Volcanic air pollution and mortality in France 1783–1784

The impact that volcanic eruptions may have upon environments far from the volcanic source is conventionally assumed to depend on climatic modification by emitted gases. However, recent research has suggested that the damage caused by the direct impact of volcanic gases, mainly H₂SO₄, may be profound. This paper highlights the severity of this mechanism by reference to human sickness and death in France and contiguous with the eruption of the Laki fissure in Iceland in 1783. This work demonstrates the gains which may be made by interdisciplinary teams of researchers and illustrates the valuable knowledge that remains to be revealed by further research in the French historical record. To cite this article: J. Grattan et al., C. R. Geoscience 337 (2005).     

Reconnaissance geology in Upper Chitral,Baroghil and Karambar districts (northern Karakorum,Pakistan)

During the summer of 1992 a geological expedition crossed the northern Karakorum range in northern Pakistan, from the Chitral to Karambar valleys, from the villages of Mastuj to Imit. Some of the areas visited were geologically unknown. A number of structural units were crossed, belonging to the Karakorum block or to other crustal blocks north of it. They are: (a) the axial batholith, in which three plutonic bodies have been identified, and (b) the northern sedimentary belt (NSB), in which three major tectonostratigraphic units form thrust stacks dipping to the north. Their internal stratigraphy and structural style are partly different. The most complete contains a crystalline basement, transgressed by a marine succession during the Early Ordovician. The youngest strata are represented by the Reshun conglomerate, of inferred Cretaceous age. The northernmost unit of the NSB is tightly folded, whereas the central one forms a monocline. Vertical faults, mainly strike-slip, dissect the thrusted slabs. Metamorphic deformation is absent or reaches only the anchizone in the studied sector of the Karakorum NSB. To the north of the Karakorum proper there are several other tectonic units, separated by vertical faults. They are, from south to north: (a) the Taš Kupruk zone, with metavolcanics of basaltic to latibasaltic composition; (b) the Atark unit, mostly consisting of massive carbonate rocks of Mesozoic age; and (c) the Wakhan slates which consist of a thick widespread succession of dark slates, metasiltites and sandstones. The fine-grained elastic rocks are supposed to be Palaeozoic to Early Triassic in age. The Wakhan slates are intruded by plutons belonging to the East Hindu Kush batholith, from which a single K/Ar age on muscovite gave a Jurassic age.     

地荫沟含煤碎屑岩地质特征

汪清县东北部中生代火山断陷盆地火山岩中夹－套含煤碎屑岩地层,本文重点叙述了该地层的分布,层序,岩石,岩相古地理特征及地层对比和时代的确定。     

内蒙达里诺尔火山群晚第四纪火山地质特征与岩浆裂隙通道研究

达里诺尔火山群位于中亚造山带中部以及大兴安岭-太行山重力梯度带中部的西侧。该区拥有上百座第四纪火山,其中不乏全新世仍有过喷发的年轻火山。本文选取以鸽子山、锡塔特乌拉等形成时代最晚,推测形成于中更新世晚期至全新世的晚第四纪火山作为研究对象,从火山锥形貌和定向排列两方面推断岩浆补给裂隙通道的几何特征。结果发现,这些火山具有较为一致的NE和NEE两个方向的裂隙通道。这些方向与区域构造最大主压应力方向相近。本文提出在NE向区域主压应力作用下,在研究区域发生NEE走向的左行剪压走滑。在这个走滑带上,瑞德尔断裂提供岩浆补给裂隙通道。而局部连通瑞德尔断裂的断裂提供了NEE向通道。     

Signature of explosive volcanic eruptions in the sediments of a high-altitude Swiss lake

The analysis of 125 years of well-dated varved sediments in Lake Silvaplana, located at 1,791 m a.s.l. in the Upper Engadine region of south-eastern Switzerland, reveals that 7 out of the 8 climatically relevant explosive volcanic eruptions between A.D. 1880 and 2004 were followed by distinct peaks in median grain-size. Although the underlying mechanisms are yet unclear, an analysis of local meteorological data suggests that this phenomenon is unlikely to be related to any change in air temperature associated with the eruptions, but instead may be related to an increase in autumn precipitation subsequent to the eruptions that led to the erosion and fluvial transport of particles larger than normal.     

Sedimentary Basin Analysis and Petroleum Potential of the Cretaceous Yuchon Group In Haenam Depression, SW Korea

The Yuchon Group in the Late Cretaceous of Haenam and Mokpo area on the southwest coast of Korea peninsula can be divided into two Formations: (1) the intermediate volcanic Formation (Hwawon Formation), about 500m thick, (2)the acidic volcanic Formation (Hwangsan Formation), about 400m thick in ascending order.The former comprises intermediate volcaniclastics interlayered with volcanic rocks, and red mudrock and tuffaceous sandstone indicating fluvial deposits. The latter is subdivided into the upper part (Hwangsan Tuff Member) consisting of subaerial pyroclastics and intercalated rhyolites, and the lower part (Byeongonri Member) including subaqueous volcaniclastics, lake deltaic sandstone and gravelstone, lacustrine black shale and limestone and chert, and lake turbidite sandstone.The Late Cretaceous basin including Haenam subbasin in southwest Korea was largely formed of extensional nonmarine depressions (volcano- tectonic) bounded by NE- SW sinistral fault system.The thermal maturation based on geochemical and mineralogical studies for the black shales and tuffaceous sandstones reached the late stage of oil generation zone or gas generation stage. It seems that black shales and limestones are fairly good as source rock. The porosity of potential reservoir sandstone and tuff ranges from 5 % to 11%, but their permeability except the fractured rocks is very low ( ＜1md) because of fine pore throats reduced by diagenetic cementation of tuffaceous sandstones. Numerous potential traps might have been formed by the later folding and faulting along with lateral facies change and abundant mudrocks and volcaniclastics should make excellent seals.     

大地电磁测深在火山区地热研究中的应用

大地电磁测深(MT)由于勘探深度范围较大,且对温度、流体、岩浆房和岩性等与热储相关的地质条件的敏感度较高,因而成为火山区地热勘探和岩石圈结构研究中常用的一种地球物理勘探手段。地壳和上地幔的电性结构与热结构之间存在着密切的联系,通过解读二者的关系,可以刻画更为精细的岩石圈结构模型,进而掌握火山区的构造特征和热演化过程,了解其岩石圈地球动力学机制。本文着重介绍了MT方法的原理以及从野外数据采集到后期数据处理的过程,综述了MT法的应用特点以及电导率与温度之间的关系,通过实例分析,介绍了国际上这一方法在火山区地热勘探和岩石圈热结构研究中的应用进展,展示了MT法在新西兰Taupo火山区Ngatamariki高温地热田0~3km地热资源勘探中的应用;以埃塞俄比亚Afar省的Tendaho地热田和Badi火山为例,分别讨论了0~20km和0~50km不同深度的电性结构特征及其与温度存在的内在联系,探讨了形成火山的驱动机制;以日本九州岛的Shinmoe-dake火山为例,介绍了大地电磁测深和温度监测在火山监测方面的应用。最后简述了国内MT法在火山区的应用进展以及存在的问题,并利用上地幔电导率与温度的关系以及岩石圈内硅酸盐熔体不同含水量引起的电导率随温度的变化关系,初步估算了长白山天池和阿尔山火山区的莫霍面以下的温度以及长白山天池火山区的高温岩浆房温度。