Testing channel flow: Architecture of the Northern Monashee Mountains, SE Canadian Cordillera

这个研究项目是由麦吉尔大学、卡尔加里大学和商业资源公司的地球科学家合作进行的，旨在详细了解加拿大东南部科迪勒拉的莫纳西山脉地壳的结构和构造演化。这些山脉中的岩石形成了前寒武纪晚期裂陷大陆边缘的一部分，在中生代和第三纪的碰撞事件中，由于褶皱和逆冲而变厚。它们当时位于地壳中部，内部结构是在接近熔化的温度下形成的。最近的模拟研究表明，在这种条件下，这些岩石可能会通过通道流入压力较低的地区。这是Monashees的主张，并得到了整个地区变质时代变化的支持，但它似乎与现有的结构解释相冲突。我们提出了一个详细的结构研究在两个良好暴露的山谷最近由冰川空出，与后续变质和地质年代学研究，旨在解决这一明显的冲突。Monashees中含有丰富的碳酸盐岩层，具有钽和铌的远景。沿其长度，可能由于变形，技能的厚度变化显著。我们计划中的研究将更好地了解厚度变化的原因，并将有助于勘探经济上可行的矿床。这项研究对我们了解世界范围内造山带深部地壳演化具有重要意义，并对研究区域和其他地区的矿产勘探具有直接意义。

This research project, a collaboration between Earth scientists from McGill University, the University of Calgary and Commerce Resources Corporation, is designed to produce a detailed understanding of the structural and tectonic evolution of the crust in the Monashee Mountains of the SE Canadian Cordillera. The rocks in these mountains form part of a late-Precambrian rifted continental margin that was thickened by folding and thrusting during collisional events in the Mesozoic and Tertiary. They were in the middle crust at the time, and the structures within them formed at temperatures close to melting. Recent modelling studies have indicated that under these conditions such rocks may flow in channels into regions of lower pressure. This has been advocated for the Monashees and is supported by variations in metamorphic ages across the region, but it appears to conflict with existing structural interpretations. We propose a detailed structural study in two well-exposed valleys recently vacated by glaciers, with follow-up metamorphic and geochronological studies, aimed at resolving this apparent conflict. The Monashees contain abundant carbonatite sills, which are prospective for tantalum and niobium. The sills vary significantly in thickness along their lengths, probably due to the deformation. Our planned research will provide a better understanding of the causes of thickness variation and will aid the exploration for economically viable deposits. This study has implications for our understanding of the evolution of the deeper crust in orogens worldwide, and direct bearing on mineral exploration in the region of study and elsewhere.