Metallogenic model of uranium with source supply from the south and the north in Manite depression of Erlian basin, Inner Mongolia

Manite depression, located in Erlian basin of Inner Mongolia, is one of the most important metallogenic zone in Northern China. Previous prospecting work paid more attention on northern Manite depression, it was thought that the south of the depression didn't have or weak metallogenic ability. While the latest exploration results show that a 6.8 km-long uranium ore belt is discovered and indicate the south has an equivalent metallogenic prospect as the north. After contrasting geological characteristics of typical uranium deposits in both sides and analyzing sedimentary-tectonic evolution of Manite depression, a double uranium sources metallogenic model was established which points out that main metallogenic type in northern and southern Manite depression is interlayer oxidation zone, while the main ore prospecting target is Upper Saihan Formation in the north and Lower Saihan Formation in the south. The uranium metallogenic epoch can be divided into 3 stages:The first stage where phreatic oxidation type uranium mineralization dominated is from late Erlian period to early Paleogene period with a representative uranium metallogenic age of(68±1.6) Ma-(63.4±5.5) Ma; the second stage, mainly an interlayer oxidized zone type and a phreatic oxidation type as supplement, is in middle Paleogene period with a representative uranium metallogenic age of(51.2±4.3) Ma; the last stage where an interlayer oxidized zone type uranium mineralization dominated is in middle-late Paleogene period with a representative uranium metallogenic age of(44±5) Ma-(37.1±1.9) Ma. The second and the third stage are the main mineralization stages and the uranium orebody grew with time. Above work indicates that emphasis of prospecting should be shifted from northern Manite depression to southern Manite and a 70 km-long mineralized belt will be proved hopefully.