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陨石状态方程形式的选择与参量的确定——以吉林球粒陨石和南丹铁陨石为例 总被引：2，自引：0，他引：2
在二级轻气炮动高压装置上用电探针技术测量了吉林球粒陨石(H5)和南丹铁陨石(ⅢCD)的冲击压缩线,然后分别选择几种可能适用于普通球粒陨石和铁陨石状态方程的数学表达式,并确定了状态方程中的有关参量值.从状态方程的P(V)关系曲线与实验数据的比较来看,吉林球粒陨石最适合采用普适状态方程形式,而南丹铁陨石则最适合采用三项式状态方程形式.吉林球粒陨石的普适状态方程参量K_(OS)=48.10GPa,K’_(OS)=4.13.南丹铁陨石的三项式状态方程参量Q=41.2353lGPa,q=12.27179,这是吉林球粒陨石和南丹铁陨石状态方程的首次报道. 相似文献
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正据估计,每年降落到地球上的陨石大约有几千颗,其中只有很少一部分被人们找到或发现,绝大部分陨石都落到了荒无人烟的地方或江河湖海中。俄罗斯陨石事件让人们切实感受到了陨石的存在及威胁。陨石是怎么来的?它是属于行星还是彗星?还是它是另外一种宇宙天体?要弄清楚这些问题,就要追根溯源,找出陨石与太阳系各天体之间的关系。 相似文献
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在岩石矿物学研究的基础上, 测定了我国两个南极陨石、以及光明山和庄河球粒陨石的稀有气体同位素丰度, 并根据宇宙成因核素的产率, 获得了这4个普通球粒陨石的宇宙射线暴露年龄和气体保存年龄. 两个南极陨石的暴露年龄分别为17.0±2.5 Ma(GRV 98002)和0.052±0.008 Ma(GRV 98004), 光明山球粒陨石为68.9±10 Ma, 庄河球粒陨石为3.8±0.6 Ma. GRV 98004(H5)的暴露年龄是目前南极陨石中已知最低的, 而光明山球粒陨石的暴露年龄高于我国其他H群球粒陨石. GRV 98002和庄河球粒陨石在宇宙射线暴露期间可能受到冲击事件或由于小的近日距轨道导致加热, 造成低的4He含量, 而GRV 98002和光明山球粒陨石的宇宙成因核素3He和4He则基本上同步丢失. 相似文献
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这块神秘陨石一半是淡淡的褐色,一半是黑色,这样的熔壳颜色极为罕见
该陨石的表面有金属镶嵌点。呈现金黄色和银白色,绝非普通的石质球粒陨石
从陨石上一块硬币大小的破损点可以观察到。它的内部物质呈现青色 相似文献
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纳米比亚霍巴陨石重约60吨
霍巴陨石是坠落在地球上的最重陨石,其表面积超过6．5平方米,重量在60吨左右。据说,在坠落地球过程中,霍巴陨石的飞行速度因与地球大气层之间发生的摩擦大大降低,使其在落地之时得以保持完整并且大部分露出地表,而不是埋入地下。其异乎寻常的扁平外形说明,这颗陨石甚至能够像漂石一样在水面上跳跃前进。 相似文献
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正人类所处的地球,只是太阳系中一颗普通的行星,陨石来袭本也是常有之事,然而这一次发生在俄罗斯的陨石事件,陨石来势突然,毫无防备,造成了大量的人员受伤和巨额财产损失,引起了全世界的高度关注,产生了广泛的社会影响。俄罗斯媒体早在16日就报道,俄罗斯的陨石坠落事件已造成10亿卢布 相似文献
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广丰县李家膨润土矿床赋存于白垩系上统南雄组第二岩性段酸性火山岩的顶底部。膨润土的主要矿物成分为蒙脱石,矿石结构构造与成矿原岩有关。矿石化学成分与酸性熔岩相近,矿体形态及空间分布受酸性熔岩流相带的控制。因此认为,膨润土矿床成矿原岩为酸性玻质熔岩,矿床是由酸性玻璃质熔岩经水解脱玻化而形成,其成因类型为风化淋滤蚀变岩型矿床。膨润土可自然改型,由原来的钠基膨润土改型成钙基膨润土和偏镁的钙基膨润土。对时代较新的酸性火山岩,在玻质熔岩发育处都有可能找到有利用价值的膨润土矿。由于膨润土常由珍珠岩、沸石脱玻化形成,三者常共生出现,是很好的找矿标志。 相似文献
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The aerodynamic behaviour of volcanic aggregates 总被引：1，自引：1，他引：0
A large proportion of solid material transported within the atmosphere during volcanic eruptions consists of particles less than 500 m in diameter. The majority of these particles become incorporated into a wide range of aggregate types, the aerodynamic behaviour of which has not been determined by either direct observation or in the laboratory. In the absence of such data, theoretical models of fallout from volcanic plumes make necessarily crude assumptions about aggregate densities and fall velocities. Larger volcanic ejecta often consists of pumice of lower than bulk density. Experimental data are presented for the fall velocities of porous aggregates and single particles, determined in systems analogous to that of ejecta falling from a volcanic plume. It is demonstrated that the fall of aggregates may be modelled in identical fashion to single particles by using a reduced aggregate density dependent on the porosity, and a size corresponding to an enclosing sphere. Particles incorporated into aggregates attain a substantially higher fall velocity than single particles. This is due to the larger physical dimensions of the aggregate, which overcomes the effect of lower aggregate density. Additionally, the internal porosity of the aggregate allows some flow of fluid through the aggregate and this results in a small increase in fall velocity. The increase in fall velocity of particles incorporated into aggregates, rather than falling individually, results in the enhanced removal of fine material from volcanic plumes. 相似文献
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Cristobalite in a rhyolitic lava dome: evolution of ash hazard 总被引：1，自引：1，他引：0
Claire J. Horwell Jennifer S. Le Blond Sabina A. K. Michnowicz Gordon Cressey 《Bulletin of Volcanology》2010,72(2):249-253
Prolonged and heavy exposure to particles of respirable, crystalline silica-rich volcanic ash could potentially cause chronic,
fibrotic disease, such as silicosis, in individuals living in areas of frequent ash fall. Here, we show that the rhyolitic
ash erupted from Chaitén volcano, Chile, in its dome-forming phase, contains increased levels of the silica polymorph cristobalite,
compared to its initial plinian eruption. Ash erupted during the initial, explosive phase (2–5 May 2008) contained approximately
2 wt.% cristobalite, whereas ash generated after dome growth began (from 21 May 2008) contains 13–19 wt.%. The work suggests
that active obsidian domes crystallise substantial quantities of cristobalite on time-scales of days to months, probably through
vapour-phase crystallisation on the walls of degassing pathways, rather than through spherulitic growth in glassy obsidian.
The ash is fine-grained (9.7–17.7 vol.% <4 μm in diameter, the respirable range) and the particles are mostly angular. Sparse,
fibre-like particles were confirmed to be feldspar or glass. 相似文献
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Pliocene–Recent volcanic outcrops at Seal Nunataks and Beethoven Peninsula (Antarctic Peninsula) are remnants of several
monogenetic volcanoes formed by eruption of vesiculating basaltic magma into shallow water, in an englacial environment. The
diversity of sedimentary and volcanic lithofacies present in the Antarctic Peninsula outcrops provides a clear illustration
of the wide range of eruptive, transportational and depositional processes which are associated with englacial Surtseyan volcanism.
Early-formed pillow lava and glassy breccia, representing a pillow volcano stage of construction, are draped by tephra erupted
explosively during a tuff cone stage. The tephra was resedimented around the volcano flanks, mainly by coarse-grained sediment
gravity flows. Fine-grained lithofacies are rare, and fine material probably bypassed the main volcanic edifice, accumulating
in the surrounding englacial basin. The pattern of sedimentation records variations in eruption dynamics. Products of continuous-uprush
eruptions are thought to be represented by stacks of poorly bedded gravelly sandstone, whereas better bedded, lithologically
more diverse sequences accumulated during periods of quiescence or effusive activity. Evidence for volcano flank failure is
common. In Seal Nunataks, subaerial lithofacies (mainly lavas and cinder cone deposits) are volumetrically minor and occur
at a similar stratigraphical position to pillow lava, suggesting that glacial lake drainage may have occurred prior to or
during deposition of the subaerial lithofacies. By contrast, voluminous subaerial effusion in Beethoven Peninsula led to the
development of laterally extensive stratified glassy breccias representing progradation of hyaloclastite deltas.
Received: 5 February 1996 / Accepted: 17 January 1997 相似文献
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L. V. Zakharikhina Yu. S. Litvinenko N. I. Ryakhovskaya V. V. Gainatulina N. Yu. Arguneeva M. A. Makarova 《Journal of Volcanology and Seismology》2016,10(3):203-217
It is found that the overwhelming majority of mobile forms of the chemical elements (up to 99%) that are thought to produce favorable effects when they arrive with volcanic ash to soils and supply additional elements that enhance the bioproductivity of ecosystems do not come in the form of ash particles, but in a gas-dissolved form directly from volcanic aerosol. Volcanic ash when considered independently of volcanic eruptions does not contain considerable amounts of accessible forms of chemical elements that would enable us to consider them as sources of nutrient elements for living organisms. However, the extensive range of elements that are contained in ash in ratios that are necessary for effective life activities invests these elements with catalytic properties that regulate the nutrient regime of plants and that can be used in agriculture in combination with lower amounts of traditional fertilizers to produce substantial (up to 72%) yield increases and to improve the quality of agricultural products. 相似文献
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V. G. Korinevskii 《Journal of Volcanology and Seismology》2011,5(1):31-42
The existing data on findings of unaltered volcanic glasses in the Paleozoic (from Late Ordovician to Late Devonian inclusive)
volcanic strata of the Ural fold belt are systematized. These glasses have compositions that correspond to tholeiitic basalts,
potassic alkaline basaltoids, andesites, and rhyolites. Relic portions of glasses of cenotypal appearance are preserved in
thick glassy crusts of pillow lava flows, in fragments among hyaloclastites, in bombs from tuffs, and in extrusive bodies
and dykes. Chemical analysis showed that the amount of dissolved water was low (1–1.3 wt %) in the primary tholeiitic magma
and higher (8–10 wt %) in the magma that formed island-arc hyalobasalts, potassic alkaline basaltoids, andesites and rhyolites. 相似文献
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D. M. Pechersky A. Yu. Kazanskii G. P. Markov V. A. Tselmovich A. A. Shchetnikov 《Izvestiya Physics of the Solid Earth》2018,54(1):106-120
The native iron particles that were previously detected by thermomagnetic and microprobe analyses in the sediments of different age in many regions of the world are of extraterrestrial origin. The similarity in the compositions, grain shapes, and sizes observed in the extraterrestrial and terrestrial particles of native iron testifies to the common production conditions of iron particles during the formation of planets. In this paper, the single finding of terrestrial iron in the lacustrine sediments of the Zhombolok volcanic region, East Sayan, is discussed. The uniqueness of the results indicates that the spatial distribution of the particles of native iron is limited to a fairly narrow area around their source—volcanic eruption or/and the fall of a large meteorite. 相似文献
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阿什库勒盆地位于NE向阿尔金断裂与NW向康西瓦断裂的"弧形"交会处,构造活动十分活跃,盆地内发育10余座火山,其中阿什火山为该火山群中最新活动的火山。文中从火山地质、熔岩和斑晶成分、显微结构特征及地质温压计4个方面对阿什火山进行了详细研究。结果表明,阿什火山由火山锥和熔岩流组成,锥体由早期的渣锥和晚期的溅落锥组成,熔岩流分布面积约33km2,可划分为4个流动单元。熔岩属于钾玄岩系列,岩性为粗安岩,显微镜下呈斑状结构。斑晶以长石(主要为中长石)和辉石(包括普通辉石、古铜辉石和紫苏辉石)为主;基质为玻璃质、隐晶质、微晶质,部分含有大量的长石和辉石。斑晶与岩浆的平衡温度为1 104~1 194℃,压力为570~980MPa,对应的岩浆房深度为18.92~32.29km。 相似文献
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The Pebble Creek Formation (previously known as the Bridge River Assemblage) comprises the eruptive products of a 2350 calendar
year B.P. eruption of the Mount Meager volcanic complex and two rock avalanche deposits. Volcanic rocks of the Pebble Creek
Formation are the youngest known volcanic rocks of this complex. They are dacitic in composition and contain phenocrysts of
plagioclase, orthopyroxene, amphibole, biotite and minor oxides in a glassy groundmass. The eruption was episodic, and the
formation comprises fallout pumice (Bridge River tephra), pyroclastic flows, lahars and a lava flow. It also includes a unique
form of welded block and ash breccia derived from collapsing fronts of the lava flow. This Merapi-type breccia dammed the
Lillooet River. Collapse of the dam triggered a flood that flowed down the Lillooet Valley. The flood had an estimated total
volume of 109 m3 and inundated the Lillooet Valley to a depth of at least 30 m above the paleo-valley floor 5.5 km downstream of the blockage.
Rock avalanches comprising mainly blocks of Plinth Assemblage volcanic rocks (an older formation making up part of the Mount
Meager volcanic complex) underlie and overlie the primary volcanic units of the Formation. Both rock avalanches are unrelated
to the 2350 B.P. eruption, although the post-eruption avalanche may have its origins in the over-steepened slopes created
by the explosive phase of the eruption. Much of the stratigraphic complexity evident in the Pebble Creek Formation results
from deposition in a narrow, steep-sided mountain valley containing a major river.
Received: 20 January 1998 / Accepted: 29 September 1998 相似文献