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，构造作用随时间的演化以及构造和构造对成矿作用的控制。该研究将集中在加拿大太古代上级克拉通、中国元古宙-中生代华南地块和古生代中亚造山带三个古山脉带。我在过去20年中对加拿大阿巴拉契亚山脉的广泛研究经验，证明对我们在上级克拉通、华南地块和CAOB的工作非常有益，阿巴拉契亚山脉是世界上研究得最好的造山带之一。 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。在太古代，板块构造（水平构造作用）的倡导者倾向于淡化垂直构造作用的重要性，如果不是否认其存在的话，反之亦然。我们在上级克拉通的工作使我们认识到垂直和水平构造作用的证据，更重要的是认识到它们的同步作用。我们提出，垂直和水平同步构造作用是新太古代的一个重要过程，代表了中（古）太古代至元古宙和中生代的主导水平构造作用。这样的结论使得在解释太古代地形时有必要考虑这两个过程（而不是一个或另一个）及其潜在的相互作用。同样重要的是，我们认为，在过渡时期的这种过程是重要的金矿化，和Hemlo存款，一个世界级的存款，超过650吨的黄金，在这个过程中形成。这些解释主要基于西部，特别是西北部上级克拉通的数据。在这里，我们建议测试这些解释和它们的普遍适用性，不仅通过继续在西部上级克拉通的工作，但更重要的是通过额外的工作在东南部上级克拉通，特别是在阿比提比绿岩带。Abitibi带可以说是世界上研究得最好和最多产的绿岩带，包含许多世界级的金矿。大量的数据是关于带和存款。此外，PI熟悉带的地质。这为拟议的研究提供了很好的基础。同样重要的是，基本上所有的主要金矿带在空间上与两个主要的剪切带在该地区（的Desptor-Porcupine和Larder湖-凯迪拉克故障）和两个剪切带空间上一致，似乎是向斜龙骨花岗岩圆顶之间，我们的模型预测。因此，该区域提供了测试模型的理想机会。此外，我们将探讨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。研究结果对太古宙地质演化和太古宙金矿化具有重要意义。后者将有助于在全球范围内寻找太古宙的勘探目标。 我们在华南地块和CAOB的工作将集中于主要剪切带的几何学、运动学和时间演化。这一结果将对这两个增生造山带的构造演化，特别是对大规模造山带平行运动的潜在作用，沿着剪切带边界的剪切带在合并的岩石有重要意义。