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: 1954583
• 负责人: Mark Schmitz
• 金额: $ 26.28万
• 依托单位: Boise State University
• 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 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1954583&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.

寒武纪时期（539-4.85亿年前）的岩石含有化石，揭示了地球上第一次多样化的动物。这种“寒武纪爆炸”的时机，原因和影响知之甚少。然而，了解这一事件的线索是建立在寒武纪史塔塔（Cambrian Stratta）建造的，当海洋淹没了世界的持续时间，沿海环境用大量的沙子，泥土和化石覆盖了景观。这些事件保存最完好的记录之一是在大峡谷的底部 - 一包被称为Tonto Group的沉积岩。尽管Tonto集团已有将近150年的时间工作，但新技术的可用性使得是重新审视这些经典暴露的时候了。该项目将破译如何沉积这些岩石的方式，何时以及为什么会导致对地球上生命的寒武纪爆炸的更多了解。这项研究的更广泛的影响包括对一套博士后，研究生和本科学者进行心理，包括招募和培训西班牙裔和美洲原住民学生。影响还包括通过丹佛自然与科学博物馆进行外展和远距离学习，以帮助这项研究激发年轻的受众，包括农村，第一代，第一代，城市内部和文化上不同环境的4至12年级学生。最后，该项目将通过公园计划，展览，媒体和NSF赞助的大峡谷地质学田间论坛来吸引大峡谷国家公园的600万游客中的许多游客。寒武纪岩石记录了地​​球系统中的巨大变化，包括大气中氧合事件，对碳循环的大量扰动以及动物生命的标点变化。这些事件在全球持续的延续性泛滥淹没中播放，通过推进将薄片，泥土和碳酸盐存放的海洋。研究计划的基础是一种新型的综合方法，用于校准该海洋违法行为的时机和节奏。这种方法结合了：a）最年轻的，孢子型沉积的锆石晶体的放射性分析约会，它们在构成这些沉积岩石的碎屑中被隐藏； b）确定相同岩石中化石类型的变化，并且； c）记录这些岩石的矿物质，化学和物理特征的变化，这些岩石记录了同时记录寒武纪地球系统中相关变化的矿物质，例如海平面的变化或持续的碰撞和破裂。最初的工作表明，大峡谷的Tonto集团比以前想象的要年轻数千万年，即海洋相对较快地淹没了北美，而其他连续的边缘则经历了同一事件。该项目将扩展在大峡谷中进行的一项试点研究，并在美国西部的当代地层中对其进行了扩展，以测试有关这些洪水事件如何与全球生物学，构造和地球物理事件和过程相关的假设，这是NSF的法定任务，并通过评估仪式来概述，这表明了NSF的任务，这是对基础的支持。

项目成果

Redefining the Tonto Group of Grand Canyon and recalibrating the Cambrian time scale

• DOI: 10.1130/g46755.1
• 发表时间: 2020-02
• 期刊: Geology
• 影响因子: 5.8
• 作者: K. Karlstrom;M. T. Mohr;M. Schmitz;F. Sundberg;S. Rowland;R. Blakey;J. Foster;L. Crossey;C. Dehler;J. Hagadorn

Novel age constraints for the onset of the Steptoean Positive Isotopic Carbon Excursion (SPICE) and the late Cambrian time scale using high-precision U-Pb detrital zircon ages

使用高精度 U-Pb 碎屑锆石年龄对 Steptoean 正同位素碳偏移 (SPICE) 和晚寒武世时间尺度的起始年龄进行限制

• DOI: 10.1130/g50434.1
• 发表时间: 2022
• 期刊: Geology
• 影响因子: 5.8
• 作者: Cothren, Hannah R.;Farrell, Thomas P.;Sundberg, Frederick A.;Dehler, Carol M.;Schmitz, Mark D.
• 通讯作者: Schmitz, Mark D.

Asynchronous trilobite extinctions at the early to middle Cambrian transition

• DOI: 10.1130/g46913.1
• 发表时间: 2020-05
• 期刊: Geology
• 影响因子: 5.8
• 作者: F. Sundberg;K. Karlstrom;G. Geyer;J. R. Foster;J. Hagadorn;M. T. Mohr;M. Schmitz;C. Dehler;L. Crossey