CAREER: Middle and Late Cenozoic Surface Uplift and Climate along the Strike of the Rocky Mountains: Refining the Development of an Intracontinental Mountain Belt

职业：新生代中晚期地表隆起和落基山脉走向的气候：完善陆内山地带的发展

• 批准号: 1454802
• 负责人: Majie Fan
• 金额: $ 48.56万
• 依托单位: University of Texas at Arlington
• 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: 2015-06-01 至 2022-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1454802&HistoricalAwards=false
• 关键词: CAREER; Middle; Late; Cenozoic; Surface

The Rocky Mountains of the western North America is the premier example of intracontinental mountain belts. Thick Cretaceous marine deposits provide unambiguous evidence that the region was near sea level at about 80 Ma ago. However, the history of subsequent vertical movements that formed present topography are less well constrained, yet crucial for understanding the tectonic processes and driving forces by which mountains form in continental interiors. This project aims to constrain the surface uplift of the Rocky Mountains and western Great Plains and associated climate changes during the last 35 million years. State-of-the-art isotopic methods will be used to estimate the paleotopography along transects in the northern and southern Rocky Mountains. The results will test the hypothesis that the timing and magnitude of uplift of the Rockies varied along its length, variations that can constrain the complex geodynamic processes the formed the Rockies during the this time period. The educational component of this CAREER award involve concerted efforts to engage students from underrepresented minorities in STEM and to provide teaching training to graduate students to better prepare them for academic careers. Specifically, the project will introduce professional activities and career outlooks of geoscientists to about 100 underrepresented minority high-school students in east Texas through a two-day long GEOCAMP, involve underrepresented high-school and undergraduate students in research, and train doctoral students to implement best practices in teaching for diverse learners as part of successful professional careers.Recent geologic and geophysical observations of this classic intracontinental mountain belt demonstrate that the geodynamic drivers of Rocky Mountain uplift are complex and include: (1) late Cretaceous-early Eocene crustal thickening and shortening, or mantle dynamic processes related to low-angle subduction or the removal of an oceanic plateau; (2) middle Cenozoic detachment of oceanic slab; and/or (3) late Cenozoic mantle upwelling and thermal isostasy. The timing of occurrence and the role each mechanism played probably varied along the strike of the range. This project explores the idea that the timing and magnitude of the uplift of the Rockies varied along strike, and that these variations resulted from complex, but decipherable, geodynamic processes during the mid- to late Cenozoic. Specifically, the project will: (1) calibrate clumped isotope geothermometer of Quaternary fluvial carbonate cement in order to evaluate its application to paleoelevation and paleoclimate reconstructions; (2) improve the chronostratigraphy of the middle and upper Cenozoic strata in the Rockies and adjacent Great Plains as well as east Texas by determination depositional ages using detrital and tuff zircon U-Pb geochronology; and (3) document the paleotopographic and paleoclimatic evolution of the Rockies and the adjacent Great Plains along strike using carbonate clumped isotope and volcanic glass hydrogen isotope paleoaltimeters in order to understand the tectonic processes of the formation of the Rockies and associated climate changes during the middle and late Cenozoic.

北美西部的落基山脉是大陆内山脉带的典型例子。厚厚的白垩纪海相沉积提供了明确的证据，表明该地区在大约80 Ma前接近海平面。然而，后来形成现在地形的垂直运动的历史并没有受到很好的限制，但对于理解大陆内部山脉形成的构造过程和驱动力来说至关重要。该项目旨在限制落基山脉和大平原西部在过去3500万年间的地表隆起和相关的气候变化。将使用最先进的同位素方法来估计落基山脉北部和南部横断面的古地形。结果将检验这样一个假设，即落基山脉的抬升时间和幅度沿其长度变化，这种变化可以限制在这段时间内形成落基山脉的复杂地球动力学过程。这一职业奖的教育部分涉及共同努力，吸引代表人数不足的少数群体学生进入STEM，并向研究生提供教学培训，以便为他们的学术生涯做好更好的准备。具体地说，该项目将通过为期两天的GEOCAMP向德克萨斯州东部约100名未被充分代表的少数民族高中生介绍地球科学家的专业活动和职业前景，让未被充分代表的高中生和本科生参与研究，并培训博士生为不同学习者实施最佳教学实践，作为成功职业生涯的一部分。最近对这一经典陆内山脉带的地质和地球物理观测表明，落基山脉隆起的地球动力学驱动因素复杂，包括：(1)晚白垩世-始新世早期地壳增厚和缩短，或与洋底高原低角度俯冲或移除有关的地幔动力学过程；(2)中新生代洋板拆离；和/或(3)晚新生代地幔上涌和热均衡。发生的时间和每一种机制所起的作用可能随着范围的不同而不同。这个项目探索了这样一种观点，即落基山脉的抬升时间和强度沿走向不同，这些变化是中新生代到晚新生代复杂但可解释的地球动力学过程的结果。具体地说，该项目将：(1)标定第四纪河流碳酸盐岩胶结物的块状同位素地质温度计，以评估其在古海拔和古气候重建中的应用；(2)通过利用碎屑和凝灰岩锆石U-Pb年代学确定落基山脉和邻近的大平原以及德克萨斯州东部的中、上新生代地层的沉积年龄，改善其年代地层学；(3)利用碳酸盐块状同位素和火山玻璃氢同位素古高度计记录落基山脉和邻近的大平原沿走向的古地形和古气候演化，以便了解落基山脉的形成过程和相关的中晚新生代气候变化。

项目成果

Prolonged high relief in the northern Cordilleran orogenic front during middle and late Eocene extension based on stable isotope paleoaltimetry

基于稳定同位素古测温的中、晚始新世伸展过程中北科迪勒拉造山锋的长期高地势

• DOI: 10.1016/j.epsl.2016.10.038
• 发表时间: 2017
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Fan, Majie;Constenius, Kurt N.;Dettman, David L.
• 通讯作者: Dettman, David L.