Erdaokan deposit, Nenjiang County, Heihe, Heilongjiang, Chinai

Regional Level Types
Erdaokan deposit	Deposit
Nenjiang County	County
Heihe	Prefecture
Heilongjiang	Province
China	Country

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The Duobaoshan Cu-Mo-Au mineralization concentrated area, situated in the eastern part of the Xing’an–Mongolia orogenic belt, represents a region that has undergone superimposed transformations associated with the Paleo-Asian Ocean, Mongol-Okhotsk Ocean, and Pacific Ocean tectonic domains.
In the mining area, two Ag ore bodies were discovered, exhibiting a steep occurrence of ore. The first ore body, named I AgB, has a controlling length of 556.27 m and a maximum dip controlling depth of 273.35 m. It possesses a maximum true thickness of 26.75 m, an average true thickness of 6.23 m. The second ore body, referred to as II AgB, spans across a controlling length of 689.39 m with a maximum dip controlling depth of up to 231.64 m. It has a maximum thickness of 40.29 m and an average thickness of approximately 10.20 m. Furthermore, its inferred economic resource quantity of the deposit is estimated to be 1777 t of silver metal content. The highest recorded grade for silver was found to be 25,516.00 g/t, with an average grade of 431.10 g/t. Additionally, the associated Mn ore reserve in Erdaokan deposit amounts to 90.0 × 104 t with an average grade of 11.75%, while the associated Pb metal quantity in Erdaokan deposit is 1.68 × 104 t with an average grade of 0.75%. Moreover, the associated Zn metal quantity in Erdaokan deposit is 0.16 × 104 t with an average grade of 1.15%.
The alteration in the Erdaokan deposit exhibits distinct spatial zoning, which can be divided into three stages: the sheet-like precipitation of quartz–sulfide minerals, the formation of galenite–sphalerite–Fe–Mn carbonate assemblages, and the occurrence of pyrite–arsenopyrite–carbonate aggregates.

The Erdaokan deposit as an epithermal type silver deposit. The outcropping stratigraphic units comprise Upper Silurian-Middle Devonian Niqiuhe formation marine sedimentary sequences (e.g., muddy limestone, dolomitic limestone, sandstone, siltstone and a small amount of carbonaceous shales), Triassic volcanic-subvolcanic rocks (such as andesite, dacite and acidic tuff) and Quaternary unconsolidated sediments. Detailed geological exploration has identified that the Erdaokan deposit has proven metal reserves of 1,777 t of silver averaging 431.1 g/t, together with 16,834 t of lead (0.75% average) and 1,648 t of zinc (1.15% average). This deposit consists primarily of two ore bodies, No. Ⅰ and Ⅱ, which are veined, lenticular, wedge shaped to irregular ore bodies and hosted in the breccia belt within the Niqiuhe Formation controlled by NW-striking fault. Among them, the ore body Ⅱ is the larger one, which is 670 m long, 2 to 30 m wide and 23 m in average thickness, with ore grades of 44.8–9297.4 g/t Ag (average 592.5 g/t) and 1.64 wt% (Pb + Zn). This ore body is lenticular to wedge-shaped, trends 315°-330° and dips 80°-85° to northeast. three mineralization periods were identified in this deposit, namely the early sedimentary period (including euhedral, subhedral, framboidal and chrysanthemum pyrite grains in wall rocks, Fig. 4a), the middle hydrothermal period and the late supergene period. The supergene ores are mainly composed of psilomelane, pyrolusite, limonite, and goethite. The hydrothermal period mineralization process consists of four stages.
Stage 1 contains coarse-grained euhedral-subhedral pyrite and aggregates (Py1), clustered or banded magnetite, as well as quartz (Qtz1) wrapping wall rock breccia (shale) intergrown with minor Fe-Mn carbonate.
Stage 2 refers to abundant coarse-grained subhedral-anhedral and minor euhedral pyrite (Py2), subhedral-anhedral sphalerite (Sp1), subhedral-anhedral galena (Gn1), commonly coexisting with subhedral-anhedral quartz (Qtz2), Fe-Mn carbonate (Fmc2) and euhedral-anhedral bitumen (Bit1), generally occurred as veins cutting stage 1 magnetite and pyrite.
Stage 3 is the main mineralization stage, which comprises abundant silver-bearing sulfides, galena (Gn2), sphalerite (Sp2), minor pyrite (Py3) and chalcopyrite. This stage is characterized by veins of Ag-bearing sulfides + Py3 + Sp2 + Gn2 + chalcopyrite + quartz (Qtz3, Qtz4) + bitumen (Bit2).
Stage 4 comprises pure calcite, quartz (Qtz5) and rare sulfide minerals (pyrite, sphalerite, and galena), which are produced as veins or fine euhedral grains, and commonly intersected stage 2 sulfides.

Commodity List

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

Mineral List

23 valid minerals.

Rock Types Recorded