0-0.7 top accumulated late Holocene (3ka BP present) Kastanozem topsoil humus horizon (15-30 cm) formation starts at 1.5-1.0 ka BP. Mid-Holocene period probably witnessed most active accumulation with warm dry windy condition prevailing. Sandy thickness 1-2 meters predominate some places reaches up 20-30 meters.