The transition from the Younger Dryas to the Preboreal: a case study from the Kattegat, Scandinavia

A two-step climatic warming and oceanographic change during the Younger Dryas/Preboreal transition was registered by diatom, foraminiferal, mollusc, lithologic data and sediment accumulation rates in a high resolution sediment core from the Swedish west coast. An abrupt climatic warming in the surface water of the Kattegat occurred at c . 10 200 BP, resulting in a rapid increase in sea surface water temperatures. The attenuation of meltwater discharge into the Kattegat led to an increase in sea surface salinity. Consequently, the difference in salinity through the water column diminished. This change happened within less than 80 years. The warming of bottom water in the deeper parts of the region took place a few hundred years after the surface water warming. The climatic amelioration was recorded by increased meltwater discharge and a slight increase in abundance of relatively warm diatoms around 10 600 BP at the time of the recession of the Fennoscandian ice sheet. An increase in the number of arctic/subarctic benthic foraminifera shows that the bottom water temperature during this period was still relatively low.     

台风决策气象服务初探——以“纳沙”台风为例

随着经济增长和社会发展,台风灾害带来的损失越发严重和致命,科学、准确地为政府决策层提供决策服务产品,在保障人民生命财产安全、促进社会经济发展乃至稳定和谐等方面都起着非常重要的作用。立足于台风决策气象服务业务实践,通过完整再现2011年最强台风＂纳沙＂的决策气象服务过程,总结和提炼出目前台风决策气象服务的主要方式和产品编制要求、流程,并挖掘出服务的经验和亮点;同时,分析现实服务中客观存在的一些弊端和问题,思考进一步改进方案,旨在不断提升决策气象服务产品的质量,全力做好台风决策气象服务工作,从而为政府及相关部门应急决策管理提供科学的依据,为台风防灾减灾工作提供决策支持。     

西藏层序地层研究进展

迄今为止,西藏区内所开展的层序地层分析主要涉及到中生代的二级或三级层序.基于露头剖面的沉积相、古生物、磁性地层以及地质事件的综合研究,探讨了三叠纪、侏罗纪和白垩纪的层序地层模式及其形成机制.现今所取得的进展主要表现在3个方面:①初步建立了区内中生代层序地层年代格架;②不同时代、不同类型盆地中的层序数量、结构与层序类型具有较大的差异;③层序地层与磁性地层的结合研究,取得了重要的成果.未来区内的层序地层研究应在3个方面展开:①高分辨率层序地层研究,树立侏罗纪-第三纪海平面变化曲线;②探索层序地层填图新方法;③多岛弧造山模式和多机制的隆升模式等大陆动力学问题也是层序地层所遇到的新挑战.     

滇东泸西地区中三叠统法郎组液态油苗的发现及意义

对南盘江地区进行野外石油地质考察,在中三叠统法郎组中发现液态油苗。该油苗位于云南省泸西地区,地表延伸长度超过12km。含油层位的岩性为全黑色生物碎屑泥晶灰岩,油气显示性质为液态油苗和稠油,呈褐黑色、褐黄色,多以浸染状、晶间孔型、溶洞型和裂缝型产出。含油层的下伏地层为中三叠统个旧组,主要为一套碳酸盐岩沉积,产2套累计厚度16m左右的油浸砂糖状白云岩。含油层上覆地层法郎组上段为一套泥质碎屑岩沉积,该套地层的泥岩段中有大量油斑产出。液态油苗的发现显示了该区良好的油气勘探前景。     

辽西凸起南段沙河街组双向物源沉积模式及油气勘探意义

古近系储层发育程度一直是制约辽西凸起南段勘探突破的关键因素。运用钻井地质、磷灰石裂变径迹分析、三维地震等基础资料,针对辽西凸起南段沙河街组储层发育问题,开展精细古热史-构造演化分析、古地貌半定量刻画,对目标区沙河街组储层进行预测,结果表明：辽西凸起南段主要经历了新生代早期构造抬升、古近纪沙河街组沉积期构造沉降、东营组沉积期构造反转和新近纪构造定型4个演化时期;断裂体系可划分为长期活动型、早断早衰型、晚断晚衰型3种断裂类型;辽西凹陷具有“盆满砂溢”的先天供源条件,构造演化的分段性特征又造成辽西凸起南段形成了特殊的“链状岛湾”沉积地貌,既可以为围区提供物源,形成近源沉积体,又可以形成较大的可容纳空间,汇聚来自于辽西凹陷满溢的砂体,在辽西凸起上形成了双向供源沉积模式。以上认识推动了旅大4-3油田的油气勘探评价,且对凸起围区的油气勘探具有较好的借鉴意义。     

甘油二醚膜类脂化合物的生物地球化学研究进展

甘油二醚膜类脂化合物相对其他类脂生物标志物而言,通常具有较特定的微生物来源及环境指示意义,目前国内外还未有相关的综述性报道。综述了该类型化合物的测试方法,古菌和细菌二醚的组成特征,重点评述了如产甲烷菌、甲烷氧化菌、嗜盐菌等古菌,以及硫酸盐还原菌、Aquificales及一些嗜热细菌,在极端环境(如冷泉、热泉、热液系统)研究中甘油二醚膜类脂化合物应用的进展和可能经历的生物地球化学过程。简要介绍了环境对甘油二醚膜类脂分布的影响,并对其及其他类脂生物标志物的应用前景和发展趋势进行了展望。     

城市高架桥合理抗震体系选择与经济性对比

探讨了基于两水准设防的城市高架桥的合理抗震设防标准与相应的结构性能目标.选取两座典型的城市高架桥结构,包括一座正线桥和一座匝道桥,分别采用延性抗震体系和减、隔震体系进行结构抗震设计.对比了不同结构抗震体系所对应的结构在各水准地震作用下具体抗震性能表现,结果表明减、隔震体系具有更优的抗震性能.在此基础上,进一步从经济性的...     

Spatial character of the gaseous and particulate state compound correlation of urban atmospheric pollution in winter and summer

The spatial/temporal variation information of atmospheric dynamic-chemical processes at observation site points of the "canopy" boundary of Beijing urban building ensemble and over urban area "surface", as well as the seasonal correlation structure of the gaseous and particulate states of urban atmospheric pollution (UAP) and its seasonal conversion feature at observation points are investigated, using the comprehensive observation data of the Beijing City Air Pollution Observation Experiment (BECAPEX) in winter and summer 2003 with a "point-surface" combined research approach. By using "one dimension spatial empirical orthogonal function (EOF)" principal component analysis (PCA) mode, the seasonal change of gaseous and particulate states of atmospheric aerosols and the association feature of pollutant species under the background of the complicated structure of urban boundary layer (UBL) are analyzed. The comprehensive analyses of the principal components of particle concentrations,gaseous pollutant species, and meteorological conditions reveal the seasonal changes of the complex constituent and structure features of the gaseous and particulate states of UAP to further trace the impact feature of urban aerosol pollution surface sources and the seasonal difference of the component structure of UAP. Research results suggest that in the temporal evolution of the gaseous and particulate states of winter/summer UAP, NOx, CO, and SO2 showed an "in-phase" evolution feature, however, O3 showed an "inverse-phase" relation with other species,all possessing distinctive dependent feature. On the whole, summer concentrations of gaseous pollutants CO, SO2, and NOx were obviously lower than winter ones, especially, the reduction in CO concentration was most distinctive, and ones in SO2 and NOx were next. However, the summer O3 concentration was more than twice winter one. Winter/summer differences in PM10and PM2.5 particle concentrations were relatively not obvious, which indicates that responses of PM10 and PM2.5 particle concentrations to the difference of winter/summer heating period emission sources are far less distinctive than those of NOx, SO2, and CO. The correlation feature of winter/summer gaseous and particulate states depicts that both PM10 and PM2.5 particles were significantly correlated with NOx, and their correlations with NOx are more significant than those with other pollutants. Through PCA, it is found that there was a distinctive difference in the principal component combination structure of winter/summer PM10 and PM2.5 particles: SO2 and NOx dominated in the principal component of winter PM10 and PM2.5 particles; while CO and NOx played the major role in the principal component of summer PM10 and PM2.5 particles. For winter/summer PM10 and PM2.5 particles, there might exist the gaseous and particulate states correlation structures of different "combinations" of such dependent pollutant species. Research results also uncover that the interaction processes of gaseous and particulate states were also related with the vertical structure of UBL, that is to say, the low value layer of UBL O3 concentration was associated with the collocation of atmospheric vertical structures of the low level inversion,inverse humidity, and small wind, which depicts summer boundary layer atmospheric character, i.e.the compound impact of the dependent factor "combination" of wind, temperature, and humidity elements and their collocation structure on the variations of different gaseous pollutant concentrations. Such a depth structure of the extremely low value of O3 concentration in the UBL accords with its "inverse-phase" relation with other gaseous pollutant species. The PCA of meteorological factors associated with PM10 and PM2.5 concentrations also reveals the sensitivity of PM10 and PM2.5 concentration to the combinatory feature of local meteorological conditions.     

东天山觉罗塔格一带晚古生代岩浆岩地球化学特征及构造意义

通过对东天山觉罗塔格一带晚古生代岩浆岩地质特征、岩石化学特征等系统研究, 认为该晚古生代岩浆岩主要由早石炭世至中二叠世的火山岩和侵入岩组成, 其形成与康古尔洋向北俯冲有关。早石炭世岩浆岩为康古尔洋初始俯冲而成的钙碱性岛弧火山岩及具有低压、低温特征的高钾钙碱性I型花岗岩;晚石炭世岩浆岩为后碰撞弧火山岩;早二叠世岩浆岩为具有后碰撞弧和板内双重特征的火山岩及高温、高压特征的I型花岗岩;中二叠世发育具有低压、高温特征的高钾钙碱性A型花岗岩。综合前人资料及本文研究成果, 初步认为觉罗塔格一带晚古生代经历了俯冲碰撞—碰撞造山—造山后陆内伸展的构造演化过程。     

多时间序列求关联维D_2

在利用Ｇ．Ｐ．法由单一时间序列计算关联维Ｄ_２的基础上，引入矩阵范数，提出了多时间序列数据联合计算关联维Ｄ_２的算法。这一算法是Ｇ．Ｐ．法的推广。验算结果表明这一算法正确、可行，能提高计算结果的可靠性。