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Assembly and break-up of the Kaapvaal Craton between 3.0 and 2.0 Ga – new constraints from the U-Pb-Hf detrital zircon record

3.0 至 2.0 Ga 期间 Kaapvaal 克拉通的组装和分解——来自 U-Pb-Hf 碎屑锆石记录的新约束

基本信息

批准号：
413510346
负责人：
Professor Dr. Armin Zeh
金额：
--
依托单位：
Abteilung Petrologie und Geochemie
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2018
资助国家：
德国
起止时间：
2017-12-31 至 2021-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/413510346?language=en
关键词：
Assembly break up Kaapvaal Craton

项目摘要

The Kaapvaal Craton (KC) in southern Africa contains a unique record of the Earth’s history over a period of nearly 2 billion years. It consists of an up to 45 km thick Archean basement made up of greenstones and granitoid rocks, the latter intruded during the successive amalgamation between 3.68 and 2.55 Ga. This basement is overlain by up to 10.000 m thick successions of sedimentary rocks, which were deposited in different basins mainly during three periods: group I at 3.5-3.2 Ga (sedimentary rocks in basins around the Barberton GSB, Swaziland, Limpopo Belt Central Zone); group II at 3.0-2.8 Ga (Witwatersrand and Pongola basins); group III at 2.65-2.08 Ga (Transvaal-Griqualand West basins, Limpopo Belt Central Zone). The sedimentary rocks of group I and II were deposited during the assembly of the KC accompanied by abundant granitoid intrusions, and those of group III during a period of magmatic quiescence. Consequently, detrital (magmatic) zircon grains in group I and II rocks have a great potential to provide detailed information about the amalgamation process of the KC, and those of group III about post-amalgamation processes, including information about an enigmatic hinterland, which supplied abundant zircon detritus during the Paleoproterozoic between 2.55 and 2.06 Ga. In this project, the amalgamation process of the proto-KC, as well as the nature of the enigmatic hinterland, its crustal evolution through time, and consequences for the late Archean to Paleoproterozoic continent reconstruction will be investigated by a systematic analysis of U-Pb-Hf isotopes and textures of detrital zircon grains in 25 key samples.

非洲南部的卡普瓦尔火山（KC）包含了近20亿年来地球历史的独特记录。它由一个厚达45 km的太古代基底组成，由绿岩和花岗岩类岩石组成，后者在3.68 - 2.55 Ga之间的连续合并期间侵入。该基底上覆盖着厚度达10.000 m的沉积岩系列，这些沉积岩主要在三个时期沉积在不同的盆地中：I组，3.5-3.2 Ga（巴伯顿GSB、斯威士兰、林波波带中心带周围盆地中的沉积岩）; II组，3.0-2.8 Ga（威特沃特斯兰德和蓬戈拉盆地）;第III组，2.65-2.08 Ga（德兰士瓦-格里夸兰西盆地，林波波带中心带）。第I组和第II组的沉积岩沉积在组装的KC伴随着丰富的花岗岩类侵入体，和第III组的岩浆静止期。因此，碎屑（岩浆）锆石颗粒在第一和第二组岩石有很大的潜力，提供详细的信息的合并过程中的KC，和那些第三组的合并后的过程，包括一个神秘的腹地，提供丰富的锆石碎屑在古元古代2.55和2.06 Ga之间的信息。在这个项目中，原KC的合并过程，以及神秘的腹地的性质，它的地壳演化，通过时间，并为晚太古代古元古代大陆重建的后果进行了系统的分析，在25个关键样品的碎屑锆石颗粒的U-Pb-Hf同位素和结构的研究。