Collaborative Research: Constraining the tempo and dynamics of Cambrian Earth systems in western Laurentia

合作研究：限制劳伦西亚西部寒武纪地球系统的节奏和动态

• 批准号: 1954634
• 负责人: James Hagadorn
• 金额: $ 13.45万
• 依托单位: Denver Museum of Nature and Science
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-08-01 至 2025-01-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1954634&HistoricalAwards=false
• 关键词: Collaborative; Research; Constraining; tempo; dynamics

Rocks from the Cambrian Period (539-485 million years ago) contain fossils that reveal the first diversification of animals on Earth. The timing, causes, and impacts of this “Cambrian Explosion” are poorly understood. Yet clues to understanding this event are buried in Cambrian strata that formed as oceans flooded the world’s continents, and coastal environments blanketed the landscape with vast swaths of sand, mud, and fossils. One of the best-preserved records of these events is in the bottom of the Grand Canyon—in a package of sedimentary rocks known as the Tonto Group. Although the Tonto Group has been studied for nearly 150 years, the availability of new techniques makes it time to revisit these classic exposures. This project will decipher how, when, and why these rocks were deposited, and lead to greater understanding of the Cambrian Explosion of life on Earth. The broader impacts of this research include mentoring a suite of post-doctoral, graduate, and undergraduate scholars, including recruiting and training Hispanic and Native American students. Impacts also include outreach and distance learning through the Denver Museum of Nature and Science, to help this research inspire younger audiences, including 4th-12th graders in rural, first-generation, first-nation, inner-city, and culturally diverse settings. Finally, this project will reach many of the six million annual visitors to Grand Canyon National Park through Park programs, exhibits, media, and NSF-sponsored field forums on Grand Canyon geology. Cambrian rocks record dramatic changes in Earth systems including atmospheric oxygenation events, large magnitude perturbations to the carbon cycle, and the punctuated evolution of animal life. These events played out within the global transgressive inundation of continents by advancing oceans that deposited sheet sands, muds, and carbonates. Underpinning the research plan is a novel, integrative approach to calibrating the timing and tempo of this marine transgression. This approach combines: a) radioisotopic dating of the youngest, penecontemporaneously deposited zircon crystals, which are hidden amidst the detritus making up these sedimentary rocks; b) identifying changes in the types of fossils in the same rocks, and; c) documenting changes in mineral, chemical, and physical signatures of these rocks that record simultaneous, related changes in the Cambrian Earth system—such as changes in sea level or the collision and breakup of continents. Initial work has shown that the Tonto Group of the Grand Canyon is tens of millions of years younger than previously thought, that seas flooded North America relatively quickly, and that other continental margins experienced the same event. The project will expand upon a pilot study that was conducted in the Grand Canyon, and augment it with contemporaneous strata throughout the western U.S. to test hypotheses about how these flooding episodes relate to global biologic, tectonic, and geophysical events and processes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

寒武纪（539-4.85 亿年前）的岩石中含有的化石揭示了地球上动物的首次多样化。人们对这次“寒武纪大爆发”的时间、原因和影响知之甚少。然而，了解这一事件的线索却埋藏在寒武纪地层中，这些地层是在海洋淹没世界大陆时形成的，沿海环境覆盖着大片的沙子、泥土和化石。这些事件保存最完好的记录之一位于大峡谷底部，位于一组被称为通托群的沉积岩中。尽管对 Tonto 集团的研究已近 150 年，但新技术的出现使得我们有时间重新审视这些经典的风险暴露。该项目将破译这些岩石的沉积方式、时间和原因，并加深对地球生命爆发的寒武纪生命大爆发的了解。 这项研究的更广泛影响包括指导一批博士后、研究生和本科生学者，包括招募和培训西班牙裔和美国原住民学生。影响还包括通过丹佛自然科学博物馆进行外展和远程学习，以帮助这项研究激励年轻观众，包括农村、第一代、原住民、市中心和文化多元化环境中的 4 至 12 年级学生。最后，该项目将通过公园项目、展览、媒体和 NSF 赞助的大峡谷地质现场论坛，吸引每年 600 万大峡谷国家公园游客。 寒武纪岩石记录了地​​球系统的巨大变化，包括大气氧化事件、碳循环的大规模扰动以及动物生命的间断进化。这些事件是在全球大陆的海侵淹没过程中发生的，海洋推进，沉积了席状砂、泥浆和碳酸盐。该研究计划的基础是一种新颖的综合方法来校准这种海洋侵入的时间和节奏。这种方法结合了：a）对最年轻的准同期沉积的锆石晶体进行放射性同位素测年，这些晶体隐藏在构成这些沉积岩的碎屑中； b) 识别同一岩石中化石类型的变化； c) 记录这些岩石的矿物、化学和物理特征的变化，记录寒武纪地球系统中同时发生的相关变化，例如海平面的变化或大陆的碰撞和分裂。初步研究表明，大峡谷的通托群比之前认为的要年轻数千万年，海洋淹没北美的速度相对较快，其他大陆边缘也经历了同样的事件。该项目将扩展在大峡谷进行的试点研究，并在整个美国西部的同期地层中进行扩展，以测试有关这些洪水事件如何与全球生物、构造和地球物理事件和过程相关的假设。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

New Cambrian vermiform organisms from Burgess Shale-type deposits of the western United States

来自美国西部伯吉斯页岩型矿床的新寒武纪蠕虫状生物

• DOI: 10.3140/bull.geosci.1858
• 发表时间: 2022
• 期刊: Bulletin of Geosciences
• 影响因子: 1.9
• 作者: Foster, J.R.;Sroka, S.D.;Howells, T.F.;Cothren, H.R.;Dehler, C.M.;Hagadorn, J.W.
• 通讯作者: Hagadorn, J.W.

Frenchman Mountain Dolostone: A new formation of the Cambrian Tonto Group, Grand Canyon and Basin and Range, USA

法国人山白云岩：美国大峡谷和盆地山脉寒武纪 Tonto 群的新构造

• DOI: 10.1130/ges02514.1
• 发表时间: 2023
• 期刊: Geosphere
• 影响因子: 2.5
• 作者: Rowland, Stephen M.;Korolev, Slava;Hagadorn, James W.;Ghosh, Kaushik
• 通讯作者: Ghosh, Kaushik

Cambrian rift magmatism recorded in subvolcanic sills of the Ediacaran-Cambrian La Ciénega Formation, NW Mexico

墨西哥西北部埃迪卡拉系-寒武系 La Ciénega 地层的地下火山岩床中记录的寒武纪裂谷岩浆作用

• DOI: 10.1016/j.apgeochem.2022.105375
• 发表时间: 2022
• 期刊: Applied Geochemistry
• 影响因子: 3.4
• 作者: Tapia-Trinidad, Jesús Fernando;Barrón-Díaz, Arturo Joaquín;Paz-Moreno, Francisco Abraham;Holm-Denoma, Christopher;Hagadorn, James W.
• 通讯作者: Hagadorn, James W.