TYPES AND BIOGENIC MINERALIZATION OF MANGANESE ROCK IN GAOYAN RHODOCHROSITE ORE, NORTH SICHUAN PROVINCE
川北高燕锰矿的锰质岩类型和生物成矿作用

The Doushantuo menganese-bearing scquence in mining area consists of black carbonaceous mudrock,manganese rock and manganiferous dolomite in proper order from bottom to top. The manganese rock can be divided divided into types:stromatloite algal oolite,algal intraclast and intraclactic manganese rocks.The manganese rock is composed of several different minerals:mainly rhodochrosite andquantz and small amount of pyrite, illite and orgenic carbon,etc.The manganese rocks were precipitated in the slope of a transition zone from shallowwater carbonate platform to deep-water muddy basin.Some part of the manganese rocksshow their graded bedding formed from intraclasts,and hence is characterized by turbidity current deposition.Abundant manganese stromatolite consists of algel mat and intraclast laminae algel ball and intraclast.Reproduction and death of the algae have played an important role in the contrate and deposition of manganese in deep-water muddy basin.