Neoproterozoic tectonometamorphic history of the exotic Cuchilla Dionisio Terrane, Uruguay and its possible links with and continuation into SW Africa

计划中的项目是在DFG资助的SPP 1375南大西洋边缘进程内开展的工作的结果，并与陆上演变联系在一起。在那里，我们可以证明：(1)主要的泛非碰撞缝合线位于南美洲；(2)南大西洋并不是沿着这个缝合线开放的，而是沿着位于缝合线以东的新元古代弧后盆地的长轴打开的。这个弧后盆地的残留物分布在现代南大西洋的两侧，包括乌拉圭东部的异地库奇拉·迪奥尼西奥地体。许多工人一致认为，这个地体是南美洲的外来物种，可能代表了卡拉哈里克拉通的一个碎片。然而，它与西南部非洲的连接和延续仍然存在争议，人们提出了不同的连接：(1)安哥拉地块，(2)纳米比亚西北部Kaoko带的沿海地体，(3)Gariep带的Marmora地体，(4)南非索尔达尼亚带的马尔梅斯伯里地体。每一环节对于Rodinia的古地理重建和西南冈瓦那的融合都有不同的意义。在这个项目中，我们计划确定库奇拉-迪奥尼西奥地体的构造热历史，并将其与南大西洋另一边可能的对应物进行比较。这需要对各个地体的变质和岩浆演化有透彻的了解，目前只能在Cuchilla Dionisio地体的侦察水平上获得。因此，我们的目标是解决(I)高、中级变质沉积岩和变质火山岩所经历的压力-温度条件和路径，(Ii)变质事件发生的构造环境，(Iii)Cuchilla Dionisio地体变质前岩浆原岩形成的构造环境。通过将预期结果与有关西南冈瓦那地质演化的已知信息相一致，我们预计能够确定Cuchilla Dionisio Terrane继续进入非洲西南部，以及它在Rodinia扩散和西南冈瓦那组装期间最可信的位置。这一结果可能对重建新元古代Rodinia超大陆的组合形态和Rodinia和Sw Gonawana各克拉通地块的古地理位置具有重要意义。

The planned project is the result of work carried out within the DFG-funded SPP 1375 South Atlantic margin processes and links with onshore evolution. There, we could demonstrate (i) that the main Pan-African collisional suture lies in South America and, (ii) that the South Atlantic did not open along this suture but followed the long axis of a Neoproterozoic back-arc basin, located to the east of the suture. Remnants of this back-arc basin occur on both sides of the modern South Atlantic, including the allochthonous Cuchilla Dionisio Terrane in eastern Uruguay. Many workers agree that this terrane is exotic to South America and may represent a splinter of the Kalahari Craton. However, its connection with and continuation into SW Africa remains controversial and different links have been proposed: (1) the Angola Block, (2) the Coastal Terrane of the Kaoko Belt in NW Namibia, (3) the Marmora Terrane of the Gariep Belt and, (4) the Malmesbury Terrane in the Saldania Belt in South Africa. Each link has a different implication for the palaeogeographic reconstruction of Rodinia and the amalgamation of SW Gondwana. In this project we plan to determine the tectonothermal history of the Cuchilla Dionisio Terrane and compare it with that of its possible counterparts on the other side of the South Atlantic. This requires a thorough knowledge of the metamorphic and magmatic evolution of the respective terranes, which, at present, is only available at a reconnaissance level for the Cuchilla Dionisio Terrane. Therefore, we aim at resolving (i) the pressure-temperature conditions and paths experienced by high- and medium-grade metasedimentary and metavolcanic rocks, (ii) the tectonic settings in which the metamorphic events occurred and, (iii) the tectonic environments in which the pre-metamorphic magmatic protoliths of the Cuchilla Dionisio Terrane formed. By reconciling the expected results with known information on the geological evolution of SW Gondwana we expect to be able to identify the continuation of the Cuchilla Dionisio Terrane into SW Africa and also its most plausible position during Rodinia dispersion and SW Gondwana assembly. The results are likely to be significant for reconstructing the configuration of the assembled Rodinia supercontinent and the palaeogeographic positions of the various cratonic blocks of Rodinia and SW Gondwana during the Neoproterozoic.