| 云南腾冲大六冲火山机构的发现及意义 |
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| 引用本文： | 李霓,魏海泉,张柳毅,赵勇伟,赵波,陈正全,陈生生,陈晓雯.云南腾冲大六冲火山机构的发现及意义[J].岩石学报,2014,30(12):3627-3634. |
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| 作者姓名： | 李霓 魏海泉 张柳毅 赵勇伟 赵波 陈正全 陈生生 陈晓雯 |
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| 作者单位： | 中国地震局地质研究所活动构造与火山重点实验室, 北京 100029;中国地震局地质研究所活动构造与火山重点实验室, 北京 100029;中国地震局地质研究所活动构造与火山重点实验室, 北京 100029;中国地震局地质研究所活动构造与火山重点实验室, 北京 100029;中国地震局地质研究所活动构造与火山重点实验室, 北京 100029;中国地震局地质研究所活动构造与火山重点实验室, 北京 100029;中国科学院青藏高原研究所, 北京 100101;中国地质博物馆, 北京 100034 |
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| 基金项目： | 本文受国家自然科学基金项目(41472305)和中国地震局地震行业专项项目(201108001)联合资助. |
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| 摘 要： | 腾冲火山群位于我国云南省西部和缅甸交界处的腾冲县境内,是我国著名的第四纪火山群,既有黑空山、打鹰山、马鞍山等一系列晚第四纪新期火山,也有早更新世以来有过喷发活动的大六冲、余家大山、来凤山等老火山。其中,位于腾冲火山区中东部的大六冲山势高峻,其顶峰是本区内的最高峰。野外地质调查发现,大六冲山体由一系列巨厚层爆发相火山碎屑堆积物和少量溢流相熔岩类岩石构成,喷发物类型极其丰富。在大六冲最高峰以南约100m处,首次发现存在着一个直径超百米的火山通道,可能是区内早期火山喷发的主通道,火山颈、熔岩穹丘、岩墙、爆发相与溢出相堆积物构成了大六冲完整的火山机构,在其周边多处地方还发现了因山体岩石破碎后形成的垮塌和滑坡堆积物。大六冲火山机构及其滑塌物的发现,不仅可以解释腾冲火山区大范围分布的火山碎屑岩的来源,也为防治以后类似大规模喷发可能造成的次生地质灾害提供了理想的研究样本和未来灾害预警。
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| 关 键 词： | 大六冲 火山机构 火山碎屑物 火山群 云南腾冲 |
| 收稿时间： | 2014/1/10 0:00:00 |
| 修稿时间： | 6/1/2014 12:00:00 AM |
Discovery of Daliuchong volcanic edifice in Tengchong, Yunnan Province and its significance |
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| LI Ni,WEI HaiQuan,ZHANG LiuYi,ZHAO YongWei,ZHAO Bo,CHEN ZhengQuan,CHEN ShengSheng and CHEN XiaoWen.Discovery of Daliuchong volcanic edifice in Tengchong, Yunnan Province and its significance[J].Acta Petrologica Sinica,2014,30(12):3627-3634. |
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| Authors: | LI Ni WEI HaiQuan ZHANG LiuYi ZHAO YongWei ZHAO Bo CHEN ZhengQuan CHEN ShengSheng and CHEN XiaoWen |
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| Institution: | Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Key Laboratory of Active Tectonics and Volcano, Institute of Geology, China Earthquake Administration, Beijing 100029, China;Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100101, China;The Geological Museum of China, Beijing 100034, China |
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| Abstract: | Situated adjacent to the border area of western Yunnan Province of China and Myanmar, Tengchong volcanic region has long been experiencing intense tectonic stress from the subduction of Indian plate to Eurasian plate and had strong volcanism as well as frequent earthquakes and geothermal activities in Cenozoic. Previous researches revealed that volcanism in Tengchong area started from Miocene, strengthened in Pliocene and prospered in Pleistocene. The volcanic activities tend to move from periphery to the middle of the region, as well as from north to the south. It is also famous Quaternary volcano group in our country. Strong hydrothermal activities still occur in the southern volcanic region, and helium emissions captured there were thought of from mantle source. Lying in a NS-stretched narrow basin, a series of well known Late Quaternary volcanoes as Heikongshan, Dayingshan and Ma'anshan and Early Pleistocene volcanoes of Daliuchong, Yujiadashan and Laifengshan are included in Tengchong volcano group. Volcanic activities in Tengchong basin relate to the subduction and collision of Indo-Eurasia plate, as a result, the volcanic rocks are a series of high alkali calcium-alkali rocks, locating above Meso-Cenozoic intrusion rocks and Paleozoic deposits layer. Among them, Daliuchong volcano with the highest peak of 2763m is located in the middle of the basin. Lithology of Daliuchong volcano consists of huge amount of thick-layered explosive volcaniclastic deposits and few effusive dacitic lava in the summit area, forming multiple types of eruption products as vitric tuff, crystal tuff, lithic tuff etc., which covering more than 100km2 in the volcanic region. The widely distributed layered volcaniclastic rocks of Daliuchong suggest a large scale explosive eruption once occurred in the region. A volcanic conduit with its diameter over one hundred meters, located about 100 meters south of its peak, was determined the first time through several seasonal field investigation works. It might be the primary eruption conduit in the Early Pleistocene eruption episodes in Tengchong area. Daliuchong volcanic plug could also be seen in the google satellite image. None of the conduit had been found and mentioned before through much previous study works conducted in this area. The lava dome in the summit was broken into rock blocks, and volcanic breccia could be seen in the hillside of the proximal facies of volcanic eruption products, while dacitic volcanic plug rocks ascended and blocked up in the conduit, with vertical conduit boundries controlled by inner layer joints paralleling to the plug body rim. Several dikes could also be found near the main peak and other peaks about 2km southwest of the main peak, whereas one dacitic dike exhibits horizontal columnar cleavages in the main peak. Pseudoflow structure, parallel bedding structure, eutaxitic structure form the distinctive features in the Daliuchong volcanic tuffs. Volcanic plug, lava dome, volcanic dikes, explosive and effusive eruption products together formed the whole volcanic edifice of Daliuchong, and some rock collapse and landslide deposits due to cracks of the hillside were also investigated around the upper part of the volcano during the field works. Daliuchong edifice and its landslide deposits not only account for the source of widely distributed volcaniclastic rocks in Tengchong volcanic area, but also provide the ideal sample site for the prevention of secondary geological disaster which might be triggered by eruptions of almost the same large scale in the future and give an early warning for the approaching volcanic disaster as well. |
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| Keywords: | Daliuchong Volcanic edifice Volcaniclastic deposits Volcanic cluster Tengchong Yunnan Province |
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