Barium Increasing Prior to Opal during the Last Termination of Glacial Ages in the Okhotsk Sea Sediments

Ba and Ti in a sediment core (10 m long) from the Okhotsk Sea, covering the last 120 kyrs, were measured. The authigenic Ba (Ba_ex) contents were calculated and compared with the opal. The correlation coefficient between Ba_ex and opal was quite small (r = 0.34), but it greatly grew larger (r = 0.90), if the Ba_ex contents were multiplied by a simple function increasing with depth, except for two intervals. This may be due to the gradual change in the sedimentation environment during the glacial ages. One of the exceptional interval is found at 60–170 cm in depth, corresponding to 10–17 calendar kyr ago, the last termination period of glacial ages, where the Ba_ex began to increase prior to opal. Since the calcium carbonate contents similarly increased prior to the opal increase, the Ba_ex may be also related to calcareous organisms besides siliceous ones. The other is the last interglacial period around 120 kyr ago when the opal contents were high, but those of the Ba_ex were not increased. This can be explained, if the Ba_ex was reduced to sulfide and dissolved away in a strongly anoxic environment during the biologically productive period. During the glacial ages, the mass accumulation rate (MAR) of lithogenic Ti was about twice the amount of that during the interglacial ages. For opal, however, the contrast between the glacial and interglacial ages was more remarkable in its MAR than in its concentration in sediments, due to the larger variation in the bulk sedimentation rates. This revised version was published online in July 2006 with corrections to the Cover Date.     

柴北缘西段新生代弧形构造带演化历史及成藏过程

本文在钻井和二、三维地震数据精细解释的基础上,详细研究了柴北缘西段晚新生代弧形构造带演化历史和油气成藏过程。认为柴北缘西段是由一系列沿造山带前缘展布的弧形逆冲断裂和褶皱组成的弧形构造带。晚新生代以来的构造演化具有自山前向盆内扩展,东西两侧向中间传播的特点,油气运聚与构造演化过程紧密耦合。各弧形构造带两侧形成时间早,生储盖配置好,且具有古构造背景,是油气运聚的长期指向,应是下一步优先勘探目标。     

Polycyclic aromatic hydrocarbons (PAHs) and Pb isotopic ratios in a sediment core from Shilianghe Reservoir,eastern China: Implying pollution sources

The history records of polycyclic aromatic hydrocarbons (PAHs), lead and its stable isotope ratios were determined in a sediment core to receive anthropogenic impacts on the Shilianghe Reservoir in eastern China. The historical changes of PAHs concentrations, PAHs fluxes, Pb/Al and Pb isotope ratios showed a synchronous trend throughout the core, suggesting changes in energy usage and correlating closely with the experience of a rapid economic and industrial development of the catchment, Linyi City in eastern China. PAHs isomer ratios results reveal PAHs in sediments are dominantly anthropogenic pyrogenic source, dominated by the combustion of coal and biomass. Furthermore, the Pb isotopic composition also clearly indicates that coal combustion dust mainly contributed to the Pb burden in the reservoir sediments. Based on mix end member model of Pb isotope ratios, coal combustion dust dominated anthropogenic Pb sources over fifty years contributing from 31% to 62% of total Pb in sediment. And the contribution of leaded gasoline was low than average 25%. In addition, a stable increase of coal combustion source was found in sediment core, while the contribution of leaded gasoline had declined in recent decades, with the phase-out of leaded gasoline in China.     

吉尔嘎郎图凹陷赛汉塔拉组沉积特征与超厚煤层异地成因分析

吉尔嘎郎图凹陷的赛汉塔拉组沉积于基底减速沉降-充填演化阶段,是凹陷进入湖泊萎缩阶段早-中期的产物,其层序地层单元属于水退体系域。自下而上由浅湖相、三角洲相和曲流河相组成。其中的超厚煤层与大量薄层浊积砂岩共生,形成于该凹陷的次级深断槽中,沉积环境应为浅湖和局部较深湖。传统的煤沉积模式难以解释其超厚煤层的成因。通过对煤层和夹矸的沉积学研究,以及凹陷充填序列分析,建立了一种陆相超厚煤层异地成因新模式--“弱风暴及水下泥质、砂质重力流亚模式”,简称为胜利盆地亚模式。推测成煤物质是由远源河流搬运而来的巨量异地高灰泥炭,可能先沉积于滨湖三角洲,后经滑塌和浊流作用转移至浅湖中,并经再次分异、沉积成为超厚的低灰煤层。     

Spaces of enclosure

Building on recent critical scholarship by authors including Retort [Retort, 2005. Afflicted Powers: Capital and Spectacle in a New Age of War. Verso, London] and Ferguson [Ferguson, J., 2006. Global Shadows: Africa in the Neoliberal World Order. Duke University Press, Durham, NC], this critical review will explore the inter-articulation of neoliberal norms and a resurgent and violent form of geo-politics through the rubric of ‘enclosure’. We believe that ‘enclosure’ serves as an appropriately flexible concept that speaks not only to the vagaries of primitive accumulation but also to the recent recrudescence of an aggrandized mode of statist violence. We argue that enclosure operates contingently, provisionally, and violently across a range of scales, sites, and networks and sketch four preliminary axes of investigation: subjectification, legal violence, the colonial present, and the politics of representation. The review goes on to suggest a set of markers through which to widen the conceptual and political purchase of enclosure through the geoeconomic, geopolitical and biopolitical, and highlights distinct spatial formations, modes of subjectification, and technologies of power through which enclosure variously operates.     

How late are K-feldspar megacrysts in granites?

Various petrologists have suggested that K-feldspar megacrysts grow in granites that are extensively crystallized, even at subsolidus conditions. However, experimental evidence indicates that, though K-feldspar nucleates relatively late in the crystallization history, abundant liquid is available for development of large crystals. A great deal of evidence, involving many different factors, favours a magmatic/phenocrystic origin for K-feldspar megacrysts in granites, namely simple twinning, oscillatory zoning, euhedral plagioclase inclusions, and concentric, crystallographically controlled arrangements of inclusions. In addition, abundant evidence has been presented of (1) mechanical accumulation of K-feldspar megacrysts in granites, (2) alignment of megacrysts and megacryst concentrations in magmatic flow foliations, (3) involvement of megacrysts in zones of magma mixing in granite plutons, and (4) occurrence of megacrysts in some volcanic rocks, implying that the megacrysts were suspended in enough liquid to be moved without fracturing or plastic deformation. Detailed trace element and isotopic data also indicate that megacrysts can move between coexisting felsic and more mafic magmas. Irregular overgrowths on megacrysts are consistent with continued magmatic growth after euhedral megacrystic growth ceased, the overgrowths being impeded by simultaneously crystallizing quartz and feldspar grains.     

微量元素在油气化探中的应用

无机组分虽然不是油气的基本组分,但它们种类繁多,与油气烃类的生成运移有着不可分割的联系。因此针对与油气田伴生的微量元素进行分析研究并寻找油气是一种有效的地球化学勘查方法。通过研究发现:油气评价的有效微量元素指标主要为Hg和w(V)/w(Ni)、w(V)/w(Fe),其次为w(N)/w(Org.C)、Pb、U;微量元素油气化探异常模式为环状,即油气藏上方为低值区,油气藏边缘为高值异常区。     

陆相拗陷湖盆陡坡带物质聚集及层序充填动力学特征——以鄂尔多斯盆地陇东地区三叠系延长组为例

陆相拗陷湖盆陡坡带具有坡度陡、构造活动强烈、物近源、多物源、相变快等特点。勘探实践表明,与拗陷湖盆陡坡带相关的各类砂体,由于具有良好的油源条件、储集条件和油气运移条件,是油气聚集成藏的极有利场所。鄂尔多斯盆地三叠纪时期为典型的内陆大型拗陷盆地,陇东地区三叠纪延长期时在西缘逆冲带的影响下处于陡坡带,该区有两种物质聚集模式,一是从长10-长7退积型三角洲模式,二是从长6-长1进积型三角洲模式。并且在盆地形成演化过程中,伴随着基准面的升降变化,不同相区、不同时期可容纳空间和沉积物供应之间的比值发生相应的变化,从而表现为不同的地层充填样式。     

河南省东濮凹陷古近系沙河街组沙三段盐岩沉积特征及其石油地质意义*

东濮凹陷是渤海湾裂谷盆地西南缘临清坳陷的一部分,和其他凹陷相比有一个显著的特征就是盐岩十分发育。东濮凹陷北部中央隆起带及周边沙三段自下而上发育了3套大的盐韵律,每套盐韵律又由若干个小盐韵律组成。在岩盐富集的地区是油田的主力产油区,油气富集与岩盐有着密切关系。通过对岩盐层岩心、测井及地震资料进行分析,总结出了盐岩的岩性、电性及地震响应特征;岩性变化为砂泥岩→含膏泥岩→膏盐→盐岩→膏盐→含膏泥岩→砂泥岩演化规律;电性主要表现为极低密度、极低自然伽马、很高电阻率及淡水钻井液扩井径等特殊电性特征;在地震剖面上常表现为强振幅、低频率的响应特征。在分析研究盐岩发育特征的基础上,总结出了盐岩的时空展布规律,同时对盐岩与烃源岩、储集层及盖层的关系进行了探讨,根据实际生产和盐岩的沉积规律对生储盖组合进行了分级。得出生、盖为同一层及生、储、盖在不同的空间与盐岩层有关的生储盖组合关系模式,在此基础上总结了东濮凹陷含盐地层油气成藏模式,明确了盐岩的石油地质学意义,对老油田的滚动勘探具有指导作用。     

Particularities of the dynamics of river channel processes in the Khabarovsk water junction

The dynamics of river channel processes were analyzed in the region of complex floodplain-channel branching of the Amur River near Khabarovsk using remote sensing data of the Earth’s surface. Zones of steady accumulation and long-term erosion of the river channel are established within the Khabarovsk water junction over the period of 1964–2004. The main problems related to restoring the Amur River back to its initial channel were distinguished in the course of these works. A map of individual streams formed in the Amur River channel under the influence of large tributaries (the Sungari and Ussuri rivers) was developed. The importance of this map for forecasting the spreading of anthropogenic pollution in the channel of the Amur River is shown using the example of the emergency situation that resulted from the explosion at the chemical plant in the Sungari River basin (Jilin, China; November 2005).