The Archaean-Proterozoic transition and iron ore genesis: the Amazon perspective from the world-class Serra Sul iron ore deposit, Carajás, Brazil

条状铁建造(BIF)和黑色页岩记录了海洋环境条件，反映了海洋-大气系统的全球化学和生物特征。它们拥有矿藏，就BIF而言，这些矿藏占世界铁矿石矿山产量的大部分。卡拉贾·S是巴西亚马孙地区的世界级铁矿产区，最近在这里对Serra Sul矿藏的勘探发现，在目前仍处于原始状态的Serra Sul地区迄今已发现的四个矿体中，仅有一个在&gt；的已探明资源量为40亿吨。这些结果使Serra Sul成为世界上最大的铁矿石矿藏之一。勘探还发现，黑色页岩就在南塞拉的BIF单元下方。地质推断表明，这些岩石形成于2.7Ga左右。黑色页岩和BIF的共存可以重建Serra Sul岩系沉积过程中海洋-大气系统的演化，这将为涉及太古代-元古界过渡和大气氧气上升的激烈辩论，即大氧化事件提供新的线索。我们的Amazon观点将在详细的岩石学和元素地球化学背景下整合钼、硫、Re-Om和Sm-Nd同位素的大量岩石分析数据，以及铁和氧同位素的微量分析数据。此外，我们的目标是确定从BIF到高品位铁矿石的沉积后过程。

Banded iron formations (BIFs) and black shales record marine environmental conditions that reflect global chemical and biological features of the ocean– atmosphere system. They host mineral deposits that, in the case of BIF, account for most of the world’s mine production of iron ore. Carajás is a world-class iron ore district in the Amazon region of Brazil, where recent exploration of the Serra Sul deposit has identified a measured resource of 4 billion tonnes at >64 wt% Fe for just one of the four orebodies hitherto recognised in the currently still pristine Serra Sul area. These results place Serra Sul as one of the world’s largest iron ore deposits. Exploration also revealed that black shales occur immediately below the BIF unit at Serra Sul. Geological inference suggests that these rocks formed at about 2.7 Ga. The coexistence of black shales and BIF allows reconstructing the evolution of the ocean–atmosphere system during the deposition of the Serra Sul rock sequence, which will shed new light on the vigorous debate involving the Archaean–Proterozoic transition and the rise in atmospheric oxygen, i.e. the Great Oxidation Event. Our Amazon perspective will integrate data from bulk-rock analysis of molybdenum, sulfur, rhenium–osmium, and samarium–neodymium isotopes, as well as microanalysis of iron and oxygen isotopes on a background of detailed petrography and elemental geochemistry. In addition, we aim at identifying the post-depositional processes which led from BIF to high-grade iron ore.