关键词: 关键词：大氧化事件, 条带状铁矿建造, 稀土元素地球化学

Abstract:

 Great Oxidation Event (GOE) is the appearance and continuous increase of oxygen in atmosphere about 2.4 Ga ago. The model for GOE generation and evolution can be summarized as two types up to the end of twentieth century: the first one is socalled C-W-K-O model which postulates an anoxic atmosphere prior to 2.2 Ga with p(O2) levels between 10^-13 and 0.1％ of present atmospheric level (PAL), and a dramatic rise of p(O2) to >15％ PAL between 2.2-1.9 Ga; the second one is D-K-O model which postulates an essentially constant atmospheric p(O2) level (probably within ±50％ of PAL) since 4.0 Ga. The Archean Biosphere Drilling Project (ABDP) has carried out in the beginning of the 21 century. The drilling targets were ArcheanProterozoic formations, such as shale and banded iron formation (BIF) etc. The investigations on microorganism, S and C isotope fractionation, REE and changes of transition metals Ni, Fe, Mo contents have produced many new results for building new and different models of the timing and generation mechanism of GOE. The appearance of free O2 in the atmosphere is at least advanced to 2.5 Ga. The BIF especially the REEFe formation are widely developed in China. Preliminary researches on the REE geochemistry of BIF have shown that the REE contents and fractionation (La/Yb), particular the enrichment or depletion of Eu have had systematic change with time. We suggest that we should carry out systematic geological and geochemical studies, in particular the REE geochemistry studies, on the BIF, which may make important contributions to the GOE study and certainly to the investigations of the iron ore deposit formation and distribution in our country.

Key words: great oxidation event, banded iron formation, REE geochemistry