Crustal motion and deformation in Greece from a decade of GPS measurements, 1993–2003   总被引：1，自引：1，他引：0  

Ch. Hollenstein  M.D. Müller  A. Geiger  H.-G. Kahle   《Tectonophysics》2008,449(1-4):17-40

The Hellenic plate boundary region, located in the collision zone between the Nubian/Arabian and Eurasian lithospheric plates, is one of the seismo-tectonically most active areas of Europe. During the last 15 years, GPS measurements have been used to determine the crustal motion in the area of Greece with the aim to better understand the geodynamical processes of this region. An extended reoccupation network covering whole Greece has been measured periodically in numerous GPS campaigns since the late eighties, and a continuous GPS network has been operated in the region of the Ionian Sea since 1995. In this paper, we present a new detailed high-quality solution of continuous and campaign-type measurements acquired between 1993 and 2003. During the GPS processing, a special effort was made to obtain consistent results with highest possible accuracies and reliabilities. Data of 54 mainly European IGS and EUREF sites were included in the GPS processing in order to obtain results which are internally consistent with the European kinematic field and order to allow for a regional interpretation. After an overview of the results of the IGS/EUREF sites, the results from more than 80 stations in Greece are presented in terms of velocities, time series, trajectories and strain rates. Previous geodetic, geological and seismological findings are generally confirmed and substantially refined. New important results include the observation of deformation zones to the north and to the south of the North Aegean Trough and in the West Hellenic arc region, arc-parallel extension of about 19 mm/yr along the Hellenic arc, and compression between the Ionian islands and the Greek mainland. Due to continuous long-term observations of 4–8 years, it was possible to extract height changes from the GPS time series. In Greece, we observe a differential subsidence of the order of 2 mm/yr between the northern and central Ionian islands across the Kefalonia fault zone. The differential subsidence of the central Ionian islands with respect to the northwestern Greek mainland amounts to 4 mm/yr.  相似文献   

Ultrahigh pressure macro diamonds from Copeton (New South Wales, Australia), based on Raman spectroscopy of inclusions   总被引：1，自引：0，他引：1  

L.M. Barron  B.J. Barron  T.P. Mernagh  W.D. Birch 《Ore Geology Reviews》2008,34(1-2):76

Mining of Cenozoic alluvial deposits at Copeton and Bingara (Eastern Australia) has produced two million macrodiamonds (0.25 ct median size). Raman spectroscopy is used to identify included minerals within uncut Copeton diamonds, with sealed chamber remnant pressures of 31.7 to 35.6 kbar for coesite, 13.6 and 22.7 kbar for clinopyroxene, and 7.6 kbar for grossular garnet. Assuming elastic behaviour, these values generate inclusion entrapment PT loci which intersect, restricting diamond formation conditions: from 250 °C, 43 kbar to 800 °C, 52 kbar. Larger than error (± 100 °C and ± 4 kbar), this range shows a systematic variation in inclusion composition with diamond zoning and N properties. Published research shows 1) Copeton and Bingara diamonds are unique, and 2) modern alluvium in the Bingara district carries mantle-formed garnet, captured by post-tectonic alkali basalt from an extensive diamondiferous ultrahigh pressure (UHP) terrane that stalled at depth because it is dominated by mafic eclogite. The combined Raman and geological results indicate two sets of subduction UHP diamond formation conditions/protolith are required, firstly cooler oceanic slab and secondly including higher temperature continental crust. The Copeton and Bingara stones are UHP macrodiamonds, and Carboniferous ⁴⁰Ar/³⁹Ar age dates on clinopyroxene inclusions should be interpreted as ages of crystallisation, representing the termination of subduction. The characteristic features of ruptured inclusions and etched percussion marks on Copeton and Bingara diamond indicate volcanic delivery to the earth's surface. Alluvial deposits elsewhere in Eastern Australia may carry similar diamond along with diamond of different origin.  相似文献   

用包埋脱水法冰冻保存海洋饵料金藻   总被引：4，自引：0，他引：4  

王起华  李贺  张恩栋  高艳萍  李大鹏 《海洋与湖沼》2005,36(2):172-178

用包埋脱水法冰冻保存绿色巴夫藻(Pavlova uiridis)、湛江等鞭金藻(Isochrysis zhanjiangensis)和球等鞭金藻(Isochrysis galbana 3011)等三种海洋饵料金藻，探讨了脱水速率、胶球含水量以及化冻后恢复方法对冰冻保存存活率的影响。结果表明，三种藻都在-0．9％含水量／h的平均脱水速率下获得最高存活率：各种藻在冰冻前的胶球最佳含水量不同，绿色巴夫藻为35％，湛江等鞭金藻和球等鞭金藻都为30％。化冻后，含绿色巴夫藻的胶球在培养基中22℃暗放置48h存活率最高；另两种藻在相对湿度为75％的气相中22℃暗放置12h存活率最高。在本实验条件下，绿色巴夫藻、湛江等鞭金藻和球等鞭金藻的冰冻保存的存活率可分别达到74％、15％和17％。  相似文献   

海藻硫酸多糖911对小鼠脾淋巴细胞增殖反应及对细胞产生IL—2作用的影响     

王文涛  张永祥  周金黄  管华诗 《中国海洋大学学报(自然科学版)》1992,(Z1)

本文以~3H—TdR掺入法观察911对小鼠脾淋巴细胞增殖反应的影响并用CTLL细胞检测了其对IL—2的作用。体外实验结果表明,911对小鼠脾淋巴细胞增殖反应有明显的增强作用,以0.5μg/ml的浓度效果最为明显,相对增殖指数RPI可达200％;体内实验则以5mg/kg体重ip,连续7d效果最好,相对增殖指数RPI可达176％;911用药组小鼠IL—2的产生量均高于对照组,以5mg/kg和10mg/kg效果最好。以上实验证明,这一多糖是一种有希望的新免疫调节药物。  相似文献   

回收法治理锯条厂氰化物污水     

柳宪民  董振芳 《海岸工程》1995,14(2):38-41

在采用回收法治理锯条厂氰化物污水中，通过改造生产工艺，减少污水量，提高氰化物浓度及污水经除油后减压蒸馏，可回收５０％～９０％的氰化铂，其他盐分也可全部回收，从污水中蒸出的蒸馏水能在系统内循环使用。  相似文献   

Evaluation of mine tailings effects on a benthic marine infaunal community over 29 years   总被引：4，自引：0，他引：4  

Burd BJ 《Marine environmental research》2002,53(5):481-519

Benthic infaunal and sediment data collected over 29 years were used to examine the extent and geographic range of effects and recovery from submarine tailings deposition. Empirical data were used to determine extreme and moderate effects, and identify near-, mid- and far-field zones. A simple probability test using overlap in frequency distributions was then used to determine less obvious effects, identify "normal" or "reference" conditions, and verify the geographic range of effect zones. Tailings thickness and sediment particulate copper were elevated from the outfall to 16-20 km distant, particularly below discharge depth (50 m). Changes in tailings thickness and copper levels before, during and after mining showed three distinct impact zones below discharge depth: near-field (<5 km from outfall); mid-field (5-16 km); and far-field (20 + km). Consistent faunal declines during mining were noted at sediment particulate copper levels >300 microg g(-1), and sediment tailings thickness > 15-20 cm. Extreme impoverishment at these sediment levels were; < 100 animals/m2, <2.5 g/m2 biomass and <7 taxa per station. No stations with >300 microg g(-1) copper and 20 cm tailings had more than 40 taxa. Amphipods were particularly affected by tailings, with distributions reflecting the instability in sediments from heavy deposition and/or shifting of tailings due to resuspension. The probability testing method assumed that reference conditions existed in far-field stations. There was no difference in abundance distributions between near-, mid- and far-field zones. Total taxa per station during mining was significantly reduced (<45) in both near- and mid-field stations compared with far-field (less than 10% overlap in distributions). One midfield station in Quatsino Sound (23) was in reference condition throughout the study period. Post-closure stations in the near- and mid-field had total taxa numbers approaching far-field conditions (overlap of 62% in distributions). Within 3 years following closure, total taxa values were within the far-field range for all stations sampled. Biomass showed a distinct decline in the near-field during mining, but with more overlap in near-field and far-field distributions (27%) than for total taxa per station, and was returning to far-field conditions in the post-closure years. A multivariate (Bray-Curtis) measure of dissimilarity indicated that the near- and mid-field infaunal compositions were distinct from the far-field during mining (< 10% overlap in distributions). The mid-field composition overlapped more with the far-field in the post-closure years, but the near-field composition did not, suggesting that the mine tailings are still affecting the fauna. The most abundant taxon in each of the reference and near-field station groups both showed significantly distinct relative abundance distributions between near- and far-field stations. In summary, the probability method showed that species richness, biomass, species composition and indicator taxa were useful for differentiating affected and non-affected stations. Polychaetes recolonize stable tailings most quickly, and have dominated the tailings stations in the post-closure years. Amphipods have recolonized sporadically, but seem to be highly sensitive to tailings stability. There was no evidence of recovery in dominant bivalves or echinoderms within three years after mine closure.  相似文献   

封闭体系有机质与有机碳氢氮恢复动力学研究   总被引：3，自引：0，他引：3  

彭平安  秦艳  张辉  刘大永  张善文  隋风贵  李钜源  李政 《海相油气地质》2008,13(2):27-36

在封闭体系的条件下,对典型的Ⅰ、Ⅱ、Ⅲ型干酪根在热演化过程中的损失进行生烃动力学研究,获得了Ⅰ、Ⅱ、Ⅲ型干酪根的总量、有机碳、氢以及氮质量损失动力学参数。用Kinetics软件计算了封闭体系干酪根有机碳丰度、氢碳原子比和氮碳原子比的恢复系数。认为在对高成熟—过成熟干酪根进行生烃评价时,Ⅰ、Ⅲ型干酪根残余有机碳丰度需要进行恢复,而Ⅱ型干酪根残余有机碳丰度不需要恢复。三种类型干酪根的氢碳原子比均需要进行恢复。  相似文献   

形变,应变短临前兆标志体系   总被引：1，自引：0，他引：1  

薄万举  吴翼麟 《华南地震》1996,16(2):20-29

建立各手段的前兆异常标志,从而组合各类前兆标志体系是“八五”地震短临预报攻关研究项目的重要目标之一。本文以形变,应变手段的主要研究对象,初步建立了一个形变应变短临前兆标志体系,并总结出了各种异常的判别标志,为利用系统优化理论和专家系统理论进一步研究形变应前兆系统和地震之间的关系,从而为提高中短期地震预报的水平打下了一定的基础。  相似文献   

Uniaxial compression and tension tests of anthracite and loading rate dependence of peak strength   总被引：2，自引：0，他引：2  

S. Okubo  K. Fukui  Qi Qingxin 《International Journal of Coal Geology》2006,68(3-4):196-204

The mechanical characteristics of coal under uniaxial compressive stress and uniaxial tensile stress are key factors in investigations of the stability of galleries and coal faces, and are vital considerations for the efficient design of coalmines, disaster prevention, and environmental preservation. These mechanical characteristics have long been a topic of research, but remain insufficiently understood. In this study we performed uniaxial compression tests and uniaxial tension tests on coal, with particular attention to two concerns. The first was to measure the loading rate dependence of the peak strength of coal. Coal shows high sample-to-sample scatter in strength; test methods that are successful in comparatively homogeneous rock types cannot be used for coal. We therefore used an alternative test method that was recently developed by the authors. Anthracite samples were subjected to alternating slow and fast strain rates. Measured variations in stress during this process were used to estimate the loading rate dependence of peak strength. The second objective was to obtain complete stress–strain curves for coal under uniaxial tensile stress. It is difficult to hold samples secure during a tensile test; consequently, such curves have yet to be obtained. This study presents a successful application of the authors' method to the analysis of coal samples, yielding a complete stress–strain curve under tensile stress. The two methods presented here hold promise for application not only to anthracite but also to a wide variety of coals. It is possible to derive the values of the constants used in constitutive equations from the obtained experimental results. Once these equations are determined, they can be incorporated into finite-element software to investigate various time-dependent behaviors of coal and aid in the efficient design of coalmines and the prevention of subsidence and mine disasters.  相似文献   

Seismic potential of Southern Italy   总被引：1，自引：2，他引：1  

S. Jenny  S. Goes  D. Giardini  H.-G. Kahle 《Tectonophysics》2006,415(1-4):81-101

To improve estimates of the long-term average seismic potential of the slowly straining South Central Mediterranean plate boundary zone, we integrate constraints on tectonic style and deformation rates from geodetic and geologic data with the traditional constraints from seismicity catalogs. We express seismic potential (long-term average earthquake recurrence rates as a function of magnitude) in the form of truncated Gutenberg–Richter distributions for seven seismotectonic source zones. Seismic coupling seems to be large or even complete in most zones. An exception is the southern Tyrrhenian thrust zone, where most of the African–European convergence is accommodated. Here aseismic deformation is estimated to range from at least 25% along the western part to almost 100% aseismic slip around the Aeolian Islands. Even so, seismic potential of this zone has previously been significantly underestimated, due to the low levels of recorded past seismicity. By contrast, the series of 19 M6–7 earthquakes that hit Calabria in the 18th and 19th century released tectonic strain rates accumulated over time spans up to several times the catalog duration, and seismic potential is revised downward. The southern Tyrrhenian thrust zone and the extensional Calabrian faults, as well as the northeastern Sicilian transtensional zone between them (which includes the Messina Straits, where a destructive M7 event occurred in 1908), all have a similar seismic potential with minimum recurrence times of M ≥ 6.5 of 150–220 years. This potential is lower than that of the Southern Apennines (M ≥ 6.5 recurring every 60 to 140 years), but higher than that of southeastern Sicily (minimum M ≥ 6.5 recurrence times of 400 years). The high seismicity levels recorded in southeastern Sicily indicate some clustering and are most compatible with a tectonic scenario where the Ionian deforms internally, and motions at the Calabrian Trench are small. The estimated seismic potential for the Calabrian Trench and Central and Western Sicily are the lowest (minimum M ≥ 6.5 recurrence times of 550–800 years). Most zones are probably capable of generating earthquakes up to magnitudes 7–7.5, with the exception of Central and Western Sicily where maximum events sizes most likely do not exceed 7.  相似文献