RUI: Using the Products of Volcano-Ice Interaction to Constrain Paleo-ice Conditions II: Documenting Fluctuations in Continental Ice-sheets

“这项奖励是根据2009年美国复苏和再投资法案（公法111-5）资助的。”现代科学面临的最大挑战之一是试图预测全球气候变化对未来的影响。虽然在了解当今对气候的控制方面取得了重大进展，但为了预测未来气候变化的方向，我们必须了解最近地质历史时期地球的气候循环。从地球海洋和格陵兰岛和南极冰样本中收集的信息有助于了解当地和全球温度的变化。然而，关于过去温度变化如何影响北美降雪和冰川形成的信息要少得多。北美西部大陆气候最重要的记录之一保存在加拿大不列颠哥伦比亚省西北部冰雪下火山爆发形成的沉积物中。该项目将试图确定其中几座火山的喷发日期，以改善北纬大陆气候对过去全球温度变化的反应的陆地记录。许多这样的火山记录了最近地质时期冰的存在，当时全球气温比现在低得多。其他火山沉积物似乎是在没有大冰块存在的时候形成的；这些沉积物也很重要，因为它们记录了大陆气候可能相对温暖的时期。将大陆记录与海洋记录进行比较将有助于科学家更好地建立综合的全球气候模型。该项目的目标是对加拿大不列颠哥伦比亚省北部Tuya-Kawdy地区的34个玄武岩冰川火山和陆上中心进行全面的实地、地球化学和地质年代学研究，以确定大陆冰盖体积的波动是否影响更新世火山活动的喷发频率和组成。拟议的研究结果将对两个相互联系但独立的科学领域产生重要影响：(1)岩浆-冰动力学和(2)更新世古气候。该研究将详细记录整个更新世科迪勒拉冰盖（CIS）北部的存在、位置和最小厚度。冰火沉积可以经受多次冰进的侵蚀，因此是记录比末次盛冰期（~30-20 ka）更早的冰体存在的少数手段之一；这些沉积物对于研究火山作用对冰波动的长期反应至关重要。在Tuya-Kawdy地区的初步工作已经记录了~700 ka和~1.8 Ma的冰川火山爆发。扩展后的数据库将显著提高我们理解更新世气候变化（由海洋代用物记录）与北美西北部大陆冰盖存在之间的关系的能力。这项研究将是最全面地利用冰火作用来记录北美西北部主要冰盖的存在/缺失，并试图将其波动与海洋代用冰量记录联系起来。这些结果将为理解陆地对海洋温度变化、冰盖动态、冰川消退景观的生物多样性和更新世侵蚀速率的响应提供重要的约束。

"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)." One of the greatest challenges for modern science is trying to predict the future implications of global climate change. While significant progress is being made towards understanding present-day controls on climate, in order to predict the direction of future climate change we must understand the Earth's climate cycle during the recent geological past. Information collected from the Earth's oceans and ice samples from Greenland and Antarctic ice help to understand changes in local and global temperature. However, much less information is available about how past temperature changes have affected snowfall and the formation of glaciers in North America. One of the most important records of continental climate in western North America is preserved within deposits formed by volcanic eruptions that occurred beneath snow and ice in northwestern British Columbia, Canada. This project will attempt to determine the eruption dates for several of those volcanoes in order to improve the on-land record of how continental climate, in northern latitudes, has responded to past changes in global temperature. Many of these volcanoes record the presence of ice during periods of the recent geological past when global temperatures were much cooler than today. Other volcanic deposits appear to have formed when no large ice masses were present; these deposits are also important as they document periods when continental climate may have been relatively warmer. Comparison of the continental record to the oceanic record will help scientists better make integrated global climate models.The goal of this project is to conduct a comprehensive field, geochemical and geochronological study of 34 basaltic glaciovolcanic and subaerial centers in the Tuya-Kawdy area in northern British Columbia, Canada, to determine if fluctuations in continental ice-sheet volumes affected the eruption frequencies and compositions of Pleistocene volcanism. The results of the proposed research will have important implications for two linked but separate scientific areas: (1) magma-ice dynamics and (2) Pleistocene paleoclimate. The proposed research will provide a detailed record of the presence, position and minimum thickness of the northern part of the Cordilleran ice sheet (CIS) throughout the Pleistocene. Glaciovolcanic deposits can survive erosion by multiple ice advances, and consequently are one of the few means of documenting the former presence of ice-bodies older than the Last Glacial Maximum (~30-20 ka); such deposits are crucial for investigating long-term responses of volcanism to ice fluctuations. Preliminary work in the Tuya-Kawdy area has already documented glaciovolcanic eruptions at ~700 ka and ~1.8 Ma. An expanded database will significantly improve our ability to understand how changes in Pleistocene climate, as recorded by marine proxies, correlate with the presence of continental ice sheets in northwestern North America. This study will be the most comprehensive to use glaciovolcanism to document the presence/absence of a major ice sheet in northwestern North America and attempt to correlate its fluctuations with the marine proxy ice-volume record. The results will give important constraints for understanding the terrestrial response to changes in ocean temperatures, ice sheet dynamics, biodiversity in deglaciated landscapes, and Pleistocene erosion rates.