Late Cenozoic tephrochronology and glass fission-track dating

大型火山喷发将广泛的火山灰(火山灰)覆盖在地貌上，有时距离源头超过1000公里。如果特弗拉岩层是独特的，并且它的年代已知，它就是一个标志层，无论它保存在哪里，都会记下该沉积层的年龄。因此，Tephra床有助于在一个时间框架内将众多独立的沉积物暴露联系起来，这些沉积物承载着地球过去条件的证据，尽管是零星的。这一领域的努力被称为“年代学”。我们的年代学研究主要集中在贝林贾东部(阿拉斯加和育空)晚新生代(&lt；3 Ma)沉积，那里有丰富的特弗拉岩层。在费尔班克斯地区、阿拉斯加中东部的育空河悬崖以及育空地区道森市附近的克朗代克金矿进行了详细的研究。目前的研究集中在育空的老乌鸦盆地和蓟溪，以及鸡，育空河沿岸的帕里塞兹和阿拉斯加的育空堡。我们预计，这些结果将有助于连接整个东贝林吉亚的冰河时代记录，并改善该地区过去300万年来气候/环境变化的时间校准。还将努力确定晚全新世白河火山灰层的成分复杂性和喷发历史的重要性，并将试图为东贝林吉亚的所有特弗拉层设计一个分类方案。其他项目包括：(1)萨斯喀彻温省南部和蒙大拿州南部的中新世火山年代学，那里有非常厚的苔藓层，毫无疑问来自黄石热点地区的火山。(2)西北地区金伯利岩管上方湖相沉积物中始新世沉积岩芯中始新世火山岩层的组成、来源和玻璃年龄。(3)填满西伯利亚古老陨石坑的湖相沉积核心中的Tephra层的玻璃英尺年龄--代表了晚新生代北极气候演变的最长、最连续的记录。(5)印度尼西亚的弗洛瑞斯人时代。

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.