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Use of Tephrochronology in the Evaluation of Accumulation Rates on Nelson Ice Cap,South Shetland Isands,Antarctica
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作者 秦大河 G A.Zielinski +3 位作者 M.S.Germain 任贾文 王晓香 王文悌 《Science China Chemistry》 SCIE EI CAS 1994年第10期1272-1280,共9页
A volcanic ash layer was observed in the 3 ice cores on the Nelson Ice Cap,Antarctica.Acomparison of major elemental composition of glass shards from the 3 tephra layers with average whole-rockcompositions of 1967-197... A volcanic ash layer was observed in the 3 ice cores on the Nelson Ice Cap,Antarctica.Acomparison of major elemental composition of glass shards from the 3 tephra layers with average whole-rockcompositions of 1967-1970 eruptions on the Deception Island and of glass shards from other suspected De-ception Island eruptions collected from Antarctic ice and firn indicate that the most reasonable source for thetephra in the Nelson Ice Cap cores is the 1970 eruption on the Deception Island.From the depth of the vol-canic ash layer and measured density profile of the cores,the net accumulation rate at the summit,CoreGW,is 1200 g·cm<sup>-2</sup>·a<sup>-1</sup> during the past 20 years,and the net accumulation rates are 700 g·cm<sup>-2</sup>·a<sup>-1</sup>and 6 g·cm<sup>-2</sup>·a<sup>-1</sup> at sites N30 and N50,respectively.In the eastern part of the Nelson Ice Cap,the accu-mulation rate may be higher than that in the northern part,because no volcanic ash in ice cores was observedat similar depths collected from this region. 展开更多
关键词 ice core STRATIGRAPHY tephrochronology composition of glass shards ACCUMULATION rate
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Synchronous Pumice Mantle Found on Santorini Volcano
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作者 Walter L. Friedrich Richard Wilson +1 位作者 Annette Højen Sørensen Samson Katsipis 《International Journal of Geosciences》 2021年第4期329-346,共18页
It is generally accepted that the vent of the 3.6 ka Minoan eruption was situated in the water-filled Santorini caldera prior to the Minoan eruption. One should therefore expect to find huge quantities of pumice and a... It is generally accepted that the vent of the 3.6 ka Minoan eruption was situated in the water-filled Santorini caldera prior to the Minoan eruption. One should therefore expect to find huge quantities of pumice and ash on the inner side of the caldera walls, but there is only a relatively small amount preserved. An unexpected discovery of remnants of a synchronous pumice mantle of the Minoan eruption appears to solve this enigma. A lengthy period of erosion and the intensive quarrying of pumice for the construction of the Suez Canal (1859 to 1869) led to the removal of an enormous amount of material and information for generations of geologists. The synchronous pumice mantle covered the whole caldera wall from rim to sea level. Archaeological finds under the pumice mantle show that the caldera wall was accessible and inhabited in the Bronze Age. Furthermore, this discovery documents that only one Minoan eruption took place and that the so-called “Lower pumice” does not exist on Santorini. 展开更多
关键词 Minoan Eruption tephrochronology Visual Geology GEOARCHAEOLOGY
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Distribution, geochemistry and age of the Millennium eruptives of Changbaishan volcano, Northeast China - A review 被引量:10
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作者 Chunqing SUN Haitao YOU +3 位作者 Jiaqi LIU Xin LI Jinliang GAO Shuangshuang CHEN 《Frontiers of Earth Science》 SCIE CAS CSCD 2014年第2期216-230,共15页
Large explosive volcanic eruptions generate extensive regional tephra deposits that provide favorable conditions for identifying the source of volcanoes, comparing the sedimentary strata of a region and determining th... Large explosive volcanic eruptions generate extensive regional tephra deposits that provide favorable conditions for identifying the source of volcanoes, comparing the sedimentary strata of a region and determining their ages. The tephra layer, referred to as B- Tm, generated by the Millennium eruption of Chang- baishan volcano, is widely distributed in Northeast China, Japan, D.P.R. Korea, and the nearby coastal area of Russia. It forms part of the widespread northeast Asian strata and is significant for establishing an isochronal stratigraphic framework. However, research on the temporal characterization and stratigraphic correlation of associated strata using this tephra layer is mainly concentrated in and near Japan. In northeastern China, this tephra layer is seldom seen and its application in stratigraphic correlations is even rarer. More importantly, the determination of accurate ages for both distal and proximal tephras has been debated, leading to controversy in discussions of its environmental impacts. Stratigraphic records from both distal and proximal Changbaishan ash show that this eruption generally occurred between 1,012 and 1,004 cal yr BP. Geochemical comparison between Changbaishan ash and the Quaternary widespread ash around Japan illustrates that Changbaishan ash is a continuous composition from rhyolitic to trachytic and its ratio of FeOT to CaO is usually greater than 4, which can be used as a distinguishing identifier among worldwide contemporary eruptions. 展开更多
关键词 Millennium eruption Changbaishan volcano tephrochronology B-Tm tephra
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