Testing Jura-Cretaceous Terrane Displacement Hypotheses - a Critical Piece of the Cordilleran Puzzle

地壳碎片在会聚板块边界（俯冲带）的碰撞是一个基本的造山过程，称为增生造山作用。对我们来说，更好地了解这一过程很重要，因为它产生了广阔的山带（造山带），深刻地影响了长期的全球气候模式，承载了多种类型的矿床，并创造了地球上一些最危险的地质环境。北美科迪勒拉是一个典型的增生造山带，它是与大陆西缘的海洋板块进行了长达1 - 2亿年的长期斜辐合的产物。随着时间的推移，倾角的变化导致构造环境在挤压和伸展状态之间切换，两者都伴随着不同程度的左旋（左旋）和右旋（右旋）侧向剪切。这种剪切作用使科迪勒拉造山带的外西部分先向南移动，然后向北移动。许多用来评估这些位移的构造和其他地质关系已经被更年轻的套印事件所掩盖。这些位移估计（100到1000公里）的不确定性阻碍了我们重建北美西部地质演化的能力，这是科迪勒拉地质最具争议的方面之一。我的研究项目的长期愿景是运用我的研究优势，以创新的方式解开复杂而神秘的造山过程，并促进对整个地球历史上构造过程的长期变化的分析。在接下来的5年里，拟议的研究将集中在验证假设，即在晚侏罗世-早白垩纪时期，科迪勒拉的外西部向南移动了约800公里。短期目标包括确定结构和岩石过程的年代，并在不列颠哥伦比亚省西南部和育空地区进行详细的实地调查，在那里将使用最先进的技术仔细分析关键的地质关系。具体来说，我们将：1)验证在晚侏罗世-早白垩世期间科迪勒拉西部向南移动的假设，以及(2)评估认为科迪勒拉西部被白垩纪缝合带与科迪勒拉更内侧部分分开的其他假设。我们的发现将对科迪勒山脉的造山过程提供更复杂的理解。这将有利于在科迪勒拉和世界范围内研究类似问题的广泛研究人员。加拿大工业也将受益于额外的见解，可以帮助制定育空和不列颠哥伦比亚省的矿床勘探战略。

Collision of crustal fragment at convergent plate boundaries (subduction zones) is a fundamental mountain building process called accretionary orogenesis. It is important for us to better understand this process because it gives rise to expansive mountain belts (orogens), profoundly influencing long-term global climate patterns, hosts multiple styles of ore deposits, and creates some of the most hazardous geologic environments on Earth. The North American Cordillera is a classic accretionary orogen that is a product of protracted oblique convergence with oceanic plates along the continent's western margin for >200 million years. Changes in the obliquity over time led to tectonic settings that switched between compressional and extensional regimes, both accompanied by varying degrees of left-handed (sinistral) and right-handed (dextral) lateral shearing. This shearing imparted southward and then northward displacements of outer western portions of the Cordilleran orogen. Many of the structures and other geological relationships used to assess these displacements have been obscured by younger overprinting events. The resulting uncertainty in estimates for these displacements (100's to 1000's km) hinders our ability to reconstruct the geologic evolution of western North America and is one of the most controversial aspects of Cordilleran geology. The long-term vision of my research program is to apply my research strengths in innovative ways to unravel complex and enigmatic processes involved in mountain building and facilitate analysis of secular changes of tectonic processes throughout Earth history. Over the next 5 years, the proposed research will focus on testing hypotheses that suggest >800 km southward displacement of the outer western portion of the Cordillera in Late Jurassic-Early Cretaceous time. Short-term objectives involve dating of structural and petrologic processes coupled with detailed field investigations within southwest BC and Yukon where critical geological relationships will be carefully analyzed using state-of-the-art techniques. Specifically, we will: 1) Test hypotheses that invoke significant southward displacement of western portions of the Cordillera in Late Jurassic-Early Cretaceous time, and (2) Evaluate alternative hypotheses that suggest the western Cordillera is separated by a Cretaceous suture zone from the more inboard portion of the Cordillera. Our findings will provide a more sophisticated understanding of Cordilleran mountain building processes. This will benefit a broad base of researchers working on similar problems in the Cordillera and worldwide. Canadian Industry will also benefit from the additional insight that can help inform exploration strategies for ore deposits in Yukon and BC.