Structured analyses at strained lithotectonic boundaries in ancient orogens

加拿大地盾包括古老的造山带（深度侵蚀的山脉带），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。这种兴趣主要源于这样一个事实，即LTB壁包含重要的地质信息，并且是含金矿脉和其他类型矿床的首选场所。因此，对LTB壁进行了研究，以更好地了解矿石就位过程和地质变形，如LTB平行（切向），韧性剪切。有关围岩剪切的信息也可能提供有价值的线索，如矿床的结构分离部分之间的位移，并提供新的洞察在古造山带的地壳深部水平的韧性变形的性质。与研究学生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年改进技术，并证明，在详细的案例研究中，传统的切向剪切分析方法可能会给出错误的结果。案例研究需要独立的LTB倾角的知识，因此，将设在屏蔽区与高地形起伏。研究生将参加所有的案例研究，旨在促进高素质人才的培训。

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.