Palynological dating (Arenig) of the sedimentary sequence overlying the Ishkarwaz Granite (upper Yarkhun valley, Chitral, Pakistan)

A sedimentary sequence overlying a granite pluton near Ishkarwaz (upper Yarkhun valley, Chitral, Pakistan; Karakorum Microplate) contains abundant, but poorly preserved, acritarchs probably referable to the late early Arenig-early late Arenig interval. The palynological assemblages of Karakorum show a marked similarity to the cold water Peri-Gondwana assemblages; i.e. to those of Li Jun's Arbusculidium-Coryphidium-Striatotheca 'Mediterranean' Bioprovince. Biogeographical and geological comparisons suggest that, before the accretion of Cimmerian microplates to the Eurasian continent, the Karakorum Microplate was located along the northern margin of Gondwana in a latitude intermediate between the Mediterranean region and South China (Yangtze Platform).     

未来长江三峡水库诱发地城垢预测技术探讨

为做好未来三峡水库诱发地震预测实践的技术准备，根据水库诱发地震的特殊性和三峡地区的区域性特点，主要论述了测震学方面部分方法的适用性。结果表明，应变蠕变曲线形态方法，小震活动“密集－平静”等常有方法和序列频度衰减系数h值，震级－频度关系系数b值，波速比，振幅比等方法是在未来预测实践中值得推荐或进一步探索的方法。     

常熟地倾斜几种预报方法及指标的探索

使用江苏省常熟地震台SQ－70石英丝水平摆倾斜仪中强震前后的观测资料，通过大量计算和分析，提取地震前兆，确定江苏形变学科可行的预报指标。     

AR6659光球色球的磁场速度场的演化特征及其与大耀斑的关系

ＡＲ６６５９是２２周以来最重要的一个活动区，它爆发了２２周最强大的高能事件。本文用云南天文台的光球、色球精细结构照片和北京天文台怀柔站的磁场速度场资料，分析了该活动区磁场速度场的二维位形和大耀斑期间的演化特征。本文分析的４个大耀斑均爆发在中性线附近的Ｎ极区磁场梯度大的地方及色球速度场的红移区。偏带观测也显示耀斑物质是向红端移动的。耀斑波沿横场传播在离本黑子群几万至十几万公里的地方激起感生耀斑，在原生耀斑与感生耀斑之间往往有耀斑环相连。此外，本文还从演化特征出发分析了耀斑爆发前活动区等离子体的宏观不稳定性。     

The Mt. Vulture volcanic complex (Italy): evidence for distinct parental magmas and for residual melts with melilite

Summary New data of mineral compositions, whole-rock major and trace element contents are presented for lava flows and dykes of Mt. Vulture volcano (southeastern Roman Magmatic Province). The dominant rock series ranges from basanite, through tephrite and foidite, to phonolite. Diopsidic to Fe-salitic (hedenbergitic) clinopyroxene is the major phenocryst phase, and shows a very strong Ti- and Al-enrichment trend (up to 5 wt% TiO₂ and 12 wt% Al₂O₃). Phonolites have Fe-rich pyroxenes low in Ti and Al, as a consequence of fractionation of Ti-magnetite and/or melanite garnet.Feldspar ranges in composition from bytownite to Ba- and Sr-rich anorthoclase (up to 7 wt % BaO and 4 wt % SrO); the latter is present in the groundmass of mafic and intermediate rocks. Phonolites are characterized by anorthoclase and sanidine with Ba-rich cores, and with Ba-depleted rims.Subordinate melilite-bearing rocks are also present, and are characterized by melilite with a very large compositional variation, Ca-rich nepheline (up to 8 wt% CaO) and lack of feldspar and amphibole. Some of them also show calcite-rich ocellar structures, possibly due to liquid immiscibility. They have also major and trace element contents different from those of the feldspar-bearing rocks. This all indicates distinct parental magmas for feldspar-bearing and melilite-bearing rocks. These latter were likely generated by differentiation processes starting from olivine- and melilite-bearing ultramafic parental magmas.Mineral compositions and suitable phase diagrams indicate that the Melfi haüynophyre, which is the most MgO-poor melilite-bearing rock of Mt. Vulture, is close to a residual melt analogous to phonolite, but in petrogenetic systems with melilite and without feldspar.The high- to very high-titanium content of most of the ferromagnesian phases, despite a relatively low TiO₂ of primitive Mt. Vulture rocks, is absent in other rocks of similar degree of evolution in the Roman Province. It resembles that found in anorogenic magmas and gives further indications for a within-plate signature in this particular volcanic complex.

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Der Mt. Vulture Vulkankomplex (Italien): hinweise für unterschiedliche Ausgangsmagmen und Residualschmelzen mit Melilith

Zusammenfassung Es werden neue Daten über Mineralzusammensetzungen sowie Haupt- und Spurenelemente des Gesamtgesteins für Lavaflüsse und Gänge des Mt. Vulture Vulkans (südöstliche Römische Magmatische Provinz) vorgestellt. Die auftretenden Gesteinsabfolgen reichen von Basaniten über Tephrite und Foidite zu Phonolithen. Diopsidischer bis Fe-salitischer (hedenbergitischer) Klinopyroxen stellt die hauptsächlichen Einsprenglinge und zeigt starke Ti- und Al-Anreicherungen (bis zu 5 Gew% TiO₂ und 12 Gew% Al₂O₃). Phonolite weisen als Konsequenz der Fraktionierung von Ti-Magnetit und/oder Melanit-Granat Fe-reiche Pyroxene mit niedrigen Ti- und Al-Gehalten auf.Der Feldspat reicht in seiner Zusammensetzung von Bytownit zu Ba- und Si-reichem Anorthoklas (bis zu 7 Gew%/o BaO und 4 Gew% SrO), der letztgenannte findet sich in der Grundmasse mafischer und intermediärer Gesteine. Phonolithe werden durch das Auftreten von Anorthoklas und Sanidin mit Ba-angereicherten Kernen und Ba-abgereicherten Rändern charakterisiert.Untergeordnet treten auch Melilith-führende Gesteine auf. Sie sind durch Melilithe mit einer großen kompositionellen Variation, durch Ca-reichen Nephelin (bis 8Gew% CaO) und durch das Fehlen von Feldspat und Amphibol gekennzeichnet. Einige dieser Melilithe zeigen auch Calcitreiche ocellare Strukturen, die möglicherweise aufgrund der Nicht-Mischbarkeit der Schmelzen entstanden sind. Sie weisen auch Gehalte an Haupt- und Spurenelementen auf, die von jenen Feldspat-führender Gesteine abweichen. All dies zeigt verschiedene Ausgangs-Magmen für Feldspat-führende und Melilith-führende vulkanische Gesteinean. Die Melilithgesteine entstanden wahrscheinlich durch Differentiationsprozesse aus Olvin- und Melilith-führenden ultramafischen Magmen.Mineralzusammensetzung und die entsprechenden Phasendiagramme zeigen, daß der Melfi Haüynophyr, welcher das MgOärmste Melilith-führende Gestein des Mt. Vulture ist, nahe an einer Ausgangschmelze analog zu einem Phonolith liegt, allerdings in einem petrogenetischen System mit Melilith und ohne Feldspat.Der hohe bis sehr hohe Titan-Gehalt der meisten ferromagnesischen Phasen fehlt, trotz des niedrigen TiO₂-Gehaltes primitiver Mte. Vulture Gesteine, in anderen Gesteinen ähnlicher Entwicklung in der Römischer Magmatischen Provinz. Dies ähnelt anorogenen alkalischen Magmen und ist ein weiterer Hinweis auf eine Intra-Platten Signatur für diesen besonderen vulkanischen Komplex.

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With 7 Figures     

Site response study in Abruzzo (Central Italy): underground array versus surface stations

In this site response study we examined local earthquakes recorded at surface stations of a local seismic network and at a temporary underground seismic array installed in a tunnel underneath the Gran Sasso Massif in Abruzzo (central Italy). This allowed us to compare the seismic site response beneath the mountain and on the surface in similar geological environment (soft rock sites). We applied spectral ratios method on different segments of the seismograms and used different reference spectra in the 1–20 Hz frequency band. We found little or no amplification effects at most of the surface stations whereas site transfer functions evaluated with respect to underground sites show an amplification factor up to 6 in the 1–8 Hz frequency range. Coda spectral ratios estimated at soft rock sites are confirmed as good estimates of shear wave transfer function.     

Preliminary Results from Paleomagnetic Records on Lake Sediments from South America

The preliminary results of paleomagnetic and radiocarbon dating of late pleistocene-holocene sediments from two lakes of south-western Argentina (41°S, 71.5°W) are presented. The magnetic susceptibility, intensity and direction of the natural remanent magnetisation were measured. The stability of the natural remanent magnetisation was investigated by alternating field demagnetisation. The magnetic parameters allowed the cores within each lake to be correlated. ¹³ C analysis, total organic content measurements and C ¹⁴ dating were carried out. A model of sedimentation is suggested. Using this model and the correlation, curves of variations of magnetic inclination and declination in time are shown.     

Human-induced sedimentological changes in Manzala Lagoon, Nile Delta, Egypt

 The Manzala Lagoon in Egypt's Nile Delta has become a sediment sink of reduced area and depth, with increased contaminant levels. Loss of much-needed fresh to brackish water reserves and decreased fish catches have serious ramifications. Herein, maps of temporal and regional sediment distributions in Manzala incorporate petrological and statistical analyses of 200 surficial and short core samples. These provide baseline information needed to help implement protection measures for this vital wetland. Four periods are considered: 1920s, 1940s, ∼1965, and 1990. Important depositional changes between 1940s and ∼1965 resulted from anthropogenic effects on this quasi-closed lagoon system, including industrial buildup, wetland conversion to agricultural land, and irrigation waterway development. Further modification from ∼1965 to 1990 is associated with closure of the Aswan High Dam, continued construction of waterways that discharge waste water into lagoon margins, and marine incursion into the northern lagoon. If current practices continue, the lagoon could be reduced to about one-third of its present area by 2050 AD. Received: 2 October 1997 · Accepted: 13 January 1998     

地质成分数据统计分析

地质学研究中遇到大量成分数据,其各行之和相同,因而组分相关性中含由闭合效应引起的伪相关,而且不服从正态分布,给统计分析带来了很大困难．分析了前人提出的一些识别成分数据中伪相关的方法的缺欠,提出对数比变换作为成分数据统计分析的基本步骤的依据、优越性及存在问题;指出闭合造成的信息损失包括基的相关结构的信息,是任何方法都找不回来的．今后应着重分析有哪些信息还保留在成分数据中,并有针对性地寻找萃取这些信息的方法．     

万维网上地球科学信息源的搜寻

信息时代呼啸而至,给科学工作者带来了极大的机遇和挑战。能否及时掌握最新信息,能否以最快速度得到所需的特殊信息,成了能否取得前沿成果的关键之一。本文主要根据Ｓｃｈｉｍｍｒｉｃｈ的文章［１］作一些补充,简要介绍在万维网上搜寻地球科学信息源的一些知识。