中国大陆及邻区6级以上强震的关联序列研究

将1次大地震后相继出现的6级地震缺震或连发与下次大地震事件的连续过程称为关联序列。分别对中国大陆及邻区近百年来69次浅源大地震前出现的6级地震缺震、连发异常图像的结构特点，各类序列的时程、时空分布及出现概率进行了对比分析。结果显示，有53次震例的关联序列，包含超过1次6级缺震及连发的2-4元序列，均在0．5-2年内完成，因此在大地震预测中，对大地震前出现的6级地震缺震、连发关联序列类型与特征的及时识别，可能作为一种新的判定依据。     

Developmental,Reproductive, and Demographic Alterations in Aquatic Wildlife: Establishing Causality between Exposure to Endocrine‐active Compounds (EACs) and Effects

This brief overview discusses the difficulty of demonstrating causal associations between exposure to endocrine active compounds (EACs) and the occurrence of developmental, reproductive, or demographic disturbances in aquatic wildlife. While for biological responses at the suborganism level correlational or causal evidence of an EAC etiology has been established in a number of cases, well proven examples of ecological consequences of endocrine disruption are rather few in number. The attribution of causality is complicated due to (i) lack of data on EAC exposure and bioaccumulation, (ii) lack of specific biomarkers and endpoints, together with insufficient knowledge on the mechanisms and conditions by which EAC‐induced disruption of endocrine functions translates into impaired organism development and reproduction, and (iii) insufficient understanding of the importance of species diversity in endocrine physiology and life histories for the consequences of endocrine disruption. Future research should address these gaps in our understanding of EAC exposure and effects, but additionally needs to pay more attention (i) to ecological determinants influencing the population‐level consequences of the endocrine disruption of developÍmental and reproductive functions, and (ii) to the use of epidemiological principles and approaches.     

Cosmogenic nuclide chronology of pre-last glacial maximum moraines at Lago Buenos Aires, 46°S, Argentina

At Lago Buenos Aires, Argentina, ¹⁰Be, ²⁶Al, and ⁴⁰Ar/³⁹Ar ages range from 190,000 to 109,000 yr for two moraines deposited prior to the last glaciation, 23,000–16,000 yr ago. Two approaches, maximum boulder ages assuming no erosion, and the average age of all boulders and an erosion rate of 1.4 mm/10³ yr, both yield a common estimate age of 150,000–140,000 yr for the two moraines. The erosion rate estimate derives from ¹⁰Be and ²⁶Al concentrations in old erratics, deposited on moraines that are >760,000 yr old on the basis of interbedded ⁴⁰Ar/³⁹Ar dated lavas. The new cosmogenic ages indicate that a major glaciation during marine oxygen isotope stage 6 occurred in the mid-latitude Andes. The next five youngest moraines correspond to stage 2. There is no preserved record of a glacial advance during stage 4. The distribution of dated boulders and their ages suggest that at least one major glaciation occurred between 760,000 and >200,000 yr ago. The mid-latitude Patagonian glacial record, which is well preserved because of low erosion rates, indicates that during the last two glacial cycles major glaciations in the southern Andes have been in phase with growth and decay of Northern Hemisphere ice sheets, especially at the 100,000 yr periodicity. Thus, glacial maxima are global in nature and are ultimately paced by small changes in Northern Hemisphere insolation.     

Experimental Investigation and Optimization of Thermodynamic Properties and Phase Diagrams in the Systems CaO-SiO2, MgO-SiO2, CaMgSi2O6-SiO2 and CaMgSi2O6-Mg2SiO4 to 1{middle dot}0 GPa

Using experimental results at 1·0 GPa for the systemsCaO–SiO₂, MgO–SiO₂, CaMgSi₂O₆–SiO₂ and CaMgSi₂O₆–Mg₂SiO₄,and all the currently available phase equilibria and thermodynamicdata at 1 bar, we have optimized the thermodynamic propertiesof the liquid phase at 1·0 GPa. The new optimized thermodynamicparameters indicate that pressure has little effect on the topologyof the CaO–SiO₂, CaMgSi₂O₆–SiO₂, and CaMgSi₂O₆–Mg₂SiO₄systems but a pronounced one on the MgO–SiO₂ binary. Themost striking change concerns passage of the MgSiO₃ phase fromperitectic melting at 1 bar to eutectic melting at 1·0GPa. This transition is estimated to occur at 0·41 GPa.For the CaMgSi₂O₆–SiO₂ and CaMgSi₂O₆–Mg₂SiO₄ pseudo-binaries,the size of the field clinopyroxene + liquid increases withincreasing pressure. This change is related to the shift ofthe piercing points clinopyroxene + silica + liquid (from 0·375mol fraction SiO₂ at 1 bar to 0·414 at 1·0 GPa)and clinopyroxene + olivine + liquid (from 0·191 molfraction SiO₂ at 1 bar to 0·331 at 1·0 GPa) thatbound the clinopyroxene + liquid field in the CaMgSi₂O₆·SiO₂and CaMgSi₂O₆·Mg₂SiO₄ pseudo-binaries, respectively. KEY WORDS: CaO–SiO₂; CaMgSi₂O₆–Mg₂SiO₄; CaMgSi₂O₆–SiO₂; experiments; MgO–SiO₂     

Magnitude and frequency in proglacial rivers: a geomorphological and sedimentological perspective

Proglacial fluvial sedimentary systems receive water from a variety of sources and have variable discharges with a range of magnitudes and frequencies. Little attention has been paid to how these various magnitude and frequency regimes interact to produce a distinctive sedimentary record in modern and ancient proglacial environments. This paper reviews the concept of magnitude and frequency in relation to proglacial fluvial systems from a geomorphic and sedimentary perspective rather than a hydrological or statistical perspective. The nature of the meltwater inputs can be characterised as low-magnitude–high-frequency, primarily controlled by ablation inputs from the source glacier, or high-magnitude–low-frequency, primarily controlled by ‘exceptional’ inputs. The most important high-magnitude–low-frequency inputs are catastrophic outburst floods, often referred to by the term jökulhlaup (Icelandic for glacier-burst). Glacier surges are an additional form of cyclical variation impacting the proglacial environment, which briefly alter the volumes and patterns of meltwater input. The sedimentary consequences of low-magnitude–high-frequency discharges are related to frequent variations in stage, the greater directional variability that sediment will record, and the increased significance of channel confluence sedimentation. In contrast, the most significant characteristics of high-magnitude–low-frequency flooding include the presence of large flood bars and mid-channel ‘jökulhlaup’ bars, hyperconcentrated flows, large gravel dunes, and the formation of ice-block kettle hole structures and rip-up clasts. Glacier surges result in a redistribution of low-magnitude–high-frequency processes and products across the glacier margin, and small floods may occur at the surge termination. Criteria for distinguishing magnitude and frequency regimes in the proglacial environment are identified based on these major characteristics. Studies of Quaternary proglacial fluvial sediments are used to determine how the interaction of the various magnitude and frequency regimes might produce a distinctive sedimentary record. Consideration of sandur architecture and stratigraphy shows that the main controls on the sedimentary record of proglacial regions are the discharge magnitude and frequency regime, sediment supply, the pattern of glacier advance or retreat, and proglacial topography. A model of sandur development is suggested, which shows how discharge magnitude and frequency, in combination with sandur incision and aggradation (controlled by glacier advance and retreat) can control sandur stratigraphy.     

年轻地下水测年最新技术——SF6法

SF6是一种无色、无嗅、无毒、不易燃的惰性气体,具有良好的绝缘性、灭弧性和散热性,广泛用于断路器和变压器的绝缘材料。电器设备的泄漏使得大气中SF6浓度增加很快,每年达7%,造成SF6的人工来源,此外还有天然来源。SF6通常用带电子捕获器(ECD)的气相色谱仪测定。SF6是一种新型的测定年轻地下水年龄的工具,特别适合研究1990年以后补给水的年龄。SF6年龄以亨利定律为基础计算。由于大气中SF6浓度逐年增加,比CFC测年法具有更大的优越性。     

Observation and analysis of geomagnetic abnormity associated with the M_S=5.7 Jiu-jiang-Ruichang earthquakeb

Introduction On November26,2005,the MS=5.7Jiujiang-Ruichang earthquake occurred with the epicen-ter of29°43′N and115°43′E.However,this area is not a major monitoring range with a few earth-quakes and therefore,it lacks conventional precursory seismic data.In the project of“2005.0China geomagnetic chart”,some three-component geomagnetic surveys,with the average distance of70km between adjacent stations,were carried out in2004in this area.And fortunately the data from these surveys can…     

Formation of Al-rich titanite (CaTiSiO4O–CaAlSiO4OH) reaction rims on ilmenite in metamorphic rocks as a function of fH2O and fO2

Reaction rims of titanite on ilmenite are described in samples from four terranes of amphibolite-facies metapelites and amphibolites namely the Tamil Nadu area, southern India; the Val Strona area of the Ivrea-Verbano Zone, northern Italy, the Bamble Sector, southern Norway, and the northwestern Austroalpine Ötztal Complex. The titanite rims, and hence the stability of titanite (CaTiSiO₄O) and Al–OH titanite, i.e. vuaganatite (hypothetical end-member CaAlSiO₄OH), are discussed in the light of fH₂O- and fO₂-buffered equilibria involving clinopyroxene, amphibole, biotite, ilmenite, magnetite, and quartz in the systems CaO–FeO/Fe₂O₃–TiO₂–SiO₂–H₂O–O₂ (CFTSH) and CaO–FeO/Fe₂O₃–Al₂O₃–SiO₂–H₂O–O₂ (CFASH) present in each of the examples. Textural evidence suggests that titanite reaction rims on ilmenite in rocks from Tamil Nadu, Val Strona, and the Bamble Sector originated most likely due to hydration reactions such as clinopyroxene + ilmenite + quartz + H₂O = amphibole + titanite and oxidation reactions such as amphibole + ilmenite + O₂ = titanite + magnetite + quartz + H₂O during amphibolite-facies metamorphism, or, as in the case of the Ötztal Complex, during a subsequent greenschist-facies overprint. Overstepping of these reactions requires fH₂O and fO₂ to be high for titanite formation, which is also in accordance with equilibria involving Al–OH titanite. This study shows that, in addition to P, T, bulk–rock composition and composition of the coexisting fluid, fO₂ and fH₂O also play an important role in the formation of Al-bearing titanite during amphibolite- and greenschist-facies metamorphism.     

Using Rock‐Eval 6 pyrolysis for tracking fossil organic carbon in modern environments: implications for the roles of erosion and weathering

This work relates to the debate on the fossil organic carbon (FOC) input in modern environments and its possible implication for the carbon cycle, and suggests the use of Rock‐Eval 6 pyrolysis as a relevant tool for tracking FOC in such environments. Considering that such a delivery is mainly due to supergene processes affecting the continental surface, we studied organic matter in different reservoirs such as bedrocks, alterites, soils and rivers in two experimental catchments at Draix (Alpes de Haute Provence, France). Samples were subjected to geochemical (Rock‐Eval 6 pyrolysis) investigations and artificial bacterial degradations. After comparing the geochemical fingerprint of samples, geochemical markers of FOC were defined and tracked in the different reservoirs. Our results confirm the contribution of FOC in modern soils and rivers and display the various influences of weathering and erosional processes on the fate of FOC during its exchange between these pools. In addition, the contrasting behaviour of these markers upon the supergene processes has also highlighted the refractory or labile characters of the fossil organic matter (FOM). Bedrock to river fluxes, controlled by gully erosion, are characterized by a qualitative and quantitative preservation of FOM. Bedrock to alterite fluxes, governed by chemical weathering, are characterized by FOC mineralization without qualitative changes in deeper alterites. Alterite to soils fluxes, controlled by (bio)chemical weathering, are characterized by strong FOC mineralization and qualitative changes of FOM. Thus weathering and erosional processes induce different FOM evolution and affect the fate of FOC towards the global carbon cycle. In this study, gully erosion would involve maintenance of an ancient sink for the global carbon cycle, while (bio)chemical processes provide a source of CO₂. Finally, this study suggests that Rock‐Eval 6 pyrolysis can be considered as a relevant tool for tracking FOC in modern environments. Copyright © 2006 John Wiley & Sons, Ltd.     

On the characterization of aerosols using the Ångström exponent in the Athens area

Ground-based spectroradiometric measurements were taken in the atmosphere of Athens during May 1995 in order to investigate various atmospheric conditions. This study focuses on the Ångström exponent α, which is the slope of the logarithm of the aerosol optical depth (AOD) versus the logarithm of the wavelength, lnλ, and is commonly used to characterize the wavelength dependence of AOD and to provide some basic information on the aerosol size distribution. Using the Volz method, Ångström exponent values, α, were derived in five narrow spectral bands, 340–380, 380–440, 440–500, 500–670 and 670–870 nm. Also using both Volz and least-squares fit methods α values were derived for the whole spectrum 340-870 nm.The results show that α depends strongly on the wavelength interval used due to the curvature of the lnAOD versus lnλ line. Using the spectral dependence of the Ångström exponent and the relationship between α computed in different spectral bands with AOD, an attempt to investigate on the aerosol types is made. The results obtained are rather contradictory and the determination of a dominant aerosol type in the Athens area is not clear. Nevertheless, in the most cases the anthropogenic aerosols seem to be the dominant type with rather significant contributions of coarse-mode particles due to particle growing or due to mixing processes with other aerosol types.