古元古代末期阿尼米克盆地苏必利尔型条带状铁建造中铁同位素及元素组成的研究

苏必利尔型条带铁建造在前寒武纪时期广泛发育，是世界级超大型铁矿的主要类型，同时也是反演地球早期环境的重要信息载体。但是，目前关于苏必利尔型条带铁建造中铁的来源是陆源成因还是热液成因存在争议，并且对于其沉积模式是原地沉积还是海水上涌沉积的认识尚不清楚。本项目拟以古元古代末期（1.8Ga）阿尼米克盆地产出的苏必利尔型条带铁建造为研究对象，选取沉积在同一盆地、不同沉积深度的三个岩芯剖面的铁建造，在分析全岩主量、微量元素组成的基础上，重点对铁建造中赤铁矿的铁同位素组成及其空间变化进行系统研究，以对苏必利尔型条带铁建造沉积所需铁的来源及沉积模式进行制约。最终通过以上研究，为解读大规模的条带状铁建造于古元古代末期沉积消失的机制提供新的思路，以期为古元古代末期海洋环境演化提供新的启示。

Superior-type banded iron formation, a primary type of world-class iron ores, was widely developed in the Precambrian, recording the significant information of the early earth’s paleo-environment. However, there is a heated debate about the source of iron in the Superior-type banded iron formation that whether it was sourced from riverine input or hydrothermal fluids. Moreover, it is still unclear on the depositional model of the Superior-type banded iron formation that it was formed by mixing locally discharged submarine hydrothermal fluids with local seawater, or by upwelling deep ocean water. In this study, three cores of Superior-type banded iron formation from different depositional depths in the late Paleoproterozoic were selected from Animikie Basin, North America. Here, the composition of major and trace elements, and the iron isotopes in hematites would be analysed to constrain the source of iron and the depositional mode of Superior-type banded iron formation. Furthermore, this study aims to provide a new sight for the cease of banded iron formation in the Paleoproterozoic, and some implications for the evolution of environment in the Paleoproterozoic ocean.