发震构造呈复杂空间关系下相互影响发震的机理研究——以汶川地震为例

对发震构造呈复杂几何关系(发震构造在平面投影呈非平行关系)下彼此发震影响的机理进行了研究.从发震的“垂震底继”影响关系研究了1933年迭溪地震M7.5和1976年松潘Ms7.2地震对后来发生汶川M8地震的龙门山地震构造的孕震能量叠加的加震作用;同时也指出汶川8级地震对周边断裂的减震作用,计算并指出了其影响减震的距离.研究对CPSHA中对发震构造呈复杂几何关系时,如何确定地震带内各潜在的震源空间分布函数fi,mj提供了大震加减震的判断理论依据.还讨论了汶川地震孕震模式的更复杂性,针对某些用巴颜喀拉块体向东南方向移动挤压龙门山孕震构造,进而解释汶川地震的逆冲性所带来的矛盾的观点,对其孕震的复杂性提出了问题所在和初步探讨.     

Application of synoptic-scale anomalous winds predicted by medium-range weather forecast models on the regional heavy rainfall in China in 2010

Atmospheric winds from observations and medium-range weather forecast model predictions can be physically decomposed as daily climate wind,planetary-scale anomalous wind,and synoptic-scale anomalous wind.The 850 hPa synoptic-scale anomalous winds were extracted from the numerical model outputs of the European Centre for Medium-Range Weather Forecasts(ECMWF) and the NCEP Global Forecast System(GFS).The results showed that most rain bands in eastern China in 2010 were located along the anomalous convergence lines.To predict the major rain bands by these convergence lines in 2010,the accuracies of the ECMWF products were 100%,85%,and 15% for leading 3,6,and 9 days,while the GFS products showed 53%,15%,and 6% accuracies,respectively.In comparison of the regional heavy rainfalls between observation and the ECMWF model prediction,the useful leading information was about 3.1 days for direct model rain prediction and 6.7 days for convergence systems predicted by ECMWF model.     

Ecological Risk Assessment of Benzo[a]pyrene in Yellow River Delta

Ecological risk assessment is of great significance to promoting the rational management effectively for the oil‐polluted areas. A comprehensive evaluation method of ecological risk, including probabilistic risk assessment and regional ecological risk assessment, is developed through employing the contaminant benzo[a]pyrene as an indicator to assess ecological risk of five oil mining plots, respectively in Yellow River Delta. In this study, firstly we evaluate the ecological risk probability of five oil mining plots using overlapping area of probabilistic curves, and the results show that local ecological risk varies between the maximum 0.4 and the minimum 0.01. Then we overlay boundaries of five administrative divisions in Yellow River Delta and the spatial distribution patterns of ecosystems to generate new risk receptor plaques, and calculate the integrated value of 30 specifically classified plaques for comprehensive evaluation of ecological risk. The results, fluctuating within the range of 0.00005 and 0.25, indicate that local government should be vigilant to ecological risk of benzo[a]pyrene to some extent, although the current situation is not severe in whole.     

Dissolution-filling mechanism of atmospheric precipitation controlled by both thermodynamics and kinetics

Affected by structural uplift,the Ordovician carbonate rockbed in the Tarim Basin,China,was exposed to dissolution and reformation of atmospheric precipitation many times,and formed a large quantity of karst caves serving as hydrocarbon reservoir.However,drilling in Tahe area showed that many large karst caves,small pores and fractures are filled by calcite,resulting in decrease in their reservoir ability.Calcite filled in the karst caves has very light oxygen isotopic composition and87Sr/86Sr ratio.Its 18OPDB ranges from 21.2‰to 13.3‰with the average of 16.3‰and its87Sr/86Sr ratio ranges from0.709561 to 0.710070 with the average of 0.709843.The isotope composition showed that calcite is related to atmospheric precipitation.Theoretic analyses indicated that the dissolving and filling actions of the precipitation on carbonate rocks are controlled by both thermodynamic and kinetic mechanisms.Among them,the thermodynamic factor determines that the precipitation during its flow from the earth surface downward plays important roles on carbonate rocks from dissolution to saturation,further sedimentation,and finally filling.In other words,the depth of the karstification development is not unrestricted,but limited by the precipitation beneath the earth surface.On the other hand,the kinetic factor controls the intensity,depth,and breadth of the karstification development,that is,the karstification is also affected by topographic,geomorphologic,climatic factors,the degree of fracture or fault,etc.Therefore,subject to their joint effects,the karstification of the precipitation on the Ordovician carbonate rocks occurs only within a certain depth(most about 200 m)under the unconformity surface,deeper than which carbonate minerals begin to sedimentate and fill the karst caves that were formed previously.     

Presence of carboxylate salts in marine carbonate strata of the Ordos Basin and their impact on hydrocarbon generation evaluation of low TOC, high maturity source rocks

The total organic carbon(TOC)in the marine source rock of the Ordos Basin mostly ranges from 0.2%to 0.5%.The industrial standard commonly states that the TOC value has to be no less than 0.5%(0.4%for high mature or over-mature source rock)to form large petroleum reservoirs.However,gas source correlation indicates that the natural gas in the Jingbian gas field does receive contribution from marine source rocks.In order to determine the effect of carboxylate salts(or called as organic acid salts)on TOC in highly mature source rocks with low TOC value,we sampled the Ordovician marine source rock and the Permian transitional facies source rock in one drilled well in the southern Ordos Basin and performed infrared and GC-MS analysis.It is found that both kerogen-derived organic acids and carboxylate salt-conversed organic acids exist in both marine and transitional facies source rocks.The carboxylate salt-conversed organic acids mainly come from the complete acidification of carboxylate salts,which confirms the presence of carboxylate salts in the marine source rocks.Although the C16:O peak is the main peak for the organic acids both before and after acidification,the carboxylate salt-conversed organic acids have much less relative abundance ahead of C16:O compared with that of the kerogen-based and free organic acids.This observation suggests that the kerogen-based and free organic acids mainly decarboxylate to form lower carboxylic acids,whereas the carboxylate salt-conversed organic acids mainly break down into paraffins.By using calcium hexadecanoate as the reference to quantify the kerogen-derived and carboxylate salt-conversed organic acids,the high TOC(>2.0%)marine source rocks have low carboxylate salt content and the low TOC(0.2%–0.5%)marine source rocks contain high content of carboxylate salt.Therefore,for the marine source rocks with 0.2%–0.5%TOC,the carboxylate salts may be a potential gas source at high maturity stage.     

GPS在地壳形变和板块运动监测中的应用

简要介绍了GPS在现代板块构造运动中的应用及其进展:GPS对于地球参考框架的建立和维持发挥着重要的作用;大量地壳运动监测网的建立使得GPS成为监测地壳运动强有力的工具;全球性、全天候的GPS卫星测高将在现代板块构造运动的监测中发挥重要作用;高精度的IGS产品为国际动力学服务提供坚实的数据基础。     

地球参考框架的建立和维持

详细总结了ITRF等参考框架的原理,分析了其优缺点和特性并分析了不同地球参考框架的区别。本文在协议研究的基础上,结合我国实际,提出了建立我国新一代地球参考系统的若干建议。     

超导重力仪检测2011年日本东北Mw9.0级地震前的重力扰动信号

对大地震前的扰动现象的研究有助于认识地震孕育的动力学过程,震前重力扰动已成为关注的热点之一. 对大地震前的扰动现象的研究有助于认识地震孕育的动力学过程,震前重力扰动已成为关注的热点之一. 为检验日本M_w9.0级地震是否存在震前扰动现象,本研究利用全球超导重力仪记录到的地震前后7天内20组秒采样数据进行分析. 经潮汐、大气改正等处理去除仪器的漂移及残余潮汐效应,得到非潮汐重力变化曲线.结果表明大部分振幅大于30×10^-8 m·s^-2的曲线反映了全球M_w≥6级地震引起的高频波动信号,其中11组数据在3月9日M_w7.3级前震之前出现了扰动现象.震前扰动可分解为三个频段,其中,低于0.1 Hz和高于0.18 Hz的分量分别反映了地震波动信号及非构造信息,中间频段(0.118~0.18 Hz)信号能够较大程度地压制地震波动信号、并同时保留异常扰动信息.它的振幅在3月7日10时之前基本保持约1×10^-8 m·s^-2,之后开始逐渐增大,到3月9日7.3级前震前后达到最大,此后振荡衰减,振幅保持约(5~10)×10^-8 m·s^-2,直至主震发生.中间频段信号的变化特征与主震前的应力迁移过程以及实验记录到的地震成核过程有许多相似之处;不过,震前重力异常是否与主震前的应力加速积累有关,仍待进一步研究.     

Late Quaternary (30.7–9.0 cal ka BP) vegetation history in Central Asia inferred from pollen records of Lake Balikun, northwest China

Surface and fossil pollen samples were collected to reconstruct the vegetation and environment since 30.7 cal ka BP in the Lake Balikun Basin, northwest China. This record demonstrates that the region was occupied by four vegetation communities during the interval 30.7–9.0 cal ka BP, including desert steppe (30.7–25.1 cal ka BP), Amaranthaceae-Asteraceae desert (25.1–17.7 cal ka BP), Amaranthaceae-Artemisia-Asteraceae desert (17.7–12.8 cal ka BP) and Amaranthaceae desert (12.8–9.0 cal ka BP), corresponding to relatively humid, the coldest and driest, cold and dry, and colder and drier conditions, respectively. The reconstructions of vegetation and environmental changes around Lake Balikun do not support the interpretation of an extremely humid LGM in Central Asia, challenging the cold-moist (glacial), warm-dry (interglacial) pattern of late Quaternary environmental change in Central Asia. The Last Glacial Maximum was cold and dry, and similarly harsh conditions continued into the early Holocene.     

全球六边形离散格网数据的三维可视化方法

针对全球六边形离散格网的三维显示化方法开展研究,设计了一种六边形格网的空间层次结构(hexagonalquaternary balanced structure,HQBS),采用四位码元对格网单元进行编码,定义并实现了格网向量的基本运算,利用这些运算可以方便地实现格网单元的空间索引。在此基础上还研究了全球离散格网的动态生成与显示算法、可视化区域裁剪等相关内容。试验表明:全球格网动态生成的效率110～370单元/ms之间,加载空间数据后,格网数据和空间数据逐层加载的时间在300 ms左右,能够保证加载空间数据后的显示刷新率在20帧/s左右。