Hongtupu Cu-Zn-Au deposit, Yizhou District, Hami Prefecture (Kumul Prefecture; Qumul Prefecture), Xinjiang, Chinai

Regional Level Types
Hongtupu Cu-Zn-Au deposit	Deposit
Yizhou District	County
Hami Prefecture (Kumul Prefecture; Qumul Prefecture)	Prefecture-level City
Xinjiang	Autonomous Region
China	Country

The Huangtupo Cu-Zn (Au) deposit consists of more than 80 orebodies with a total proven reserve of 0.30 Mt Cu (1.49%), 0.28 Mt Zn (3.51%), 7.1 t Au (0.6 g/t) and 281 t Ag (26 g/t). It has a typical two-layer structure, with the upper massive sulfide unit of the submarine basin and the lower stockwork mineralization unit. The main Cu-Zn orebodies are characterized by the zoning of metals upward from a deep stockwork mineralized zone (Cu > Zn) to a shallow massive mineralized zone (Zn > Cu). The massive Cu-rich ores are in the core, with banded Zn-rich ores, breccia Zn-rich ores, and pyrite-rich hydrothermal sedimentary siliceous rocks appearing outward from the center. Some late sulfide veins intersperse massive orebodies. The lower part of the massive ore body is a sulfide-silicate stockwork vein system, which is hosted in a series of pyrite-rich volcaniclastic breccias, and amygdaloidal andesitic-basaltic rocks.

Ore bodies occur along the lithological contact between Unit 2 and Unit 3 of the Daliugou Formation, beneath a 290–560 m thick volcanic cover sequence characterized by andesitic to dacitic lavas and associated pyroclastics. The core of the stratiform ore body consists of a massive copper-rich mineralization, while outward from the center, banded zinc-rich ores, brecciated zinc-rich ores, and sedimentary siliceous rocks containing pyrite can be observed. The stockwork mineralization occurs mainly in the proximal footwall of massive sulfide ore bodies, representing the upflow channels of sub-seafloor hydrothermal systems.

Mineralization is hosted by volcanic and volcaniclastic rocks of the Late Ordovician–Early Silurian Daliugou Formation. The stratigraphy can be divided into a basal unit of intermediate to felsic volcaniclastic rocks interlayered with basaltic andesite and andesite (Unit 1), overlain by intermediate–acidic volcanic rocks (Units 2–3). The principal mineralized horizon lies within Unit 3 at depths of ∼290–560 m, consisting mainly of andesite, dacite, and dacitic lava. Disseminated and network-style Cu sulfides are concentrated in Unit 2 breccia, pyroclastic dacite, and dacitic lava.
Mineral paragenetic sequence in the Huangtupo deposit.
(1) pre-ore massive pyrite mineralization (Stage 1);
(2) massive/disseminated Cu–Zn sulfide mineralization (Stage 2);
(3) vein-type sulfide mineralization (Stage 3).
The combined sulfur isotope and trace-element composition of pyrite from the Huangtupo Cu–Zn deposit reveals systematic variations between pre-ore, syn-ore, and late-stage mineralization, reflecting progressive changes in fluid source, temperature, and redox conditions within this arc-related VMS system.

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