SUMMARY

The forming model of carbonate-hosted hydrothermal Pb-Zn ores of Chợ Điền

Nguyễn Văn Niệm, Lê Thị Tuyết, Nguyễn Văn Học,

Mai Trọng Tú, Đỗ Đức Nguyên, Nguyễn Minh Long

The deposited environment of Chợ Điền lead-zinc ores is mostly opened space (opened fractures, tectonic broken zones).

Source of S^2- is contributed by surrounding rocks. This is characterized by the contrast between the components that created ore in phases and space as well as: the occurrence of autogenous Bi in the final stages, rare are Se content and surrounding rocks of ore body alternated with rich black or gray ash bitumen layer that shown disinfectant environment. Simultaneously, they also controlled the flexibility of CO₂ in carbonate systems (the appearance of siderite is very little and only in the Đèo An area); on the other hand, at the end as well as low part of ore zone there is very few oxidic mineralization, etc. Metal resources creating ores occurred mainly in the Triassic period or earlier. Pb isotopic age of lead-zinc mineralization is 230 Ma [3]. Ratio of δ³⁴S isotope in Chợ Điền lead-zinc ore range narrowly of +7,19 to +7,65‰ that shown the ore solution origin is magma.

Ore-forming method: Ore-forming solution moved from the critical zone in the eastern wing of Phia Khao Anticline (where the schist layer was interrupted by fault and displaced) in the surface - layers faults up to the open fault in the centre of this anticline. With this method, the forming temperature (inclusions, combination of minerals and elements) will decrease when they are far from the source.

The deep hidden magmatic source is new idea of this paper. However, the dolomitizing process could prepare previous material sources and gradually additional contributions.

Người biên tập: PGS. TS Trần Trọng Hòa