Collaborative Research: Tectonic Significance of Long Run-Out Coarse-Grained Facies in the Cordilleran Foreland Basin

合作研究：科迪勒拉前陆盆地长程粗粒相的构造意义

• 批准号: 1524578
• 负责人: John Geissman
• 金额: $ 11.23万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2023-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524578&HistoricalAwards=false
• 关键词: Collaborative; Research; Tectonic; Significance; Long

Sediments deposited in basins in front of fold-and-thrust belts, also known as foreland basins, record the tectonic growth and development of the belts. One prevalent model for sedimentation in these basins is that fine-grained sediments in record tectonic growth of the thrust belt whereas coarse-grained sediments accumulate during periods of thrust belt inactivity. This project aims to test this model using innovative methods to determine the timing of sedimentation in the Idaho-Wyoming fold-and-thrust belt. A successful challenge of the prevalent model has the potential to change geological understanding of how fold-and-thrust belts belts develop. This is of particular importance because the Idaho-Wyoming thrust belt and associated foreland basins host important hydrocarbon resources. A better understanding of basin development will provide important insights into hydrocarbon exploration. The project would advance other desired societal outcomes through: (1) full participation of women in STEM; (2) improved STEM education and educator development through engagement of a K-12 science teacher or undergrad student in the UTeach program, and participation in the Geoscience Teacher Symposium for K-12 science teachers; (3) increased public scientific literacy and public engagement with STEM through development of displays and videos for the University of Arizona Flandau Center; and (4) development of a globally competitive STEM workforce through training of graduate and undergraduate students.For over two decades foreland basin stratigraphers and sedimentologists have used the two-phase model of foreland basin subsidence to interpret stratigraphic sequences in foreland settings. This model hypothesizes that episodes of fine-grained distal sedimentation are the syntectonic response to orogenic growth and rapid flexural subsidence, whereas coarse-grained distal facies accumulate during periods of thrust belt inactivity, erosion, and isostatic rebound. This research project will test this model using geo/thermochronologic and magnetic polarity stratigraphic study of mid- to Upper Cretaceous foreland basin deposits in northeast Utah and southwest Wyoming, a classic foreland. Detrital geochronology (U-Pb on detrital zircon and apatite) and thermochronology (apatite fission track) will determine detrital lag-times (the time difference between the exhumation age of a sediment grain from the source terrane and its depositional age in the basin). Second, better age control in the poorly dated proximal part of the basin fill will be established by using magnetic polarity stratigraphy on fine-grained interbeds within thick alluvial fan deposits located adjacent to major thrust faults. This combined approach allows accurate correlation of the proximal and distal facies, and establishment of the time difference between exhumation and depositional ages of the distal, coarse-grained intervals. Long lag-times in the distal coarse-grained facies and irregular long-term trends in lag-time, this would support the two-phase model whereas relatively brief (5 Myr) lag-times and a steady to decreasing lag time trend would indicate that coarse-grained sediments prograded directly into the distal basin during tectonic events in the thrust belt and therefore would nullify the two-phase model.

沉积物沉积在盆地前，褶皱带（也称为前陆盆地），记录了皮带的构造生长和发育。这些盆地中沉积的一种普遍模型是，在推力带的构造构造生长中，细粒度的沉积物在推力皮带不活动期间积累了粗粒的沉积物。该项目旨在使用创新的方法测试该模型，以确定爱达荷州自愿的褶皱和直觉带中沉积的时机。普遍模型的成功挑战有可能改变对折叠皮带如何发展的地质理解。这尤其重要，因为爱达荷州的推力带和相关的前陆盆地具有重要的碳氢化合物资源。对盆地发展的更好理解将为碳氢化合物勘探提供重要的见解。该项目将通过：（1）妇女在STEM中的全面参与来推动其他期望的社会成果； （2）通过参与K-12科学老师或本科生参加UTEACH计划，改善了STEM教育和教育者的发展，并参加了K-12科学老师的地球科学教师研讨会； （3）通过为亚利桑那大学Flandau中心开发展示和视频的开发，增加了公共科学素养和与STEM的公众参与； （4）通过培训研究生和本科生来发展全球竞争激烈的STEM劳动力。在二十年中，前陆盆地地层学家和沉积物学家使用了前陆盆地盆地沉积物的两阶段模型来解释前景环境中的地层序列。该模型假设细粒度远端沉积物的发作是对造山生长和快速弯曲沉降的含量反应，而在推力皮带不活跃，侵蚀和等静态反弹的期间，粗粒远的远端相处会累积。该研究项目将使用犹他州东北部和西南怀俄明州中部白垩纪前盆地盆地沉积物中的地理/热力学和磁性极性地层研究测试该模型。碎屑地质学（碎屑锆石和磷灰石上的U-PB）和热团学（磷灰石裂变轨道）将确定碎屑滞后时间（源地形地层的沉积物颗粒的发掘年龄与盆地沉积年龄之间的散布年龄之间的时间差）。其次，将通过在厚厚冲积扇形沉积物中使用磁性极性地层上使用磁性极性地层来建立盆地填充较差的近端部分的更好年龄控制。这种合并的方法允许近端和远端相的准确相关，并建立了远端，粗粒间隔的挖掘与沉积年龄之间的时差。远端粗粒剂相的长时间滞后时间和滞后时间的不规则长期趋势，这将支持两相模型，而相对短暂的（5 Myr）滞后时间，并且稳定地减少延迟时间趋势，这将表明在推力领域的构造模型中，远端的底层中的粗粒颗粒的沉积物将直接延伸到远端，并将两种模型置于两个模型中。