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

乌拉圭异域库奇拉迪奥尼西奥地体的新元古代构造变质历史及其与西南非洲的可能联系和延续

基本信息

批准号：
318297424
负责人：
Professor Dr. Thomas Michael Will, Ph.D.
金额：
--
依托单位：
Lehrstuhl für Geodynamik und Geomaterialforschung
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2022-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/318297424?language=en
关键词：
Neoproterozoic tectonometamorphic history exotic Cuchilla

项目摘要

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.

计划中的项目是 DFG 资助的 SPP 1375 南大西洋边缘流程以及与陆上演变的联系内开展的工作的结果。在那里，我们可以证明（i）主要的泛非碰撞缝合线位于南美洲，（ii）南大西洋并不是沿着这条缝合线打开的，而是沿着位于缝合线以东的新元古代弧后盆地的长轴延伸。这个弧后盆地的遗迹出现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。许多工作人员一致认为，这个地体对南美洲来说是陌生的，可能代表喀拉哈里克拉通的一个碎片。然而，它与西南非洲的联系和延续仍然存在争议，并且提出了不同的联系：（1）安哥拉地块，（2）纳米比亚西北部考科带的沿海地体，（3）加里普带的马尔莫拉地体和（4）南非萨尔达尼亚带的马姆斯伯里地体。每个环节对于罗迪尼亚的古地理重建和西南冈瓦纳的合并都有不同的影响。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全面的了解，目前，这些知识只能在 Cuchilla Dionisio 地体的勘察水平上获得。因此，我们的目标是解决（i）高品位和中品位变沉积岩和变火山岩所经历的压力-温度条件和路径，（ii）发生变质事件的构造背景，以及（iii）Cuchilla Dionisio地体的变质前岩浆原岩形成的构造环境。通过将预期结果与冈瓦纳西南部地质演化的已知信息相协调，我们期望能够确定库奇拉迪奥尼西奥地体向非洲西南部的延续，以及其在罗迪尼亚分散和西冈瓦纳聚集期间最合理的位置。这些结果可能对于重建罗迪尼亚超大陆的构造以及新元古代罗迪尼亚和冈瓦纳西南部各个克拉通块体的古地理位置具有重要意义。