Cosmogenic surface exposure dating of Cordilleran-Laurentide ice-sheet separation during the last deglaciation: implications for abrupt sea-level rise

在最后一次冰消期（21，000 - 6，000年前），海平面的上升被称为融水脉冲（MWP）的海平面突然上升的间隔所打断，这表明地球上一个或多个冰盖的不稳定性发展。最大的MWP，MWP-1A，发生在14，600 - 14，300年前，全球平均海平面上升约14米。最近有人假设，当两个冰盖分离时，科迪勒支（CIS）和劳伦泰德（LIS）冰盖之间的冰鞍的崩溃可能导致MWP-1A。这项研究的结果将为冰盖破裂是否导致海平面迅速上升提供重要数据。确定冰盖分离是否导致MWP将提供对北大西洋气候演变及其与融水排放到北冰洋的关系的洞察，其中大部分冰盖分离融水将被路由。这些发现也将对格陵兰冰盖的不稳定发展产生影响，因为它有一个类似于以前在科迪勒兰-劳伦蒂德看到的冰鞍。最后，这些结果将确定科迪勒拉和劳伦泰德冰盖之间形成无冰走廊的时间，这对人类向美洲的迁徙路线具有重要影响。该项目将在50°N和60°N之间沿沿着冰盖缝合带的6个位置，用50个巨砾宇宙成因表面暴露年龄确定CIS-LIS分离的结束日期。这些年龄将决定CIS-LIS分离何时完成，以及它是否与MWP-1A或另一个海平面快速上升的时间段同时发生。他们还将记录CIS-LIS分离是否发生在几个世纪内，这可能导致MWP，或数千年内，这将与导致MWP的分离不一致。

The rise in sea level during the last deglaciation (21,000-6,000 years ago) was punctuated by intervals of abrupt sea-level rise, called meltwater pulses (MWP), which indicate the development of instability in one or more of Earth's ice sheets. The largest MWP, MWP-1A, occurred 14,600-14,300 years ago with ~14 m of global-mean sea-level rise. It was recently hypothesized that the collapse of an ice saddle between the Cordilleran (CIS) and Laurentide (LIS) ice sheets could have caused MWP-1A when the two ice sheets separated. Results from this research will provide important data on whether the ice sheet failure caused rapid jumps in sea level. Determining if the ice sheet separation caused a MWP will provide insight into the evolution of North Atlantic climate and its relationship to meltwater discharge to the Arctic Ocean where much of the ice sheet separation meltwater would be routed. These findings will also have implications for development of instability in the Greenland ice sheet as it has an ice saddle similar to the one previously seen in the Cordilleran-Laurentide. Finally, these results will date when an ice-free corridor formed between the Cordilleran and Laurentide ice sheets, which has important ramifications for human migration routes to the Americas. This project will date the end of CIS-LIS separation with 50 boulder cosmogenic surface exposure ages at six locations along the suture zone of the ice sheets between 50°N and 60°N. These ages will determine when CIS-LIS separation was complete, and if it was concurrent with MWP-1A or another interval of rapid sea-level rise. They will also document if CIS-LIS separation occur over centuries, which could cause a MWP, or over millennia which would be inconsistent with separation causing a MWP.