A~200 ka pollen record from Okinawa Trough:Paleoenvironment reconstruction of glacial-interglacial cycles

Pollen analysis was carried out on the Core MD982194 of 29.78 m retrieved from the Middle Okinawa Trough which was dated as old as~200 ka BP.The results revealed that pollen assemblages mainly presented an alternation of coniferous and herb pollen.The coniferous saccate pollen,principally Pinus and Tsuga,predominated in most parts of the core,especially highlighted in the interstadial stages including MIS 1,3,5 and MIS7,whereas the herb pollen significantly increased in the glacial periods.Thus the pollen flora and their percentages showed the sensitive changes under the influence of ice volume during the glacial and interglacial periods.Our record from this core has first documented that the percentage of Cyperaceae was extremely high in the glacial stages with a notable increase in Artemisia,Gramineae,Asteraceae,Chenopodiaceae,and freshwater algae,which can be used as a proxy for sea-level change at the study site because of their close negative correlation of the orbital-scale changes in sea level.The distance between the continental coastline and the Okinawa Trough has deeply shortened due to the sea-level drop in the LGM.As a result,the sediment materials from Yangtze River were extensively deposited on the flat,exposed continental shelf owing to the rapid decline of river flow speed,leading to that pollen grains from Okinawa Trough are derived mainly from the flat coastal vegetation of exposed continental shelf at glacial stages.Changes of pollen assemblage were consistent with the variation of temperature and humidity,which showed that the percentage of arboreal pollen was highly augmented at MIS 7,5 and MIS 1,corresponding to the strengthening of the East Asian summer monsoon and increasing of rainfall.Moreover,the peak of Pinus percentage in MIS 5.3,5.1 and MIS 3.3 may be closely linked by orbital and sub-orbital cycles of solar radiation and monsoonal variability.The present study of core MD981294 implied lower temperature and precipitation during the lowest sea-level stage(LGM),and more visibly testified that the vegetation of the flat plain on the exposed continental shelf was dominated by intrazonal communities such as halophyte grasslands and freshwater wetlands instead of zonal steppe or semi-arid desert.All above evidence demonstrated that the fundamental changes of pollen assemblage and their origins in Okinawa Trough since~200 ka BP were affected by combine factors including the coastline position and climate fluctuation.Moreover,the substantial shortening of distance between shoreline and the Okinawa Trough driven by orbital insolation cycles was clearly indicated by the pollen spectra,whereas the source-area climate signal of the pollen record was largely weakened.     

日本MW9.0地震前的舒曼谐振异常分析

2011年3月11日日本本州岛东海岸附近海域发生了M_W9.0地震. 基于中国云南的舒曼谐振(SR)观测站的磁场观测数据, 分析了与该次地震有关的SR疑似异常现象. 分析表明, 震前3—4天低阶谐振开始出现比较明显的幅度增强现象, 以2011年3月8日(北京时间)这一天的现象最明显, 南北向在7:00—10:00和12:00—15:00异常比较明显, 而东西向只在12:00—15:00异常相对比较强. 根据对2011年3月1—11日及对应每天前后各15天共41天的数据的联合分析, 3月8日部分时间段的低阶谐振磁场差明显高于一倍甚至两倍标准差; 相比而言, 正常的一天内各阶磁场差要明显低于一倍标准差. 最后, 根据一些日本地震学者提出的SR异常机理, 进一步分析了在云南观测站能观测到日本地震异常的可能性. 结果表明, 在永胜观测站可以观测到日本地震引起的一阶到三阶SR异常, 与发现的异常主要集中在低阶的现象比较吻合.      

：~orous-grain-upper-boundary model and its application to Tarim Basin carbonates

Most of the carbonates in the Tarim Basin in northwest China are low-porosity and low-permeability rocks. Owing to the complexity of porosity in carbonates, conventional rock- physics models do not describe the relation between velocity and porosity for the Tarim Basin carbonates well. We propose the porous-grain-upper-boundary （PGU） model for estimating the relation between velocity and porosity for low-porosity carbonates. In this model, the carbonate sediments are treated as packed media of porous elastic grains, and the carbonate pores are divided into isolated and connected pores The PGU model is modified from the porous-grain-stiff-sand （PGST） model by replacing the critical porosity with the more practical isolated porosity. In the implementation, the effective elastic constants of the porous grains are calculated by using the differential effective medium （DEM） model. Then, the elastic constants of connected porous grains in dry rocks are calculated by using the modified upper Hashin-Shtrikman bound. The application to the Tarim carbonates shows that relative to other conventional effective medium models the PGU model matches the well log data well.     

Timing of uplift and evolution of the Lüliang Mountains,North China Craton

This study analyses evidence for reformed basin development and basin-mountain coupling associated with development of the Ordos Basin and the Lüliang Mountains, China. Gaining an improved understanding of the timing and nature of uplift and evolution of the Lüliang Mountains is important for the reconstruction of the eastern sedimentary boundary of the Ordos Basin(a major petroliferous basin) as well as for providing insight into the evolution and breakup of the North China Craton(NCC). Based on systematic sampling for fission track analysis, it is suggested that the main phase of uplift of the Lüliang Mountains occurred since later part of the Early Cretaceous. Three evolutionary stages of uplift and development are identified: slow initial uplift(120–65 Ma), accelerated uplift(65–23 Ma), and intensive uplift(23 Ma to present), with the majority of the uplift activity having occurred during the Cenozoic. The history of uplift is non-equilibrium and exhibits complexity in temporal and spatial aspects. The middle and northern parts of the Lüliang Mountains were uplifted earlier than the southern part. The most intensive episode of uplift activity commenced in the Miocene and was associated with a genetic coupling relationship with the eastern neighboring Cenozoic Shanxi Grabens. The uplifting and evolutionary processes of the Lüliang Mountains area since later part of the Early Cretaceous share a unified regional geodynamic setting, which was accompanied by uplift of the Mesozoic Ordos Basin and development of the neighboring Cenozoic Shanxi Grabens. Collectively, this regional orogenic activity is related principally to the far-field effects of both the compression sourced from the southwestern Tibet Plateau and westward subduction of the Pacific Plate in Cenozoic.     

Petrogenesis of diabase from accretionary prism in the southern Qiangtang terrane,central Tibet: Evidence from U–Pb geochronology,petrochemistry and Sr–Nd–Hf–O isotope characteristics

The Bangong–Nujiang suture (BNS) between the Lhasa and Qiangtang terranes is an important boundary and its petrogenesis is controversial. Diabase from the accretionary prism in the southern Qiangtang terrane yields a zircon U–Pb age of 181.3 ± 1.4 Ma. All the diabases show tholeiitic basalt compositions, gentle enrichment patters of light rare earth elements (REE), variable enrichment in incompatible element concentrations (e.g. Th and Rb), and no anomaly in high field strength elements (e.g. Nb and Ta), similar to that of enriched mid‐ocean ridge basalt (E‐MORB). They have relatively homogeneous whole rock Nd (εNd(t) = 7.3–9.1) and zircon Hf–O isotopic compositions (εHf(t) = 14.8–16.1, and δ¹⁸O = 4.57–6.12‰), possibly indicating melting of the depleted mantle and no significant crustal contamination during the petrogenesis. The element variations suggest that the diabases were formed by plume–ridge interaction at a mid‐ocean ridge within the Bangong–Nujiang ocean.     

Sorption of heavy oil onto Jiaozhou Bay sediment

The sorption of heavy oil onto sediment collected from Jiaozhou Bay was studied in a series of kinetic and equilibrium experiments using NaCl solutions. The effects of temperature, salinity, and pH of the medium on sorption behavior were investigated.Sorption equilibrium of the heavy oil and sediment was established within 60 min. The process was shown to follow a pseudo-second-order kinetic rate model. The sorption rate decreased with increasing initial heavy oil concentration in the solution. Batch equilibrium experiments showed that the sorption isotherm could be described by the Freundlich model. The standard free energy change and enthalpy change at the temperatures studied (283, 288, 293, and 298 K) were negative. These findings indicated that the process was spontaneous and exothermic. Salinity, pH and temperature influenced sorption performance. Sorption was favored by higher concentrations of NaCl, by lower pH values and by lower temperatures.     

对加强地震政府网站地震突发事件信息保障工作的思考

地震政府网站是地震行业面向社会宣传防震减灾工作、服务公众的重要窗口.汶川、玉树地震后,地震工作越来越受到社会的关注,地震政府网站已成为社会公众和主流媒体、网站获取地震信息的重要平台,在抗震救灾中发挥着越来越重要的作用.本文通过地震政府网站在汶川、玉树等地震突发事件中信息保障工作的实践,从网站应急制度建设、编制网站应急预...     

1991—2004年GPS观测的中国大陆地壳动态变形特征

Based on GPS data from 1991- 2004 and the least-squares collocation method,we analyze the crustal deformation in the Chinese mainland. The results show that the first-order crustal deformation is unchanged in different periods in the Chinese mainland,which reflects the background of regional tectonic activity. The strain rate is much higher in Western China,especially in the Qinghai-Tibetan Plateau and Sichuan-Yunnan area. The variations in different periods are related with seismicity of strong earthquakes during the same time. The GPS data after 2004 shows the post-seismic deformation of the 2001 Kunlun Mountains M S8. 1 earthquake.     

皖东北地区农村民居抗震性能调查与研究

皖东北地区位于郯庐断裂带中南段附近,具备发生中强地震的构造背景.本文基于现场调查,并结合汶川地震的震害,对该地区农村民居的结构特点、抗震能力及地震安全农居示范工程现状进行了阐述,对农村民居抗震性能的薄弱环节及对策进行了探讨,以期为该地区抗震设防工作提供参考.     

智能大厦节能管理的措施和方法

通过智能大厦的节能管理，实现能源的科学与合理的消费；使其发挥作用来降低机电设备的维护成本，降低管理与营运费用，从而达到最大限度的节约能源的目的。以上海博物馆为例，系统地总结了综合节能的措施和方法，对大厦的管理和合理运行有着极其重要的意义。