Chemostratigraphy of a Paleoproterozoic BIF-MnF succession - the Voelwater Subgroup, Transvaal Supergroup, South Africa

古元古代 BIF-MnF 序列的化学地层学 - 南非德兰士瓦超群 Voelwater 亚群

• 批准号: 28294136
• 负责人: Professor Dr. Harald Strauß
• 金额: --
• 依托单位: Institut für Geologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2006
• 资助国家: 德国
• 起止时间: 2005-12-31 至 2009-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/28294136?language=en
• 关键词: Chemostratigraphy; Paleoproterozoic; BIF; MnF; succession

When and how the oxygen content of the Earth s atmosphere rose and how this build-up of oxygen reflects the evolution of photosynthesis and early microbial life constitutes an important unresolved question in Earth System Sciences. The rise of atmospheric oxygen may in fact have been efficiently delayed until the late Paleoproterozoic by the deposition of banded iron formations (BIF) and manganese formations (MnF). Until today, the exact origin of BIF and MnF successions, chemical sediments that have no analogue in the Phanerozoic, has not found an unequivocal explanation. The early Paleoproterozoic Hotazel Formation, Transvaal Supergroup, South Africa, is a unique succession of BIF and MnF, accompanied by shallow water stromatolitic dolomites. The succession is virtually undeformed and unmetamorphosed, is extremely well exposed and hosts the world s largest resource of minable manganese ore. The Hotazel Formation is, thus, the ideal unit to conduct a systematic chemostratigraphic study focusing on stable (C, O) and radiogenic (Sr, Pb, Nd, Hf) isotope systematics in order to constrain the factors that controlled precipitation and spatial separation of BIF, MnF and shallow water carbonates during this critical interval of Earth s history.

地球大气的氧气含量何时以及如何升起，以及这种氧的积聚如何反映光合作用和早期微生物寿命的演变构成了地球系统科学中的一个重要的未解决的问题。实际上，大气中的氧气的兴起可能已经有效地延迟了，直到通过带状铁地层（BIF）和锰地层（MNF）的沉积为止，直到晚期的古元古代。直到今天，BIF和MNF演替的确切起源，即在Phanerozoic中没有类似物的化学沉积物的确切起源，尚未发现明确的解释。南非Transvaal Supergroup的早期古元核形成是BIF和MNF的独特继承，并伴有浅水基质质白云素。该继承实际上是未完整的且未变形的，暴露得非常好，并拥有世界上最大的锰矿石资源。因此，Hotazel​​的形成是进行系统的化学化学研究研究的理想单位，该研究重点是稳定（C，O）和放射原（SR，PB，PB，ND，HF）同位素系统学，以限制在本次数的降水和空间分离的因素，以控制BIF，MNF和Hallow Water Carbonate在此广泛的地球历史上的空间分离。