Cordilleran tectonics

科迪勒拉构造

• 批准号: 92417-2008
• 负责人: Price, Raymond
• 金额: $ 1.05万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2009
• 资助国家: 加拿大
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=421604
• 关键词: Cordilleran; tectonics

This research aims to elucidate some of the processes involved in the formation of mountain belts as exemplified by the Canadian Cordillera. The focus is on the origin and evolution of the Cordilleran foreland thrust-and-fold belt in southern Canada and northern Montana, which formed during convergence between ancestral North America and subduction zones along its western margin. The thrust-and-fold belt consists of sheets and slices of supracrustal strata that have been scraped off the under-riding ancestral North American continent and its western margin by an over-riding tectonic collage of accreted, mainly ocean-basin, volcanic rocks called "Intermontane terrane". The research involves preparation of "restored" paleogeological structure sections and maps that portray the supracrustal rocks in the locations and configurations in which they existed prior to the thrusting and the folding. Three deep sedimentary basins from which most of the displaced rocks came (Belt-Purcell, Windermere, and Cordilleran miogeocline) will be restored to their original relationships with each other and with the deep crustal structures in the Paleoproterozoic basement of North America that extends under the Cordillera. The reconstructions will be based mainly on geological maps and balanced deep structure sections. Five additional 1:50,000-scale geologic maps, with structure sections and two new regional. deep, balanced structure sections will be completed from available field data to close a critical information gap in the centre of the region. Deep seismic imaging, together with gravity and magnetic anomaly maps, geological maps, and thermochronometric and geobarometric data from metamorphic and igneous rocks will provide constraints on regional and temporal variations in deformation and on the deep crustal and lithospheric structure. Preliminary analyses indicate that the cumulative displacement across the belt is >300 km. The results of this research can be expected to clarify how, when, and why the southeastern Canadian Cordillera and its rich fossil fuel and mineral resources formed, and also to inform the many people whose fascination with the Rockies arouses their curiousity about the mountains came to be.

这项研究的目的是阐明一些过程中所涉及的山区带的形成为例，加拿大科迪勒拉。重点是加拿大南部和北方蒙大拿州的科迪勒拉前陆冲断褶皱带的起源和演化，该冲断褶皱带是在祖先北美与沿其西缘沿着的会聚过程中形成的。逆冲褶皱带由地壳上的岩层片和岩片组成，这些岩层是被称为“山间火山岩”的增生的主要是洋盆的火山岩的上层构造拼贴物从下层的北美大陆及其西缘刮下来的。研究工作包括制作“复原的”古地质结构剖面图和地图，描绘逆冲推覆和褶皱作用之前表壳岩的位置和结构。三个深沉积盆地，其中大部分的位移岩石（带珀塞尔，温德米尔，和科迪勒拉miogeocline）将恢复到原来的相互关系，并在北美的古元古代基底，在科迪勒拉下延伸的深部地壳结构。重建将主要基于地质图和平衡的深部结构剖面。增加5幅1：50 000比例尺地质图，附有构造剖面图和2幅新的区域图。将根据现有的实地数据完成结构深入、平衡的部分，以填补该区域中心的一个重要信息缺口。深部地震成像，加上重力和磁力异常图、地质图以及来自变质岩和火成岩的热时和地质压力数据，将对变形的区域和时间变化以及深部地壳和岩石圈结构提供制约。初步分析表明，该带的累积位移大于300公里。这项研究的结果有望澄清加拿大东南部科迪勒拉山脉及其丰富的化石燃料和矿产资源是如何、何时以及为什么形成的，并告知许多对落基山脉着迷的人，他们对山脉的好奇心。