南黄海辐射沙洲西太阳沙海域钻孔沉积环境分析

南黄海辐射沙洲枢纽区的西太阳沙海域钻孔岩芯很好地揭示了研究区全新世中晚期潮成沙脊沉积序列和晚更新世末期滨岸潮滩沉积序列.潮成沙脊在垂向上由两个基本的沉积相构成:出现在-5m水深以上的沙脊-浅潮下相以发育小型沙波交错层理、水平层理、块状层理和缺乏生物扰动为特点; 发育在水深 -5m以下的沙脊-深潮下相以出现脉状层理、波状层理和沙波交错层理组合为特点,具有丰富的生物扰动,并保存有风暴沉积.14C测年数据表明潮成沙脊是中全新世以后形成的,在辐射沙脊群形成之前,研究区经历了晚更新世的滨岸潮滩环境以及早全新世的海侵环境.烂沙洋靠西太阳沙一侧潮流通道目前已切入晚更新世滨岸潮滩相地层,潮道底部约8m厚的淤积层夹有强烈变形的滑塌堆积,可能与台风、风暴潮引起的骤然淤积有关,目前已被1992～2003年的海图资料证实.     

Bar and dune development during a freshet: Fraser River Estuary, British Columbia, Canada

Bi-weekly multi-track sonar surveys collected along a 2-km reach of the estuarine South Arm of the Fraser River, British Columbia, Canada, during seasonal high flows document the initiation, development and interaction of dune and bar morphologies. Bedforms of several scales developed in well-delineated fields. Bedforms that appear to fit accepted equilibrium depth-scaling developed in the main channel during rising discharge when there was little local aggradation. During the rising stage, a bar also formed along the tidal shelf of the channel, migrated downstream and expanded into the main channel. Dunes that formed along the bar crest, a region of rapid deposition, lagged flow conditions and were larger than expected based on depth-scaling relations. The larger dunes developed simultaneously, although bar growth lagged dune development and was initially partially obscured by the more rapidly developing dune field. It appears that rapid deposition enhances dune development along the channel tidal shelf to dimensions larger than would be expected by simple depth-scaling rules. Smaller dunes that fit equilibrium depth-scaling relations re-established themselves throughout the study area during falling discharge when there was again little or no aggradation. Bed-material transport rates estimated from the migration rates of the large dunes suggest that, at high flows, the dunes transport the majority of the material found within the bar.     

鄂尔多斯盆地横山地区下石盒子组盒8段优势砂体研究

横山地区位于盆鄂尔多斯盆地北部,上古生界下石盒子组盒8期处于辫状河三角洲平原与三角洲前缘过渡区。由于地形平缓、间歇性水流供给使得河流频繁改道。不同形态与规模的河道砂体交错叠置,加大连续沉积砂体的寻找难度。通过连井剖面追踪主河道内的单一砂体,揭示其空间展布规律,多条砂体追踪得到不同厚度砂体的空间延伸形态,其结果表明连续沉积越厚的砂体,其延伸距离越远。基于砂泥叠置关系与砂体发育规模确定优势砂体为多期次叠加的且隔夹层较少的具有一定规模的整套砂体。优势砂体空间延伸较远、沉积厚度较大、岩性较为均一,为理想的储集砂体。确定优势砂体的平面发育情况,为优势储层的寻找奠定基础。     

福建浅海潮流沙脊分布及形态特征

福建浅海海砂资源丰富,沿海岸线分布广且资源量大,主要以潮流沙脊为主。对潮流沙脊的形态和分布特征进行研究,有利于海砂资源的勘查开发以及对资源量进行合理评价。基于福建海域多波束全覆盖资料,利用ArcGIS的ArcMap对多波束资料进行配准和数据化,对区内潮流沙脊的形态特征进行初步分析。结果显示,福建浅海潮流沙脊形态上长宽分别在2.8～31.3、1.9～12.3 km之间,面积在3.7～200.9 km2之间;分布上由北往南、自西向东,走向由东西向变为北东—南西向,沙脊发育规模逐渐增大且沙质变好,近岸以粉沙为主,远岸以沙为主。对比沙脊主体长与宽,将福建浅海潮流沙脊划分为A型（长度＞10 km,宽度＞5 km）、B型（长度＞10 km,宽度＜5 km）和C型（长度＜5 km,宽度＜5 km）3种类型。综合福建浅海潮流沙脊分布及形态特征,海砂资源勘查时可优选南部远岸区域。     

A field quantification of coastal dune perennial plants as indicators of surface stability, erosion or deposition

Dune plants both modify the wind field around them and are impacted by various stress factors, among them sand erosion and sand deposition. As coastal dunes are being either stabilized or remobilized, in response to the changes in the rates of sand and dune movement, the vegetation cover and composition are expected to vary reflecting the differences in the sedimentary conditions. In this field study 315 quadrats of 100 m², in which the perennial plant species were sampled, were analysed with respect to annual rates of sand erosion and deposition that were measured using erosion pins. A visual exploratory data analysis was introduced, based on selective filtering of samples according to their vegetation cover. This method, combined with established statistical tools, enabled the authors to uncover the inclination and indicative power of nine perennial dune plants to either a stabilized or a mobile environment, and to establish whether they are more prevalent in places undergoing sand erosion or sand burial. Two species were found to be clear indicators of a stabilized environment, Stipagrostis lanata , and Retama raetam . Of the species indicating a mobile environment, only one may be stated as a clear indicator of sand erosion: Silene succulenta , with Cyperus macrorrhizus coming close to being an indicator of a less mobile erosive environment. The best indicator species for sand burial was found to be, as expected, Ammophila arenaria , with Artemisia monosperma also indicating high rates of sand mobility especially when its relative cover is higher than 80%. Such information can be used to monitor natural processes of dune stabilization or reactivation, or to assess the success of a management plan that aims at stabilizing a dune, or at remobilizing it by removing vegetation.     

准噶尔盆地车排子凸起西翼侏罗系骨架砂体连通性研究

骨架砂体作为油气输导体系的重要组成要素,控制着油气在空间上侧向的运移以及分布,其有效连通常受到砂体内部断层发育以及砂体微观非均质性的影响.通过对准噶尔盆地车排子凸起西翼地区主要井位进行单井分析,在明确区域地层格架与沉积相的基础上,划分侏罗系头屯河组及八道湾组各段的骨架砂体;并在此基础上绘制骨架砂体连井剖面图以及平面分布等值线图,对研究区骨架砂体的宏观连通性进行研究;再进一步通过对各层位的砂体系统取样,进行孔渗性分析,定性描述其微观连通情况;运用地质统计学方法,对骨架砂体微观连通性进行定量评价.结果表明,从剖面、平面、微观3个方面针对侏罗系头屯河组和八道湾组骨架砂体进行综合评价,研究区骨架砂体连通性相对较好的组段为侏罗系头屯河组三段及八道湾组三段.     

Slump-initiated and controlled syndepositional sandstone remobilization: an example from the Namurian of County Clare, Ireland

Remobilization of sandstones can dramatically reconfigure original depositional geometries and results in very unusually shaped sandstones, which resemble little, if any, of the original geometry. A number of deformational sandstone bodies, dykes and volcanoes from the upper part of the Carboniferous Ross Formation are described, which offer the opportunity to examine a suite of field-scale reconfigured sandstones. These structures are located in close proximity to the Ross Slide, which outcrops along a 2-km section on the northern coast of the Loop Head Peninsula, County Clare, Ireland. Dome- and ridge-shaped deformational sandstone bodies, dykes and volcanoes are interpreted to be the product of remobilization of a turbiditic sandstone. Liquification and remobilization were triggered by translation, cessation and loading of the underlying turbiditic sandstone by the Ross Slide. Deformational sand body, dyke and volcano development occurred in an asynchronous fashion with deformational sand bodies formed during slump translation. Sand dykes and volcanoes developed after the cessation of slump movement. During slump translation, the minimum principal stress (σ₃) was orientated vertically and the slump behaved in a `ductile' manner. After slump arrest, the minimum principal stress was oriented horizontally, and the unit regained shear strength to behave in a `brittle' manner. The relative change in rheological states with changing applied shear stress is indicative of thixotropic-like behaviour within the slump mass. Ridge-shaped deformational sand bodies are aligned parallel to slump folds, and their morphology is inferred to be controlled by compressional slump deformation associated with heterogeneous cessation of slump movement that was initiated by frontal arrest of the translating mass.     

云南腾冲山寨盆地水下冲积扇特征及对砂锡的控矿作用

水下冲积扇是山间谷地被堵截堰塞,山麓堆积进入水盆地的一种特殊“相”,以重力流堆积为主体,间夹湖沼和上迭河流沉积。熔岩流多次堵塞增高,堰塞坝的侵蚀和盆地的沉积充填,这三种因素综合作用的结果,形成了具有一定厚度的不同沉积类型组合。各类沉积因其搬运分选机制不同而形成不同的聚锡能力,决定了对砂锡的控矿作用。     

The equilibrium gravel coverage of the deflated gobi above the Mogao Grottoes of Dunhuang, China

Blown sand has caused considerable damage to the Dunhuang Mogao Grottoes of China. Controlling the blown sand requires a clear understanding of the processes that govern its production and movement. Experiments were conducted in a wind tunnel and in the field to define the relationships between sand production and gravel coverage in the gobi above the Mogao Grottoes. The gravel that covers the gobi’s surface controls wind erosion, irrespective of its shape and size. The equilibrium coverage by gravel over which no further sand is emitted due to wind erosion increases and the equilibration time that is taken to form the equilibrium gravel coverage decreases with increasing wind velocity. Gravel coverage has reached an equilibrium state in the portion of the gobi directly above the grottoes, but decreases towards the Mingsha Mountains. Drifting sand from these mountains is the main source of sand damage at the Mogao Grottoes. If no additional sand from the mountains were supplied to the gobi, gravel pavements would reach an equilibrium level of coverage and prevent further production of blowing sand. Sand blown from the gobi represents secondary reactivation of sediments originally produced in the Mingsha Mountains. Therefore, to control the blowing sand above the Mogao Grottoes, emphasis should be placed on controlling erosion from the Mingsha Mountains rather than local erosion of sand in the gobi.     

罗安达砂物理力学性质初探

在罗安达及其周边,浅部广泛分布有红色和黄色两种色调的粉砂层。结合实际工程,采用现场调查、室内试验、现场标贯试验和载荷试验等手段对该种砂土进行了分析,结果表明,罗安达砂层在自然状态下可直立,具湿陷性和浸水后力学性质明显变差等独特物理力学特性;湿陷性随孔隙比增大,含水率减小,试验压力增大,黏粒和粉粒含量增大而增强,重塑砂土也具有湿陷性;力学性质随含水率的变化可逆,当含水量增加后再减小,其力学性质可明显恢复。     

鄂尔多斯盆地苏里格气田西南部致密储层非均质性特征及对成藏的制约

致密砂岩气藏是我国非常规油气资源的重要组成,其储层非均质性严重影响了致密气成藏和甜点区优选,进而制约了气田高效开发。为进一步揭示储层非均质性成因及对致密气成藏的影响,选取鄂尔多斯盆地苏里格气田西南部山1段和盒8段致密储层为例,通过岩芯观察、扫描电镜、薄片鉴定、生产和测井分析等技术手段,研究储层非均质特征,探讨沉积作用和微观孔隙演化对非均质性和成藏的影响。结果表明,储层非均质性多表现为层内粒度的垂向韵律性、夹层的不均匀分布、渗透率的平面分布差异等;储层非均质性受沉积作用和成岩作用共同影响,沉积作用控制了水动力条件、砂体展布、厚度和砂体构型,储层微观非均质性受岩矿组构和孔隙演化影响;不同厚度和构型的复合砂体,多样的矿物组分、孔隙结构,致密气的选择性充注,共同造成了苏里格地区致密储层的非均质性及含气性差异。复合砂体的高孔渗部位是致密气开采的甜点区,但是在优选有利区时不应只关注这些厚层的高孔渗砂体,也应关注规模小、非均质性稍强的透镜状砂体,需要充分考虑到储层非均质性对致密气成藏的影响。     

Experimental,numerical and analytical study on conventional and innovative Grid-Anchor system in the pull-out test

With increasing use of geosynthetic applications in earth structures the need to develop more efficient reinforcement elements becomes evident. In this paper a conventional and an innovative geogrid system (named Grid-Anchor) are tested. The Grid-Anchor system consists of a conventional geogrid with anchors attached to it. The pull-out test has been used to highlight the capabilities of the product. Experimental investigation along with numerical studies using a finite element computer code was carried out. It was found that the ultimate pull-out resistance of a Grid-Anchor is more than that for an ordinary geogrid. Analytical study has been performed and the effect of an anchor group on the ultimate resistance of a geogrid was investigated.     

Origin and evolution of polygonal cracks in hydrous sulphate sands,White Sands National Monument,New Mexico

The nucleation and propagation of polygonal cracks in hydrous sulphate dunes at White Sands National Monument, New Mexico, are affected by water availability, transport through the sand and exchange with the atmosphere. These gypsum sands are cohesive enough to crack due to capillary forces and gypsum cements formed during evaporation. Surface cracks form five‐sided polygons with a variety of triple‐junction angles. Cracks extend down to variable depths and polygons increase in size with depth, showing a maturation similar to experimentally produced polygonal columns in drying corn starch. Results from two years of monitoring crack geometries, temperature and humidity demonstrate that cracks form when water is lost to the atmosphere through the transport of water vapour. Subsurface relative humidity below 5 to 10 cm is almost always maintained at 100% by the evaporation and condensation of water in thin films on grains. The amplitude of daily temperature and thus absolute humidity changes decreases with depth, consistent with lower evaporation and condensation rates with increasing depth. Changes in absolute humidity and the contrast between humidity in pore spaces versus the overlying atmosphere result in significant water loss from the dunes except during times of precipitation and frost/dew condensation. This water loss allows cracks to nucleate and propagate into the dunes. This study hypothesizes that crack tips propagate into sand to the depth at which thin films of water on grains are drying, and that this depth varies from the surface of the dune during precipitation events to depths greater than 45 cm when dunes are drier.     

A 1900‐year paleohurricane record from Wassaw Island,Georgia, USA

We present here the first paleotempestology record from Wassaw Island on the Georgia Bight, located in the south Atlantic coast of the United States. In the historical period, the Georgia Bight has experienced less frequent hits by hurricanes than other locations along the US Gulf and Atlantic coasts. The 1900‐year record inferred from the overwash sand layers from a back‐barrier marsh on Wassaw Island suggests that the island was directly struck by major storms on nine occasions during this interval. The Wassaw Island record shows alternating regimes, with periods of increased activity from >2000 a BP until ～1100 a BP, and ～100 a BP until the present, sandwiching a quiet period from ～1100 to 250 a BP. Storm deposits from the most recent active period are perhaps amalgamated, indicating that site‐specific conditions may result in event undercounting and suggests that the relative thickness of sand layers in the sedimentary record is not always indicative of hurricane strength. Copyright © 2011 John Wiley & Sons, Ltd.     

准噶尔盆地哈山东部地区侏罗系骨架砂体展布特征及连通性研究

骨架砂体是油气输导体系的组成要素之一,但其内油气分布常受到砂体内部断层封堵能力与砂体非均质性的影响.在明确区域地层格架与沉积相的基础上,对哈拉阿拉特山东部地区侏罗系八道湾组及三工河组内发育的骨架砂体进行了展布特征与连通性研究.通过对研究区砂体宽厚比分析,认为骨架砂体单井厚度在30 m以上时,其在井间可以彼此接触.建立区域连井剖面,发现八道湾组一段、三段及三工河组三段3套骨架砂体规模较大,展布范围广.八道湾组一段作为研究区侏罗系油气分布的主要层段,其内断层产状以及断层成岩封闭作用的差异,是造成油气在骨架砂体内差异性分布的主要原因.该段骨架砂体渗透率与孔隙度整体变化趋势基本一致,但存在较为明显的东西分区性,中部交接区孔渗性差,油气平面分布与微观非均质性有明显的相关关系,证明骨架砂体的物性特征也是影响其输导运移油气能力的关键因素.     

东海陆架沙脊三维地震地貌学、演化及成因

线状陆架沙脊一直是海洋地质学和沉积学研究的热点。基于东海近海底1700 km2的三维地震数据,对陆架沙脊开展地震地貌学、沉积构型、成因和演化研究,并取得以下3点认识：（1）研究区发育7条NW-SE向陆架沙脊体系,海底呈槽脊相间地形特征。沙脊表面发育NE-SW向沙波体系。脊1、脊2、脊4和脊6表现为2～3条交叉或合并的沙脊体系,而脊3、脊5和脊7呈现为独立沙脊体系。（2）线状陆架沙脊横剖面左右不对称,宽2～11 km,脊高3～31 m,坡面相对较缓,倾角大多小于1°。（3）研究区水深变化和近海底潮流速度等因素指示研究区沙脊处于活动沙脊和衰亡沙脊的过渡阶段。研究第四纪陆架沙脊对沙脊储层的预测具有一定的指导意义。     

砂土液化判定评价与对策

砂土液化的评定、评价及对策虽然要概念不同,但有着必然的联系,本文通过工程实例分析,对液化判定、评价及对策进行较为详细的阐述。     

Coupled wellbore erosion and stability analysis

This paper extends earlier work on sand erosion and presents an attempt to couple sand erosion to mechanical damage of rock around a wellbore. Porosity which evolves in time and space as surface erosion progresses, is chosen as the coupling parameter. Both rock elasticity and strength (cohesion) are assumed to depend on porosity in such a way that the material becomes weaker with increasing porosity. The mathematical model, consists of erosion equations, mixture flow equations and stress equilibrium equations, is solved numerically by Galerkin finite element method. Numerical results suggest that erosion, resulting in sand production, is high close to the free surface. Erosion is accompained by changes in porosity and a significant permeability increase. Erosion in the vicinity of the wellbore induces alterations in the mechanical behaviour of the medium. Weakening of rock stiffness leads to severe alteration of both effective stresses and pore pressure near the cavity. Since cohesion decreases with increasing porosity, one can also identify the time instant at which rock mechanical failure starts. © 1998 John Wiley & Sons, Ltd.     

新疆古尔班通古特沙漠砂的工程地质特性浅析

新疆古尔班通古特沙漠风积砂分选良好,矿物成分以石英为主,砂粒磨圆度好,具有孔隙率大、内摩擦角小、承载力低等特性.通过在沙漠北部、中部和南部试验段进行的专题工程地质研究,介绍了新疆准噶尔盆地古尔班通古特沙漠风积砂的基本物理力学特性和压实性、压缩性、渗透性、冻胀性等工程地质特性.     

Sand Dunes Fixation in Baiji District,Iraq

This study was carried out at Sand Dunes Stabilization Researches Station in Baiji district (230km north of Baghdad,Iraq) to evaluate the effects of local soil conditioners manufactured from oil derivatives and plant residuals on sand dunes fixation as the first step for sand dunes stabilization.The results indicate that the fuel oil has the first place in improving wind erosion parameters in the study area,such as increasing mean weight diameter,dry aggregates percentage,the needed time for complete disaggregation by dry sieving,and decreasing the disaggregation rates.Bitumen emulsion occupies the second place ,while the plant residuals occupies the third place and has slight effects on the studied pa-rameters.Effects of conditioners on natural vegetation cover are negative in oil derivatives treatments,while positive in plants residuals treatments.