Insight into early craton nucleation and stabilization – a case study from crustal and mantle xenoliths from the Star kimberlite mine, East Kaapvaal craton

深入了解早期克拉通成核和稳定——来自东卡普瓦尔克拉通 Star 金伯利岩矿的地壳和地幔捕虏体的案例研究

• 批准号: 448405043
• 负责人: Professor Dr. Horst Marschall
• 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: 2020
• 资助国家: 德国
• 起止时间: 2019-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/448405043?language=en
• 关键词: Insight; into; early; craton; nucleation

Early craton nucleation and stabilization processes can be deciphered from geochemical and petrological information of a physically coherent crust-mantle section. Xenoliths from the Star diamond mine in South Africa (60 pelitic granulites, 15 harzburgites, 27 large-sized peridotitic garnet xenocrysts) provide a unique opportunity to probe a crust-mantle profile of a stable Archean continental region. We will investigate a) the depth distribution and compositional profile from the lower crust to the upper mantle, b) the geochronological comparison on processes in the crust and mantle and c) the thermal evolution of the lithosphere.The depth profile will be obtained by thermobarometry and by the evaluation of petrogenetic grids, which will also provide a chemical stratigraphy when combined with the results of trace-element analyses. The latter will also enable us to estimate the degrees of depletion and re-enrichment in the peridotitic assemblages and to constrain the nature of the pelitic precursors and their components.Age information will be obtained from a) the Re-Os isotope system of the harzburgites, b) the Lu-Hf and Sm-Nd isotope systems of subcalcic garnets and c) the U-Pb dating of zircon and garnet in granulites. This information will be combined into a thermal evolutional history of the East-Kaapvaal craton lithosphere.

早期克拉通成核和稳定化过程可以从物理相干壳幔剖面的地球化学和岩石学信息中解读。南非星星金刚石矿捕虏体（60个泥质麻粒岩，15个方辉橄榄岩，27个大型橄榄岩石榴石捕虏晶）提供了一个独特的机会，探测一个稳定的太古宙大陆区域的壳幔剖面。通过热压法和成岩网格评价，获得下地壳到上地幔的深度分布和成分剖面，B）壳幔过程的年代学对比，以及岩石圈的热演化，结合微量元素分析结果，提供化学地层学。通过方辉橄榄岩的Re-Os同位素体系、次钙质石榴石的Lu-Hf和Sm-Nd同位素体系以及麻粒岩中锆石和石榴石的U-Pb定年，可以获得时代信息。这些信息将被组合成东卡普瓦尔克拉通岩石圈的热演化历史。