Late Cenozoic tephrochronology and glass fission-track dating

大型火山喷发在地表上留下了大面积的火山灰，有时距离源头超过1000公里。如果一个岩床是独特的，它的年龄是已知的，它就可以作为一个标记层，指出它被保存在哪里，沉积层的年龄。因此，Tephra床有助于在一个时间框架内将大量独立暴露的沉积物联系起来，这些沉积物提供了地球过去条件的证据，尽管是零碎的。这一领域的研究被称为“同步年代学”。我们的毯层年代学研究主要集中在白令陆桥东部（阿拉斯加和育空地区）晚新生代（<3Ma）的沉积物上，那里有丰富的毯层。详细的研究已经在费尔班克斯地区，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。目前的研究集中在育空地区的老乌鸦盆地和蓟溪，以及育空河沿岸的鸡、帕利塞德和阿拉斯加的育空堡。我们期望这些结果能够促进东白令陆桥冰期记录的联系，并改善该地区近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白河灰床的组成复杂性和喷发历史的意义，并将尝试为东白令陆桥的所有火山床设计一个分类方案。其他项目包括：(1)萨斯喀彻温省南部和蒙大拿州中新世温层年代学，那里有非常厚的温层，毫无疑问是来自黄石热点轨道的火山。(2) NWT地区金伯利岩管上湖相沉积物沉积岩心中始新世温层的组成、来源和玻璃时代。(3)西伯利亚一个老陨石坑的湖相沉积物岩心中温层的玻璃英尺年龄——这些岩心代表了晚新生代北极气候演化的最长、最连续的记录。(5)印度尼西亚弗洛勒斯人的时代。

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.