Structural and tectonic evolution of orogenic belts, with an emphasis on kinematics of shear zones, Archean tectonics and implications for mineralization

造山带的结构和构造演化，重点是剪切带的运动学、太古代构造及其对矿化的影响

• 批准号: RGPIN-2014-04346
• 负责人: Lin, Shoufa
• 金额: $ 3.13万
• 依托单位: University of Waterloo
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=587748
• 关键词: Structural; tectonic; evolution; orogenic; belts

My long term objective of research is a better understanding of structural and tectonic evolution of mountain belts of various ages, evolution of tectonic processes through time and structural and tectonic control on mineralization. The proposed study will focus on three ancient mountain belts, the Archean Superior craton in Canada, the Proterozoic to Mesozoic South China Block and the Paleozoic Central Asian Orogenic Belt (CAOB) in China. My extensive experience with the Canadian Appalachians in the last two decades, one of the best studied orogens in the world, has proved to be very beneficial to our work in the Superior craton, the South China Block and the CAOB. A fundamental debate concerning Archean tectonic processes is that of vertical vs. horizontal tectonism. There is a tendency for advocates of plate tectonics (horizontal tectonism) in the Archean to downplay the significance, if not deny the presence, of vertical tectonism, and vice versa. Our work in the Superior craton has led to the recognition of evidence for both vertical and horizontal tectonism, and more importantly for their synchronous operation. We have proposed that synchronous vertical and horizontal tectonism was an important process in the Neoarchean and represented a transition from dominant vertical tectonism in the Meso-(and Paleo-?) Archean to dominant horizontal tectonism in Proterozoic and Phanerozoic. Such a conclusion makes it necessary that both processes (as opposed to either one or the other) and their potential interactions are considered in interpretations of Archean terrains. As importantly, we have suggested that such a process in the period of transition was important for gold mineralization, and the Hemlo deposit, a world-class deposit with >650 tons of gold, formed during the process. These interpretations were mostly based on data from the western, in particular the northwestern Superior craton. Here we propose to test these interpretations and their general applicability, not only through continuing work in the western Superior craton, but more importantly through additional work in the southeastern Superior craton, in particular in the Abitibi greenstone belt. The Abitibi belt is arguably the best studied and most prolific greenstone belt in the world, containing numerous world-class gold deposits. Vast amount of data is available concerning the belt and the deposits. In addition, the PI is familiar with the geology of the belt. These form a very good basis for the proposed study. As importantly, essentially all major gold deposits in the belt are spatially associated with two major shear zones in the area (the Desptor-Porcupine and Larder Lake-Cadillac faults) and the two shear zones spatially coincide with what appear to be synclinal keels between granitoid domes, as predicted by our model. This area thus provides an ideal opportunity to test the model. In addition, we will investigate the relative significance of vertical and horizontal tectonism and its variation with time and space (if any). We suspect that there exists a feedback relationship between the two processes and will explore the possible mechanisms for this. The results will have significant implications for Archean geological evolution in general and for Archean gold mineralization. The latter will help exploration targeting in Archean terranes worldwide. Our work in the South China Block and the CAOB will focus on the geometry, kinematics, and temporal evolution of major shear zones. The results will shed significant light on the tectonic evolution of these two accretionary orogens, in particular on the potential role of large-scale orogen-parallel motion along terrane-bounding shear zones in the amalgamation of the terranes.

我的长期研究目标是更好地了解不同时代山带的构造和构造演化、构造过程随时间的演化以及构造和构造对矿化的控制。拟议的研究将集中在三个古老的山地带上，即加拿大的太古代克拉通、元古代至中生代的华南地块和中国的古生代中亚造山带（CAOB）。过去二十年里，我在加拿大阿巴拉契亚山脉（世界上研究最深入的造山带之一）方面获得了丰富的经验，事实证明，这对我们在苏必利尔克拉通、华南地块和中亚造山带的工作非常有益。 关于太古代构造过程的一个基本争论是垂直构造作用与水平构造作用的争论。太古代板块构造论（水平构造论）的拥护者倾向于淡化垂直构造论的重要性（如果不否认垂直构造论的存在的话），反之亦然。我们在上克拉通的工作使人们认识到了垂直和水平构造运动的证据，更重要的是它们的同步运行的证据。我们提出，同步的垂直和水平构造作用是新太古代的一个重要过程，代表着从中古宙（和古？）太古宙的垂直构造作用占主导地位到元古代和显生宙的水平构造作用占主导地位的转变。这一结论使得在解释太古代地形时必须考虑这两个过程（而不是其中一个或另一个）及其潜在的相互作用。同样重要的是，我们认为过渡时期的这一过程对于金矿化非常重要，而 Hemlo 矿床（金矿量超过 650 吨的世界级矿床）就是在此过程中形成的。这些解释主要基于来自西部的数据，特别是上克拉通西北部的数据。在这里，我们建议测试这些解释及其普遍适用性，不仅通过在苏必利尔克拉通西部的持续工作，而且更重要的是通过在苏必利尔克拉通东南部，特别是在阿比蒂比绿岩带的额外工作。阿比蒂比带可以说是世界上研究最透彻、产量最多的绿岩带，蕴藏着众多世界级金矿。有关传送带和矿床的大量数据是可用的。此外，PI 熟悉该带的地质情况。这些为拟议的研究奠定了良好的基础。同样重要的是，基本上该带中的所有主要金矿床在空间上都与该地区的两个主要剪切带（德斯普托-豪猪断层和拉德湖-凯迪拉克断层）相关，并且这两个剪切带在空间上与花岗岩穹顶之间的向斜龙骨重合，正如我们的模型所预测的那样。因此，该区域提供了测试模型的理想机会。此外，我们还将研究垂直和水平构造作用的相对意义及其随时间和空间的变化（如果有的话）。我们怀疑这两个过程之间存在反馈关系，并将探讨其可能的机制。这些结果将对太古代地质演化和太古代金矿化产生重大影响。后者将有助于全球太古宙地体的勘探目标。 我们在华南区块和 CAOB 的工作将集中于主要剪切带的几何形状、运动学和时间演化。这些结果将为这两个增生造山带的构造演化提供重要线索，特别是沿着地体边界剪切带的大规模造山带平行运动在地体合并过程中的潜在作用。