MINERALS HOSTED BY TRIASSIC CARBONATE ROCKS OF THE ANYUI RIVER BASIN (NORTH SIKHOTE-ALIN)

The Late Triassic carbonate sequence (25–27 m) in the Anyui river basin composed of low-magnesium calcite with subordinate dolomite, magnesian calcite, and ankerite includes interbeds, lenses and nodules of cherts. The major ore accessory minerals are oxides and hydroxides of iron, iron sulfides, and apatite. The other accessories like sulfides of Cu and Zn, native Ag, rutile, zircon, monazite, xenotime, and cerianite are present in subordinate amounts. Barium mineralization (barite, hyalophane, celsian, and romanèchite) often occurs in carbonates and associated siliceous rocks. Microtextures and microstructures of carbonate layers and their mineral composition suggest the post-sedimentary dolomitization that was induced by the supply of magnesium with low-temperature hydrotherms during Middle-Late Jurassic basaltic and Late Cretaceous granitic magmatism. Dia- catagenetic and hypergene changes in the mineral composition of carbonate-siliceous deposits occurred episodically from the Triassic to the Quaternary. They seem to be important factors that determined the mineral composition and geochemical specialization of sedimentary units and rocks in the region.