The canadian cordillera: testing contrasting models of orogenesis

加拿大山脉：测试造山运动的对比模型

• 批准号: 217314-2009
• 负责人: Johnston, Stephen
• 金额: $ 3.5万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=477984
• 关键词: canadian; cordillera; testing; contrasting; models

Plate tectonics provides an explanation for mountain systems: the collision of continents along a convergent margin. The Himalayan-Alpine chain stems from the attempted subduction of Africa, in the west, and India, in the east, beneath Europe-Asia. Explaining the Rocky Mountains of the Canadian Cordillera, is more difficult. Deformation occurred 80 to 50 million years ago. But ancient North American continental crust extends west to the coast, and there was no collision at 80 Ma. Hence the Rocky Mountains are thought to have formed 2000 kms inboard of a plate margin, and in the absence of a continental collision. The Cordilleran crust sits beneath thrust sheets of oceanic character. Accretion of these "terranes" was thought to explain the Rockies. However, terrane accretion ended by 200 Ma, >100 Ma before the Rockies formed. How do you explain an 80 Ma mountain belt as the result of a 200 Ma collision?

板块构造学为山脉系统提供了一种解释：大陆沿着会聚边缘碰撞。喜马拉雅山-阿尔卑斯山链源于西边的非洲和东边的印度试图俯冲到欧亚之下。解释加拿大科迪勒拉的落基山脉更加困难。变形发生在80至5000万年前。但古代北美大陆地壳向西延伸至海岸，80Ma时并未发生碰撞。因此，人们认为落基山脉是在板块边缘内侧 2000 公里处形成的，并且是在没有大陆碰撞的情况下形成的。科迪勒拉地壳位于具有海洋特征的冲断层之下。这些“地体”的堆积被认为可以解释落基山脉。然而，地体增生在落基山脉形成前 200 Ma 结束，>100 Ma。你如何解释 80 Ma 山带是 200 Ma 碰撞的结果？