Structured analyses at strained lithotectonic boundaries in ancient orogens

加拿大地盾包括古老的造山带(被深度侵蚀的山带)，其中充满了经济矿藏。在大多数造山带中，大型岩体之间的剪切接触，也称为岩石构造边界(LTB)，引起了研究地球科学家和经济地质学家的极大兴趣。人们之所以感兴趣，主要是因为LTB围岩包含重要的地质信息，是含金脉和其他类型矿床的首选地点。因此，对LTB墙进行了研究，以更好地了解矿体侵位过程和LTB平行(切向)、韧性剪切等地质变形。有关围岩剪切的信息还可能提供关于矿床构造分离部分之间的位移的有价值的线索，并为了解古代造山带深部地壳水平的韧性变形的性质提供新的见解。与研究人员和一位英国同事一起，我开发了更强大的技术来研究暴露良好的LTB墙段的切向韧性剪切。我们建议在2006-2010年改进这些技术，并在详细的案例研究中证明，传统的切向剪切分析方法可能会给出错误的结果。案例研究需要独立了解LTB倾角，因此将位于地形起伏较高的盾构区域。研究型学生将参加所有案例研究，旨在为培养高素质人才做出贡献。

The Canadian Shield includes ancient orogens (deeply-eroded mountain belts) replete with economic mineral deposits. In most orogens, sheared contacts between large rock masses, also called lithotectonic boundaries (LTBs), have attracted much interest by research geoscientists and economic geologists. The interest stems mainly from the fact that LTB walls contain important geological information, and are a preferred locus of gold-bearing veins and other kinds of ore deposits. LTB walls have therefore been studied to gain a better understanding of ore-emplacement processes and geological deformations such as LTB-parallel (tangential), ductile shear. Information about the wall-rock shear may also furnish valuable clues as to the displacement between structurally separated parts of ore deposits, and provide new insight into the nature of ductile deformation at deep-crustal levels in ancient orogens. Together with research students and a British colleague, I developed more powerful techniques for investigating the tangential ductile shear of well-exposed LTB-wall segments. We propose to refine the techniques in 2006-2010, and demonstrate, in detailed case studies, that the conventional methods of tangential-shear analysis may give erroneous results. The case studies require independent knowledge of LTB-dip angles, and will therefore be sited in shield areas with high topographic relief. Research students will participate in all case studies, designed to contribute to the training of highly qualified personnel.