Hydrothermal Plumes and the Delivery of Iron to Banded Iron Formation

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In the snow dome era, another mechanism of the striped iron layer suggests that iron deposits from metal-rich salt water near the lift zone of hydrothermal activity. Alternatively, some geochemists believe that ribbon iron can be formed by the direct oxidation of iron by microbial anaerobic phototrophs. The iron belt in northern Minnesota is right under the thick jet layer of the collision layer of the Sudbury Basin. During its formation, the earth had a supercontinent called Colombia and had a large continental shelf. An asteroid (estimated 10 km) hit a water area of ​​about 1,000 m deep, about 1.85 billion years ago. The computer model shows that the tsunami is at least 1000 meters in the center and up to 100 meters at a distance of about 3,000 kilometers. The huge wave caused by the impact and the landslide of the large water stirred the sea and carried the oxygenated water from the sea to the seabed.

A large amount of iron deposits were seen in the iron layer of the strip. These strata are a type of rock in which alternating thin layers of iron oxide and less iron shale and meteorite belt alternate. These iron bands were built 3.7 billion years ago and 1.8 billion years ago. Starting from the historical time, the iron compounds mentioned are used as pigments (compared with meteorites) and also to the color of the various strata, eg Buntsandstein (Bunter, UK). In Germany's Eisensandstein (such as the Jurassic "iron sandstone" in Donzdorf and the UK bass stone) iron pigments contribute to the pale yellow color of many historic buildings and sculptures. The well-known red color of the surface of Mars comes from a weathered layer rich in iron oxide.

The structure of the striped iron is important as an indicator of the source of iron and the evolution of the atmosphere. The striped iron ore structure is a special sedimentary rock where alternating layers of iron-rich (red) and iron diffused (gray) layers overlap (Figure 7-4 on page 237). Most of this type of rock is over 2 billion years ago. They account for the majority of iron ore mined in the world today. Weak oxidation of iron formed by striped iron strongly indicates that oxygen has begun to accumulate in the environment at that time.