Probabilistic seismic hazard zonation of Syria

Earthquake hazard maps for Syria are presented in this paper. The Peak Ground Acceleration (PGA) and the Modified Mercalli Intensity (MMI) on bedrock, both with 90% probability of not being exceeded during a life time of 50, 100 and 200 years, respectively are developed. The probabilistic PGA and MMI values are evaluated assuming linear sources (faults) as potential sources of future earthquakes. A new attenuation relationship for this region is developed. Ten distinctive faults of potential earthquakes are identified in and around Syria. The pertinent parameters of each fault, such as theb-parameter in the Gutenberg-Richter formula, the annual rate ₄ and the upper bound magnitudem ₁ are determined from two sets of seismic data: the historical earthquakes and the instrumentally recorded earthquake data (AD 1900–1992). The seismic hazard maps developed are intended for preliminary analysis of new designs and seismic check of existing civil engineering structures.     

冀西北长城纪宣龙式铁矿层中微体植物化石的发现及其意义

本文研究的是笔者等在冀西北长城系串岭沟组宣龙式铁矿层中发现的微体植物化石,这些化石都保存在铁质叠层石(肾状赤铁矿)和铁质核形石(鲕状赤铁矿)的基本层中。微化石以丝状体为主,部分为球状体。归属于原核生物蓝藻门颤藻科的两个属和色球藻科的一个属。化石层同位素年龄约在1800—1757Ma。这些化石与北美冈弗林特组微化石比较,既有些相似,又有些区别。该化石的发现为研究铁矿的成因,指示沉积环境及层位对比都很有意义。     

Chemical aspects of iron oxide coagulation in water: Laboratory studies and implications for natural systems

Initial coagulation rates of colloidal hematite (-Fe₂O₃) particles (diameter less than 0.1 µm) were measured experimentally in well-defined laboratory systems at constant temperature. The relative stability ratio,W, was obtained at various ionic strengths in NaCl medium and at pH values in the range from 3 to 12. ExperimentalW values ranged from 1 to 10⁴ in various systems. The results delineate the roles ofspecific andgeneralized coagulation mechanisms for iron oxides. Among the specifically-interacting species (G _ads ⁰ >G _coul ⁰ ) studied were phosphate, monomeric organic acids of various structures, and polymeric organic acids. The critical coagulation-restabilization concentrations of specifically-interacting anions (from 10^–7 to 10^–4 molar) can be compared with the general effects of non-specific electrolyte coagulants (10^–3 to 10^–1 molar). The laboratory results are interpreted with the help of a Surface Complex Formation/Diffuse Layer Model (SCF/DLM) which describes variations of interfacial charge and potential resulting from variations of coagulating species in solution. Comparison of these laboratory experiments with observations on iron behavior in estuarine and lake waters aids in understanding iron removal mechanisms and coagulation time scales in natural systems.     

An experimental study of anorthosite dissolution in lunar picritic magmas: Implications for crustal assimilation processes

Experiments characterizing the kinetics of anorthosite dissolution in lunar picritic magmas (very low-Ti, low-Ti, and high-Ti picritic glasses) were conducted at 0.6 GPa and 1250-1400 °C using the dissolution couple method. Reaction between the anorthosite and lunar picritic magmas at 1250-1300 °C produced a spinel + melt layer. Reaction between the anorthosite and an olivine-saturated low-Ti magma at 1250-1300 °C produced a crystal-free region between the spinel + melt layer and the olivine-saturated magma. The anorthosite dissolution experiments conducted at 1400 °C simply dissolved anorthosite and did not result in a crystal-bearing region. The rate of anorthosite dissolution strongly depends on temperature and composition of the reacting melt. Concentration profiles that develop during anorthosite dissolution are nonlinear and extend from the picritic glass compositions to anorthite. These profiles feature a large and continuous variation in melt density and viscosity from the anorthosite-melt interface to the initial picritic magmas. In both the low-Ti and high-Ti magmas the diffusive fluxes of TiO₂, Al₂O₃, and SiO₂ are strongly coupled to the concentration gradients of CaO and FeO. Anorthosite dissolution may play an important role in producing the chemical variability of the lunar picritic magmas, the origin of spinel in the lunar basalts and picritic glasses, and the petrogenesis of the high-Al basalts.     

Study of stable isotopes for highly deformed aquifers in the Hsinchu-Miaoli area, Taiwan

This study was based on the analysis of isotopic compositions of hydrogen and oxygen in samples from precipitation, groundwater and stream water. In addition, parts of groundwater samples were dated by carbon-14 and tritium. These data are integrated to provide other views of the hydrologic cycle in the Hsinchu-Miaoli groundwater district. The groundwater district is principally composed of Pleistocene and Holocene aquifers. The Pleistocene aquifers are highly deformed by folding and faults into small sub-districts with areas of only tens of square kilometers. These aquifers are exclusively recharged by local precipitation. The Holocene aquifers cover narrow creek valleys, only tens of meters in thickness. The local meteoric water line (LMWL), constructed from rainfall samples in the Hsinchu Science Park, is described by the equation δD=8.02δ¹⁸O+10.16, which agrees with the global meteoric water line. In addition, the precipitation isotopic compositions can be categorized into two distinct end members: typhoon type and monsoon type. The groundwater isotopic compositions are perfectly located on an LMWL and can be considered a mixture of precipitations. Based on the mass balance of isotopic compositions of oxygen and hydrogen, infiltration is more active in the rainy season with depleted isotopic compositions. The amount of infiltration during May–September is roughly estimated to comprise at least 55% of the whole year’s recharge. The isotopic compositions of stream water are expressed by a regression equation: δD=7.61δ¹⁸O+9.62, which is similar to the LMWL. Although precipitation isotopic compositions are depleted during summer time, the isotopic compositions contrarily show an enriched trend in the upstream area. This is explained by the opposite altitude effect on isotopic compositions for typhoon-related precipitations.     

GIS-based flood hazard mapping at different administrative scales: A case study in Gangetic West Bengal, India

This paper addresses the need for an efficient and cost-effective methodology for preparing flood hazard maps in data poor countries, particularly those under a monsoon regime where floods pose a recurrent danger. Taking Gangetic West Bengal, India, as an example and using available historical data from government agencies, the study compiled a regional map indicating hazard prone subregional areas for further detailed investigation, thereby isolating actual high risk localities. Using a GIS (Geographical Information System), a composite hazard index was devised incorporating variables of flood frequency, population density, transportation networks, access to potable water, and availability of high ground and maximum risk zones were mapped accordingly. A digital elevation model derived from high resolution imagery available in the public domain was used to calculate elevated areas suitable for temporary shelter during a flood. Selecting administrative units of analysis at the lowest possible scales – rural development blocks (regional) and revenue villages (subregional) – also ensures that hazard mapping is prepared in line with the existing rural planning and administrative authorities responsible for remedial intervention.     

桂北地区早石炭世杜内期的长身贝类的发现及其生物古地理意义

在广西北部兴安县高尚镇金子山剖面下石炭统鹿寨组底部，新发现了长身贝类腕足化石，包括1新种、1个相似种、6个未定种和2个属种未定类型。这些长身贝类以Productellidae和Productidae科的分子为主，另有少量Echinoconchidae和Monticuliferidae科的分子。这些长身贝类全部属于生活在静水环境中的薄壳类型，无一与华南同期地层中已知类型相同。它们之间的差异可能反映了不同沉积环境条件对腕足动物群属种的控制。在鹿寨组底部发现的长身贝类以及近年在桂林南边村和黔南睦化剖面腕足动物群的发现显示出华南台缘斜坡―盆地相区杜内阶中的腕足动物群具有极高的属种分异度，不但有大量见于世界其他地方同期动物群中的分子，也包含有不少原本认为只在维宪阶或更高层位出现的类型或全新的类型，说明华南台缘斜坡―盆地相区不但与世界其他地区的腕足动物群之间存在密切的生物地理区系联系，而且华南台缘斜坡―盆地相区是杜内期腕足动物起源和辐射演化的重要策源地之一。许多属种可能是在这里起源，并迁移扩散到其他地方。