珠江口伶仃洋海底沉积

在前人工作的基础上,利用2003—2005年广州海洋地质调查局1∶10万《珠江三角洲近岸海洋地质环境与地质灾害调查》项目的实测资料,综合分析了伶仃洋海底的沉积特征,认为伶仃洋表层沉积物类型有:砂、黏土质砂、砂-粉砂-黏土、砂质黏土、黏土质粉砂、粉砂质黏土等6种类型。伶仃洋晚更新世以来的海底地层主要有两套:层A为全新世冰后期海侵以来逐渐堆积而成的沉积物,钻孔揭示的沉积物类型主要为黏土质砂和砂—粉砂—粉砂质黏土;层B为一套晚更新世的黏土质粉砂、细砂—粗砂(含砾)、粉砂质黏土—黏土,以陆相沉积和剥蚀为主,局部为海陆交互相沉积,其下地层则为基岩风化物和基岩。     

青岛海岸带及邻近海域地形和沉积物类型研究

研究了青岛海岸带及邻近海域的地形特征、沉积物类型及分布特征。总体看来,沿海岸粒度较粗,为砂、粉砂质砂等,向海深处粒度有逐渐变细的趋势,海深处的沉积物主要为砂—粉砂—黏土,局部为粉砂质黏土、黏土质粉砂和黏土质砂。灵山岛周围,沉积物粒度较粗。胶州湾口内外为一海底深槽,水深流急,冲刷强烈,沉积物粒度非常粗,主要为粗砂、中砂,局部有基岩出露。深槽南北两侧各有一条突出海底的砂脊,平行于深槽延伸方向砂脊由中砂组成,混有少量黏土,北侧砂脊表面呈不规则起伏,南侧砂脊表面则较为平整。胶州湾内沉积物粒度总体较细,主要为粉砂质黏土、黏土质粉砂及砂—粉砂—黏土等。根据沉积物类型及分布特征,可把青岛海岸带及邻近海域的沉积划分为4个沉积区:胶州湾口及滨岸现代沉积区、北部浅海沉积区、南部浅海沉积区和残留—残余沉积区。     

海洋碎屑沉积物的分类

比较研究了以Shepard和Folk等为的海洋碎屑沉积物分类方案，提出沉积物的分类应兼具描述与解释两种功能。Shepard分类已经过时，Folk等的分类方案有显著的优点，但亦有不足之处，应予以改进。沉积物的成分分类受到忽视的现象应予以改变。为适应我国海洋地质测量的需要，作者提出了一套结构分类与成分分类相匹配的多重分类系统，解决了海洋碎屑沉积物分类中的矛盾和问题。     

登州浅滩海域表层沉积物分布特征

依据2010年在登州浅滩海域采集的沉积物样品资料,划分了研究区表层沉积物的分布类型,分析了登州浅滩海域沉积物的分布特征和粒度参数变化规律,在此基础上初步探讨了沉积物分布的影响因素.研究结果表明,登州浅滩海域表层沉积物主要包括砾石、砾砂、粗砂、中粗砂、中砂、细砂、粉砂质砂、砂质粉砂、粉砂、黏土质粉砂、粉砂质黏土等11种类...     

Sound velocity and related properties of seafloor sediments in the Bering Sea and Chukchi Sea

The Bering Sea shelf and Chukchi Sea shelf are believed to hold enormous oil and gas reserves which have attracted a lot of geophysical surveys. For the interpretation of acoustic geophysical survey results, sediment sound velocity is one of the main parameters. On seven sediment cores collected from the Bering Sea and Chukchi Sea during the 5th Chinese National Arctic Research Expedition, sound velocity measurements were made at 35, 50, 100, 135, 150, 174, 200, and 250 k Hz using eight separate pairs of ultrasonic transducers. The measured sound velocities range from 1 425.1 m/s to 1 606.4 m/s and are dispersive with the degrees of dispersion from 2.2% to 4.0% over a frequency range of 35–250 k Hz. After the sound velocity measurements, the measurements of selected geotechnical properties and the Scanning Electron Microscopic observation of microstructure were also made on the sediment cores. The results show that the seafloor sediments are composed of silty sand, sandy silt, coarse silt, clayey silt, sand-silt-clay and silty clay. Aggregate and diatom debris is found in the seafloor sediments. Through comparative analysis of microphotographs and geotechnical properties, it is assumed that the large pore spaces between aggregates and the intraparticulate porosity of diatom debris increase the porosity of the seafloor sediments, and affect other geotechnical properties. The correlation analysis of sound velocity and geotechnical properties shows that the correlation of sound velocity with porosity and wet bulk density is extreme significant, while the correlation of sound velocity with clay content, mean grain size and organic content is not significant. The regression equations between porosity, wet bulk density and sound velocity based on best-fit polynomial are given.     

Geotechnical Surveys Indicate Potential Offshore Port Facilities off Subarnarekha Outflow Sector,Orissa, India

Deficiency in major port facilities off Orissa prompted the State Government to promote development of a port facility in the Subarnarekha river outflow sector utilizing the inland water network of Orissa coast canal and Contai canal. Marine and Coastal Surveys Division of Geological Survey of India carried out geotechnical feasibility surveys to explore possibilities of setting up a port facility in this sector. Bathymetry reveals smooth, parallel isobaths signifying gentle slopes with varying gradients. The East-West profile delineates a natural channel that could be dredged into a navigational channel. Sediments are dominantly sandy silt marginally varying either into silty sand or clayey silt. Geotechnical characteristics suggest a stable substratum ideal for developing the offshore port facility. Side-scan sonar surveys reveal a seafloor bereft of any hazardous rocks or reefs. The surveys espouse immense potential for developing this sector into an offshore port facility.     

厦门吴冠海岸潮间带沉积物粒度特征及其沉积动力学涵义

潮滩沉积物的粒度参数可以用来反映沉积物沉积的水动力、沉积物来源和沉积物搬运趋势等环境信息。对厦门吴冠潮间带35个表层样的粒度资料进行分析的结果表明,研究区沉积物类型以黏土质粉砂和粉砂质砂为主;沉积物主要来源于海岸侵蚀物质的输入,随着沉积物向海方向搬运,沉积物粒度参数表现出有规律的变化趋势,即由岸向海粒径具有细化趋势,分选程度变好。与开敞海岸淤泥质潮滩粒度特征相比,研究区的粒度参数组合特征具有明显差异,这可能是由于水动力条件的差异引起的。     

东海油气资源区海底沉积物的工程地质特征

根据“灾害地质环境调查与评价”项目1995年11月、1996年6月和1998年10月的航次调查及随后的沉积物样品的试验室分析资料，从物理性质和力学特征各方面对东海油气资源区海底沉积物进行了综合工程地质特征研究。发现本区沉积物结构、剪切特征、含水量和液塑限随深度的变化而变化；本区海底沉积物类型既分布有中砂、细砂和粉砂3种砂性土，也分布有淤泥、淤泥质粘土和粘质粉土3种粘性土，沉积物的物理力学性质与相应的土类变化相一致。     

南海东部海域表层沉积物类型的研究

南海东部海域表层沉积物可被分为11种类型:含岩块砾石黏土质粉砂、贝壳珊瑚砂、黏土质粉砂、钙质黏土、钙质软泥、有孔虫砂、深海黏土、含铁锰微粒粉砂质黏土、硅质黏土、含火山灰硅质黏土、含火山灰粉砂质黏土.这些类型按物源和成因可被分为陆源碎屑、钙质碎屑和硅质碎屑、火山碎屑3大类型,其中陆源碎屑分布面积约占50%,钙质碎屑占20%,硅质碎屑和火山碎屑各占15%.在物质来源、海底地形、火山作用、生物作用、水动力条件等因素影响和控制下,由于沉积环境的差异,故区内褐色类沉积物最多(60.68%),灰色类沉积物次之(38.20%),黄色类沉积物最少(1.12%).台湾省以南到17°N以北海区沉积物以陆源沉积物分布为主;巴士海峡以西海区沉积物较粗,常含砂岩块和砾石;东沙群岛以东海区钙质生物碎屑沉积丰富;中、西部海区以含铁锰微粒沉积物为主;中、南部海区水深大,主要分布硅质沉积物;南部海区、礼乐滩北缘沉积物受礼乐滩珊瑚碎屑影响大,沉积物类型为钙质软泥.     

渤海湾西岸QG01钻孔沉积物黏土矿物分布及古气候替代指标研究

对渤海湾西岸QG01钻孔12.7~17.4 m段沉积物进行了粒度测试、X射线衍射(XRD)和光释光(OSL)测年,分析了该段岩心的黏土矿物特征及其对古气候的响应。该段沉积物由砂质粉砂、粉砂质砂和黏土质粉砂组成,平均粒径介于4.11~7.79 Φ之间;黏土矿物以伊利石为主,其次为绿泥石和高岭石,蒙脱石含量最少。将伊利石结晶度(KI)和黏土矿物组合比值((伊利石+绿泥石)/(高岭石+蒙脱石))作为古气候替代指标,发现当KI与黏土矿物组合比值反映的气候变化趋势一致时,可反映气候变化特征;当KI与黏土矿物组合比值反映的气候变化趋势不一致时,沉积物来源发生改变,不能反映气候特征。     

潮流场对渤、黄、东海陆架底质分布的控制作用

运用二维潮流数学模型，模拟了渤、黄、东海陆架的M2潮汐、潮流。结果表明，渤、黄、东海陆架的潮流有强弱之分以及往复流和旋转汉之别。在此基础上，计算了8种粒径沙的湖平均悬移输沙率、潮平均推移输沙以及相应的输沙率散度。根据输沙率散度的正负，划分了海底冲刷区与淤积区。根据不同粒径泥沙输沙率散度的相对大小，确定出海底的主要底质类型为砂质沉积、粉砂质泥沉积和以粉砂为主的混合沉积。计算结果表明，海底3种主要底负类型的分布格局与海底的冲淤格局以及与输沙率矢量的发散和聚合状况基本一致。在渤、黄、东海陆架，沙脊主要在强往复流区形成，沙席主要在强或较强的旋转流区形成，泥质沉积主要在弱潮流区形成。砂质沉积、泥质沉积以及混合沉积这3种主要底质类型并非孤立存在，而是受渤、黄、东海陆架潮流场控制而形成的一个完整的潮流沉积体系。渤、黄、东海陆架的砂质沉积与泥质沉积并非残留沉积，而是潮流沉积。在没有冷涡的情况下，黄、东海陆架的典型泥质沉积在弱潮流环境中同样可以形成，因此，认为冷涡并非黄、东海陆架典型泥质沉积形成的必要条件。     

广东台山淤泥质海岸高分辨率地震资料解释

根据广东台山广海湾150km高分辨率地震资料,研究岬湾型海岸起伏多变的基底和上覆的第四纪沉积层序、沉积演化以及复杂的新构造作用。该区晚第四纪自下而上发育有5个层序：（1）滨海相杂色粘土,下部为河道充填;（2）河道冲积砂;（3）内大陆架粉砂质粘土;（4）滨海相潮坪沉积;（5）河口湾淤泥质沉积。研究区基底形态起伏较大,主要为黑云母花岗岩风化壳及少量变质岩。NNE和NEE向两组断裂系统最为发育,它们控制了盆地发展并经历了两期活动。     

Preliminary investigation of the surficial sediments in the Cap-Breton Canyon (southwest France) and the surrounding continental shelf

A total of 120 grab samples of the surficial sediments in the Cap-Breton submarine canyon and surrounding continental shelf were collected and analyzed by grain-size sieving. A Q-mode Factor Analysis was made on the grain-size data in order to define the most meaningful facies types. Four distinct lithological facies were found to exist: silt and clay, very fine sand, fine sand, and coarse sand. Comparison with previous work and a ¹⁴C date on the silt and clay facies showed that the facies are not contemporaneous. The sands and coarse sands on the shelf were emplaced during the pre-Würm and Würm regressions, and later probably reworked during the Holocene (Flandrian) transgression. The silty clays found in the canyon and on the shelf to the south are younger and represent sediments brought in as suspended load by the Adour and other nearby rivers during the Holocene (Flandrian) transgression.     

A Comparative Evaluation of the Geotechnical Index Properties of Clayey Sediments along the West Coast of India

Sediment core samples collected during geotechnical surveys along the West Coast of India in the near shore areas of Arabian Sea have generated data on the geotechnical index properties of clayey sediments up to nearly 5 m depth below seafloor. A comparative study of three sectors within themselves is attempted before carrying out a final evaluation between the sectors. Cohesive clayey sediments of Gujarat sector are comparable though widely variant in a few aspects; in the Maharashtra-Goa-Karnataka sector though, plasticity levels and clay type vary, and activity and consistency levels are quite similar. Though broadly comparable, the clayey sediments of Kerala-Tamilnadu sector have quite diverse characteristics that fail to conform to any particular pattern as each area has an exclusive set of geotechnical properties.     

闽浙沿岸沉积物的工程地质特性及其成因简析

根据闽浙沿岸沉积物的实验室分析资料,从物理性质和力学特征对海底沉积物的综合工程地质特征进行了研究,结果发现,本区沉积物以淤泥和淤泥质黏土为主,含少量细砂、粉砂、黏土和粉质黏土等,总的表现为含水率高、孔隙比大、压缩性强、塑性大和强度低。从微观结构、物质来源、物质成分、水动力条件等方面对沉积物的工程特性进行了成因分析,这些因素是造成本区沉积物工程性质不良的主要原因。     

埕北海域底质沉积物粒度分布特征及其动力环境意义

通过分析181个埕北海域底质沉积物样品的粒度资料,并应用Flemming三角图示法对研究区进行沉积动力环境分区,结果表明:研究区底质沉积物主要为粉砂质砂、砂质粉砂、粉砂和黏土质粉砂4种类型,整体上由岸向海粒度呈现细-粗-细的分布特征,且呈条带状与岸线平行;粒度相对较粗,粒径频率曲线多以单峰为主,分选中等偏差,多为正偏;沉积动力环境分区表明该海域沉积物多以悬浮和跃移为主;粒度特征和沉积动力强度以6 m和12 m等深线为轴对称分布,12 m水深等值线两侧沉积物的分布类型和运移趋势主要受季节的风浪变化控制,6 m水深等值线两侧沉积物分布和运移趋势主要受波浪破碎的紊流作用控制。     

东海油气资源区海底沉积物的工程地质特征

根据2001年6月的航次调查及随后的沉积物样品的试验室分析资料,从物理性质和力学特征各方面对东海油气资源区海底沉积物进行了综合工程地质特征研完。发现本区沉积物结构、剪切特征、含水量和液塑限随深度的变化而变化;本区海底沉积物类型既分布有中砂、细砂和粉砂3种砂性土,也分布有扮质粘土、淤泥质粘土和粘质扮土3种粘性土,沉积物的物理力学性质与相立的土类性质相一致。     

山东半岛东部南北岸典型砂质海岸沉积、地貌的横向差异及成因分析———以海阳万米海滩岸段和威海国际海水浴场岸段为例

根据2011年在海阳万米海滩岸段与威海国际海水浴场岸段调查获得的夏、冬两季海岸实测地形剖面与沉积物粒度数据,并收集相关水文资料,对南北两海岸地貌与沉积差异性进行分析,探讨了半岛东部南北岸典型砂质海岸动力环境的差异。研究结果表明,南部海岸宽广平缓,发育滩脊、滩肩、沙波纹等地貌,沉积物在水下岸坡上段以中粗砂、中细砂为主,水下岸坡以下段以粉砂、黏土质粉砂为主;北部海岸地形陡,发育滩肩陡坎、水下沙坝等地貌,沉积物以砾质砂为主。导致这些差异的动力为风、波浪、潮汐及沿岸流堆积。     

Physical and elastic properties of marine sediments off Bombay,India

Abstract

Keeping in view the paucity of information as to the nature of the marine sediments from the continental shelf adjoining the Indian subcontinent, a number of shallow seismic surveys were carried out, nearshore and offshore Bombay between 18°45'N and 21°00'N. Representative core samples preserving their natural state were also retrieved from the region in the water depths ranging from 5 to 70 m for the determination of physical properties in the laboratory. Data on the physical, acoustic, and elastic properties of the sediment cores are reported for the first time. Useful individual least‐squares relations are presented for acoustic impedance, reflection coefficient, and bulk modulus against density; for the dependence of rigidity and bulk moduli on the constrained modulus; for the association between impedance and field sediment velocity against P‐velocity; and for rigidity against Poisson's ratio. Results indicate that the bulk modulus and Young's modulus are higher for silty clay and clayey silt samples than for the clay samples. Similarly, the acoustic impedance, reflection coefficient, and constrained modulus of silty clay and clayey silt are also higher than clay. The results are found to be comparable to the North Atlantic and Bay of Bengal sediments.     

黄河口埕岛海域表层沉积物土性的区域变化及其机理分析

搜集汇总黄河口埕岛海域地质勘察资料,研究该区土性参数区域分布特征,包括分析海域内土体类别,绘制不同区域内地基承载力、标贯击数、粘粒含量、含水量、孔隙比和液塑限等值线图.研究发现,海域表层土体主要由粉土和粉质粘土组成,此外还有小面积的粉砂和淤泥质土,中部大面积地区为粉土,东南区域分布有粉质粘土和淤泥质土;地基承载力较高的区域主要分布在海域中部与西南部,海域的北部与东南部土体强度较低,并且含水量、孔隙比和液塑限也较大,土性区域变化与水深变化特性较为一致.最后分析土性区域变化机理认为,极端海况下该区土体发生液化剪切破坏,沿斜坡滑移运动一定距离后再次沉积可形成这种现象.