Collaborative Research on Surface-Exposure Dating of a Quaternary Glacial Sequence for the White Mountains, CA-NV

很少有长期的冰川记录存在，而那些存在的记录在地理上是分散的。位于加州和内华达州内华达山脉中部东部的怀特山脉拥有北美最完整的冰川沉积序列之一。新的地表暴露测年方法的前后应用使得通过分析地表巨石中积累的多种宇宙成因同位素来确定地貌表面的年龄成为可能。这个合作项目的目标是利用这些地表暴露测年方法，结合相关火山、岩石清漆、土壤和风化的测年数据，为怀特山脉开发一个数值冰川年代学。研究人员将在内华达山脉使用同样的方法，以便准确地比较两种记录，并区分天气气体学和构造历史的影响对山脉的冰川作用的控制。这项研究预计将提供北美冰川事件最完整的大陆记录之一。所获得的结果还将提供一个年表，用于将大陆冰川记录与大陆和环境变化的其他长期记录以及与已确立的海洋记录进行比较。这项研究将使用多种不同的年代测定技术，其中一些技术还处于发展的初始阶段，以帮助解开怀特山脉的冰川年代学。这项跨学科的研究工作将有助于评估新的测年方法以及自然地理学家和其他地球科学家使用的各种传统冰川、土壤和地貌学技术的可行性。这项研究将有助于我们了解怀特山脉保存完好的冰川序列与气候、构造活动和植被变化的关系。这项研究将把白山冰川序列与其他区域大陆地貌调查和漫长的冰川-海洋记录联系起来，并将提供对美国西部水文平衡大变化的规模和时间的见解。

Few long-term glacial records exist, and the ones that do are geographically scattered. The White Mountains, immediately east of the central Sierra Nevada in California and Nevada have one of the most complete sequences of deposits from glacial events in North America. New pre- and post-applications of new surface exposure dating methods make it possible to determine ages of geomorphic surfaces through analyses of multiple cosmogenic isotopes that accumulate in surface boulders. The goal of this collaborative project is to develop a numerical glacial chronology for the White Mountains using these surface-exposure dating methods in conjunction with dates based on associated volcanics, rock varnish, soils, and weathering. The investigators will use the same approach in the Sierra Nevada in order to an accurately compare the two records and to discriminate the effects of synoptic climatology versus tectonic history as controls on the glaciation of the mountain ranges. The research is anticipated to provide one of the most complete continental records of glacial events in North America. The results obtained also will provide a chronology for comparing a continental glacial record with other long-term records of continental and environmental change and with the well-established marine record. The study will use multiple and varied dating techniques, some of which are in the intial stages of development, to help unravel the glacial chronology of the White Mountains. This interdisciplinary research effort will help assess the viability of new dating approaches and various traditional glacial, soils, and geomorphological techniques used by physical geographers and other earth scientists. The research will contribute to our understanding of how the well-preserved glacial sequence in the White Mountains relates to changes in climate, tectonic activity, and vegetation. The study will correlate the White Mountain glacial sequence to other regional continental geomorphic investigations and to the lengthy glacio-marine record, and it will provide insight into the scale and timing of large changes in the hydrologic balance of the Western United States.