A diagnostic technique to differentiate between buried gleysolic and chernozemic B horizons

It is often difficult to establish in the field the origin of the B horizon of buried truncated palaeosols. However, infrared spectral configurations of electrodialyzed humic acids can be used as a diagnostic tool. Decreased absorption on passing from 2500 to 1800 cm^-1 indicates the presence of a chernozemic B horizon. The difference was explained on the basis of the conditions that existed at the time of the formation of these horizons. Burial did not change the structure of the humic substances responsible for the infrared spectral configurations.     

江汉平原全新世埋藏古树的发现及其意义

全新世埋藏古树对其埋藏时代的古环境和古气候有重要的指示意义,作为探究古环境的重要途径,一直是国内学者研究的热点话题~([1-4]).2009年6月我们在野外调查中,在江北农场人工取土开挖的全新世剖面底部4.6m处发现12棵埋藏古树.     

Stratigraphic position and significance of carbonate rocks related to neoproterozoic glacial horizons of the Urals

Some Neoproterozoic glacial deposits of the Urals associate with cap carbonates and carbonateterrigenous members. In addition, carbonate lenses and layers are observed in glacial series. Cap carbonates are characterized by quite variable textures and structures; because of this, it is considered that they were formed under different conditions and in the course of various processes accompanying glaciations and deglaciations. Cap carbonates have a regional stratigraphic significance. Multiplicity and complex age structure of glacial events in the Neoproterozoic do not allow us to apply cap carbonates for interregional correlations and construction of the general stratigraphic scale of the Neoproterozoic without additional biostratigraphic, geochronological, and chemostratigraphic control.     

太平洋海山磷酸盐的产状、特征及成因意义

为了更好地认识大洋富钴结壳的成矿作用,作者对与其伴生的海山磷酸盐的产状、化学成分、种类及X射线衍射特征等进行了研究。研究发现,海山磷酸盐(磷块岩或磷酸盐化岩石)的产状可划分为以下6种类型:①作为结壳的下伏基岩;②作为砾状、球状(椭球状)结壳和海山结核的核心;③呈胶结物状胶结老结壳的碎块;④呈细脉穿插于板状结壳中;⑤呈断续的“夹层状”及⑥呈碎屑状、浸染状等产于结壳中。海山磷酸盐的平均化学成分w(CaO)/w(P2O5)(1.62)与碳氟磷灰石的w(CaO)/w(P2O5)(1.621)几乎一致,而与氟磷灰石的w(CaO)/w(P2O5)(1.318)相差甚远,表明海山磷酸盐为碳氟磷灰石,其形态主要有针状-柱状微晶碳氟磷灰石、粒状微晶碳氟磷灰石及显微隐晶质碳氟磷灰石3种类型,它们在分布丰度上存在差异。研究表明,碳氟磷灰石的结构CO2含量介于5.73%～6.05%之间,属高碳氟磷灰石,其晶胞参数α变化于0.932～0.933nm之间,平均值为0.933nm。各种交代残余结构(交代角砾状结构、交代生物结构、交代凝灰结构、交代生物假象结构、交代填间结构等)表明,太平洋水下海山上的磷酸盐主要属交代成因。因此,积极开展海山磷酸盐的地球化学研究,对加快勘探和开发结壳资源,有着十分重要的理论和实际意义。     

Nature and palaeoenvironmental significance of a buried soil sequence from Magilligan Foreland, Northern Ireland

Soil horizons delimit three periods of sand deposition and subsequent topographic stability at Magilligan Foreland, Co. Londonderry. All the deposits are composed of texturally and mineralogically similar material. The earliest topography is a beach ridge plain; podzols cap the ridges and peats occur in the inter-ridge depressions, together comprising a buried palaeocatena. The podzols are visually distinct but chemically and mineralogically immature. Peat and podzol genesis probably began between 3,000 and 2,500 years B.P., and were terminated between c . 1,100 years B.P. and c . 600 years B.P. by burial under an extensive layer of aeolian sand. This sand was eroded to a planar surface before developing a sand-pararendzina, which represents a second period of surface stability. The third deposit, a discontinuous dune sand, is presently also developing a sand-pararendzina. Difficulties of using ¹⁴C dates to erect absolute chronologies are discussed.     

The spatiality of multifunctional agriculture: A human geography perspective

Based on reconceptualisations of multifunctional agriculture as a normative spectrum of decision-making (strong to weak multifunctionality) bounded by productivist and non-productivist action and thought [Hollander, G.M., 2004. Agricultural trade liberalization, multifunctionality, and sugar in the south Florida landscape. Geoforum 35, 299-312; Holmes, J., 2006. Impulses towards a multifunctional transition in rural Australia: gaps in the research agenda. Journal of Rural Studies 22, 142-160; Wilson, G.A., 2007. Multifunctional Agriculture: A Transition Theory Perspective. CAB International, Wallingford], this paper argues that there is currently insufficient research into the geography of multifunctionality. Building on current human geography debates about issues of scale, the paper suggests that we should conceive of multifunctionality as a spatially complex nested hierarchy comprising different interlinked ’layers’ of multifunctional decision-making ranging from the farm level to the national and global levels. It suggests that the notion of multifunctional agriculture only makes sense if it is applied at the farm level as the most important spatial scale for the implementation of multifunctional action ‘on the ground’. Multifunctionality can be interpreted as having ’direct’ expression only at the ’lower’ geographical scales (i.e. farm, community and regional levels in particular) while the regional, national and global levels show ’indirect’ expressions of multifunctionality that are mediated by local level actors in order to find tangible expression on the ground. The notion of global-level multifunctionality is the most challenging, as this level lacks political and ideological coherence about the required directions necessary for implementation of strong multifunctionality pathways. The paper concludes by arguing that much work still awaits those investigating the spatiality of multifunctionality, in particular with regard to the question whether global-level strong multifunctionality is possible, or whether strong multifunctionality in one territory is predicated on weak multifunctionality in others.     

The protocontinental growth of the Indian Shield and the antiquity of its rift valleys

The evolution of the Indian Shield has been envisaged from the analysis of available tectono-lithostratigraphic, geochronological, geochemical and geophysical data. It appears that the Dharwar schist belts and their equivalents, except the Kolar schist belt, are not typical greenstone belts, but are representative of a transitional era of rapid transformation from simatic to sialic crust. In the Archaean—Proterozoic tract of India, relics of rocks older than 3.0 b.y. are identified in five widely separated regions of distinct tectono-litho-stratigraphic assemblages which probably represent the primordial continental nucleii. It is suggested that the growth of the Indian Shield has taken place through nucleation, accretion and merger into three protocontinents named Dharwar, Aravalli and Singhbhum. The cratonisation of the Indian unit seems to have been rapid and almost completed by the middle Proterozoic, as there is no significant variation in the composition of the clastic sediments and basalts from middle Proterozoic onwards. The continental nucleii appear to merge along the deep-seated lineaments, which are reflected on the tectonic map of India. Further, the Dharwar, Aravalli and Singhbhum protocontinents also seem to merge along a Y=shaped Narmada—Son—Godavari lineament which along with the Mahanadi lineament, between the two continental nucleii of the Singhbhum protocontinent have later developed into rift valleys.     

辽河断陷古潜山古生界的厘定及其地质意义

辽河断陷以碳酸盐岩和砂页岩为主的古潜山地层一直全部划归中、新元古界。由于在该套地层的部分岩石薄片中发现交代残余的动物化石碎片，因此提出辽河断陷有古生界存在的新观点。通过牙形石、微古植物、动物化石和岩性组合的研究，对这套地层进行了重新厘定，建立了古生代寒武纪、奥陶纪、石炭纪和二叠纪地层层序。研究成果表明，辽河断陷存在古生界储层，古生代潜山并非单斜．而是由被断裂改造的褶皱组成的断块。这一成果为重新认识潜山的内幕构造特征和油气储层分布规律奠定了基础。     

The East African monsoons and their effects on agriculture

Though the East African monsoons may be considered as mere extensions of the South Asian monsoonal system, they possess a number of characteristics which make them unique amongst the world's monsoons. The most important of these is the relative dryness of both the North and the South monsoon, caused by a prevalent low-level divergence over eastern Africa. Most rainfall in the region therefore occurs during the intermediate seasons between the monsoons, when this divergence is temporarily replaced by more convergent flow patterns. As a result, total rainfall in East Africa is relatively low. Over most of the region it is strongly concentrated during two short seasons and it is highly variable from year to year, both in total amount and in time of occurrence.As in most parts of the tropics, rainfall is the main limiting factor in agricultural production in East Africa. The relations between rainfall and agriculture can be illustrated by the usual water balances, but an alternative method, employing the Agricultural Rainfall Indicator, is more useful for planning purposes. Drought frequencies, based on a simple relation between actual and average rainfall, also represent the effects of the monsoons on East African agriculture very clearly.     

滑坡变形对输气管道安全的影响分析

在对某输气管道线上一个正在活动滑坡变形和管道应变系统监测的基础上,分析了滑坡活动特征及其对管道安全的影响。滑坡监测采用地表位移监测,从而判断滑坡边界、掌握滑坡滑动状态对管道的影响;管道监测采用弦式应变计测其应变,利用强度理论评判管道的安全性。利用监测数据分析管道的轴向稳定性。监测结果表明,在该滑坡区域范围内管道尚属安全,但滑坡仍处于滑动阶段,对管道安全存在隐患。     

深基坑工程数值分析研究

数值分析方法是深基坑工程研究的重要手段,将Mindlin厚板理论和优化反分析法有机结合,建立可用于深基坑围护结构变形的分析理论与计算方法,包括依据现场位移量测信息,确定水土压力的分布及被动区地层抗力系数,以及运用由反分析计算确定的参数对基坑变形及其稳定性作出预报分析等,从而为深基坑工程数值分析及信息化施工提供理论方法.     

热流体对深埋白云岩储集性影响及其油气勘探意义——塔里木盆地柯坪露头区研究

深埋条件下白云岩能否形成有效储层是塔里木盆地深层油气勘探面临的主要挑战之一,塔深1井大于8000m深度白云岩岩芯仍具有多孔洞带发育,并具有形成储层的孔渗性,揭示了深部白云岩有效储层的存在。研究证实,该类孔洞的形成与热流体活动相关,但其在地层中分布的特征和广泛性有待揭示。通过野外露头观察及室内测试分析,在柯坪地区经历过深埋条件的上震旦统-下奥陶统白云岩中发现了与塔深1井相似的溶蚀孔洞的普遍存在现象。孔洞内充填的石英、自形白云石以及方解石矿物原生盐水溶液包裹体均一温度依次可达到368℃、314℃和303℃,远高于相应地层最大埋深(约6000m)条件下推测的正常地层温度范围(120~240℃),盐度分布范围依次为3.39%~9.86% NaCleqv、1.05%~18.13% NaCleqv和4.34%~9.98% NaCleqv。同时,研究也发现了黄铁矿、萤石、重晶石、石英、菱铁矿、毒砂和鞍形白云石等热流体相关矿物组合,并在相应流体包裹体内发现了CO₂、H₂S和烃类气体等对白云岩具有溶蚀性的气体存在。综合以上测试成果,证实柯坪露头区白云岩地层内存在大规模的异常热流体活动,推断可能与盆地深部大规模岩浆热事件相关。研究揭示热流体活动产生了顺层溶蚀、冷缩裂缝、差异性溶蚀以及热流体再作用的大型溶塌等多种孔隙空间结构,孔隙类型主要为缝-洞复合型。揭示热流体溶蚀改造作用主要受构造裂缝和地层界面等因素控制,其对白云岩地层孔隙空间的改造主要表现为建设性与破坏性共存,研究区则以建设性为主。     

江苏洋口港地区埋藏古潮成砂脊年代学特征及古环境意义

江苏如东县洋口港地区普遍发育末次冰盛期(MIS 2)“第一硬粘土层”。全新世早期,该区暴露侵蚀,仅局部地区发育潮汐水道。全新世中期(7 000 a B.P.)以来,在最大海侵作用影响下,研究区大部分地区以潮坪沉积为主; 高海平面时期(5 220 a B.P.),研究区大部分地区处于水下沉积环境; 随着海平面下降,北部地区发育古潮成砂体,属于滨海潮坪—潮成砂脊沉积体系。根据地层沉积特征,识别出4期埋藏古潮成砂脊。地层AMS ¹⁴C年龄表明,4期砂脊是依次在5 220～1 000 a B.P.沉积形成的,反映了潮汐动力作用下古潮成砂脊的动态演化过程。     

川东北二叠系长兴组碳酸盐岩深埋成岩过程及其意义

上二叠统长兴组储层是川东北地区主力产层之一,储层岩性主要为结晶白云岩、残余生屑/砂屑白云岩、生物礁白云岩和亮晶生屑灰岩,储集空间以晶间孔、晶间溶孔为主,生物体腔孔、残余粒间孔次之,溶洞和裂缝少量发育。长兴组优质储层主要分布于台地边缘生物礁、台地边缘滩等沉积相带,该相带发育大量原生孔隙,易遭受大气淡水溶蚀改造。原生孔隙的发育为白云岩化流体与岩石相互作用提供空间,早期孔隙演变为晶间孔。白云岩抗压实能力较强,有利于高孔隙白云岩的保存。早三叠世快速深埋使长兴组迅速进入中深埋藏,深埋阶段,裂缝少量发育,部分被方解石充填,对储层贡献有限。晚三叠世油气充注隔绝了岩石与地层水的接触,抑制了孔隙内白云石的溶蚀和沉淀,储层先存孔隙得到较好的保存。快速深埋使孔隙迅速被埋藏封闭,深埋阶段水-岩反应处于近封闭的平衡状态,溶蚀-沉淀现象有限,深埋藏环境主要是储层孔隙保存和调整的场所,孔隙空间的位置可能重新分配。     

准噶尔盆地南缘深层侏罗系储层沥青成因及其对油气成藏的启示

准噶尔盆地南缘深层下组合(下白垩统吐谷鲁群泥岩之下的储盖组合)勘探潜力大,但勘探程度较低。独山子背斜位于四棵树凹陷的东部,在该背斜浅层的新近系沙湾组砂岩发现了准南最早的油田,而对其深层油气成藏的潜力尚有待研究。深探井独山1井钻探至上侏罗统齐古组(J₃q)储层,在6410～6418m上侏罗统齐古组岩心发现大量沥青沿着断裂面及其周围裂缝定向分布。通过有机地球化学分析,发现独山1井J₃q储层沥青抽提物的Pr/Ph值主要分布在0.12～3.48之间,δ¹³C值多数集中分布在-29.9‰～-25.3‰之间;部分沥青抽提物的γ-蜡烷谱峰明显且存在异构体;规则甾烷C₂₉明显占优势且重排甾烷丰富;烃类是侏罗系和下白垩统烃源岩产生原油的混合产物。通过储层沥青产状、R_b、拉曼光谱及烃类包裹体GOI指数、储层定量颗粒荧光等实验分析,发现独山1井深层下组合存在两期油气运移,但未形成规模油气聚集。四棵树凹陷侏罗系和下白垩统烃源岩在新近纪开始大量生烃,且构造圈闭发育,有利于晚新生代油气成藏,但独山1井位于...     

Effects of drilling fluid invasion on hydraulic characterization of low-permeability basalt horizons: A field evaluation

Low-permeability basalts at the Hanford Site, in south-central Washington State, are currently being investigated for suitability as repository horizons for the terminal storage of commercial, high-level radioactive wastes As part of on-going Basalt Waste isolation Project (BWIP) studies, a field evaluation was conducted to assess the effect that drilling fluid invasion may have on the hydraulic characterization of low-permeability basalts The test formation selected for the field evaluation was a 24 7-m section of basalt flow interior that had been previously core-drilled utilizing only fresh water. The test design of the field evaluation included an initial phase (phase I) of hydrologic testing followed by the injection of bentonite-base drilling fluid into the test section, removal of the drilling fluid from the borehole, and a final phase (phase II) of hydrologic testing Hydrologic tests conducted during each phase included overpressure pulse tests (pressurized slug tests) and a multiple-step, constant head injection test Results of the field evaluation indicate that no discernible impact on hydraulic property estimates or test response could be attributed to drilling fluid invasion.     

太平洋西部富稀土深海沉积物的地球化学特征及其指示意义

深海富稀土沉积物已成为潜在的战略资源。为探讨富稀土粘土的地球化学特征及其来源和富集机制,对太平洋西部深海区域进行底层水和深层沉积物的系统采样,分析了样品的主、微量元素和稀土元素地球化学特征,并采用氧化还原环境、稀土元素的迁移和分馏以及海洋稀土循环的分析方法对富稀土沉积物的成因进行探讨。结果显示:沉积物的∑REY与Ce/Ce*表现出负相关关系,并与生物成因的P和Ca关系密切。样品Th/U、V/Sc、(La/Yb)_N、(La/Sm)_N和(Sm/Yb)_N值呈系统的变化,沉积物均处于氧化或次氧化环境。底层海水具重稀土富集的特征,海水-沉积物界面轻、中稀土含量上升,下覆的较深层沉积物表现出中、重稀土富集。初步推断沉积物的稀土元素来源于海水,与生物相关的物质是其REY富集和Ce负异常的主要控制因素。宽的氧化或次氧化环境和生物相关氧化物的强吸附能力导致稀土元素未扩散至海水而引起了沉积物稀土元素的富集。     

场地和断层对埋地管道破坏的影响分析

场地条件和断层活动是埋地管道破坏的主要原因,避免因为场地岩土和断层的影响而造成管道破坏,是城市地下生命线工程建设中急需解决的问题。采用ADINA软件的Parasolid建模方式,通过定义合适的体类型和布尔操作,建立了埋地管道破坏分析的几何模型,实现了土体－断层－管道破坏有限元建模。借助模型参数选择,确定了基岩与岩土性质、管道特性等模型参数;定义了管-土摩擦和约束条件、地震波和断层位移荷载等。依据计算结果,分析了场地条件和断层参数对地下管道地震破坏的影响;结果表明：管道埋藏越深,断层断距越大,管道的变形越大,破坏越严重。给出了管-土摩擦系数和断层与管道交角的最优值,并给出了几点工程建议。