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

南部非洲的卡普瓦尔克拉通(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公里的太古宙基底组成，由绿岩和花岗岩类岩石组成，后者在3.68~2.55Ga之间的连续融合期间侵入。该基底被厚达10.000米的沉积岩序列覆盖，主要在三个时期内在不同的盆地中沉积：第一组3.5Ga-3.2Ga(位于斯威士兰林波波带中央地带Barberton GSB周围盆地的沉积岩)；第二组3.0Ga-2.8Ga(威特沃特斯兰德盆地和蓬格拉盆地)；第三组2.652.08Ga(林波带中央带德兰斯-格里夸尔盆地和西部盆地)。第I组和第II组的沉积岩是在伴随大量花岗岩类侵入岩的KC组装过程中沉积的，而第III组的沉积岩则是在岩浆静止期沉积的。因此，I组和II组岩石中的碎屑(岩浆)锆石颗粒具有很大的潜力提供关于KC的融合过程的详细信息，以及III组的关于混合后过程的详细信息，包括关于2.55~2.06 Ga之间的古元古代提供丰富的锆石碎屑的神秘腹地的信息。在这个项目中，将通过对25个关键样品的U-Pb-Hf同位素和碎屑锆石颗粒结构的系统分析，研究原始KC的融合过程，神秘腹地的性质，地壳随时间的演化，以及对晚太古代-古元古代大陆重建的影响。

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.