Geology and ore composition studies of Dulaan khar uul poly metal deposit

Abstract

Dulaan khar uul deposit is situated in the NW of the Deluun-Sagsay metallogenic zone, identified within Devonian rift-like structure of Western Mongolia. As for geologic settings, it consists of Devonian Baast uul, Otog formation bimodal volcanic, sedimentary, tufogenic rock units and spatially and genetically interrelated subvolcanic units. The poly metal mineralization develops lenses, layers and vein-like bodies within NE-SW-directed quartz-sericite metasomatite zones extending 700m in length and 300m in width. As a result of geological survey there are identified totally five ore bodies and three of which (id no. I, II-1 and II) are exposed at the surface while the ore bodies no. III and IV are concealed. The ore body no. I continues 600m in extension and dips into the west with an angle of 48-72^o. As well, along the dip it extends up to 210m and ranges from 1.33m to 12.2m in width; the oxidation zone is approx.50m in thickness. The ore body no. II contains most of the ore resources and marginally converges into the depth of 50-100m. It also shapes like lenses with dipping angle of 36-87^o to the west and occurs in 600m in length extension along strike and extends 350m along dip; the thickness ranges between 0.5m and 18.0m. The ore body no. II-1 exists between the ore bodies no. I and II and is 350m in extension along strike direction and up to 300m along dipping. This vein-like body extends with dipping angle of 51-73^o; the thickness ranges from 0.5m to 19.3m. The ore body no. III is concealed in the depth interval of 150-200m below the surface, extends 600m along strike with the thickness of 10.94m. It dips toward the NW with dipping angles of 45-70^o as split veins and plates. The ore body no. IV is in 350m in strike length extension and 80m along dipping. The thickness is between 1.15m and 18.3m.  The mineral composition of the deposit ore is characterized by mainly sphalerite and galena with pyrite, slight amount of chalcopyrite, occasionally tennantite, marcasite, ilmenite, cerussite, smithsonite, hematite, malachite, arsenopyrite, siderite, gold etc. Two types of sphalerite are identified: (Zn, Fe)S, marmanite with iron and (ZnS) native zin sulfide cleiophane.