Late Wisconsinan and holocene depositional chronologies of aeolian sands in central and northern Alberta: implications for deglaciation patterns and environmental evolution

艾伯塔省中部和北部威斯康星州晚期和全新世风沙沉积年表：对冰消模式和环境演化的影响

• 批准号: 342892-2008
• 负责人: Munyikwa, Kennedy
• 金额: $ 1.09万
• 依托单位: Athabasca University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2011
• 资助国家: 加拿大
• 起止时间: 2011-01-01 至 2012-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=482522
• 关键词: Late; Wisconsinan; holocene; depositional; chronologies

The landscape of the province of Alberta features accumulations of wind deposited sands that occur in many places as fossil dune structures. Over the last two to three decades, a technique called luminescence dating has been developed by which sand grains from such landforms can be made to glow in a laboratory setting as a means of deciphering the amount of time that has elapsed since the sands were last buried. Investigations performed on dune structures from southern Alberta using such methods have demonstrated that the dune structures there have not remained fixed since their first emplacement. Instead, the sands have been remobilized at various times over the last 10 000 years. These episodes of reactivation have been linked to variations in climate. Contrastingly, only a limited number of studies have been carried out on dune sequences from central Alberta and results obtained suggest the dune structures in the region range in age between 15 700 and 10 500 years before present. No study to date, however, has constrained the duration over which deposition by wind occurred at any one location in central Alberta such that it remains unknown when precisely the activation by wind began, when it ended or whether it was recurrent. This study will collect samples from dune structures in central and northern Alberta containing depositional sequences longer than any investigated in the area to date. The collected samples will be dated using luminescence dating techniques to provide depositional chronologies. The results will be compared with data from southern Alberta as well those from across the Canadian prairies to elucidate on patterns in environmental change over the last 20 000 years. Such medium range data on climate change will help put the current global warming debate into context. In addition, sediments from lower sections of the dune structures should provide age constraints for the withdrawal of ice sheets from western Canada at the end of the last glacial period. Hence, such ages will be used to address the long standing question of whether an inland 'ice-free corridor' did exist in western Canada around about 14 000 years ago or earlier that would have been used by the first Americans to migrate south to the mid latitudes.

艾伯塔省省的景观具有在许多地方以化石沙丘结构而出现的风沉积的沙子。在过去的两到三十年中，已经开发了一种称为发光日期的技术，通过该技术可以通过该技术在实验室环境中发光的沙粒，以此作为破译以来自从沙滩最后埋葬以来经过的时间的手段。使用这种方法对来自艾伯塔省南部的沙丘结构进行的调查表明，自第一次增态以来，那里的沙丘结构一直没有固定。取而代之的是，在过去的10 000年中，沙子在不同时间进行了重新验证。这些重新激活的发作与气候变化有关。相比之下，仅对艾伯塔省中部的沙丘序列进行了数量有限的研究，结果表明该地区的沙丘结构在15 700至10 500年前的年龄范围内。然而，迄今为止，还没有限制在艾伯塔省中部的任何一个地点发生的持续时间，因此，当风开始的激活开始，终止还是反复发生时，它仍然未知。这项研究将从艾伯塔省中部和北部含有沉积序列的沙丘结构中收集样品，其序列比迄今为止在该地区的任何研究更长。收集的样品将使用发光约会技术进行日期，以提供沉积时间。结果将与来自艾伯塔省南部的数据以及来自加拿大大草原各地的数据进行比较，以阐明过去20 000年的环境变化模式。这种有关气候变化的中等范围数据将有助于将当前的全球变暖辩论置于上下文中。此外，在最后一个冰川时期结束时，来自沙丘结构较低部分的沉积物应为从加拿大西部退出冰盖的年龄限制。因此，这种年龄将用于解决一个长期存在的问题，即大约14 000年前或更早的加拿大西部是否确实存在内陆“无冰走廊”，这是第一个美国人将南方迁移到中纬度地区的美国人。