共查询到20条相似文献，搜索用时 187 毫秒
1.
长白山火山灾害及其对大型工程建设的影响 总被引：2，自引：0，他引：2
长白山火山是世界著名的活火山,历史时期有过多次喷发,有再次爆发的危险.长白山火山最大的一次爆发发生在公元1199-1200年,这次大爆发的火山灰最远到达距其1 000km远的日本北部.依据这次大爆发由火山喷发空中降落堆积物、火山碎屑流和火山泥流造成的巨大火山灾害,预测了长白山火山未来爆发火山灾害的类型、强度和范围,并编制了长白山火山未来爆发火山喷发空中降落堆积物灾害预测图、火山碎屑流灾害预测图和火山泥流灾害预测图.该研究可预防和减轻火山灾害,指导核电站等大型工程选址. 相似文献
2.
世界各地几乎都有火山分布,平均每年约有50次喷发。火山喷发在给人类创造财富的同时也带来许多灾害。火山灾害取决于火山喷发的类型、性质、规模和所处的地点等因素。火山喷发动力作用引起冲击波、地震、海啸、滑坡、泥石流等灾害,火山喷出的气体、灰烬、碎屑流和熔岩流等也会造成很大灾害。由于火山造成的灾害严重又来得突然,因此必须采取有效的防范措施,认真监测以掌握火山活动的脉搏。火山监测工作主要有两方面,一是基础地质调查,二是火山活动指标的监视和测量。在中国,具有潜在危险的火山主要分布在长白山、五大连池、台湾、雷琼、腾冲以及西昆仑阿什库勒等地,其中潜在危险最大的是长白山火山。 相似文献
3.
五大连池、天池和腾冲火山岩Sr、Nd同位素地球化学特征与岩浆演化 总被引：27，自引：0，他引：27
在的年来对长白山天池火山、五大连池火山和腾冲火山三个火山区火山岩岩石学的主、微量元素研究的基础上，新做出18个火山岩Sr-Nd同位素数据，进一步讨论地幔源区特征与岩浆成因演化。五大连池富钾火山岩浆源区由原始地幔与EMI两个地幔端员混合而成，岩浆直接来自地幔，未受地壳物质明显混染和分离结晶作用影响；天池火山各阶段火山岩一致的似原始地幔特征，可能指示存在巨大的壳内岩浆房和持续的幔源岩浆的补给；腾冲火山岩的高钾钙碱性岩浆源区为由陆内壳－幔相互作用导致的原始地幔与EMⅡ两个地幔端员不同程度混合而成。 相似文献
4.
长白山火山１０００年前大喷发,火山泥流堆积物沿松花江中上游分布。距火山较近的是火山泥流的岩屑流堆积,远离火山变为火山泥流的超高密度流堆积。探讨了火山泥流的成因,并指出长白山火山一旦再次爆发,火山泥流将是主要的火山灾害,沿松花江中上游可能造成巨大破坏,并可能危及鸭绿江、图们江中、上游。 相似文献
5.
长白山天池火山公元1014-1019年大喷发的历史记录 总被引：2，自引：1，他引：2
长白山火山是世界著名的火山之一，是我国规模最大、最具有潜在喷发危险的一座近代活动火山。目前，国内外许多火山学者为了研究长白山火山最近一次大喷发年代问题，做了大量工作，并取得了一些年代资料，但一直未取得有关这次大喷发历史记载的证实。笔者等通过再次收集和查阅了大量文史古籍资料，通过整理、筛选、考证、对比和分析处理，首次发现了长白山（白头山）火山，于公元1014～1019年间一次大喷发的历史记载。这对于研究长白山火山喷发历史具有重要的意义。 相似文献
6.
东北地区是中国新生代火山活动最强烈的地区,新生代火山５００多座,火山熔岩和火山喷发碎屑堆积物分布面积５万余ｋｍ２。火山活动最强烈的时期始自渐新世,直至现代,分中新世、上新世、更新世三个高潮期。东北也是中国活火山最多、活火山群最集中的地区。它们是：①长白山火山,历史记载长白山火山有５次喷发,分别发生在公元１４１３,１５９７,１６６８,１７０２,１９０３年。长白山火山１０００年前的一次大爆发,火山灰向东一直到达日本,超过１０００ｋｍ,因此是世界历史时期最大的火山喷发之一。这次大爆发的火山泥流沿松花江… 相似文献
7.
发生于公元946年的长白山天池火山千年大喷发（Millennium Eruption,ME）形成的火山碎屑堆积物体积高达100~172km3,并可分为大规模的ME-Ⅰ和小规模的ME-Ⅱ两个喷发阶段。通过对围绕长白山天池火山53个典型露头剖面进行火山地质测量（单元构成、垂向堆积序列和堆积特征）,结合筛析法粒度分析、偏光显微镜成分分析,刻画了长白山千年大喷发火山碎屑流堆积物特征,探讨了相和亚相划分,并建立了火山碎屑流搬运和堆积模式。根据火山碎屑的堆积特征,将长白山千年大喷发火山碎屑流堆积分为峡谷充填火山碎屑流相（包括块状峡谷充填亚相和层状峡谷充填亚相）和火山碎屑流冲击扇相（包括扇头亚相和扇体亚相）等两相四亚相。峡谷充填火山碎屑流相主要发育在天池火山锥体周缘距离喷发中心8~23km左右范围内（坡度在15°~60°之间）的火山U型谷中;火山碎屑流冲积扇相主要发育在距离喷发中心23~45km左右范围内,地形相对平缓的熔岩台地处（坡度在5°~15°之间）,火山碎屑流的搬运不受地形限制,一般形成较大纵横比扇状堆积。块状峡谷充填亚相和扇体亚相以块状混杂堆积为主要特征,而层状峡谷充填亚相和扇头亚相则以多火山碎屑流单元垂向叠加为主要特征。多单元叠加现象是由搬运过程中火山碎屑流单元发生分离增生作用形成。根据火山碎屑流的最大分布范围和厚度,如果再次发生与长白山千年大喷发类似规模的普林尼式喷发,至少距长白山天池火山喷发中心45km范围内具有巨大的火山碎屑流灾害风险。该研究有利于进一步深入认识长白山千年大喷发火山碎屑流堆积物的空间分布特征和相变规律,对火山碎屑喷发灾害的预防具有指导作用。 相似文献
8.
近年来,有关长白山火山是否存在潜在喷发危险的讨论引起了国内外地学研究者的广泛关注,但人们目前对其壳幔岩浆系统的了解却十分不足,已有的研究对长白山火山壳内岩浆房存在的深度位置、形态规模及其部分熔融程度的认识仍存在较大分歧。本研究通过汇集长白山火山及邻区(包括朝鲜境内)多个密集流动地震台阵和区域固定地震台网的观测资料,采用背景噪声成像方法获得了长白山火山区高精度的Rayleigh面波相速度模型。成像结果表明:长白山火山中-下地壳深度位置存在显著低波速异常,可能指示了岩浆房的存在。上地壳局部低速区可能反映了壳内深部岩浆向上运移的通道或者是区域小尺度的岩浆聚集体。长白山火山上地幔顶部的低速可能揭示了软流圈热物质上涌,其减压熔融为壳内岩浆房提供了幔源岩浆补给。 相似文献
9.
10.
火山地层学与火山架构:以长白山火山为例 总被引：1，自引：0，他引：1
将长白山火山喷出物按成岩方式和岩相可分为柱状节理熔岩、火山碎屑流和火山泥石流等20种基本类型,它们均可构成可识别的19种火山地层单元。火山架构是由被火山地层界面所围限的诸多基本地层单元叠置而成。一个复杂的火山组合体,可以通过界面识别,拆分成若干火山地层单元,从而实现对火山堆积体的分解描述和整体认知。基性火山喷发区常见的5种火山架构(单源火山田、洪泛玄武岩田、熔岩盾火山、中心式火山和层状复合火山),在长白山地区相继发育。本区火山灾害可分为原发和次生2种。原发性灾害指火山再次喷发引发的灾害,巨量天池水可沿火山断裂下渗,使气水-岩浆喷发的可能性和爆炸强度增加,同时还能引发火山泥石流。次生灾害主要源于火山碎屑堆积物的再搬运和熔岩火山体的崩塌。熔岩火山在本区分布最广,但其底座常为3～7m厚的松散沉积层,这犹如坐落在软地基之上的摩天大厦,是很不稳定的火山架构。熔岩体下伏的这些风化壳型松散层,只要发生流变或差异性沉陷,就会引发山体滑坡和山崩。因此,加强相关基础地质调查,对事关国计民生的重点区段开展次生火山灾害风险评估,势在必行。 相似文献
11.
We present the first seismic image of the upper mantle beneath the active intraplate Changbai volcano in Northeast Asia determined by teleseismic travel time tomography. The data are measured at a new seismic network consisting of 19 portable stations and 3 permanent stations. Our results show a columnar low-velocity anomaly extending to 400-km depth with a P-wave velocity reduction of up to 3%. High velocity anomalies are visible in the mantle transition zone, and deep-focus earthquakes occur at depths of 500–600 km under the region, suggesting that the subducting Pacific slab is stagnant in the transition zone, as imaged clearly by global tomography. These results suggest that the intraplate Changbai volcano is not a hotspot like Hawaii but a kind of back-arc volcano related to the deep subduction and stagnancy of the Pacific slab under Northeast Asia. 相似文献
12.
Yonghong Duan Dapeng Zhao Xiankang Zhang Shaohong Xia Zhi Liu Fuyun Wang Li Li 《Tectonophysics》2009,470(3-4):257-266
Three-dimensional P-wave velocity structure beneath the Changbai and other intraplate volcanic areas in Northeast Asia is determined by inverting 1378 high-quality P-wave arrival times from 186 teleseismic events recorded by 61 broadband seismic stations. Low-velocity (low-V) anomalies are revealed beneath the Changbai, Longgan, Xianjindao volcanoes. High-velocity (high-V) anomalies are found in the mantle transition zone, where deep-focus earthquakes under Hunchun occur at depths of 500–600 km. The high-V anomaly reflects the deep subduction of the Pacific slab under NE Asia which may have contributed to the formation of the Changbai, Longgang, Xianjindao and Jingpohu intraplate volcanoes. A low-V anomaly is also revealed in the mantle transition zone, which may have a close relationship with the occurrence of deep earthquakes under the Hunchun area. Our results support the Big Mantle Wedge (BMW) model by Zhao et al. [Zhao, D., Lei, J., Tang, Y., 2004. Origin of the Changbai volcano in northeast China: evidence from seismic tomography, Chin. Sci. Bull. 49, 1401–1408; Zhao, D., Maruyama, S., Omori, S., 2007. Mantle dynamics of western Pacific and East Asia: insight from seismic tomography and mineral physics. Gondwana Res. 11, 120–131.] who proposed that the intraplate volcanoes in NE Asia are caused by the back-arc magmatism associated with the deep dehydration process of the subducting slab and convective circulation process in the BMW above the stagnant Pacific slab. 相似文献
13.
Dapeng Zhao Franko Pirajno Nikolai L. Dobretsov Lucy Liu 《Russian Geology and Geophysics》2010,51(9):925-938
We present seismic images of the mantle beneath East Russia and adjacent regions and discuss geodynamic implications. Our mantle tomography shows that the subducting Pacific slab becomes stagnant in the mantle transition zone under Western Alaska, Bering Sea, Sea of Okhotsk, Japan Sea, and Northeast Asia. Many intraplate volcanoes exist in these areas, which are located above the low-velocity zones in the upper mantle above the stagnant slab, suggesting that the intraplate volcanoes are related to the dynamic processes in the big mantle wedge above the stagnant slab and the deep slab dehydration. Teleseismic tomography revealed a low-velocity zone extending down to 660 km depth beneath the Baikal rift zone, which may represent a mantle plume. The bottom depths of the Wadati–Benioff deep seismic zone and the Pacific slab itself become shallower toward the north under Kamchatka Peninsula, and the slab disappears under the northernmost Kamchatka. The slab loss is considered to be caused by the friction between the slab and the surrounding asthenosphere as the Pacific plate rotated clockwise at about 30 Ma ago, and then the slab loss was enlarged by the slab-edge pinch-off by the hot asthenospheric flow and the presence of Meiji seamounts. 相似文献
14.
<正>We synthesize significant recent results on the deep structure and origin of the active volcanoes in mainland China.Magmatism in the western Pacific arc and back-arc areas is caused by dehydration of the subducting slab and by corner flow in the mantle wedge,whereas the intraplate magmatism in China has different origins.The active volcanoes in Northeast China(such as the Changbai and Wuda-lianchi) are caused by hot upwelling in the big mantle wedge(BMW) above the stagnant slab in the mantle transition zone and deep slab dehydration as well.The Tengchong volcano in Southwest China is caused by a similar process in the BMW above the subducting Burma microplate(or Indian plate). The Hainan volcano in southernmost China is a hotspot fed by a lower-mantle plume which may be associated with the Pacific and Philippine Sea slabs' deep subduction in the east and the Indian slab's deep subduction in the west down to the lower mantle.The stagnant slab finally collapses down to the bottom of the mantle,which can trigger the upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and may cause the slab—plume interactions. 相似文献
15.
In this article, we review the significant recent results of geophysical studies and discuss their implications on seismotectonics, magmatism, and mantle dynamics in East Asia. High-resolution geophysical imaging revealed structural heterogeneities in the source areas of large crustal earthquakes, which may reflect magma and fluids that affected the rupture nucleation of large earthquakes. In subduction zone regions, the crustal fluids originate from the dehydration of the subducting slab. Magmatism in arc and back-arc areas is caused by the corner flow in the mantle wedge and dehydration of the subducting slab. The intraplate magmatism has different origins. The continental volcanoes in Northeast Asia (such as Changbai and Wudalianchi) seem to be caused by the corner flow in the big mantle wedge (BMW) above the stagnant slab in the mantle transition zone and the deep dehydration of the stagnant slab as well. The Tengchong volcano in Southwest China is possibly caused by a similar process in BMW above the subducting Burma microplate (or Indian plate). The Hainan volcano in southernmost China seems to be a hotspot fed by a lower-mantle plume associated with the Pacific and Philippine Sea slabs’ deep subduction in the east and the Indian slab’s deep subduction in the west down to the lower mantle. The occurrence of deep earthquakes under the Japan Sea and the East Asia margin may be related to a metastable olivine wedge in the subducting Pacific slab. The stagnant slab finally collapses down to the bottom of the mantle, which may trigger upwelling of hot mantle materials from the lower mantle to the shallow mantle beneath the subducting slabs and cause the slab–plume interactions. Some of these issues, such as the origin of intraplate magmatism, are still controversial, and so further detailed studies are needed from now. 相似文献
16.
《Gondwana Research》2010,17(3-4):401-413
We present new pieces of evidence from seismology and mineral physics for the existence of low-velocity zones in the deep part of the upper mantle wedge and the mantle transition zone that are caused by fluids from the deep subduction and deep dehydration of the Pacific and Philippine Sea slabs under western Pacific and East Asia. The Pacific slab is subducting beneath the Japan Islands and Japan Sea with intermediate-depth and deep earthquakes down to 600 km depth under the East Asia margin, and the slab becomes stagnant in the mantle transition zone under East China. The western edge of the stagnant Pacific slab is roughly coincident with the NE–SW Daxing'Anling-Taihangshan gravity lineament located west of Beijing, approximately 2000 km away from the Japan Trench. The upper mantle above the stagnant slab under East Asia forms a big mantle wedge (BMW). Corner flow in the BMW and deep slab dehydration may have caused asthenospheric upwelling, lithospheric thinning, continental rift systems, and intraplate volcanism in Northeast Asia. The Philippine Sea slab has subducted down to the mantle transition zone depth under Western Japan and Ryukyu back-arc, though the seismicity within the slab occurs only down to 200–300 km depths. Combining with the corner flow in the mantle wedge, deep dehydration of the subducting Pacific slab has affected the morphology of the subducting Philippine Sea slab and its seismicity under Southwest Japan. Slow anomalies are also found in the mantle under the subducting Pacific slab, which may represent small mantle plumes, or hot upwelling associated with the deep slab subduction. Slab dehydration may also take place after a continental plate subducts into the mantle. 相似文献
17.
Deep slab subduction and dehydration and their geodynamic consequences: Evidence from seismology and mineral physics 总被引：14，自引：9，他引：5
We present new pieces of evidence from seismology and mineral physics for the existence of low-velocity zones in the deep part of the upper mantle wedge and the mantle transition zone that are caused by fluids from the deep subduction and deep dehydration of the Pacific and Philippine Sea slabs under western Pacific and East Asia. The Pacific slab is subducting beneath the Japan Islands and Japan Sea with intermediate-depth and deep earthquakes down to 600 km depth under the East Asia margin, and the slab becomes stagnant in the mantle transition zone under East China. The western edge of the stagnant Pacific slab is roughly coincident with the NE–SW Daxing'Anling-Taihangshan gravity lineament located west of Beijing, approximately 2000 km away from the Japan Trench. The upper mantle above the stagnant slab under East Asia forms a big mantle wedge (BMW). Corner flow in the BMW and deep slab dehydration may have caused asthenospheric upwelling, lithospheric thinning, continental rift systems, and intraplate volcanism in Northeast Asia. The Philippine Sea slab has subducted down to the mantle transition zone depth under Western Japan and Ryukyu back-arc, though the seismicity within the slab occurs only down to 200–300 km depths. Combining with the corner flow in the mantle wedge, deep dehydration of the subducting Pacific slab has affected the morphology of the subducting Philippine Sea slab and its seismicity under Southwest Japan. Slow anomalies are also found in the mantle under the subducting Pacific slab, which may represent small mantle plumes, or hot upwelling associated with the deep slab subduction. Slab dehydration may also take place after a continental plate subducts into the mantle. 相似文献
18.
中国东北地区太平洋板块精细俯冲特征 总被引：1，自引：0，他引：1
中国东北地区的火山较为活跃。一些学者认为这些火山的起源与西太平洋板块的俯冲和软流圈物质的上涌存在密切联系。尽管天然地震层析成像结果明显地显示出火山区下方存在着太平洋板块,但板块的厚度、存在范围等俯冲特征仍然不是特别清晰。为此,采用远震层析成像和走时拟合相结合的方法深入研究了中国东北地区的壳幔速度结构,特别是太平洋俯冲板块的精细结构。研究结果表明:(1)板块的平均厚度和速度异常分别为85 km和1%,而且与日本海地区结果进行对比可推测板块并未增厚;(2)板块以低角度俯冲进入地幔过渡带,到达过渡带底部后弯曲成水平状,向西延伸至东经127°而停止;(3)水平延伸的板块恰好位于火山区的下方。这些俯冲特征有助于人们更好地理解陆内火山的起源及地球深部动力学过程。 相似文献
19.
长白山火山下方地幔转换带中滞留的俯冲太平洋板块存在空缺吗? 总被引：5，自引：3，他引：2
针对近年来长白山火山下方地幔转换带中是否存在低波速异常指示的太平洋板块"空缺"而引起的不同科学认识的热烈辩论,本文主要回顾了我国东北地区地幔转换带的体波成像结果。使用相对走时残差的远震体波成像结果显示,长白山火山以西地幔转换带中存在低波速异常指示的太平洋板块"空缺";而使用绝对走时残差的区域成像和全球成像结果,尽管展示出长白山火山以西比以东略低的波速异常,但长白山火山以东至我国东北重力梯度带区域下方的地幔转换带均展示出明显的连续的高波速异常。在接收函数分析时,如果以全球平均值660km而非我国东北地区平均值670km作为基准,来分析660km间断面是抬升还是下沉;以全球平均值250km而非我国东北地区平均值260km作为基准,来分析地幔转换带是增厚还是减薄的话,则可以得到长白山火山以东至我国东北重力梯度带区域660km间断面下沉与地幔转换带增厚的认识。这种与绝对走时残差成像结果展示的地幔转换带为连续的高波速异常结果相一致的结果,说明太平洋板块俯冲前缘已由日本海沟抵达我国东北松辽盆地与大兴安岭交界处。结合高温高压实验、数值模拟与岩石地球化学研究结果,本文并不支持长白山火山以西的地幔转换带存在低波速异常指示的板块"空缺"和地幔转换带"减薄"的认识。长白山火山的深部起源与太平洋板块深俯冲至我国东北松辽盆地与大兴安岭交界处形成的"大地幔楔"结构动力学相关。 相似文献
20.
The intraplate Baegdusan (Changbai) and Ulleung volcanoes located on the border of China, North Korea, and East/Japan Sea, respectively, have been explained by appeals to both hotspots and asthenospheric mantle upwelling (wet plume) caused by the stagnant Pacific plate. To understand the origin of the Baegdusan and Ulleung volcanism, we performed geochemical analyses on the tephra deposits in the East/Japan Sea basins originating from the Baegdusan and Ulleung volcanoes. The volcanic glass in the tephra from the Baegdusan and Ulleung volcanoes ranged from alkaline trachyte to peralkaline rhyolite and from phonolite to trachyte, respectively. The tephra from the two intraplate volcanoes showed highly enriched incompatible elements, such as Tb, Nb, Hf, and Ta, distinct from those of the ordinary arc volcanoes of the Japanese islands. The straddle distribution of the Th/Yb and Ta/Yb ratios of the tephra deposits from the Baegdusan volcano may originate from the alkali basaltic magma resulting from mixing between the wet plume from the stagnant Pacific plate in the transition zone and the overlying shallow asthenospheric mantle. In contrast, the deposits from the Ulleung volcano show a minor contribution of the stagnant slab to the basaltic magma, implying either partial melting of a more enriched mantle, smaller degrees of partial melting of a garnet-bearing mantle source, or a combination of both processes as the magma genesis. Our study indicated that the Baegdusan and Ulleung volcanoes have different magma sources and evolutionary histories. 相似文献