The Oyu Tolgoi copper-gold porphyry deposits are situated in a poorly exposed inlier of Devonian mafic to intermediate volcanic, volcaniclastic, and sedimentary rocks that have been intruded by Devonian to Permian felsic plutons. These rocks are unconformably overlain by poorly consolidated Cretaceous sedimentary rocks and younger unconsolidated sedimentary deposits.
Oyu Tolgoi consists of Oyut, Hugo Dummett (Hugo South and Hugo North) and Heruga deposits. The
Oyu Tolgoi copper-gold deposits currently comprise, from north to south:
• Hugo North – The Hugo Dummett Deposit north the 110 Fault.
• Hugo South - The Hugo Dummett Deposit south the 110 Fault.
• Oyut - The Oyut Deposit includes the Southwest Oyu, South Oyu, Wedge, Central Oyu,
Bridge, Western, and Far South zones.
• Heruga – is within the area governed by the arrangements between Oyu Tolgoi LLC and
Entrée LLC except for a small northern portion that lies within the Oyu Tolgoi.
Hugo Dummett deposits
The Hugo Dummett deposits, Hugo North and Hugo South, contain porphyry-style mineralization associated with quartz-monzodiorite intrusions, concealed beneath a sequence of Upper Devonian and Lower Carboniferous sedimentary and volcanic rocks. The deposits are highly elongated to the north northeast and extend over 3 km. The Hugo North zone is virtually contiguous with the Hugo South zone and lie within a similar geological setting. The two deposits are separated ........
