The oxygen isotopic composition and temperature of Southern Ocean bottom waters during the last glacial maximum     

Mitchell J Malone  Jonathan B Martin  Ulysses S Ninnemann  Timothy S White 《Earth and Planetary Science Letters》2004,222(1):275-283

We provide two new determinations of the oxygen isotopic composition of seawater during the last glacial maximum (LGM). High-resolution oxygen isotopic measurements were made on interstitial waters from Ocean Drilling Program (ODP) Sites 1168 and 1170 in the southeast Indian Ocean sector of the Southern Ocean. We use a diffusion-advection numerical model to calculate the glacial-interglacial change in bottom-water δ¹⁸O_sw from the pore water δ¹⁸O profiles; the first such determinations from this part of the oceans. Statistical analyses of the model runs indicate that Circumpolar Deep Water (CDW) δ¹⁸O_sw changed by 1.0-1.1±0.15‰ since the last glacial maximum (LGM). Our results are consistent with a previous calculation from a South Atlantic Southern Ocean location (ODP Site 1093) also situated within CDW. The new values determined in this study, together with previous estimates, are converging on a global average Δδ¹⁸O_sw of 1.0-1.1‰.Using the calculated bottom-water δ¹⁸O_sw, we have extracted the temperature component from the benthic foraminiferal δ¹⁸O record at Sites 1168 and 1170. Since the LGM, bottom waters at these two sites warmed by 2.6 and 1.9°C, respectively. The absolute temperature estimates for the LGM (−0.5°C [Θ=−0.6°C] at Site 1168 and −0.2°C [Θ=−0.4°C] at Site 1170) are slightly warmer than those reported from previous studies using the same technique, but are consistent with more homogenous deep-ocean temperatures during the LGM relative to the modern.  相似文献   

漳州新城大厦基础方案选择研究     

宋荣杰 《江苏地质》2002,26(4):230-232

根据拟建的新城大厦场地的工程地质条件和建筑物特点，通过预制桩、冲钻孔灌注桩等桩型的施工可行性、单桩承载力、经济效益等因素的对比分析，选择静压预制桩为拟建建筑物的基础，并综合分析岩土体工程性质后给出了桩基的设计参数。  相似文献   

中国大陆科学钻探工程项目进展综述   总被引：1，自引：0，他引：1       下载免费PDF全文

王达 《探矿工程》2002,(6):47-53

阐明了中国大陆科学钻探工程的意义与目标，论述了工程建设的主要内容和项目的组织管理，介绍了项目的进展情况。  相似文献   

利用GIS组件建立工程地震WebGIS系统   总被引：3，自引：0，他引：3       下载免费PDF全文

屈春燕  叶洪  刘治 《地震地质》2002,24(2):258-264

利用GIS软件组件建立了工程地震WebGIS系统。该系统采用浏览器 /服务器体系结构 ,实现了工程地震空间信息的网络共享和初步的协同工作。用户可以直接从网上通过浏览器来浏览、查询、分析和使用工程地震研究中的各类空间数据及GIS应用 ,同时还可以将需要的数据下载到本地机上使用或将自己的研究成果提交到远程服务器上发布 ,以实现共享。对地图在网上的传输显示速度问题和系统的安全性问题也采取适当的措施给以解  相似文献   

新疆塔里木河油田工程地质及工程地震特征研究     

袁文福  罗福忠  向志勇  陈建波 《内陆地震》2002,16(2):160-164

塔里木河油田建筑工程场地以冲、风积形成的粉细砂、粉质粘土为主 ,地下浅水位为 2— 4 m。由于该地区属大陆型干燥气候 ,强烈的蒸腾作用使大量盐碱聚集在地表形成易溶盐富集层 ,这对建筑基础具有强腐蚀作用。建筑工程场地属 类 ,场地土为软弱土类型。场地特征周期 Tg 为 0 .6 s,属远震影响。  相似文献   

Determination of the cleat angle distribution of the RECOPOL coal seams, using CT-scans and image analysis on drilling cuttings and coal blocks   总被引：1，自引：1，他引：0  

Karl-Heinz A.A. Wolf  Frank van Bergen  Rudy Ephraim  Henk Pagnier 《International Journal of Coal Geology》2008,73(3-4):259-272

Cleat orientation, cleat frequency and cleat angle distribution of deep coal seams are only available by the use of drilling cores and from coal mine samples. Coal drilling cuttings are a cheap and fast alternative to measure cleat angle distributions with the use of image analysis techniques. In this study oriented coal samples and drilling cuttings of the RECOPOL field experiment are compared and used to explain and validate the proposed method. In other words, cleat angle distributions from drilling cuttings are measured by image analysis. The geological framework of the polish coals is described. The image analysis methodologies for the measurement of fracture faces of cuttings and from CT-scan images, derived from these coals, are explained. The results of the methods on the cuttings are compared with cleat orientation distributions from CT-scans and artificial fragments from coal blocks of the same seams. These evaluations show high agreements between the methods. The cleat angle distributions of drilling cuttings of four seams are compared with the cleat orientation distributions of a regional structural geological study. The high correlation in this study shows that cleat angle distributions of coal seams can be used as input parameters for reservoir modelling.  相似文献   

Geotechnical and mineralogical characteristics of marl deposits in Jordan   总被引：1，自引：0，他引：1  

Fathi M. Shaqour  Ghaleb Jarrar  Steve Hencher  Mostafa Kuisi 《Environmental Geology》2008,55(8):1777-1783

Marls and marly limestone deposits cover most of Northern Jordan, where Amman City and its suburbs are located. These deposits serve as foundations for most buildings and roads as well as fill material for structural back filling, especially road bases and sub-bases. The present study aims at investigating the geotechnical characteristics and mineral composition of the marl units of these deposits through field investigations and laboratory testing. Using X-ray diffraction technique along with chemical analysis, representative samples of marl horizons were tested for mineral composition, and for a set of index and geotechnical properties including: specific gravity, grain size, Atterberg limits, Proctor compaction and shear strength properties. The test results show a positive linear relationship as expected between the clay content and both liquid and plastic limits. The tests results also show an inverse linear relationship between the clay content and the maximum dry density in both standard and modified compaction. This is attributed to the adsorption of water by the clay minerals. The relationship is more prominent in the case of modified compaction test. The results also indicate a similar relationship for the angle of internal friction. No clear correlation between cohesion and clay content was apparent.  相似文献   

大体积采空区岩体结构面聚类分布特征研究     

徐必根  王春来  唐绍辉 《工程地质学报》2008,16(5):639-644

广西北山矿业有限责任公司4#特大采空区具有体积大、形状不规则等特征。该采空区围岩发育有上甫肯跃背斜和印支期、燕山期断裂构造,根据采空区围岩发育构造、岩层界线划分和泥灰岩、礁灰岩蚀变等特征,结合其岩石物理力学指标,划分了泥灰岩、白云岩、礁灰岩等3个工程地质岩组。采用测线法和体积密度法,开展了详细的采空区周边岩体工程地质条件现场调查。基于现场调查数据,通过结构面聚类分析,得出了结构面分布的几何参数概率特征,建立了主优势结构面倾向为52和300及主优势结构面倾角为75的正态分布。分析计算结果显示:该模型可以有效的描述4#采空区节理产状分布特征。  相似文献   

中国汶川特大地震损毁城镇恢复重建选址的工程地质评价   总被引：5，自引：1，他引：4  

李渝生  黄润秋 《工程地质学报》2008,16(6):764-773

在损毁城镇震后恢复重建工作中,场址的合理选择及安全性评估极为重要。选址问题涉及地震断裂、地质灾害、场地稳定及国计民生、经济发展等诸方面的复杂因素,是一个复杂的系统工程问题。考虑问题的基本原则应是,对于震后位于地震断裂带上,且地质环境恶化、存在严重地质灾害隐患的城镇,必须异地迁建;对于虽然损毁较严重,但远离断裂带,且不存在致命的地质灾害隐患的城镇,应按照科学规划、规范避让、合理调整抗震设防标准的原则,原址重建。灾后重建过程中,应重视地质灾害的隐蔽性、诱发因素的多重性与长期持续性等,加强地质环境的适宜性评价及地质灾害的风险性评估。本文结合震后的实际调查,对北川、青川两个县城及青川县木鱼镇的重建选址问题进行了探讨,在对场址工程地质和环境地质适宜性评估的基础上,提出了上述典型城镇的重建选址意见。  相似文献   

顶管工程中沉井与搅拌桩的综合应用     

付思峰  刘晶  王国田 《岩土钻凿工程》2008,(1):123-125

某顶管工程的管道施工转角较多,必须多设工作井和接收井,应用沉井和搅拌桩为挡土防水围护结构,并取得了成功。  相似文献