Cold-based Laurentide ice covered New England’s highest summits during the Last Glacial Maximum
Cold-based Laurentide ice covered New England’s highest summits during the Last Glacial Maximum
复制标题
末次盛冰期期间，冷基劳伦泰德冰覆盖了新英格兰的最高峰
作者：
P. Bierman;P. Davis;L. Corbett;N. Lifton;R. Finkel
为了更好地了解新英格兰（美国东北部）（劳伦泰冰盖覆盖的山区）的冰川历史和过程，我们测量了九个高地样本中的三种宇宙成因核素。考虑到现场证据表明，末次盛冰期大陆冰覆盖了所有新英格兰山峰，在卡塔丁（缅因州）、华盛顿山和小干草堆山（新罕布什尔州）山顶附近收集的一些样品中 10Be 和 26Al 的浓度比单次暴露时期预期高出 2-10 倍。山顶的原位 14C 暴露年龄要年轻得多，这表明高海拔采样点在末次盛冰期之前和期间被冰覆盖。现场和同位素数据与新英格兰山顶部分被冷基大陆冰覆盖一致，这些冰没有侵蚀太多岩石。稳定的山顶和深度侵蚀的山谷之间的侵蚀率对比可能有助于阿巴拉契亚北部地形的发展和维护。
To better understand glacial history and process in New England (northeastern United States), a mountainous area overrun by the Laurentide Ice Sheet, we measured three cosmogenic nuclides in nine upland samples. The concentrations of 10Be and 26Al in some samples collected near the summits of Katahdin (Maine) and Mount Washington and Little Haystack Mountain (New Hampshire) are 2–10 times higher than expected for a single exposure period, considering field evidence indicating that continental ice-covered all New England peaks during the Last Glacial Maximum. In-situ 14C exposure ages from the summits are much younger, suggesting that high-elevation sampling sites were ice-covered before and during the Last Glacial Maximum. Field and isotopic data are consistent with New England summits being covered in part by cold-based continental ice that did not erode much rock. The contrast in erosion rates between stable summits and deeply eroded valleys likely contributes to the development and maintenance of northern Appalachian topography.