Archaean Crystalline Rocks of the Eastern Kaapvaal Craton
Archaean Crystalline Rocks of the Eastern Kaapvaal Craton
复制标题
DOI：
10.1007/978-3-319-78652-0_1
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
A. Kröner;J. Hoffmann;J. Wong;H. Geng;K. Schneider;H. Xie;Jin-Hui Yang;N. Nhleko
中科院分区：
文献类型：
--
作者：
A. Kröner;J. Hoffmann;J. Wong;H. Geng;K. Schneider;H. Xie;Jin-Hui Yang;N. Nhleko
卡普瓦尔克拉通东部代表典型的花岗岩-绿岩地形，包含非洲大陆最古老的岩石，从 3.66 Ga 到 2.67 Ga 表现出约 1000 Ma 的地壳演化。花岗岩岩石主要由英闪长岩-长角闪长岩-花岗闪长岩 (TTG) 组合组成，真正的花岗岩在大约 3 Ga 时变得丰富。绿岩以保存完好的以及经过充分研究的 3.54–3.2 Ga 巴伯顿绿岩带和较小的约。 3.45 Ga 绿岩带残余物包裹在 BGB 周围的 TTG 片麻岩中以及斯威士兰的古代片麻岩杂岩中。 TTG 和绿岩单元的起源仍然存在争议，因为强烈的变形和中高级变质作用已经消除了大部分原始岩石关系。这主要是由于大约发生在大约的一次广泛的构造-岩浆-变质事件。 3.2 Ga 几乎影响了克拉通的整个东部地区。在此事件期间，地幔熔体提供的热量导致了广泛的地壳内熔化，熔体迁移导致下地壳中放射性元素和其他可移动元素的消耗。花岗岩岩浆的长期提取高达约 2.67 Ga，增加了下地壳的刚性，导致卡普瓦尔克拉通的构造稳定。
The eastern part of the Kaapvaal Craton represents a classical granitoid-greenstone terrain and contains the oldest rocks of the African continent, exhibiting about 1000 Ma of crustal evolution from 3.66 to 2.67 Ga. The granitoid rocks predominantly consist of the tonalite–trondhjemite–granodiorite (TTG) association with true granites becoming abundant at about 3 Ga. Greenstones are represented by the well-preserved and well-studied 3.54–3.2 Ga Barberton Greenstone Belt and smaller ca. 3.45 Ga greenstone belt remnants infolded in TTG gneisses around the BGB as well as in the Ancient Gneiss Complex in Swaziland. The origin of both the TTGs and greenstone units is still debated as strong deformation and medium- to high-grade metamorphism have obliterated most of the original rock relationships. This is largely due to an extensive tectono-magmato-metamorphic event at ca. 3.2 Ga that affected virtually the entire eastern part of the craton. Heat provided by mantle-derived melts during this event led to extensive intracrustal melting, with melt migration resulting in depletion of the lower crust in radioactive and other mobile elements. Long-lived extraction of granitoid magmas up to about 2.67 Ga increased the rigidity of the lower crust, causing tectonic stabilization of the Kaapvaal Craton.