Collaborative Research: The Age of Grand Canyon: Applying New Tests to Resolve the 150-year-old Debate

关于大峡谷年龄的问题，由约翰·韦斯利·鲍威尔在19世纪末提出，涉及大峡谷地区的构造和景观演变以及塑造它的构造事件。最近的论文重新引发了争论，并支持两个“老”的模型。（70-17百万年）和“年轻”（5-6百万年）的大峡谷雕刻，与相应的构造模型“老”与“年轻”隆起的科罗拉多高原。支持“古老”峡谷模型的研究表明，一条8000 - 7000万年前的东流河，然后是一条5500 - 3000万年前的西流河，在与现代大峡谷相同的位置和几乎相同的深度切割出一个峡谷。在这个模型中，科罗拉多河在大峡谷的开凿过程中并没有发挥重要作用，而科罗拉多高原的构造隆起主要发生在大约7000万年前。相比之下，“年轻”的峡谷模型表明，大峡谷的大部分已经雕刻在过去的600万年，一旦科罗拉多河成为一体，从落基山脉到加州湾和科罗拉多高原地区的隆起已经发生在多个事件，并可能正在进行由于区域地幔上涌。该项目测试的“古峡谷分辨率”的大峡谷辩论中，有3个“年轻”的部分，1个“老”的部分，和1个“中间”年龄段，共同提供了一个复杂的多阶段构造隆起的历史记录为美国西南部的两个互补的方法来测试这一假设。首先，磷灰石三重测年（裂变径迹，（U-Th）/He测年，和4 He/3 He分析）应用于新的样品从每个部分重建岩石的冷却路径和破译过去（现在侵蚀）的景观和断层位移。其次，碎屑锆石和透长石测年的关键保存古河流遗迹提供必要的地面真理校准热年代学调查。国家和国际公众对大峡谷地区作为地球上的一部分的强烈兴趣，增强了大峡谷更广泛的意义和重要性。标志性的地质特征。这个项目的结果可能会改变目前的大峡谷切割年龄的范例。长达一个世纪的大峡谷争论的讨论和解决说明了科学方法和科学的进步。该项目将对学生培训、增加地球科学工作者的多样性、与该地区美洲原住民部落的联系、公共非正式科学教育以及增加不同地球科学社区之间的合作进展产生重大影响。

Questions about the age of Grand Canyon, framed by John Wesley Powell in the late 1800s, address the tectonic and landscape evolution of the Grand Canyon region and the tectonic events that have shaped it. Recent papers reinvigorate the debate, and support models for both "old" (70-17 million years) and "young" (5-6 million years) carving of Grand Canyon, with corresponding tectonic models for "old" versus "young" uplift of the Colorado Plateau. Studies supporting the "old" canyon model suggest that an 80-70 million year old east-flowing river, then a 55-30 million year old west-flowing river, incised a canyon in the same location and to nearly the same depth as modern Grand Canyon. In this model, the Colorado River did not play a significant role in excavating Grand Canyon, and the preponderance of tectonic uplift of the Colorado Plateau took place about 70 million years ago. In contrast, "young" canyon models suggest that most of the Grand Canyon has been carved in the last 6 million years once the Colorado River became integrated from the Rocky Mountains to the Gulf of California and that uplift of the Colorado Plateau region has taken place in multiple episodes and may be ongoing due to regional mantle upwelling. This project tests a "paleocanyon resolution" for the Grand Canyon debate in which there are 3 "young" segments, 1 "old" segment, and 1 "intermediate" age segment that collectively provide a record of a complex multi-stage tectonic uplift history for the southwestern U.S. Two complementary methods are used to test this hypothesis. First, apatite triple dating (fission track, (U-Th)/He dating, and 4He/3He analyses) are applied to new samples from each segment to reconstruct cooling paths for rocks and decipher past (now-eroded) landscapes and fault displacements. Second, detrital zircon and sanidine dating of key preserved paleoriver remnants provide essential ground truth to calibrate the thermochronological investigations.The project?s broader significance and importance are enhanced by intense national and international public interest in the Grand Canyon region as one of Earth?s iconic geologic features. The results of this project may change the current paradigm for the incision age of the Grand Canyon. Discussion and resolution of the century-long Grand Canyon debate illustrates the scientific method and progress of science. The project will have significant impacts on student training, increased diversity of the geoscience workforce, outreach to Native American tribes in the region, public informal science education, and increased collaborative progress among diverse geosciences communities.