Niu

Occurrence

Hydrothermal deposit along fault

Minerals in the pelitic schist of the Sambagawa metamorphic rocks contacting with the Median Tectonic Line, the boundary fault between the Late Cretaceous (100 Ma) low-P Ryoke metamorphic rocks and the early Paleocene (65 Ma) high-P Sambagawa metamorphic rocks. Protoliths of the Sambagawa metamorphic rocks and the Ryoke metamorphic rocks are the Late Jurassic to Early Cretaceous (150-130 Ma) accretionary complex. Ages of sedimentary rocks were determined by microfossils, and metamorphic ages by K-Ar radiometric dating of muscovite.

Reported Minerals

• Dawsonite
• Alumohydrocalcite
• Nordstrandite
• Dolomite
• Pyrite

Mineral Assemblages

• Dolomite - Dawsonite - Alumohydrocalcite