内蒙古阿鲁科尔沁旗新民组“豆状”凝灰岩岩石学特征及成因探讨

内蒙古阿鲁科尔沁旗新民组出露有“豆状”凝灰岩,其中含“火山豆”（火山灰球）65%左右.“火山豆”发育同心韵律环带构造,有的发育有玻璃质边,有的可见长石晶屑嵌入其边缘,填隙物中可见有长石晶屑聚集现象.通过分析岩石结构及碎屑成分特征,认为“火山豆”凝灰岩是火山喷发过程中,由炽热的高能量高密度火山灰涌流向外迁移并伴随大气降水共同作用形成.     

Boundary crossing and non‐linear theory in earth‐system sciences – a proof of concept based on tsunami and post‐eruption scenarios on Java Island,Indonesia

Although volcanic eruptions are well‐known to be the trigger of some weather and climatic changes, land‐cover changes by pyroclastic‐flows and lahars do not get this recognition, neither do major hazards such as tsunami. These two earth processes are even lesser considered as being able to modify other earth processes they are not directly connected to, such as landslides or river discharge in non‐connected basins more than a hundred kilometres away. In this contribution the authors argue that these ideas are mainly driven by the process of being ‘educated’ in a single academic discipline and once put to the test interactions and retroactions between earth processes and atmospheric processes are far more reaching than commonly thought. For this study, the site of Java Island (Indonesia) was chosen to conduct (1) an analysis of a major tsunami impact – in the same area as the 2006 Java tsunami and (2) an analysis of the post‐eruption impacts of Merapi Volcano after a major eruption – excluding any ejecta in the atmosphere for the sake of the demonstration. The atmospheric feedback simulations were conducted using the regional climate model (RegCM‐4) with calibration from weather stations in Java Island. As a result, both simulations have proven that large scale deposits of pyroclasts (not introducing the ejectas sent in the atmosphere) and tsunamis can have outstanding impacts on the atmospheric situation and the bio‐geomorphologic evolution of the landscape in the following weeks to months. Interestingly enough these impacts are not limited to the area impacted by the earth process and the effect are not linear in time as they work following thresholds. These rainfalls ‘tele‐impacts’ are important enough to, in turn, modify earth‐surface processes in areas remote from the original phenomenon. This system acts in the same manner as a famous butterfly in Africa that could trigger a hurricane on the other side of the Atlantic Ocean. Copyright © 2012 John Wiley & Sons, Ltd.     

山东省邹平火山岩盆地北西部覆盖区找矿潜力分析

为了合理有效地勘查开发邹平火山岩盆地的铜矿资源,从2004年开始,在该区开展了地质调查工作,在北部第四系覆盖区重点部署了物探调查工作。从基本特征、成矿地质条件、地球物理场等方面,与地质特征相似的已知矿床进行类比、预测,认为邹平火山岩盆地北西部第四系覆盖区地球物理异常具有磁异常低、电阻率低、极化率高、重力场低的特征。并圈定出异常叠合区,认为该区找矿潜力大,成矿远景良好,目标矿种为铜矿及多金属矿。     

On Correlational Properties for Volcanic Earthquakes Associated with Asamayama (Japan), 1983–2005

To a first approximation, earthquakes directly associated with volcanic activity may be studied as point-stochastic processes. The earthquakes associated with B-type (movements located at 1 km or shallower) eruptive activity in the caldera of Asamayama differ in correlational properties from concurrent deep-seated seismic activity (A-type, located deeper than approximately 1 km). A-type activity occurs either in the form of independently distributed intervals between events or as dependently distributed intervals which are most appropriately analysed in contiguous sub-samples (“windows”). The cross correlations between the magnitudes of A-type earthquakes and depth of events for three periods from 1983 to 2005 may be of significance for interpreting aspects of the volcanic history of Asamayama. The lag-1 serial correlation coefficient for the A-type sequence from 1983 to 1990 is not significantly different from zero. In the case of the sets for 1991–2002 and 2003–2005, the coefficients are small but not zero. The difference is in part, at least, probably due to the well-known confounding effect of trending as opposed to true serial correlation between successive events. The serial correlation coefficient for the B-type crater sequence is not significant. The novel aspect of the present study concerns the relationship between depth of A-type earth movements and magnitude of associated shocks.     

内蒙古二连盆地洪浩尔舒特凹陷白垩系火山岩储集层

内蒙古二连盆地火山岩分布极为广泛,在古生界（含变质岩） 及中生界的侏罗系和白垩系均有分 布。位于盆地内乌尼特坳陷的洪浩尔舒特凹陷发育有３套火山岩,主要分布在白垩系阿尔善组上段、阿尔善组 下段和腾格尔组一段,火山岩主要为安山岩,次为凝灰岩和少量火山角砾岩。火山岩储集空间类型主要为气孔 和火山灰溶孔,孔缝组合类型有孔隙型、裂缝-孔隙型、孔隙-裂缝型和裂缝型。储集层物性受火山岩岩相、 成岩作用和构造活动影响,以岩相影响最显著。储集层发育总体上中央洼槽中部和东部较好。     

Geochemistry and geochronology of Late Triassic volcanic rocks in the Chiang Khong region, northern Thailand

The Chiang Khong segment of the Chiang Khong–Lampang–Tak Volcanic Belt is composed of three broadly meridional sub‐belts of mafic to felsic volcanic, volcaniclastic, and associated intrusive rocks. Associated sedimentary rocks are largely non‐marine red beds and conglomerates. Three representative Chiang Khong lavas have Late Triassic (223–220 Ma) laser ablation inductively coupled mass‐spectroscopy U–Pb zircon ages. Felsic‐dominated sequences in the Chiang Khong Western and Central Sub‐belts are high‐K calc–alkaline rocks that range from basaltic to dominant felsic lavas with rare mafic dykes. The Western Sub‐belt lavas have slightly lower high field strength element contents at all fractionation levels than equivalent rocks from the Central Sub‐belt. In contrast, the Eastern Sub‐belt is dominated by mafic lavas and dykes with compositions transitional between E‐mid‐oceanic ridge basalt and back‐arc basin basalts. The Eastern Sub‐belt rocks have higher FeO* and TiO₂ and less light rare earth element enrichment than basalts in the high‐K sequences. Basaltic and doleritic dykes in the Western and Central sub‐belts match the composition of the Eastern Sub‐belt lavas and dykes. A recent geochemical study of the Chiang Khong rocks concluded that they were erupted in a continental margin volcanic arc setting. However, based on the dominance of felsic lavas and the mainly non‐marine associated sediments, we propose an alternative origin, in a post‐collisional extensional setting. A major late Middle to early Late Triassic collisional orogenic event is well documented in northern Thailand and Yunnan. We believe that the paucity of radiometric dates for arc‐like lavas in the Chiang Khong–Lampang–Tak Volcanic Belt that precede this orogenic event, coupled with the geochemistry of the Chiang Khong rocks, and strong compositional analogies with other post‐collisional magmatic suites, are features that are more typical of volcanic belts formed in a rapidly evolving post‐collisional, basin‐and range‐type extensional setting.     

大兴安岭地区中生代火山岩岩石地层的划分与对比问题

通过在本区长期从事区域地质调查与研究的实践及认识,结合新一轮国土资源大调查的实际资料,运用火山喷发旋回、火山岩岩石学、岩石化学、地层古生物及同位素地质测年等方面的研究与对比,将大兴安岭地区中生代火山岩划分了6个火山喷发旋回,分别对应6个火山岩石地层单位.     

Simulating the dispersal of tephra from the 1991 Pinatubo eruption: Implications for the formation of widespread ash layers

PUFF and HAZMAP, two tephra dispersal models developed for volcanic hazard mitigation, are used to simulate the climatic 1991 eruption of Mt. Pinatubo. PUFF simulations indicate that the majority of ash was advected away from the source at the level of the tropopause (~ 17 km). Several eruptive pulses injected ash and SO₂ gas to higher altitudes (~ 25 km), but these pulses represent only a small fraction (~ 1%) of the total erupted material released during the simulation. Comparison with TOMS images of the SO₂ cloud after 71 and 93 h indicate that the SO₂ gas originated at an altitude of ~ 25 km near the source and descended to an altitude of ~ 22 km as the cloud moved across the Indian Ocean. HAZMAP simulations indicate that the Pinatubo tephra fall deposit in the South China Sea was formed by an eruption cloud with the majority of the ash concentrated at a height of 16–18 km. Results of this study demonstrate that the largest concentration of distal ash was transported at a level significantly below the maximum eruption column height (~ 40 km) and at a level below the calculated height of neutral buoyancy (~ 25 km). Simulations showed that distal ash transport was dominated by atmospheric circulation patterns near the regional tropopause. In contrast, the movement of the SO₂ cloud occurred at higher levels, along slightly different trajectories, and may have resulted from gas/particle segregations that took place during intrusion of the Pinatubo umbrella cloud as it moved away from source.     

A multidisciplinary effort to assign realistic source parameters to models of volcanic ash-cloud transport and dispersion during eruptions

During volcanic eruptions, volcanic ash transport and dispersion models (VATDs) are used to forecast the location and movement of ash clouds over hours to days in order to define hazards to aircraft and to communities downwind. Those models use input parameters, called “eruption source parameters”, such as plume height H, mass eruption rate Ṁ, duration D, and the mass fraction m₆₃ of erupted debris finer than about 4 or 63 μm, which can remain in the cloud for many hours or days. Observational constraints on the value of such parameters are frequently unavailable in the first minutes or hours after an eruption is detected. Moreover, observed plume height may change during an eruption, requiring rapid assignment of new parameters. This paper reports on a group effort to improve the accuracy of source parameters used by VATDs in the early hours of an eruption. We do so by first compiling a list of eruptions for which these parameters are well constrained, and then using these data to review and update previously studied parameter relationships. We find that the existing scatter in plots of H versus Ṁ yields an uncertainty within the 50% confidence interval of plus or minus a factor of four in eruption rate for a given plume height. This scatter is not clearly attributable to biases in measurement techniques or to well-recognized processes such as elutriation from pyroclastic flows. Sparse data on total grain-size distribution suggest that the mass fraction of fine debris m₆₃ could vary by nearly two orders of magnitude between small basaltic eruptions ( 0.01) and large silicic ones (> 0.5). We classify eleven eruption types; four types each for different sizes of silicic and mafic eruptions; submarine eruptions; “brief” or Vulcanian eruptions; and eruptions that generate co-ignimbrite or co-pyroclastic flow plumes. For each eruption type we assign source parameters. We then assign a characteristic eruption type to each of the world's  1500 Holocene volcanoes. These eruption types and associated parameters can be used for ash-cloud modeling in the event of an eruption, when no observational constraints on these parameters are available.     

Observations of Mt. Etna volcanic ash plumes in 2006: An integrated approach from ground-based and polar satellite NOAA–AVHRR monitoring system

Mt. Etna, in Sicily (Italy), is one of the world's most frequent emitters of volcanic plumes. During the last ten years, Etna has produced copious tephra emission and fallout that have damaged the inhabited and cultivated areas on its slopes and created serious hazards to air traffic. Recurrent closures of the Catania International airport have often been necessary, causing great losses to the local economy. Recently, frequent episodes of ash emission, lasting from a few hours to days, occurred from July to December 2006, necessitating a look at additional monitoring techniques, such as remote sensing. The combination of a ground monitoring system with polar satellite data represents a novel approach to monitor Etna's eruptive activity, and makes Etna one of the few volcanoes for which this surveillance combination is routinely available.In this work, ash emission information derived from an integrated approach, based on comparing ground and NOAA–AVHRR polar satellite observations, is presented. This approach permits us to define the utility of real time satellite monitoring systems for both sporadic and continuous ash emissions. Using field data (visible observations, collection of tephra samples and accounts by local inhabitants), the duration and intensity of most of the tephra fallout events were evaluated in detail and, in some cases, the order of magnitude of the erupted volume was estimated. The ground data vs. satellite data comparison allowed us to define five different categories of Etna volcanic plumes according to their dimensions and plume height, taking into account wind intensity. Using frequent and good quality satellite data in real time, this classification scheme could prove helpful for investigations into a possible correlation between eruptive intensity and the presence and concentration of ash in the volcanic plume. The development and improvement of this approach may constitute a powerful warning system for Civil Protection, thus preventing unnecessary airport closures.