三峡地区更新世滑坡与新裂活动、气候变化关系的再认识

滑坡是三峡地区主要的地质灾害之一。三峡地区滑坡形成及发展的阶段性与新构造活动密切相关,与气候的冷暖变化也有密切关系。在系统收集三峡地区断裂活动同位素测试年龄的基础上,做出了断裂活动的年龄分布直方图。与滑坡年代分布对比发现,断裂活跃峰期与滑坡活跃峰期相间分布,后者明显滞后于前者;与气候期对比发现,断裂活跃期多对应于气候的由暖转冷阶段。综合分析表明,断裂活跃峰期的构造活动主要为后期滑坡的发生准备了充分的条件,而暖湿气候环境的强降水及地震活动,则是触发滑坡发生的主要因素。     

从矿物学角度探讨芝罘岛黄土状黄土成因及古气候变化

沉积矿物是记录物源信息和古气候变迁的良好载体。通过显微镜碎屑矿物鉴定和黏土矿物X射线衍射峰能谱分析对芝罘岛黄土状黄土2 个剖面13 个样品进行处理, 并对数据进行数学统计分析。结果表明, 芝罘岛黄土状黄土矿物种类、矿物形态特征、磁铁矿和岩屑的高含量等都揭示了黄土来源的多源性和近源性, 末次冰期时的海底平原沉积物以及洪积、残积物是芝罘岛黄土状黄土的重要物源, 而西北内陆沙漠吹来的细颗粒物质相对较少。普通角闪石、绿帘石含量较高的黄土堆积后期是以远源沉积为主, 且以风力搬运为主; 磁铁矿、岩屑含量较高的早、中期是以近源沉积为主, 搬运动力较复杂。根据黄土状黄土的剖面层序特征, 碎屑矿物以及黏土矿物垂相变化特征, 说明黄土堆积的早期, 气候是相对温暖湿润的, 之后变得寒冷干燥, 后来又逐渐回暖, 然后再转冷, 呈现出末次冰期该地冷暖交替的气候旋回。     

辽河西部凹陷南段油气运移史研究与有利聚集区预测

通过流体包裹体均一温度测试、含油气包裹体指数GOI统计和盆地模拟,研究了渤海湾盆地辽河西部凹陷南段的油气运移史,预测了油气聚集的有利地区.包裹体均一温度资料表明,本区有三期成藏:东二期、东一期和明化镇期;以前两期为主.盆地模拟研究表明,尽管沙河街组烃源岩在沙一期末开始生烃,但在东营期才开始大规模排烃和成藏.GOI的统计分析表明,GOI>5%的区域为油气聚集的有利地区,其中的圈闭应成为下步首选的钻探目标,已发现的欢喜岭油田和双南油田就分布在GOI>5%的区域内.     

Office GIS在城市规划管理中的应用

结合我国城市规划管理工作的业务特点,归纳总结城市规划管理工作信息化的技术要求,讨论分析传统GIS技术应用于城市规划管理的局限性,详细阐述Office GIS的总体技术架构,重点论述Office GIS应用于城市规划管理领域的可行性和适用性,继而提出基于Office GIS的城市规划管理信息化应用的完整解决方案,并通过Office GIS在城市规划管理中的应用实践,验证Office GIS应用于城市规划管理业务的有效性和实用性。     

城市创新跨边界合作与辐射距离探析——基于城市间合作申请专利数据的研究

基于跨城市边界合作申请的发明专利数据,对中国(不包括港澳台地区)跨区域合作创新现状进行了分析,同时提出城市知识创新辐射距离的概念和计算方法,进一步研究具有辐射效应城市的8个合作方向以及不同行业的辐射距离。结果显示知识创新辐射距离随着地理距离增长呈递减趋势,且不一定与该城市信息流量成正比;北京、上海、深圳3个城市起到一定的技术创新"辐射和带动"作用;一些城市存在对某些方向地区"带动"作用的忽视;在不同的行业中,城市知识创新辐射距离体现出不同的特征。     

亚洲大洋洲区域综合地球观测系统计划进展

亚洲大洋洲区域综合地球观测系统是为实现国际地球观测组织总体战略目标而设立的区域地球观测合作计划,旨在面向亚大区域国家对地球观测技术的应用需求,保障亚大区域地球观测空间信息的精准获取与主动服务,增强地球观测技术支撑区域可持续发展的综合能力。该计划由地球观测组织亚大区域成员国共同提出,并对亚大地区的所有国家和参与组织开放。通过国际地球观测组织亚大区域政府间合作机制,在国家、区域和全球层面建立有效的合作框架,积极协调区域内的地球观测资源设施的互联互通、技术合作与共享服务,促进亚大区域国家在社会经济关键领域的应用,共同应对可持续发展、全球变化和重大灾害的挑战。     

Zircon SHRIMP U-Pb age, geochemical, Sr-Nd isotopic, and in-situ Hf isotopic data of the Late Carboniferous-Early Permian plutons in the northern margin of the North China Craton

The main rock types of the Boluonuo and Daguangding plutons are diorite, quartz diorite, tonalite, granodiorite, and subordinate plagioclase-bearing hornblendite and hornblende gabbro. Zircon SHRIMP U-Pb dating for a quartz diorite of the Boluonuo pluton suggests that the pluton was emplaced at about 296±4 Ma. Plagioclase-bearing hornblendites show typical cumulative textures, which, in combination with their convex-upward REE patterns and the large variation of compatible elements such as Co, V and Sc, suggests that these hornblendites formed through accumulation of hornblende during magma evolution. Microgranular mafic enclaves (MMEs) are common in the Boluonuo and Daguangding intermediate to felsic plutons. Many plagioclase grains show compositional and textural disequilibrium, with calcium-rich cores (An 46-50 ) mantled abruptly by sodium-rich plagioclase (An 26-33 ). Whole-rock samples of the plutons are characterized by quite negative ε Nd (t) values (-16.5 to -11.8) and ε Hf (t) values (-22.5 to-16.8), and the ε Nd (t) values are negatively correlated with silica contents. All these features suggest that the intermediate to felsic plutons formed through magma mixing of enriched mantle-derived, evolved basaltic magma with granitic, crustal melts, followed by fractional crystallization of mainly hornblende and small amounts of pyroxene, apatite and zircon. The hornblende-dominated fractionation contributed significantly to the adakite-like features of the intermediate to felsic plutons, like the high Sr and Sr/Y ratios and low Yb abundance. In addition, the Boluonuo and Daguang- ding plutons are highly enriched in LILEs (e.g., Ba and Sr), but depleted in HFSEs (e.g., Nb, Zr and Ti), which is typical of arc magmas. Therefore, the formation of Boluonuo and Daguangding plutons was probably related to the subduction of the Paleo-Asian oceanic slab beneath the North China Craton in the Paleozoic.     

Convection in rotating annular channels heated from below. Part 2. Transitions from steady flow to turbulence

We report the results of fully three-dimensional numerical simulations of nonlinear convection in a Boussinesq fluid in an annular channel rotating about a vertical axis with lateral no-slip or stress-free sidewalls, stress-free top and bottom, uniformly heated from below, a problem first studied by Davies-Jones and Gilman (1971 Davies-Jones, RP and Gilman, PA. 1971. Convection in a rotating annulus uniformly heated from below.. J. Fluid Mech., 46: 65–81.  [Google Scholar]) and Gilman (1973 Gilman, PA. 1973. Convection in a rotating annulus uniformly heated from below. Part 2. Nonlinear results. J. Fluid Mech., 57: 381–400.  [Google Scholar]). A substantial range of the Rayleigh number R (R_c≤R≤O(100 R_c)), where R_c denotes the critical value at the onset of convection) is considered. It is found that the wall-localized convection mode, unaffected by the velocity boundary condition imposed on the sidewalls, is nonlinearly robust. Both directions of travelling waves, one propagating against the sense of rotation near the outer sidewall and the other propagating in the same sense as the rotation in the vicinity of the inner sidewall, are always present in the nonlinear solutions. In contrast to nonlinear convection in a rotating Bénard layer, neither convection rolls nor the Küpper–Lortz instability can exist in a rotating annular channel because of the effect of the sidewalls. It is the nonlinear interaction between the wall-localized modes and the internal mode that plays an essential role in determining the nonlinear properties of convection in a rotating annular channel. Our studies reveal systematically the various nonlinear phenomena, from steady travelling waves trapped in the vicinities of the sidewalls to convective turbulence exhibiting columnar structure.     

Convection in rotating annular channels heated from below. Part 1. Linear stability and weakly nonlinear mean flows

Convection in a Boussinesq fluid in an annular channel rotating about a vertical axis with lateral rigid sidewalls, stress-free top and bottom, uniformly heated from below is investigated. The sidewalls are assumed to be either perfectly insulating or conducting. Three different types of convection are identified when the channel is rotating sufficiently fast: (i) global oscillatory convection preferred for small Prandtl numbers in channels with intermediate or large aspect ratios (width to height ratio), (ii) wall-localized oscillatory convection representing the most unstable mode for moderate or large Prandtl numbers in channels with intermediate or large aspect ratios and (iii) global stationary convection preferred in channels with sufficiently small aspect ratios regardless of the size of the Prandtl number. The corresponding weakly nonlinear problem describing differential rotation and meridional circulation is also examined, showing that geostrophic, multiple-peaked (two prograde and two retrograde) differential rotation can be maintained by the Reynolds stresses in wall-localized convective eddies in a rapidly rotating channel.     

Geochronology,petrology,and geochemistry of the Yaojiazhuang ultramafic-syenitic complex from the North China Craton

The Yaojiazhuang ultramafic-syenitic complex is one of the representative Triassic alkaline plutons on the northern margin of the North China Craton(NCC).Based on detailed study of the zircon U-Pb age,petrological,mineralogical,and geochemical data of the complex,the characteristics of the magmas system,the petrogenesis of different rock types,and the nature of the mantle source were discussed to provide new constraints on the origin and tectonic setting of the Triassic alkaline belt.Cumulus ultramafic rocks,clinopyroxene-syenites and syenites are the main rock types of the complex.The zircons from the syenites yielded a U-Pb age of 209 Ma.Diopside-augite,biotite,and sanidine-orthoclase are the major minerals,with subordinate apatite and magnetite.Rocks from the complex are enriched in large ion lithophile elements(LILE)and light rare earth elements(LREE),depleted in high field strength elements(HFSE)and heavy rare earth elements(HREE),and the initial 87Sr/86Sr ranges from 0.7057 to 0.7061 and ε Nd(t)from-9.4 to-11.4.Mineralogy and geochemical data demonstrate that the parent magma of the complex is SiO2-undersaturated ultrapotassic alkaline-peralkaline,and is characterized by high CaO content and fluid compositions(P2O5,CO2,H2O),and by high oxygen fugacity and high temperature.The complex was originated from a phlogopite-clinopyroxenite-rich lithospheric mantle source in the garnet-stable area(> 80 km)that had previously been metasomatized by melts/fluids from altered oceanic crust.The parent magma has been contaminated by little ancient TTG gneisses during magma emplacement.The development of the Yaojiazhuang complex indicates that the northern margin of the NCC has entered into an extensively extensional regime in the Late Triassic.