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

虽然大多数人认为阿巴拉契亚山脉应该在很久以前就被侵蚀了，但它们在形成后的两亿多年里仍然屹立不倒。对这个经典问题有两种可能的解释：要么它们侵蚀得非常缓慢，要么它们在地质学上最近的过去再次隆起。格兰杰和他的同事们建议通过使用最先进的方法来测试这两种情况，以确定整个阿巴拉契亚山脉南部保存下来的古代景观的分散遗迹，从第一次世界大战期间开采的锰矿石到田纳西州东部道路建设期间发现的富含化石的天坑。该项目将使用40 Ar/39 Ar来确定钾的形成时间，含有锰矿石，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26铝和10铍将被用来日期阶地沿着田纳西州和谢南多厄河，以确定河流切割率，并在灰岩坑存款，田纳西州的日期含化石的存款。这项工作代表了普渡大学的格兰杰和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州大学的约会专家之间的新合作，并直接涉及STEM教师将地球科学带入课堂。

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.