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: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633738
• 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，构造过程的时间演化以及构造和构造对成矿的控制。研究对象包括加拿大太古宙上克拉通、中国南方元古代—中生代地块和中国古生代中亚造山带三个古山带。加拿大阿巴拉契亚山脉是世界上研究得最好的造山带之一，过去20年我在这里的丰富经验对我们在Superior克拉通、华南地块和CAOB的工作非常有益。关于太古宙构造过程的一个基本争论是垂直构造与水平构造的争论。太古宙板块构造论（水平构造论）的拥护者有一种倾向，即如果不否认垂直构造论的存在，也会淡化其重要性，反之亦然。我们在上克拉通的工作使我们认识到垂直和水平构造作用的证据，更重要的是它们的同步作用。我们认为，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、古太古代垂直构造主导作用的过渡。元古代和显生宙太古宙至主导水平构造。这样的结论使得在太古宙地形的解释中有必要考虑这两个过程（而不是其中一个或另一个）及其潜在的相互作用。重要的是，我们认为这一过渡时期的成矿作用对金矿化具有重要意义，并在此过程中形成了含金量达50650吨的世界级矿床Hemlo矿床。这些解释大多基于西部，特别是西北部苏必利尔克拉通的数据。为了验证这些解释及其普遍适用性，我们不仅要在西部上优克拉通继续开展工作，更重要的是在东南部上优克拉通，特别是在阿比提比绿岩带开展额外的工作。阿比提比带可以说是世界上研究得最好、最丰富的绿岩带，包含许多世界级的金矿床。有关该带和矿床的资料非常丰富。此外，PI熟悉该带的地质情况。这些构成了本研究的良好基础。同样重要的是，该带所有主要金矿床在空间上基本上都与该地区的两个主要剪切带（Desptor-Porcupine断层和Larder Lake-Cadillac断层）有关，并且这两个剪切带在空间上与花岗岩类穹窿之间的向斜龙骨相吻合，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，并将探索可能的机制。研究结果对太古宙地质演化和金矿化具有重要意义。后者将有助于全球太古宙地层的勘探定位。我们在华南地块和CAOB的工作将侧重于主要剪切带的几何、运动学和时间演化。研究结果将对这两个造山带的构造演化，特别是沿地界剪切带的大规模造山带平行运动在地体合并中的潜在作用提供重要的启示。