The Kinematic Significance of Folds in the Paleoproterozoic Foxe Fold Belt, Melville Peninsula, Nunavut, Canada

加拿大努勒维特梅尔维尔半岛古元古代福克斯褶皱带褶皱的运动学意义

• 批准号: 0911609
• 负责人: John Hepburn
• 金额: $ 21.5万
• 依托单位: Boston College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0911609&HistoricalAwards=false
• 关键词: Kinematic; Significance; Folds; Paleoproterozoic; Foxe

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The principal investigator will use results from numerical modeling of the rotation of fold hinges to elucidate the tectonic history of the Foxe Fold Belt (FFB) in Nunavut, Canada. Orientations of fold hinges and related structures yield invaluable information about past relative movements of tectonic domains. These structures develop and rotate with increasing strain and their rotation paths can be predicted by numerical modeling. The numerical models, which may have wide application in structural geology and mineral exploration, will be tested on the rocks of the Melville Peninsula. The investigators will also constrain the ages of deformation by radiometric dating techniques. The project is in collaboration with the Geological Survey of Canada (GSC) and scientists from other universities. Two Masters students at Boston College will take part in this multidisciplinary project and gain invaluable experience working in remote field areas and cutting-edge laboratories. Local Nunavut Inuit students will be employed in the field by the GSC as part of the Canadian Geo-mapping for Energy and Minerals (GEM) program, which is designed to provide economic and training opportunities to the Inuit community in Nunavut. An Inuit student will work directly with the PI in the field.The ENE-trending FFB comprises Archean basement with overlying and infolded Paleoproterozoic rocks. The investigators will study the kinematics of the deformation, the contacts between the Paleoproterozoic and Archean rocks, as well as regional Archean province boundaries, many of which were active during assembly of the supercontinent Columbia. FFB structures in Melville Peninsula have previously been interpreted as indicating transport to the WSW, based primarily on sheath fold hinge lines. However, results from Baffin Island indicate an opposed direction of transport, and this forms the basis for the numerical testing of two hypotheses. If WSW transport is correct, the issue of oblique transport directions in adjacent segments of the FFB remains unresolved. If the opposite is true, the WSW trend of linear structures may be explained by, for example, extension parallel to the trend of the belt, or other tectonically plausible scenarios. The two hypotheses will be tested through field and laboratory microscopy studies of fold geometries and shear fabrics. In addition, crosscutting relationships and the age of the folds and kinematics of the shear zones will be constrained through U-Pb ion-probe and U-Th-Pb electron-probe techniques, which allow for accurate dating of accessory minerals, particularly in thin-section.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。首席研究员将使用褶皱铰链旋转的数值模拟结果来阐明加拿大努纳武特福克斯褶皱带（FFB）的构造历史。褶皱枢纽和相关构造的方位提供了有关构造域过去相对运动的宝贵信息。这些构造随着应变的增加而发展和旋转，它们的旋转路径可以通过数值模拟来预测。 这些数值模型在构造地质学和矿产勘探中可能有广泛的应用，将在梅尔维尔半岛的岩石上进行测试。研究人员还将通过放射性测年技术来确定变形的年龄。该项目与加拿大地质调查局（GSC）和其他大学的科学家合作。波士顿学院的两名硕士生将参加这个多学科项目，并获得在偏远地区和尖端实验室工作的宝贵经验。当地的努纳武特因纽特学生将被GSC雇用，作为加拿大能源和矿产地理测绘方案的一部分，该方案旨在为努纳武特的因纽特社区提供经济和培训机会。 因纽特人学生将直接与PI在现场工作。ENE方向的FFB包括太古代基底以及上覆和内褶的古元古代岩石。 研究人员将研究变形的运动学，古元古代和太古代岩石之间的接触，以及区域太古代省的边界，其中许多在超大陆哥伦比亚组装期间活跃。 梅尔维尔半岛的FFB结构以前被解释为表明向西澳大利亚州的运输，主要基于鞘褶皱铰链线。然而，巴芬岛的结果表明相反的方向的运输，这形成了两个假设的数值检验的基础。 如果WSW输运是正确的，则FFB的相邻段中的倾斜输运方向的问题仍然没有解决。如果相反，线性结构的WSW趋势可以解释为，例如，平行于带的趋势的延伸，或其他构造上合理的情况。这两个假设将通过现场和实验室显微镜研究褶皱的几何形状和剪切组构进行测试。 此外，将通过U-Pb离子探针和U-Th-Pb电子探针技术，对横切关系和褶皱的年龄以及剪切带的运动学进行限制，从而可以对副矿物，特别是薄片进行准确的定年。