SUMMARY
Structural features and
their control on mineralization
at Núi Pháo polymetallic deposit, Đại Từ, Thái Nguyên
Trần Thanh Hải, M. Farmer, J. Stemler and S. Duka
The
Núi Pháo Polymetallic Deposit, a skarn deposit hosted by the Ordovician-Silurian
Phú Ngữ Formation, is related to the intrusion of the late Cretaceous two-mica
granite of the Pia Oắc Complex. The host rocks were affected by at least 3
regional deformational phases, which include two phases of ductile deformation
and one late phase of brittle deformation. The first deformational phase
strongly folded terrigenous-carbonate rocks of the Phú Ngữ Formation, creating
numerous isoclinal folds which led to the significant increase of thickness of
this formation, and displaced it from its original depositional position. The
second deformational phase refolded structures of the first phase, forming main
regional structure. The brittle fracturing of the third deformational phase
complicated earlier structures, but did not strongly influenced to the regional
structural plan. The skarn polymetallic ore bodies are relatively simple in
structure as they were formed after the main ductile deformations. However, the
shape and size of the ore bodies may be strongly controlled by premineralization
structures. So, the correct structural interpretation is not only important to
the understanding of regional deformational nature, but also contributes to the
extrapolation of size and developing direction of the mineralization.
Người biên tập: Võ Năng Lạc