Lower Urgen Porphyry Mo Deposit, Ergun City (E'erguna Co.), Hulunbuir City (Hulunbei'er Prefecture), Inner Mongolia, Chinai

Regional Level Types
Lower Urgen Porphyry Mo Deposit	Deposit
Ergun City (E'erguna Co.)	County
Hulunbuir City (Hulunbei'er Prefecture)	Prefecture-level City
Inner Mongolia	Autonomous Region
China	Country

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The Lower Urgen deposit in Inner Mongolia, NE China, is a newly discovered porphyry molybdenum deposit, with estimated reserves of 44,856 t of molybdenum at an average grade of 0.141%. Mineralization is characterized by veinlet-disseminated and vein-type quartz–sulfide orebodies primarily occurring in the cupola of the Early Cretaceous granite porphyry stock. Molybdenite Re-Os dating yielded two model ages of 141.2 ± 1.5 and 147.7 ± 1.7 Ma, coeval with the regional Late Jurassic–Early Cretaceous molybdenum metallogenesis. The hydrothermal process can be divided into three stages: the quartz–molybdenite(–pyrite) stage, quartz–polymetallic sulfide stage, and quartz–carbonate stage.

At present, the deposit has estimated reserves of 44,856 t Mo with a grade of 0.414 %. The stratigraphic units exposed in the ore district comprise the Tamulangou Formation of Middle Jurassic, Manketouebo Formation of Upper Jurassic, Baiyingaolao Formation of Lower Cretaceous, and Quaternary sediments. Mafic to intermediate volcanic rocks, such as trachyandesite, andesite, and basaltic trachyandesite, make up the Tamulangou Formation. Felsic volcanic rocks, including rhyolite, volcanic agglomerate, and volcanic breccia, make up the Manketouebo Formation. Tuff, rhyolitic breccia lava, and rhyolite make up the Baiyingaolao Formation, which is only exposed in the district’s northwest. Mineralization at the Lower Urgen deposit is characterized by concealed veinlet-dissemination and quartz-sulfide veins, mainly hosted in the cupola of the Late Jurassic granite porphyry.
Four paragenetic stages are distinguished, each characterized by distinct vein assemblages:
Stage 1 represents the transition from magmatic to hydrothermal conditions. Veins of this stage are devoid of sulfides.
Stage 2 is separated into two substages according to vein mineralogy and contains the majority of the Mo mineralization. Sub-stage 2.1 veins are characterized by quartz–molybdenite–chalcopyrite–(pyrite) assemblages and crosscut Stage 1 veins. Sub-stage 2.2 veins consist of quartz–molybdenite–(pyrite) and are observed to cut Sub-stage 2.1 veins. Stage 2 veins lack magnetite.
The shallow and outlying areas of the deposit are where stage 3 veins primarily form. They contain quartz, sericite, chlorite, sphalerite, galena, pyrite, and chalcopyrite, with no molybdenite.
The last hydrothermal activity episode is represented by Stage 4. Quartz, calcite, fluorite, and a small amount of fine-grained pyrite make up veins.

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.

Mineral List

13 valid minerals.

Rock Types Recorded