The Archean to Paleoproterozoic transition as recovered in the FAR DEEP cores: LA-ICP-MS U-Pb geochronology of detrital zircons and accompanying provenance analysis of siliciclastic sedimentary rocks

在太古代-古元古代过渡时期，地球系统发生了许多全球性的环境变化，同时构造重组导致了超大陆Kenorland的分裂。在FAR-DEEP/ICDP项目中，在俄罗斯北方（Fennoscandia）成功地钻探了记录这些事件的地层序列。- 我们的研究的第一部分，旨在提高激光烧蚀ICP-MS的碎屑锆石U-Pb年代学在FAR深芯记录的这些事件中的三个年龄限制。这些事件是休伦冰川作用、Lomagundi-Jatuli δ 13 C的正偏移和富含Corg沉积物的沉积增强的Shunga事件。我们的数据导致这些事件的时间限制更严格。在标志着从Lomagundi-Jatuli到Shunga事件的过渡的岩石中，我们还发现了U-Pb年龄，现在已被ID-TIMS证实，这些年龄就其地层位置而言太年轻，并且鉴于据称未受干扰的地层序列，很难解释。这些需要通过额外的分析来验证。此外，分析的锆石的来源和性质的回收，部分古太古代地壳将建立由LA ICP-MS铪同位素分析的锆石和离子微探针分析的重矿物，如电气石和金红石。

During the Archaean-Palaeoproterozoic transition many global environmental changes occurred in the Earth’s system at the same time as tectonic reorganisations led to the break-up of the supercontinent Kenorland. Stratigraphic successions registering these events were successfully drilled in northern Russia (Fennoscandia) in the FAR-DEEP/ICDP project. - The first part of our study aimed at improving age constraints by Laser Ablation ICP-MS U-Pb geochronology on detrital zircons for three of these events recorded in the FAR DEEP cores. The events are the Huronian glaciation, the Lomagundi-Jatuli positive excursion of δ13C, and the Shunga event of enhanced deposition of Corg-rich sediments. Our data resulted in tighter temporal constraints for these events. In rocks marking the transition from the Lomagundi-Jatuli to the Shunga event we also found U-Pb ages, now confirmed by ID-TIMS, which are too young regarding their stratigraphic position, and which are difficult to explain in view of the allegedly undisturbed stratigraphic succession. These need to be verified by additional analyses.- Also, the provenance of the analysed zircons and the nature of the recycled, partly Palaeoarchaean crust will be established by LA ICP-MS Hf isotope analysis on dated zircons and by ion microprobe analysis of heavy minerals like tourmaline and rutile.