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1.
Siwan M. Davies Gudrun Larsen Stefan Wastegård Chris S. M. Turney Valerie A. Hall Lisa Coyle Thor Thordarson 《第四纪科学杂志》2010,25(5):605-611
The Eyjafjöll AD 2010 eruption is an extraordinary event in that it led to widespread and unprecedented disruption to air travel over Europe – a region generally considered to be free from the hazards associated with volcanic eruptions. Following the onset of the eruption, satellite imagery demonstrated the rapid transportation of ash by westerly winds over mainland Europe, eventually expanding to large swathes of the North Atlantic Ocean and the eastern seaboard of Canada. This small‐to‐intermediate size eruption and the dispersal pattern observed are not particularly unusual for Icelandic eruptions within a longer‐term perspective. Indeed, the Eyjafjöll eruption is a relatively modest eruption in comparison to some of the 20 most voluminous eruptions that have deposited cryptotephra in sedimentary archives in mainland Europe, such as the mid Younger Dryas Vedde Ash and the mid Holocene Hekla 4 tephra. The 2010 eruption, however, highlights the critical role that weather patterns play in the distribution of a relatively small amount of ash and also highlights the spatially complex dispersal trajectories of tephra in the atmosphere. Whether or not the preservation of the Eyjafjöll 2010 tephra in European proxy archives will correspond to the extensive distributions mapped in the atmosphere remains to be seen. The Eyjafjöll 2010 event highlights our increased vulnerability to natural hazards rather than the unparalleled explosivity of the event. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
2.
The examination of the Main Pugachevo gas-water-lithoclastic volcano during the summer of 2005 and GPS-controlled large-scale (1: 1000) mapping revealed its regular but rather peculiar eruption. It was the largest among the eruptions investigated since 1911 and produced a very unusual lithoclastic field with an area of about 100 000 m2 and a volume of about 100 000 m3. The eruption occurred from three distinct active centers and began with a vigorous explosion-like gas burst from one center followed by the noncontemporaneous discharge of a gas-and water-saturated liquid lithoclastic mass from the three centers, which produced a number of flows of different directions and sizes. The flows almost completely covered the smoothed flat open area of the volcano and even invaded the larch forest surrounding the volcano, where they bent, overturned, broke, and occasionally uprooted and dragged over some distance some large trees. The analysis and comparison with all the previously documented eruptions of the Main Pugachevo gas-water-lithoclastic volcano revealed their fairly diverse, sometimes strongly variable character with respect to many parameters: the amount of ejected lithoclastic material; the number of eruption centers; and the proportions of the erupted gaseous, liquid, and solid components. In general, the eruptions show a distinctly multirank periodic character: relatively minor or small low-rank eruptions take place once every 1–2 yr, and large eruptions of a higher rank are much less frequent (supposedly, once in 70 years). 相似文献
3.
强火山活动是气候变化的重要自然驱动因素,可导致中国降水出现年际或年代际变化,甚至极端的旱涝现象。探究位于中国邻域的印度尼西亚—菲律宾一带的强火山喷发与中国旱涝分布格局的关系,有助于阐释中国旱涝发生的时空规律及机制,为预测未来火山爆发可能导致的降水异常提供借鉴。本文基于1500—2000年期间世界强火山活动和中国旱涝资料,运用时序叠加分析的方法辨识了印度尼西亚—菲律宾一带的强火山喷发后中国旱涝在年际尺度上的时空变化特征,并对1815年Tambora火山喷发进行案例分析。结果表明印度尼西亚—菲律宾一带的强火山喷发对中国的旱涝格局有一定的影响:强火山喷发后第0年至第2年,中国中东部各站点的整体变化为偏涝;在第3年,整体出现了偏旱的转变,且变化幅度相比其他年份较大;就地区而言,喷发后华北、华南地区分别出现了由旱转涝、由涝转旱的变化,并且这些变化大概持续了2~3年,随后2个区域均恢复了喷发前的旱涝趋势;印度尼西亚1815年Tambora火山喷发后0~3年,中国以涝情为主,但发生涝情的区域逐年在发生变化。 相似文献
4.
火山活动与气候变化研究进展 总被引：12，自引：1，他引：12
综述了火山活动对气候影响的研究进展。不同岩浆成分及喷发类型的火山活动对气候的影响不同：中酸性普林尼（Pl inian）式火山喷发主要造成气候变冷和臭氧层破坏，它导致气候变化的时间较短，但空间范围较大；大火成岩省造成气候变化的时空范围及程度均较大，它能够导致地表温度、海平面大幅度变化，最终引起生物灭绝；中小规模玄武质裂隙式喷发主要造成火山盆地内气候较大幅度变化，但对气候影响的持续时间较短，主要气候效应是导致附近地区温度快速下降和形成酸雨。简要阐述了第四纪火山活动的特点。 相似文献
5.
The importance of disaster reduction has gained increased awareness within the international development community and thereby highlighted a need for a preliminary assessment of natural hazard risk in developing countries of the Asia?CPacific, including that for volcanic eruption. In this paper, we present a key component of such an assessment, which involved qualifying the frequency and potential consequences of large??Volcanic Explosivity Index of four or more??volcanic eruptions. The frequencies of large eruptions from volcanoes grouped by region were determined from frequency?Cmagnitude plots using data provided by the Smithsonian Institution??s Global Volcanism Program. However, calculated frequencies represent only minimum values due to an incomplete eruption record. Unfortunately, limited data precluded the calculation of eruption frequencies for the Solomon Islands, Fiji and Samoa. A first-order analysis of the populations potentially impacted by large volcanic eruptions suggest that (1) volcanic disasters affecting populations of >100,000 can be expected at least every decade in Indonesia and once every few decades in the Philippines and (2) a volcanic disaster impacting >1% of the population can be expected twice a century in Vanuatu, twice a millennium for Indonesia and the Philippines, and around every millennium in Papua New Guinea and Tonga. 相似文献
6.
WEI Haiquan HONG Hanjing R.S.J. SPARKS J.S. WALDER HAN Bin Institute of Geology China Seismological Bureau Beijing Department of Earth Sciences Bristol University UK Cascades Volcano Observatory US Geological Survey USA 《《地质学报》英文版》2004,78(3):790-794
Since the eruption of the Tianchi volcano about 1000 years ago, there have been at least 3 to 5 eruptions of small to moderate size. In addition, hazardous avalanches, rock falls and debris flows have occurred during periods between eruptions. A future eruption of the Tianchi volcano is likely to involve explosive interaction between magma and the caldera lake. The volume of erupted magma is almost in a range of 0.1-0.5 km3. Tephra fallout may damage agriculture in a large area near the volcano. If only 1% of the lake water were ejected during an eruption and then precipitated over an area of 200 km2, the average rainfall would be 100 mm. Moreover, lahars are likely to occur as both tephra and water ejected from the caldera lake fall onto flanks of the volcano. Rocks avalanching into the caldera lake also would bring about grave hazards because seiches would be triggered and lake water with the volume equal to that of the landslide would spill out of the existing breach in the caldera and cause flooding 相似文献
7.
Many years of low growth identified in a western USA regional chronology of upper forest border bristlecone pine (Pinus longaeva and Pinus aristata) over the last 5000 yr coincide with known large explosive volcanic eruptions and/or ice core signals of past eruptions. Over the last millennium the agreement between the tree-ring data and volcano/ice-core data is high: years of ring-width minima can be matched with known volcanic eruptions or ice-core volcanic signals in 86% of cases. In previous millennia, while there is substantial concurrence, the agreement decreases with increasing antiquity. Many of the bristlecone pine ring-width minima occurred at the same time as ring-width minima in high latitude trees from northwestern Siberia and/or northern Finland over the past 4000-5000 yr, suggesting climatically-effective events of at least hemispheric scale. In contrast with the ice-core records, the agreement between widely separated tree-ring records does not decrease with increasing antiquity. These data suggest specific intervals when the climate system was or was not particularly sensitive enough to volcanic forcing to affect the trees, and they augment the ice core record in a number of ways: by providing confirmation from an alternative proxy record for volcanic signals, by suggesting alternative dates for eruptions, and by adding to the list of years when volcanic events of global significance were likely, including the mid-2nd-millennium BC eruption of Thera. 相似文献
8.
长白山火山活动历史、岩浆演化与喷发机制探讨 总被引：18，自引：0，他引：18
广义的长白山火山在我国境内包括著名的天池火山、望天鹅火山、图们江火山和龙岗火山,是我国最大的第四纪火山岩分布区。图们江火山和望天鹅火山活动都始于上新世,喷发活动分别介于上新世—中更新世（5.5~0.19 Ma）和上新世—早更新世（4.77 ~2.12 Ma）。天池火山和龙岗火山属于第四纪火山,喷发活动从早更新世（~2 Ma）持续到全新世。图们江火山岩为溢流式喷发的拉斑玄武岩,望天鹅火山、天池火山和龙岗火山母岩浆都是钾质粗面玄武岩,但经历了不同的演化过程。天池火山和望天鹅火山都经历了钾质粗面玄武岩造盾、粗面岩造锥和晚期碱性酸性岩浆（碱流岩和碱性流纹岩）的喷发;龙岗火山来自地幔的钾质粗面玄武岩浆则未经演化和混染直接喷出地表。图们江火山岩以溢流式喷发的拉斑玄武岩为主,少量玄武质粗安岩等。天池火山造盾之后,地壳岩浆房和地幔岩浆房具互动式喷发特点,来自地幔的钾质粗面玄武岩浆一方面在天池火山锥体内外形成诸多小火山渣锥,另一方面持续补给地壳岩浆房发生岩浆分离结晶作用和混合作用,分别导致双峰式火山岩分布特征和触发千年大喷发。火山岩微量元素和Sr-Nd-Pb同位素示踪揭示,长白山东（图们江火山、望天鹅火山和天池火山）、西（龙岗火山）两区显示地幔非均一性,东区岩浆源区具有软流圈地幔与富集岩石圈地幔混合特征,西区岩浆源区具有相对亏损的较原始地幔特征。西太平洋板块俯冲—东北亚大陆弧后引张是长白山火山活动的动力学机制。 相似文献
9.
The 2011 eruption of Nabro volcano, Eritrea, produced one of the largest volcanic sulphur inputs to the atmosphere since the 1991 eruption of Mt. Pinatubo, yet has received comparatively little scientific attention. Nabro forms part of an off-axis alignment, broadly perpendicular to the Afar Rift, and has a history of large-magnitude explosive silicic eruptions, as well as smaller more mafic ones. Here, we present and analyse extensive petrological data obtained from samples of trachybasaltic tephra erupted during the 2011 eruption to assess the pre-eruptive magma storage system and explain the large sulphur emission. We show that the eruption involved two texturally distinct batches of magma, one of which was more primitive and richer in sulphur than the other, which was higher in water (up to 2.5 wt%). Modelling of the degassing and crystallisation histories demonstrates that the more primitive magma rose rapidly from depth and experienced degassing crystallisation, while the other experienced isobaric cooling in the crust at around 5 km depth. Interaction between the two batches occurred shortly before the eruption. The eruption itself was likely triggered by recharge-induced destabilisation of vertically extensive mush zone under the volcano. This could potentially account for the large volume of sulphur released. Some of the melt inclusions are volatile undersaturated, and suggest that the original water content of the magma was around 1.3 wt%, which is relatively high for an intraplate setting, but consistent with seismic studies of the Afar plume. This eruption was smaller than some geological eruptions at Nabro, but provides important insights into the plumbing systems and dynamics of off-axis volcanoes in Afar. 相似文献
10.
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
11.
Andrew Tupper Christiane Textor Michael Herzog Hans-F. Graf Michael S. Richards 《Natural Hazards》2009,51(2):375-401
A critical factor in successfully monitoring and forecasting volcanic ash dispersion for aviation safety is the height reached by eruption clouds, which is affected by environmental factors, such as wind shear and atmospheric instability. Following earlier work using the Active Tracer High Resolution Atmospheric Model for strong Plinian eruptions, this study considered a range of eruption strengths in different atmospheres. The results suggest that relatively weak volcanic eruptions in the moist tropics can trigger deep convection that transports volcanic material to 15–20 km. For the same volcanic strength there can be ~9 km difference between eruption heights in moist tropical and dry subpolar environments (a larger height difference than previously suggested), which appears consistent with observations. These results suggest that eruption intensity should not be estimated from eruption height alone for tropospheric eruptions and also that the average height of volcanic eruptions may increase if the tropical atmospheric belt widens in a changing climate. Ash aggregation is promoted by hydrometeors (particularly liquid water), so the smaller modelled eruptions in moist atmospheres, which have a relatively small ash content for their height and water content, result in a relatively small proportion of fine ash in the dispersing cloud when compared to a dry atmosphere. This in turn makes the ash clouds much more difficult to detect using remote sensing than those in dry atmospheres. Overall, a weak eruption in the tropics is more likely to produce a plume above cruising levels for civil aviation, harder to detect and track, but with a lower concentration of fine ash than a mid-latitude or polar equivalent. There is currently no defined ‘acceptable’ concentration of ash for aircraft, but as these results suggest low-grade encounters in the tropics from undetected clouds are likely, it would be desirable to explore that issue. 相似文献
12.
Explosive volcanic eruptions are known to be a leading cause of natural climate change. There has been a growing recognition that there is a measurable climate system response even to moderate-sized volcanic eruptions. In this study, we investigated the hindcast skills of the Pacific Sea Surface Temperatures (SSTs) using the hindcast experiments based on the near-term climate prediction system DecPreS developed by the Institute of Atmospheric Physics (IAP)(hereafter DP-EnOI-IAU experiments). The DP-EnOI-IAU experiments were run for initial years from 1960 to 2005. These hindcasts took into account observed stratospheric aerosol concentrations that included the four large tropical volcanic eruptions during that period. The time evolution over the entire hindcast period for skill in predicting the patterns of the 3~7 year prediction averages for Pacific SSTs showed that there was statistically significant skill for most years except for a dramatic drop in skill during the 1980s and 1990s. Decadal hindcast skill is reduced if the post-eruption model response deviates the internal El Niño variability in the observations. The simulations showed a post-eruption SST of a La Niña-like pattern in the third northern winter after the 1982 El Chichon eruption and a El Niño-like pattern after the 1991 Pinatubo eruption, which were opposite in sign to what was in the observations. This lead to the loss of hindcast skill for years in the 1980s and 1990s affected by the eruptions. Agung (1963) happened to have post-eruption Pacific SSTs more similar to the observations and thus did not degrade prediction skill in the hindcasts. 相似文献
13.
爆炸式喷发过程中,火山碎屑物气孔记录了挥发分出溶、膨胀和合并等信息,其大小、形态、数量密度、空间分布等局域特征是推断火山喷发动力条件的重要参考。文章基于天池火山三期喷发(50 000年前大喷发的黄色浮岩、千年大喷发的灰白色浮岩和1668年八卦庙期喷发的黑色浮岩)野外地质工作,以非线性火山喷发动力学为指导,开展了火山通道内气泡生长的流体动力学研究,揭示出岩浆流体黏性力和界面张力的共同作用对于岩浆减压和气泡生长过程的约束。在浮岩气孔结构的定量化分析基础上,进一步研究了天池火山三期喷发的浮岩气孔参数,通过气泡生长流体动力学方程得到了千年大喷发灰白色浮岩毛细管数Ca值为253, 明显高于50 000年前大喷发黄色浮岩(Ca值为94)和八卦庙期喷发黑色浮岩(Ca值为111),表明了千年大喷发曾发生过明显的成分变化,推测可能与幔源基性岩浆注入有关;而50 000年前大喷发黄色浮岩气孔不规则形态参数(1-Ω)值为0.098,大于后两期喷发(分别为0.052和0.064),可能意味着天池火山系统动力学平衡的弛豫周期变小或浮岩气泡生长受动力学、流变学改造过程减弱,这可为进一步研究天池火山活动规律提供参考。三期浮岩毛细管数Ca量级为102,气孔不规则形态参数(1-Ω)量级为10-1,从动力学上首次证实了天池火山属于普林尼型或超普林尼型喷发。 相似文献
14.
Mangakino, the oldest rhyolitic caldera centre delineated in the Taupo Volcanic Zone of New Zealand, generated two very large (super-sized) ignimbrite eruptions, the 1.21 ± 0.04 Ma >500 km3 Ongatiti and ~1.0 Ma ~1,200 km3 Kidnappers events, the latter of which was followed after a short period of erosion by the ~200 km3 Rocky Hill eruption. We present U/Pb ages and trace-element analyses on zircons from pumice clasts from these three eruptions by Secondary Ion Mass Spectrometry (SIMS) using SHRIMP-RG instruments to illustrate the evolution of the respective magmatic systems. U–Pb age spectra from the Ongatiti imply growth of the magmatic system over ~250 kyr, with a peak of crystallisation around 1.32 Ma, ~100 kyr prior to eruption. The zircons are inferred to have then remained stable in a mush with little crystallisation and/or dissolution before later rejuvenation of the system at the lead-in to eruption. The paired Kidnappers and Rocky Hill eruptions have U–Pb zircon ages and geochemical signatures that suggest they were products of a common system grown over ~200 kyr. The Kidnappers and Rocky Hill samples show similar weakly bimodal age spectra, with peaks at 1.1 and 1.0 Ma, suggesting that an inherited antecrystic population was augmented by crystals grown at ages within uncertainty of the eruption age. In the Kidnappers, this younger age peak is dominantly seen in needle-shaped low U grains with aspect ratios of up to 18. In all three deposits, zircon cores show larger ranges and higher absolute concentrations of trace elements than zircon rims, consistent with zircon crystallisation from evolving melts undergoing crystal fractionation involving plagioclase and amphibole. Abundances and ratios of many trace elements frequently show variations between different sectors within single grains, even where there is no visible sector zoning in cathodoluminescence (CL) imaging. Substitution mechanisms, as reflected in the molar (Sc + Y + REE3+)/P ratio, differ in the same growth zone between the sides (along a-axis and b-axis: values approaching 1.0) and tips (c-axis: values between 1.5 and 5.0) of single crystals. These observations have implications for the use of zircons for tracking magmatic processes, particularly in techniques where CL zonation within crystals is not assessed and small analytical spot sizes cannot be achieved. These observations also limit applicability of the widely used Ti-in-zircon thermometer. The age spectra for the Ongatiti and Kidnappers/Rocky Hill samples indicate that both magmatic systems were newly built in the time-breaks after respective previous large eruptions from Mangakino. Trace element variations defining three-component mixing suggest that zircons, sourced from multiple melts, contributed to the population in each system. 相似文献
15.
《Physics and Chemistry of the Earth, Part A: Solid Earth and Geodesy》2000,25(9-11):719-724
Volcanological studies in the Bronze Age settlement of Akrotiri (Santorini, Greece) and in the Roman towns of Pompeii and Herculaneum (Vesuvius, Italy) provided information about the precursory phenomena preceding the Minoan and AD 79 plinian eruptions. Both the eruptions were characterised by seismic precursors with very different magnitudes and effects. The Minoan eruption was preceded by strong earthquake(s) that destroyed the Akrotiri settlement and forced an early evacuation of the island before the onset of the eruption. Instead, only some low magnitude shakings occurred before the AD 79 eruption of Vesuvius, which caught Roman towns and their inhabitants in the middle of their every-day life. Clear evidences of real volcanic precursors (both magmatic and phreatic) are not recorded in the deposits of the two eruptions. The onset of volcanic activity in both cases was represented by phreatomagmatic pulses of low energy shortly followed by the main eruption. 相似文献
16.
Volcanic eruptions can significantly cool the global troposphere on the time scales from several months up to a decade due to reflection of solar radiation by sulfate aerosols and feedback mechanisms in the climate system. The impact of volcanic eruptions on global climate are discussed in many studies. However, few studies have been done on the impact of volcanic eruption on climate change in China in the past millennium. The 1300-year and 600-year temperature series were reconstructed based on the six tree-ring temperature proxy data in northeastern and southeastern Tibetan Plateau, respectively. Three warm periods occurred in 670-920,1000-1310 and 1590-1930, and three cold periods happened at 920-1000,1310-1590 and 1930-2000 in the northeastern Tibetan Plateau. There were two obviously warm periods (1385-1450 and 1570-1820) and two cold periods (1450-1570 and 1820-2000) in southeastern Tibetan Plateau. Contrasting with volcanic eruption chronology, we analyzed the relationship between volcanic activity and temperature variation in the eastern Tibetan plateau during the past millennium using Superposed Epoch Analysis (SEA) method. The results indicated that the temperature decreased one year after large volcanic eruptions located beteen 10°S and 10°N in latitude in northeastern Tibetan Plateau and two years in southeastern Tibetan Plateau. The volcanic eruptions occurred at different latitudes have different impacts on the temperature variations, which may be caused by regional difference, the nature of the eruption, the magnitude of the resulting change in incoming solar radiation, prevailing background climate and internal variability, season, latitude, and other considerations. 相似文献
17.
Building reliable chronologies from lake sediments, peat and other paleoenvironmental archives can be challenging, especially for historical times where radiocarbon is unreliable. Nineteenth- and 20th-century eruptions from Mount St. Helens (MSH) provide important chronostratigraphic markers for regional paleoenvironmental studies within this time frame, but are constrained by poorly geochemically characterized tephra and/or limited published data. Here, we present glass geochemistry from the most significant eruptions from this time. This includes proximal, medial and distal deposits of the 18 May 1980 MSH eruption, layer T ( ad 1799/1800), a new tephra that we argue represents the ad 1842 eruption, and the 22 July 1980 eruption that had reported ashfall in Canada. Our results indicate that most tephras ejected during these eruptions, within a time frame of ~200 years, have distinct glass geochemical characteristics that can be used to identify distal deposits for tephrochronological studies. Layer T is on trend with analyses of the 1980 eruption but has a distinct dacitic glass population. The 1980 and ad 1842 eruptions are similar, both having rhyolitic glass compositions, but the ad 1842 event can be differentiated by a more constrained SiO2 range in the main geochemical population, and the presence of a unique SiO2 sub-population. 相似文献
18.
D. M. Pyle 《Environmental Geology》1997,30(1-2):59-61
The Minoan eruption of Santorini was a large-magnitude natural event. However, in terms of scale it ranks smaller in erupted
volume and eruptive intensity than the historical eruption of Tambora in 1815 AD, and smaller in sulphur emission and, by
inference, climatic effects than both the Tambora and Mt. Pinatubo, 1991, eruptions. Eruption statistics for the past 2000
years indicate that Minoan-size eruptions typically occur at a rate of several per thousand years. Eruptions resulting in
a Minoan-scale injection of sulphur to the stratosphere occur far more frequently – at a rate of one or two per century. Inferences
of massive sociological, religious and political impacts from such eruptions owe more to mythology than reality.
Received: 28 November 1995 · Accepted: 9 January 1996 相似文献
19.
本文分析得到:1957—1982年间,全球低纬度火山爆发有73.9％和高纬度火山爆发有62.5％,分别发生在地球自转年际变化的减速段和加速段;火山爆发的日期,一般多发生在3天内遇到3个以上天文奇点引潮力共振加压的叠加之时,强火山爆发都发生在4个以上此种共振加压之时。表明地球自转速度变化和天文奇点引潮力共振加压在不同时间尺度上,分别对火山爆发具有调制和触发作用。其物理机理,两者都是引起火山附近地壳异常加压,促使岩浆受到挤压而累积能量或触发爆发。 相似文献
20.
《International Geology Review》2012,54(10):1295-1313
The environment where the Permian Emeishan large igneous province (LIP) of Southwest China erupted remains controversial, especially regarding whether it was terrestrial, involving a 1 km scale domal uplift, or submarine. Slightly younger Daqiao conglomerate and Binchuan pillow lavas suggest that the Emeishan LIP erupted in a submarine environment. We show that at Binchuan, sandstone and rhyolite lie beneath the pillow lavas. In the Daqiao cross-section, there is an eastwards-verging syncline that reverses the succession of basalt and conglomerate. The conglomerate is not a basal conglomerate, and it does not contain any magmatic hydrovolcanic deposits. The basalt underlying the conglomerate is not the first of the LIP eruptions; that first eruption is found ~420 m below, on top of the Permian Maokou limestone. All together, these observations show that the deposits, including the conglomerate and pillow lava, do not represent the environment at the very start of the LIP volcanic eruptions, but represent conditions that existed before and possibly during the Emeishan LIP eruptions. Based on field investigations, the petrology of the rocks, and structural features, we conclude that submarine sedimentation and subaerial basalt eruptions coexisted in time and space in the region during or prior to the Emeishan LIP basalt eruptions. 相似文献