羌塘盆地双湖地区曲色组冷泉碳酸盐岩及其地质意义

羌塘盆地南部双湖地区曲色组地层发育大量碳酸盐岩结核,这些结核多呈丘状、椭球状、透镜状、似层状、脉状、树枝状产出。其物质组分主要为泥微晶碳酸盐矿物,少量粘土矿物、石英及草莓状、半自形黄铁矿等。草莓状黄铁矿平均粒径在5.0μm左右,内部可见葵花状构造。发育凝块状、气孔状和渗漏孔等特殊构造。产双壳类、菊石类、蠕虫状或树枝状生物及超微生物化石,生物密度极高。碳同位素明显负偏,硫同位素则明显正偏,其特征与现代海底天然气水合物的渗漏、释放所形成的冷泉碳酸盐岩机理一致,因而推测为古代海底天然气渗漏喷发形成。大量海底天然气泉口的存在,可能表明羌塘盆地双湖地区早侏罗世大洋缺氧事件与海底天然气水合物喷发存在极大关联。     

鄂尔多斯盆地华庆地区侏罗系富县组油藏主控因素研究

侏罗系是鄂尔多斯盆地石油勘探与开发的重要目的层。华庆地区富县组油藏是近年鄂尔多斯盆地侏罗系勘探取得重大突破的新区块和新层系,已展现出良好的勘探前景和资源潜力。本文利用印模法等方法精细刻画了华庆地区前侏罗纪古地貌特征,深入分析了侏罗系富县组油藏控制因素和富集规律。结果表明,华庆地区侏罗系富县组油藏主要来源于下部三叠系延长组优质烃源岩,油藏类型为构造油藏和岩性-构造油藏,发育在古地貌斜坡带背景之上的河道边滩沉积主砂带内。油藏富集主要受控于前侏罗纪古地貌特征,充足的油源供给、河道边滩相沉积、优越的输导条件、鼻隆构造及良好的泥岩封堵等是华庆地区富县组油藏富集的主要控制因素。     

Carbon and oxygen isotopic constraints on paleoclimate and paleoelevation of the southwestern Qaidam basin,northern Tibetan Plateau

We investigate the growth of the northern Tibetan Plateau and associated climate change by applying oxygen and carbon isotopic compositions in Cenozoic strata in the southwestern Qaidam basin. The X-ray diffraction and isotopic studies reveal that the carbonate minerals are mainly authigenic and they do not preserve any evidence for detrital carbonate and diagenesis. The isotope data show large fluctuations in the δ¹⁸O and δ¹³C values in the middle–late Eocene, indicating relatively warm and seasonal dry climate. The positive correlation of the δ¹⁸O and δ¹³C values in the Oligocene and the positive shift of the δ¹³C values from the Eocene to Oligocene suggest that the climate changed to arid in the Oligocene. However, the δ¹⁸O values show negative shift, which is closely related to the global cooling event. During the Miocene, the δ¹³C values vary between –2‰ and –4‰, whereas the δ¹⁸O values show continuous negative shift. The mean δ¹⁸O values decrease from –8.5‰ in the early Miocene to –10.0‰ in the late Miocene. The stable isotope-based paleoaltimetry results suggest that the elevation of the southwestern Qaidam basin was approximately 1500 m in the middle–late Eocene and Oligocene. Subsequently, during Miocene the crustal uplift process started and the elevation reached approximately 2000 m in the early Miocene and 2500 m in the late Miocene, which suggests large-scale growth of the northern Tibet Plateau during the Miocene.     

稠油热采储层非均质性及其对开发的影响——以辽河西部凹陷某试验区于楼油层为例

本文以辽河西部凹陷某试验区为例,基于7 口井岩心、镜下薄片、分析测试及400口井测井等多种资料,采取点、线、面相结合的研究思路,利用地质统计学方法,开展稠油热采储层非均质性研究。整体上,于楼油层储层非均质性较强,储层非均质性受沉积作用、成岩作用和构造作用等影响（以沉积作用为主）。单井岩电特征与层内韵律非均质性关系密切,目的层可见3种沉积韵律模式,包括正韵律、反韵律和复合韵律（其中以正韵律和复合韵律为主）。沉积微相空间上的快速变化,导致储层非均质性增强。单层之间隔层分布较稳定,隔层厚度多大于2 m。非均质性强、中、弱的区域大体呈条带状,以北西-南东向展布,与物源方向基本一致。储层非均质性直接影响到了油藏的开发效果,研究储层非均质性可为油藏开发方式的转换提供参考。     

Assessing the extent of mangrove change caused by Cyclone Vance in the eastern Exmouth Gulf, northwestern Australia

Changes in mangal area were quantified in the eastern Exmouth Gulf over six years (1999–2004) after Cyclone Vance using Landsat TM satellite imagery and aerial photography. Vance was the strongest tropical cyclone ever to impact the Australian mainland before 2006 and produced wind gusts of more than 280 km h⁻¹. Image data were processed using ENVI™ and IDRISI™ software. Three sets of Landsat TM images from 1999 (a few days before the cyclone), 2002 and 2004 were used, along with 2004 digital aerial photography. A ‘common’ subset of 904 km² was selected from all images and classification was developed using ISODATA™ unsupervised classification to identify spectrally distinct areas followed by principal component analysis (PCA), vegetation indices and supervised classification. Some 12,800 ha of mangrove habitat was present before the cyclone and approximately 5700 ha (44%) was removed by it. Most mangroves lost (74%) between 1999 and 2004 were converted either to bare sediment or to live saltmarshes and this occurred mostly between 1999 and 2002. Five basic categories of damage were conspicuous from imagery and field observations, and evidence suggests that much of the loss was due to the longer term consequences of sediment deposition or smothering, rather than the immediate effects of wind or waves. Mangroves exhibited accelerated recovery between 2002 and 2004, and around 1580 ha regenerated during this time, amounting to a return of 68% of their former coverage. At this recovery rate we estimate that they should have returned to their pre-cyclone area by 2009. Over half of the saltmarsh habitats (54%) were removed by the cyclone (4060 ha) but their recovery has been far more rapid than mangroves. After 5 years, saltmarshes had returned to 87% of their previous area. The 5700 ha of mangrove habitat damaged by Cyclone Vance exceeds any anthropogenic impact that has ever taken place in Western Australia by several orders of magnitude.     

Petroleum composition in the Cuu Long Basin (Mekong Basin) offshore southern Vietnam

The Cuu Long Basin (Mekong Basin) is a rift basin off southern Vietnam, and the most important petroleum producing basin in the country. However, information on petroleum type and characteristics has hitherto been largely unavailable to the public. This paper presents petroleum geochemical data on nine oil samples from four different producing fields in the Cuu Long Basin: the Dragon (Rong), Black Lion (Sutu-Den), Sunrise (Rang ?ong) and White Tiger (Bach Ho) Fields. The oils are highly paraffinic with bimodal normal alkane distributions and show moderate pristane to phytane ratios and a conspicuous hyperbolic decrease in abundance with increasing carbon number of hopane homologues from C₃₀ to C₃₅. The TPP-index of Holba et al. (Holba, A.G., Dzou, L.I., Wood, G.D., Ellis, L., Adam, P., Schaeffer, P., Albrecht, P., Greene, T., Hughes, W.B., 2003. Application of tetracyclic polyprenoids as indicators of input from fresh–brackish water environments. Organic Geochemistry 34, 441–469) is equal to 1 in all samples which in combination with tricyclic triperpane T26/T25 ratios >1 and the n-alkane and hopane distributions mentioned above provide a strong indication of an origin from lacustrine source rocks. This is supported by the absence of marine C₃₀ desmethyl steranes (i.e. 24-n-propylcholestanes) and marine diatom-derived norcholestanes. Based on the overall biological marker distributions, the lakes probably belonged to the overfilled or balanced-fill types defined by Bohacs et al. (Bohacs, K.M., Carroll, A.R., Neal, J.E., Mankiewicz, P.J., 2000. Lake-basin type, source potential, and hydrocarbon character. An integrated sequence-stratigraphic–geochemical framework. AAPG Studies in Geology 46, 3–34). The oils were generated from source rocks at early- to mid-oil-window maturity, presumably Oligocene lacustrine shales that are present in the syn-rift succession. Oils from individual fields may, however, be distinguished by a combination of biological marker parameters, such as the oleanane index, the gammacerane index, the relative abundance of tricyclic terpanes, the proportions of diasteranes and 28-norspergulane, complemented by other parameters. The oils of the Cuu Long Basin show an overall similarity to the B-10 oil from the Song Hong Basin off northern Vietnam, but are markedly different from the seepage oils known from Dam Thi Nai on the coast of central Vietnam.     

鄂尔多斯盆地塔巴庙地区上古生界源岩热演化特征

鄂尔多斯盆地北部主力气源岩太原组、山西组煤系地层热成熟史的研究对本区天然气充注过程和有利目标区预测具有重要的参考价值。在对研究区烃源岩评价和一维、二维地质建模研究的基础上。利用BasinMod盆地模拟软件对单井以及研究区内二维剖面、平面进行了煤系烃源岩热演化史模拟研究。研究结果表明：（1）该区在中三叠世进入生烃门限,中侏罗世以后,烃源岩持续埋深,早白垩世末期至最大埋深（4000m左右）,绝大多数的天然气都在这一阶段生成,早白垩世末构造抬升以后只有少量天然气生成;（2）研究区上古生界太原组和山西组煤系源岩最大累积生烃强度可达到2200×10^8m^3／km^2,对现今天然气的分布具有较强的控制作用。     

A 44-year high-resolution ocean and atmospheric hindcast for the Mediterranean Basin developed within the HIPOCAS Project

A set of 44-year (1958–2001) homogeneous and high-resolution hindcasts of atmospheric, sea level residuals, and wave states was performed for the Mediterranean Basin within the framework of the HIPOCAS European Project. To this aim, different numerical models were used. As a first step, a Mediterranean high-resolution atmospheric database, suitable to provide realistic and homogeneous forcing for ocean hindcast runs was generated. The HIPOCAS atmospheric database was created by means of dynamical downscaling from the global reanalysis NCEP, using for that the limited area model SN-REMO along with a spectral nudging technique. In a second stage, different Mediterranean oceanic hindcasts were performed. On one hand a long-term database of sea state over the western Mediterranean was generated by means of the wave model WAM and on the other hand a sea level residual database containing storm surge events was obtained from a long-term integration of the HAMSOM model over the entire basin. The three different hindcast runs have been exhaustively validated. On that score, various simulated parameters have been compared to both satellite and in situ measurements. Such comparisons provide a measure of the skills of the different simulated fields to realistically reproduce the observed features. Once these skills are evaluated, a study of the ocean and atmospheric climate trends as well as the interannual variability for the whole 44-year period was carried out with the hindcasted data. The reliability of the data as shown by its comparison to measurements and a proven temporal homogeneity over the 44 years of simulation make the Mediterranean HIPOCAS ocean–atmosphere hindcasted database a useful tool for studies focused on regional climatic variability, as well as for further applications in coastal and environmental decision processes in the Mediterranean area.     

鄂尔多斯盆地延长组深水重力流岩相发育特征及其储集性

鄂尔多斯盆地陇东地区长7、长6油层组广泛发育深水重力流,基于对长7-长6段共计852.7 m岩心的精细分析并结合测井、录井等数据,总结分析了湖盆重力流沉积岩相的类型、成因、特征和发育规律。综合岩石类型、沉积构造和发育规模,共识别出8种岩相类型,分别是：滑动砂岩相(Sl)、滑塌砂岩相(Ss)、滑塌泥岩相(Sm)、中-薄层块状含砾砂岩相(Sc)、中-薄层块状纯净砂岩相(Sp)、厚层块状含砾砂岩相(St)、块状含砾泥岩相(Mc)、中-薄层具层理砂岩夹泥岩相(Tb)。按照Shanmugam基于重力流沉积过程的分类方法,Sl是滑动成因,Ss、Sm是滑塌成因,St、Sp、Sc、Mc是碎屑流成因,Tb是浊流成因。不同岩相发育规模差别较大,从累计厚度和发育频次上看,St、Sp规模最大。砂岩岩相可构成良好储层,St储层质量最好,其次为Sp、Sc,但Sp、Sc的发育规模远大于St,综合认为在实际勘探中Sp、Sc是重力流储层最有利的勘探目标。     

Circulation and currents in the southwestern East/Japan Sea: Overview and review

A review is made of circulation and currents in the southwestern East/Japan Sea (the Ulleung Basin), and the Korea/Tsushima Strait which is a unique conduit for surface inflow into the Ulleung Basin. The review particularly concentrates on describing some preliminary results from recent extensive measurements made after 1996. Mean flow patterns are different in the upstream and downstream regions of the Korea/Tsushima Strait. A high velocity core occurs in the mid-section in the upstream region, and splits into two cores hugging the coasts of Korea and Japan, the downstream region, after passing around Tsushima Island located in the middle of the strait. Four-year mean transport into the East/Japan Sea through the Korea/Tsushima Strait based on submarine cable data calibrated by direct observations is 2.4 Sv (1 Sv = 10⁶ m³ s⁻¹). A wide range of variability occurs for the subtidal transport variation from subinertial (2–10 days) to interannual scales. While the subinertial variability is shown to arise from the atmospheric pressure disturbances, the longer period variation has been poorly understood.Mean upper circulation of the Ulleung Basin is characterized by the northward flowing East Korean Warm Current along the east coast of Korea and its meander eastward after the separation from the coast, the Offshore Branch along the coast of Japan, and the anticyclonic Ulleung Warm Eddy that forms from a meander of the East Korean Warm Current. Continuous acoustic travel-time measurements between June 1999 and June 2001 suggest five quasi-stable upper circulation patterns that persist for about 3–5 months with transitions between successive patterns occurring in a few months or days. Disappearance of the East Korean Warm Current is triggered by merging the Dok Cold Eddy, originating from the pinching-off of the meander trough, with the coastal cold water carried Southward by the North Korean Cold Current. The Ulleung Warm Eddy persisted for about 20 months in the middle of the Ulleung Basin with changes in its position and spatial scale associated with strengthening and weakening of the transport through the Korea/Tsushima Strait. The variability of upper circulation is partly related to the transport variation through the Korea/Tsushima Strait. Movements of the coastal cold water and the instability of the polar front also appear to be important factors affecting the variability.Deep circulation in the Ulleung Basin is primarily cyclonic and commonly consists of one or more cyclonic cells, and an anticyclonic cell centered near Ulleung Island. The cyclonic circulation is conjectured to be driven by a net inflow through the Ulleung Interplain Gap, which serves as a conduit for the exchange of deep waters between the Japan Basin in the northern East Sea and the Ulleung Basin. Deep currents are characterized by a short correlation scale and the predominance of mesoscale variability with periods of 20–40 days. Seasonality of deep currents is indistinct, and the coupling of upper and deep circulation has not been clarified yet.