Late Cenozoic tephrochronology and glass fission-track dating

晚新生代岩石年代学和玻璃裂变径迹测年

• 批准号: 3565-2013
• 负责人: Westgate, John
• 金额: $ 1.97万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=568311
• 关键词: Late; Cenozoic; tephrochronology; glass; fission

Big volcanic eruptions shed widespread blankets of tephra (volcanic ash) on the landscape, sometimes more than 1000 km from the source. If a tephra beds is distinctive and its age known, it serves as a marker bed, noting wherever it is preserved, the age of that sedimentary horizon. Tephra beds, therefore, help to link in a temporal framework, the numerous, separate exposures of sediments, which bear the evidence, albeit fragmentary, of Earth's past conditions. This field of endeavour is known as "tephrochronology". Our tephrochronological studies are focused on the late Cenozoic (<3Ma) sediments of eastern Beringia (Alaska and Yukon), where tephra beds are abundant. Detailed studies have been done in the Fairbanks area, bluffs of the Yukon River in east-central Alaska, and the Klondike goldfields near Dawson City, Yukon. Current research concentrates on tephra-bearing sites in the Old Crow Basin and Thistle Creek in Yukon as well as at Chicken, The Palisades along the Yukon River, and Fort Yukon in Alaska. We anticipate the results will facilitate connection of Ice-Age records across eastern Beringia and improve the temporal calibration of climate/environmental change in this region during the last 3 million years. Efforts will also be made to determine the significance of compositional complexity and eruptive history of the late Holocene White River Ash beds and an attempt will be made to devise a classification scheme for all the tephra beds of eastern Beringia. Other projects include: (1) Miocene tephrochronology of southern Saskactchewan and Montana, where very thick tephra beds occur and are undoubtedly derived from volcanoes of the Yellowstone hotspot track. (2) Composition, source, and glass-ft age of Eocene tephra beds in a sedimentary core recovered from lacustrine sediments above a kimberlite pipe in NWT. (3) Glass-ft age of tephra beds in cores of lacustrine sediments that infill an old meteorite crater in Siberia - cores that represent the longest, most time-continuous record of late Cenozoic Arctic climate evolution. (5) Age of Homo floresiensis in Indonesia.

大规模的火山爆发会在地表上留下广泛的火山灰（火山灰），有时距离源头超过1000公里。如果火山灰层是独特的，并且它的年龄已知，它就可以作为一个标志层，记录下它保存的地方，沉积层的年龄。火山灰层，因此，有助于连接在一个时间框架，众多的，单独暴露的沉积物，承载的证据，虽然零碎，地球的过去条件。这一领域的努力被称为“火山灰年代学”。我们的火山灰年代学研究主要集中在白令海东部（阿拉斯加和育空地区）的晚新生代（<3 Ma）沉积物中，那里有丰富的火山灰层。在费尔班克斯地区、阿拉斯加中东部的育空地区的悬崖以及育空地区道森市附近的克朗代克金矿区进行了详细的研究。目前的研究集中在育空地区的老乌鸦盆地和蓟溪以及鸡，沿着育空地区河的栅栏，和阿拉斯加的育空地区堡的火山灰轴承网站。我们预计，这些结果将有助于连接整个东白令海的冰期记录，并改善该地区过去300万年来气候/环境变化的时间校准。还将努力确定全新世晚期怀特河灰床的成分复杂性和喷发历史的意义，并试图设计一个分类方案，为所有的火山灰床东白令。其他项目包括：（1）萨斯卡彻万南部和蒙大拿州的中新世火山灰年代学，那里有非常厚的火山灰层，毫无疑问是来自黄石热点轨道的火山。(2)西北地区金伯利岩管上方湖相沉积物中沉积岩芯始新世火山灰层的组成、来源和玻璃-英尺年龄。(3)填充西伯利亚古老陨石坑的湖相沉积物核心中火山灰层的玻璃英尺年龄-核心代表了晚新生代北极气候演变的最长，最连续的记录。(5)印度尼西亚的弗洛雷斯人时代。