DATING THE CENOZOIC INCISION HISTORY OF THE TENNESSEE AND SHENANDOAH RIVERS WITH COSMOGENIC NUCLIDES AND 40Ar/39Ar IN MANGANESE OXIDES

用宇宙成因核素和氧化锰中的 40Ar/39Ar 测定田纳西河和 Shenandoah 河的新生代切割历史

• 批准号: 1700821
• 负责人: Darryl Granger
• 金额: $ 48.51万
• 依托单位: Purdue University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-07-01 至 2022-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1700821&HistoricalAwards=false
• 关键词: DATING; CENOZOIC; INCISION; HISTORY; TENNESSEE

While most accounts hold that the Appalachian Mountains should have eroded away long ago, they remain standing more than 200 million years after they were formed. There are two possible explanations to this classic problem: either they eroded extremely slowly, or they were uplifted again in the geologically recent past. Granger and his colleagues propose to test these two scenarios by using state-of-the-art methods to date scattered remnants of an ancient landscape preserved throughout the southern Appalachians, from manganese ores mined during World War I to a fossil-rich sinkhole uncovered during road construction in East Tennessee.This project will use 40Ar/39Ar to date the formation of potassium-bearing manganese ores that form in the weathering zone near the ground surface, traditionally identified as relicts of an ancient landscape. Cosmogenic 26Al and 10Be will be used to date terraces along the Tennessee and Shenandoah Rivers to determine river incision rates, and also to date fossil-bearing deposits at a sinkhole deposit at Gray, Tennessee. This work represents new collaborations between Granger and graduate student Odom at Purdue University with researchers at East Tennessee State University and dating specialists at the U.S. Geological Survey and the University of Queensland, Australia, and directly involves a STEM teacher to bring geoscience to the classroom.

虽然大多数说法认为阿巴拉契亚山脉早就应该被侵蚀了，但它们在形成后的2亿多年里仍然屹立不倒。对于这个经典问题，有两种可能的解释：要么它们被侵蚀得极其缓慢，要么它们在最近的地质时期再次被抬升。格兰杰和他的同事们建议用最先进的方法来测试这两种情况，他们用最先进的方法来确定阿巴拉契亚南部保存下来的古代景观的散落遗迹的年代，从第一次世界大战期间开采的锰矿石到东田纳西州筑路期间发现的富含化石的天坑。该项目将使用40Ar/39Ar来确定含钾锰矿石的形成日期，这些锰矿石形成于地表附近的风化带，传统上被认为是古代景观的遗迹。宇宙成因26Al和10Be将用于测定田纳西河和谢南多厄河沿岸的阶地的年代，以确定河流的切割速率，也用于测定田纳西州格雷市一个天坑矿床的含化石沉积物的年代。这项工作代表了格兰杰和普渡大学研究生奥多姆与东田纳西州立大学的研究人员以及美国地质调查局和澳大利亚昆士兰大学的年代专家之间的新合作，并直接涉及STEM教师将地球科学带入课堂。

项目成果

The Pliocene-to-Present Course of the Tennessee River

田纳西河上新世至今的河道

• DOI: 10.1086/719951
• 发表时间: 2022
• 期刊: The Journal of Geology
• 作者: Odom, William E.;Granger, Darryl E.
• 通讯作者: Granger, Darryl E.

New 26Al/10Be and (U-Th)/He constraints on the age of the Upland Complex, central Mississippi River Valley

• DOI: 10.1016/j.geomorph.2020.107448
• 发表时间: 2020-10
• 期刊: Geomorphology
• 影响因子: 3.9
• 作者: W. Odom;F. Hofmann;R. V. Arsdale;D. Granger