SUMMARY
Some types of tin-wolfram ore-bearing structures in the Đại
Từ - Tam Đảo area
Vũ Xuân Độ
Most of the tin-wolfram ore bodies widespread in the
Đại Từ - Tam Đảo area consist of veins and lenses of different configurations
and dimensions. They are hydrothermal formations filling up various fissures of
tectogenic and magmatogenic origin. To the first group may be attributed the
system of ore-bearing plumose fissures accompanying principal faults of Núi
Pháo, Khuôn Phầy - Ngòi Lẹm and La Bằng ore fields, as well as series of en
echelon fissures in shear zone of the Sơn Dương wedge-shaped tectonic block. In
the second group there are veins in the intensively greisenized endocontact zone
of the Thiện Kế two-mica granite massif. The above types of ore-bearing
structures were formed later than surrounding them intrusive, volcanic and
sedimentary complexes.
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