Message from the new President and Secretary-General of IAVCEI     

H-U Schmincke 《Bulletin of Volcanology》2000,62(1):5-7

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The Masaya Triple Layer: A 2100 year old basaltic multi-episodic Plinian eruption from the Masaya Caldera Complex (Nicaragua)     

W. Pérez  A. Freundt  S. Kutterolf  H.-U. Schmincke 《Journal of Volcanology and Geothermal Research》2009,179(3-4):191-205

The Masaya Caldera Complex has been the site of three highly explosive basaltic eruptions within the last six thousand years. A Plinian eruption ca. 2 ka ago formed the widespread deposits of the Masaya Triple Layer. We distinguish two facies within the Masaya Triple Layer from each other: La Concepción facies to the south and Managua facies to the northwest. These two facies were previously treated as two separated deposits (La Concepción Tephra and the Masaya Triple Layer of Pérez and Freundt, 2006) because of their distinct regional distribution and internal architectures. However, chemical compositions of bulk rock, matrix and inclusion glasses and mineral phases demonstrate that they are the product of a single basaltic magma batch. Additionally, a marker bed containing fluidal-shaped vesicular lapilli allowed us to make a plausible correlation between the two facies, also supported by consistent lateral changes in lithologic structure and composition, thickness and grain size.We distinguish 10 main subunits of the Masaya Triple Layer (I to X), with bulk volumes ranging between 0.02 and 0.22 km³, adding up to 0.86 km³ (0.4 km³ DRE) for the entire deposit. Distal deposits identified in two cores drilled offshore Nicaragua, at a distance of ～ 170 km from the Masaya Caldera Complex, increase the total tephra volume to 3.4 km³ or ～ 1.8 km³ DRE of erupted basaltic magma.Isopleth data of five major fallout subunits indicate mass discharges of 10⁶ to 10⁸ kg/s and eruption columns of 21 to 32 km height, affected by wind speeds of < 2 m/s to ～ 20 m/s which increased during the course of the multi-episodic eruption. Magmatic Plinian events alternated with phreatoplinian eruptions and phreatomagmatic explosions generating surges that typically preceded breaks in activity. While single eruptive episodes lasted for few hours, the entire eruption probable lasted weeks to months. This is indicated by changes in atmospheric conditions and ash-layer surfaces that had become modified during the breaks in activity. The Masaya Triple Layer has allowed to reconstruct in detail how a basaltic Plinian eruption develops in terms of duration, episodicity, and variable access of external water to the conduit, with implications for volcanic hazard assessment.  相似文献   

IAVCEI news     

H -U Schmincke 《Bulletin of Volcanology》1991,53(3):232-238

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The observational side of volcanology     

Don Swanson  H. -U. Schmincke 《Bulletin of Volcanology》1994,56(2):133-133

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Linking the North Atlantic to central Europe: a high‐resolution Holocene tephrochronological record from northern Germany     

Christel van den Bogaard  Hans‐Ulrich Schmincke 《第四纪科学杂志》2002,17(1):3-20

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IAVCEI news     

H. -U. Schmincke 《Bulletin of Volcanology》1989,52(1):78-79

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A new model for the evolution of table mountains: volcanological and petrological evidence from herdubreid and Herdubreidartögl volcanoes (Iceland)     

R. Werner  H. -U. Schmincke  G. Sigvaldason 《International Journal of Earth Sciences》1996,85(2):390-397

We present a new model for the evolution of volcanic table mountains, based on volcanological and petrological studies of Herdubreid/Herdubreidartögl, an upper Pleistocene volcanic complex within the active Icelandic rift zone. The evolution of these table mountains is highly complex and influenced substantially by different eruptive environments as well as changing magma sources and volcanic and magmatic processes. Whereas current models imply entirely subglacial conditions and continuous compositional (“monogenetic”) evolution for these volcanoes, we subdivide their evolution into four eruptive periods characterized by different environments: (a) Subaerial lava flows erupted during an interglacial period. (b) Lavas and voluminous hydroclastic deposits formed in a lake during a waning period of the last glaciation. (c) Subglacial eruptions during thickening of the ice sheet as a result of a climatic deterioration built pillow lava piles overlain by steep-sided complexes of hydroclastic deposits. These deposits differ from those of the second eruptive period in structure, texture, and degree of alteration. Subaerial lava flows and agglutinates covered these deposits after buildup above the ice sheet. (d) Subaerial lava flows and fallout deposits during a postglacial period. The detailed analysis of volcanic table mountains appears to be a very sensitive indicator of climatic fluctuations. Although most deposits of the studied volcanoes were formed during the waning period of the last glaciation, the subglacial deposits in the upper part of the volcanic complex reflect a temporary, but major, thickening of the ice sheet.  相似文献   

南极长城站和中山站贼鸥种群生态学比较研究          下载免费PDF全文

王自磐 《极地研究》2002,14(2):83-92

对南极长城站和中山站两地的贼鸥种群进行包括营巢行为、觅食习性、种群变化、繁殖生态 ,以及贼鸥栖息地的地理和生态环境等的比较研究 ,结果表明两地贼鸥种群存在明显的生态学差异。这种差异不仅反映了贼鸥的生态习性与栖息地自然环境和生态结构的密切相关性 ,更体现了该种海鸟对南极不同生存环境极强的适应能力。人类活动以及贼鸥对人类废弃食物的依赖 ,在一定程度上改变动物食物结构 ,并对贼鸥生态习性乃至种群数量变化均产生一定影响。两地贼鸥种群通过改变觅食对策和调整产卵、孵化时间和延长育雏期等 ,达到对不同地理纬度和气候条件的适应 ,确保物种的延续  相似文献   

IAVCEI news     

H-U Schmincke  RW Johnson 《Bulletin of Volcanology》1992,54(3):249-251

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New K-Ar ages,chemical analyses and magnetic data of rocks from the islands of santa maria (azores), porto santo and madeira (madeira archipelago) and gran canaria (Canary Islands)     

G. Feraud  J. Gastaud  H. U. Schmincke  G. Pritchard  J. Lietz  U. Bleil 《Bulletin of Volcanology》1981,44(3):359-375

K/Ar-determinations, major and trace element chemical analyses and magnetic data are reported for rocks from Santa Maria (Azores), Madeira and Porto Santo, and Gran Canaria. Based on these data, the age of the basement of Santa Maria is believed to have formed between about 5.2. and 4.6 m.y.; the unconformably overlying pillow complex interbedded with fossiliferous calcarenites about 3.8 to 3.3 m.y. with the capping subaerial basalt being part of the same magmatic phase. The major erosional phase levelling the basement is thus approximately synchronous with the major Pliocene regression (R2) on Gran Canaria (Lietz andSchmincke, 1975), possibly indicating a widespread eustatic event. The upper part of the submarine, partly fossiliferous series of Porto Santo was dated as ca. 12 to 13 m.y., and the Quaternary age for the major basalt formation in Eastern Madeira (Watkins andAbdel Monem, 1971) is confirmed. The ages of several formations on Gran Canaria were slightly revised. Chemical differences between basement (shield) and later posterosional series on Gran Canaria are re-emphasized by the new data, while such differences are much less pronounced between the basement and younger series on Santa Maria.  相似文献