太平洋火山特征与深部成因机制

太平洋板块边界和内部均发育大量火山，是研究地球火山的天然实验场。综述了太平洋火山特征与深部成因机制，表明研究人员对地球不同环境下的火山（包括大洋中脊、俯冲带岛弧、板内地幔柱等）进行了系统性研究，分别构建了减压熔融、俯冲板片脱水与富水地幔楔熔融、地幔柱高温熔融的经典模式。但目前学界对于板内非地幔柱型火山的深部岩浆起源以及浅部喷发通道等重要科学问题仍缺乏清晰的认识。未来需要采用创新观测手段，开展多学科交叉研究以取得突破。     

皮纳图博火山喷发对气候影响的数值试验

用俄勒冈州立大学（ＯＳＵ）的两层大气环流模式，研究１９９１年６月中旬菲律宾的皮纳图博（Ｐｉｎａｔｕｂｏ）火山喷发对短期气候的影响．数值试验的结果表明：①火山喷发引起低纬太阳辐射减少，导致次年１，２月模式大气的北半球主要大气活动中心（阿留申低压、冰岛低压、东亚冷高压、北美冷高压等）的强度明显减弱，亚洲和北美大陆中高纬度大部分地区的地面气温明显上升．模拟结果与实况相当一致．皮纳图博火山喷发对北半球中高纬许多地区（如前苏联的西伯利亚的中西部、中国北方地区、日本和西欧以及美国等地）１９９２年１，２月所出现的异常暖冬天气有重要的作用．②火山喷发引起的热带太平洋海平面气压场变化有利于南方涛动的减弱．     

2022年汤加火山喷发与海啸观测

2022年1月15日世界标准时间4∶14，位于南太平洋汤加俯冲带火山链区域的Hunga Tonga-Hunga Ha’apai(HTHH,175.39°W,20.55°S)火山爆发并激发全球性海啸。聚焦火山喷发和海啸波的观测方法，介绍了海底传感器、大气波变化卫星图、电离层扰动对火山喷发和海啸的最新监测结果。结合该区域的地质构造与火山喷发历史资料，综述了2022年汤加HTHH火山喷发引起的海啸特征、最新观测手段，提出了对俯冲带火山海啸等进行详细的海洋地球物理调查、基于观测综合量化研究海底火山大规模喷发对全球气候的潜在影响等建议。     

徐东地区营城组一段火山喷发模式特征

从火山喷发的构造环境、火山喷发旋回特征出发,结合原始岩浆来源、火山岩岩性特征、火山喷发类型等,总结了徐深气田徐东地区营城组一段火山喷发模式,分析了其对储层的影响。结果表明,切穿基底的深大断裂在火山喷发中起着决定性的作用。目的层自下而上划分为3 个旋回,旋回I 对应YC1III,旋回II 对应YC1II1 和YC1II2,旋回III对应小层YC1I1 和YC1I2。火山喷发以裂隙–中心式喷发为主,中心式喷发为辅。火山喷发模式控制着不同类型火山岩相的发育特征。靠近火山口的爆发相的高部位、溢流相下部亚相、顶部亚相、上部亚相、火山通道相的火山颈亚相等是有利的开发区域。     

陕西略阳陈家坝古火山机构的探讨

概述了位于陕西省略阳县境内的陈家坝古火山机构，是碧口群中保存较好，发育较全的一个古火山机构。它由火山通道相、爆溢相、喷发———沉积相和次火山相组成，并经历了两次完整的火山喷发———沉积旋回过程，形成了与其相关的金———银多金属矿和铁矿，锰矿、磷矿等。     

1525-2000年强火山喷发与ENSO事件的关系

根据美国Smithsonian研究院的全球火山计划发布火山喷发年表,筛选出1525-2000年强火山喷发(火山喷发指数IVE≥4),并分为强火山喷发(IVE=4)和极强火山喷发(IVE≥5);利用Gergis重建了1525-2000年ENSO 年表,得到不同类型的ENSO 事件,分别对强火山喷发和ENSO 事件进行10a累计统计.对1525-2000年强火山喷发次数和ENSO事件次数进行匹配.结果表明:1525-2000年,强火山喷发出现195次,其中IVE=4的强火山喷发153次,极强火山喷发42次;ENSO 事件出现399次,包括188次厄尔尼诺事件和211次拉尼娜事件.强火山喷发后的ENSO 事件次数明显多于出现前2a内无强火山喷发的ENSO 事件次数,且强火山喷发后的ENSO 事件中厄尔尼诺、拉尼娜次数相当,而出现前2a内无强火山喷发的ENSO 事件中拉尼娜事件明显多于厄尔尼诺事件.强火山喷发后的厄尔尼诺事件出现137次,拉尼娜出现136次,两者出现次数持平.不同强度的火山喷发后,厄尔尼诺事件与拉尼娜事件出现概率基本相等.      

岩浆，关不住的红色猛兽

它们被冠以“火神”的称号当之无愧：火山喷发在历史上曾是灾难之最。它会带来气候的变化，炽热的熔岩到处肆虐，吞噬一切。但它们并非只会毁灭，在地球形成的进程中它们也起到了举足轻重的作用。火山喷发就像是一扇扇窗户，透过它们，我们可以了解地球内部发生的一切。     

亚太地区1991年春夏两季自然灾害的探讨

对亚太地区１９９１年春季和夏初火山，地震及特大暴雨等自然灾害频繁发生的突出现象与深原因，本文进行了初步探索，归因于天体影响，岩浆运行，火山喷发和半球间宏观天气系统，从而解释了文中提到了几个疑难问题。     

汤加海底火山喷发或将持续

连日来,南太平洋岛国汤加洪阿哈阿帕伊岛火山发生多次喷发,火山灰混着气体在太平洋上空升腾,火山喷发还触发了局地海啸. 该火山前身是一座海底火山,2009年喷发后形成新岛屿.它此前也曾多次喷发,但没有如此剧烈.有新西兰地质学家表示,事发地火山已苏醒,此次喷发可能持续下去.     

全球气候变化的原因及其对策

全球气候变化问题正在全世界被广泛地讨论。尽管许多人半信半疑地接受了温室气体是全球气候变化的主要因素这一观点,但许多科学家仍然持怀疑态度,他们用大量的证据驳斥了这一观点,并认为自然驱动是全球气候变化的主要因素,但他们并没有找出具有说服力的自然驱动力。近来作者的研究也表明尽管温室气体能使局部地区短期出现变暖现象,但火山活动能改变地球的轨道,因而是引起气候明显变化的关键因素,这是一直被人们忽略的。如果一次大的火山喷发主要发生在夜晚,它可能导致全球变暖;如果它主要发生在白天,它可能导致全球变冷;特别地它还能使地球进入冰河时期或间冰期。如果我们要使地球变暖,就应该使火山喷发主要发生在夜晚;如果我们要使地球变冷,就应该使火山喷发主要发生在白天。我们再也不怕因气候变化引起的世界末日的到来。     

火山活动的环境资源效应

火山活动是一种自然地质现象 ,其喷发活动具有双重的环境效应 .其不利的一面主要表现为对人类环境造成的灾害效应 ,主要有火山碎屑流灾害、熔岩流灾害、火山泥石流灾害、火山灰云灾害和火山气体导致的灾害等 ;同时火山活动也会对气候产生影响 ,大规模的强火山喷发 ,会在一定的时间范围内 ,导致全球平均气温降低 .火山活动会给人类带来巨大的灾难 ,同时也给人类社会带来了巨大的财富 ,如丰富的矿产资源、地热资源和旅游资源等 .本文主要从灾害、气候和资源三个方面阐述了火山活动对人类环境的深刻影响 .     

Detection of bromine monoxide in a volcanic plume

The emission of volcanic gases usually precedes eruptive activity, providing both a warning signal and an indication of the nature of the lava soon to be erupted. Additionally, volcanic emissions are a significant source of gases and particles to the atmosphere, influencing tropospheric and stratospheric trace-gas budgets. Despite some halogen species having been measured in volcanic plumes (mainly HCl and HF), little is known about bromine compounds and, in particular, gas-phase reactive bromine species. Such species are especially important in the stratosphere, as reactive bromine-despite being two orders of magnitude less abundant than chlorine-accounts for about one-third of halogen-catalysed ozone depletion. In the troposphere, bromine-catalysed complete ozone destruction has been observed to occur regularly during spring in the polar boundary layers as well as in the troposphere above the Dead Sea basin. Here we report observations of BrO and SO2 abundances in the plume of the Soufrière Hills volcano (Montserrat) in May 2002 by ground-based multi-axis differential optical absorption spectroscopy. Our estimate of BrO emission leads us to conclude that local ozone depletion and small ozone 'holes' may occur in the vicinity of active volcanoes, and that the amount of bromine emitted from volcanoes might be sufficiently large to play a role not only in the stratosphere, but also in tropospheric chemistry.     

Linking mantle plumes, large igneous provinces and environmental catastrophes

Large igneous provinces (LIPs) are known for their rapid production of enormous volumes of magma (up to several million cubic kilometres in less than a million years), for marked thinning of the lithosphere, often ending with a continental break-up, and for their links to global environmental catastrophes. Despite the importance of LIPs, controversy surrounds even the basic idea that they form through melting in the heads of thermal mantle plumes. The Permo-Triassic Siberian Traps--the type example and the largest continental LIP--is located on thick cratonic lithosphere and was synchronous with the largest known mass-extinction event. However, there is no evidence of pre-magmatic uplift or of a large lithospheric stretching, as predicted above a plume head. Moreover, estimates of magmatic CO(2) degassing from the Siberian Traps are considered insufficient to trigger climatic crises, leading to the hypothesis that the release of thermogenic gases from the sediment pile caused the mass extinction. Here we present petrological evidence for a large amount (15?wt%) of dense recycled oceanic crust in the head of the plume and develop a thermomechanical model that predicts no pre-magmatic uplift and requires no lithospheric extension. The model implies extensive plume melting and heterogeneous erosion of the thick cratonic lithosphere over the course of a few hundred thousand years. The model suggests that massive degassing of CO(2) and HCl, mostly from the recycled crust in the plume head, could alone trigger a mass extinction and predicts it happening before the main volcanic phase, in agreement with stratigraphic and geochronological data for the Siberian Traps and other LIPs.     

化学危险性气体泄漏扩散模拟及其影响因素

分析了描述易燃易爆及有毒有害气体泄漏扩散过程的数学模型,包括Gaussian模型、Gaussian轨迹烟云模型、BM模型、Sutton模型及FEM3模型。重点介绍了目前广泛使用的Gaussian模型及Gaussian轨迹烟云模型。针对事故泄漏扩散过程的复杂性,详细讨论了气象条件及地形条件对危险性物质泄漏扩散过程的影响,此外还对不确定参数的选取进行了探讨。     

Transient dynamics of vulcanian explosions and column collapse

Several analytical and numerical eruption models have provided insight into volcanic eruption behaviour, but most address plinian-type eruptions where vent conditions are quasi-steady. Only a few studies have explored the physics of short-duration vulcanian explosions with unsteady vent conditions and blast events. Here we present a technique that links unsteady vent flux of vulcanian explosions to the resulting dispersal of volcanic ejecta, using a numerical, axisymmetric model with multiple particle sizes. We use observational data from well documented explosions in 1997 at the Soufrière Hills volcano in Montserrat, West Indies, to constrain pre-eruptive subsurface initial conditions and to compare with our simulation results. The resulting simulations duplicate many features of the observed explosions, showing transitional behaviour where mass is divided between a buoyant plume and hazardous radial pyroclastic currents fed by a collapsing fountain. We find that leakage of volcanic gas from the conduit through surrounding rocks over a short period (of the order of 10 hours) or retarded exsolution can dictate the style of explosion. Our simulations also reveal the internal plume dynamics and particle-size segregation mechanisms that may occur in such eruptions.     

Atmospheric oxygenation caused by a change in volcanic degassing pressure

The Precambrian history of our planet is marked by two major events: a pulse of continental crust formation at the end of the Archaean eon and a weak oxygenation of the atmosphere (the Great Oxidation Event) that followed, at 2.45?billion years ago. This oxygenation has been linked to the emergence of oxygenic cyanobacteria and to changes in the compositions of volcanic gases, but not to the composition of erupting lavas--geochemical constraints indicate that the oxidation state of basalts and their mantle sources has remained constant since 3.5?billion years ago. Here we propose that a decrease in the average pressure of volcanic degassing changed the oxidation state of sulphur in volcanic gases, initiating the modern biogeochemical sulphur cycle and triggering atmospheric oxygenation. Using thermodynamic calculations simulating gas-melt equilibria in erupting magmas, we suggest that mostly submarine Archaean volcanoes produced gases with SO(2)/H(2)S?相似文献   

The chemical structure of the Hawaiian mantle plume

The Hawaiian-Emperor volcanic island and seamount chain is usually attributed to a hot mantle plume, located beneath the Pacific lithosphere, that delivers material sourced from deep in the mantle to the surface. The shield volcanoes of the Hawaiian islands are distributed in two curvilinear, parallel trends (termed 'Kea' and 'Loa'), whose rocks are characterized by general geochemical differences. This has led to the proposition that Hawaiian volcanoes sample compositionally distinct, concentrically zoned, regions of the underlying mantle plume. Melt inclusions, or samples of local magma 'frozen' in olivine phenocrysts during crystallization, may record complexities of mantle sources, thereby providing better insight into the chemical structure of plumes. Here we report the discovery of both Kea- and Loa-like major and trace element compositions in olivine-hosted melt inclusions in individual, shield-stage Hawaiian volcanoes--even within single rock samples. We infer from these data that one mantle source component may dominate a single lava flow, but that the two mantle source components are consistently represented to some extent in all lavas, regardless of the specific geographic location of the volcano. We therefore suggest that the Hawaiian mantle plume is unlikely to be compositionally concentrically zoned. Instead, the observed chemical variation is probably controlled by the thermal structure of the plume.     

Volcanically emitted sodium chloride as a source for Io's neutral clouds and plasma torus

The atmosphere of Jupiter's satellite Io is extremely tenuous, time variable and spatially heterogeneous. Only a few molecules--SO2, SO and S2--have previously been identified as constituents of this atmosphere, and possible sources include frost sublimation, surface sputtering and active volcanism. Io has been known for almost 30 years to be surrounded by a cloud of Na, which requires an as yet unidentified atmospheric source of sodium. Sodium chloride has been recently proposed as an important atmospheric constituent, based on the detection of chlorine in Io's plasma torus and models of Io's volcanic gases. Here we report the detection of NaCl in Io's atmosphere; it constitutes only approximately 0.3% when averaged over the entire disk, but is probably restricted to smaller regions than SO2 because of its rapid photolysis and surface condensation. Although the inferred abundance of NaCl in volcanic gases is lower than predicted, those volcanic emissions provide an important source of Na and Cl in Io's neutral clouds and plasma torus.     

Evidence from episodic seamount volcanism for pulsing of the Iceland plume in the past 70 Myr

The North Atlantic volcanic province has been attributed to continental rifting about 60 Myr ago over an Iceland plume head with a diameter of 1,000-2,000 km (refs 1, 2). But evidence from a few igneous centres has been used to infer that earlier plume activity occurred in this region. The three seamounts in the Rockall trough off the Atlantic coast of Scotland are among the few accessible remnants of such early plume activity. Here we present 40Ar-39Ar incremental-heating ages of samples from these seamounts, which show that volcanism began there in the late Cretaceous period (70 +/- 1 Myr ago), and then continued for the next 30 Myr in at least four discrete phases: 62, 52, 47 and 42 Myr ago. We relate this activity to pulsing of large masses (approximately 10(8) km3) of hot Iceland plume material on timescales of 5-10 Myr. This significantly extends the time span for Iceland plume activity both backwards and forwards in time, and provides a possible alternative to the 'plume head' models for the formation of continental flood basalts.     

川西二叠系火山碎屑岩储层特征及发育有利区

火山岩是四川盆地重要的有效储集体,中石化在川西地区部署的YS1井钻遇厚层火山岩,气显示强烈,为盆地内火山岩勘探新区域。基于对已有钻井资料分析,综合研究区域地质背景,从岩性组合方式、储集空间类型、地化特征和储层孔隙演化等方面开展川西地区火山碎屑岩储层基本特征研究。研究区火山岩的形成与峨眉山地幔柱活动具有一定关联,岩石类型复杂,储层储集性能非均质性强,具高孔低渗特征,为一套裂缝-孔隙型储层。火山角砾岩为主要储集岩类,储集空间以残余气孔、基质微孔、次生溶孔为主,见少量构造裂缝和冷凝收缩缝。同生成岩阶段,挥发逸散、脱玻化作用和冷凝收缩作用促使气孔、玻屑孔和收缩孔缝发育,但热液充填作用使孔隙度大幅度降低;表生成岩阶段,构造破裂和风化淋滤作用小幅改善储层储集性能;埋藏成岩阶段压实作用、充填作用和溶蚀作用对储层进行改造,最终储层残余面孔率4%左右。YS1井区、广汉、知新场和龙宝梁地区为储层发育有利区。