海洋地质学的发展现状与未来展望

近几十年来,海洋的重要性愈明显,而海洋地质学也取得了很大的发展。本文对海洋地质学的发展现状,包括海洋研究技术及基础理论的进展民政部等均作了详细的综述,并在此基础上,依据各相邻学科的发展,对其发展趋势,特别是在未来５０ａ及１００ａ望取得的进展进行了预测。     

渤海海域及邻区新构造运动特征与环境地质意义

渤海湾盆地是我国东部典型的中新生代断陷一坳陷盆地,具有拉张型盆地典型的双层结构,上下构造层间普遍发育裂后不整合面,而且在不整合事件之后出现沉降现象。在对渤海新构造研究基础上确定了渤海区域新构造运动的时间,分析了渤海海域及邻区的构造背景;从区域重力场、火山活动、断裂活动、地震等方面对该区的新构造运动特征进行分析,并阐明了新构造运动对渤海区域的环境地质意义,表明该区域新构造运动活跃以及对人类的生产生活意义重大。     

莺歌海油气资源开发区工程地质和灾害地质特征

根据单道地震、浅地层剖面、旁扫声纳和海底取样等实测资料,分析和评价了莺歌海油气资源开发区的工程地质和灾害地质环境。研究结果表明,研究区海底地形地貌较为复杂,存在潮流沙脊、侵蚀冲沟、海底沙波、麻坑、埋藏古河道和古湖泊、浅层气、埋藏珊瑚礁和滑塌断层等潜在的灾害地质因素,对海上石油平台和输油管线等工程设施构成直接或潜在的危害。根据地形、地貌和沉积物物理力学特征,将研究区划分为内陆架堆积平原区、陆架潮流沙脊区、内陆架侵蚀平原区、外陆架平原区和大陆坡区5个工程地质区。其中研究区东部的潮流沙脊区和东南部的陆坡区,海底地形复杂,活动性的潮流沙脊和断层发育,是海底工程建设的危险区,应引起高度重视。     

河流阶地的形成及其对构造与气候的意义

河流系统演化是一个堆积与切割相互作用的过程。通过对河流阶地成因的研究,指出气候成因阶地的堆积主要发生在冰期,其他时期虽有堆积,但保存下来的较少;切割作用发生在冰期一间冰期的过渡期。构造成因阶地切割作用发生的时段就是构造运动的时期,也是古河床开始废弃的时期,提出了判定不同成因河流阶地的地质学特征。气候成因阶地每一级都说明有一个或多个冰期一间冰期的旋回,构造成因阶地的每一级都表示有一期较强烈的构造事件,有些阶地是构造与气候共同作用的结果。     

PACMANUS 热液区Si-Fe-Mn 氧化物的显微结构特征及意义

用显微镜、电子探针和扫描电镜等分析技术,对2008年"KX08-973"航次中国首次在东马努斯海盆PACMANUS热液区用拖网取得的少量Si-Fe-Mn氧化物海底热液产物样品进行显微结构特征研究。研究表明,显微镜下,样品呈隐晶质结构;扫描电镜下可见已石化的硅藻;电子探针分析结果显示,Fe和Mn的分布具有明显的分带性,呈现出Si-Mn质层被Si-Fe质层包裹的特征,反应了Si-Fe-Mn氧化物的形成具有多期多阶段性特征。样品是富Si,Fe和Mn的低温热液流体直接沉淀产物。本研究结果对该区热液氧化物的进一步研究,如Si-Mn质层和Si-Fe质层中Si与Mn和Fe的化合方式、微生物在热液氧化物形成过程中的作用具有指导意义。     

游艇旅游研究进展及其启示

作为现代海洋旅游的重要组成部分,游艇旅游正随着人们收入水平的不断增长而得到蓬勃发展,引起了旅游管理者和学术界的高度关注。本文通过对国内外游艇旅游文献资料的全面检索和分析,发现国外学者对游艇旅游的研究时间较早,研究内容更加广泛和深入,主要包括游艇旅游基础概念探讨,游艇旅游需求与供给研究,游艇旅游对经济、社会文化和环境影响的研究,以及游艇旅游政府管理和协同治理研究等5个方面。而在研究方法上,国外主要采用多学科研究方法,注重实地调研和数据库的建立,通过模型构建与数理统计支撑定性描述。我国未来应不断拓展研究领域,完善游艇旅游理论和实践治理体系,借鉴国际经验探索游艇旅游本土化发展范式,并加强定量研究方法使用,以期为中国游艇旅游发展实践提供参考。     

Geology of the Edda Field Reservoir

The Edda Field, which was discovered in 1972, is located in the southern part of the Norwegian Sector of the North Sea. As in the nearby Ekofisk Field, chalk reservoir in the Danian (Lower Paleocene) and Maastrichtian (Upper Cretaceous) contain oil which originated in the Upper Jurassic organic rich shale sequence. A 15 slots drilling-production platform was installed on the basis of the results of 3 exploration appraisal wells. Seven producer wells were drilled and completed in 1979 and a production peak of about 33000 BOPD was reached in January 1980. All the development wells encountered less yield than expected and the 3 wells drilled on the southern flank of the structure were dry. Most of the characteristics of the chalk reservoir were known at that time but the existence of a pre-Maastrichtian paleo-relief in that area had not yet been established. This paleo-feature, the Lindesnes Ridge, strongly influenced the distribution and characteristics of the reservoir. Variation in initial porosity is the result of changes in sedimentation mode and rate as well as differential early cementation and mechanical compaction over the paleo-high. Differential porosity preservation is partly due to progressive infill of the trap by hydrocarbons but, as in most chalk fields, overpressure in the porous chalk layers was an important prerequisite.     

现代海洋地质学及其发展

近几十年来,海洋的重要性愈来愈明显,海洋地质学作为海洋科学中最活跃的一门科学也取得了很大的发展。对海洋地质学的研究内容、意义以及当前发展的现状和趋势作了介绍。     

Comparative mitochondrial genome analysis of Sesarmidae and its phylogenetic implications

Here, we sequenced the complete mitogenome of Parasesarma eumolpe (Brachyura: Grapsoidea: Sesarmidae) for the first time. The characteristics of this newly sequenced mitogenome were described and compared with other Sesarmidae species. The 15 646-bp mitogenome contains 13 protein-coding genes (PCGs), two ribosomal RNA genes (rRNAs), 22 transfer RNA genes (tRNAs), and an A-T rich region. All of the PCGs are initiated by the start codon ATN and terminated by the standard TAN codon or an incomplete T. The pairwise Ka/Ks ratio analysis shows that all 13 PCGs are under purifying selection, whereas the ATP8 gene is an outlier, with pairwise comparison values ranging from neutral selection (0.000) to positive selection (1.039). The gene arrangement of P. eumolpe compared with ancestral Decapoda shows the translocation of two tRNAs (tRNA-His and tRNA-Gln), which is identical to other Sesarmidae species. Phylogenetic analyses show that all Sesarmidae species are placed into one group, and the polyphyly of Eriphioidea, Ocypodoidea, and Grapsoidea is well supported. The relationship between gaps in the QIM region and the phylogeny of Sesarmidae is analyzed. It is obvious that both the G5 (the gap between Q and I) and G6 (the gap between I and M) decrease progressively with the evolution process. These results will help to better understand the genomic evolution within Sesarmidae and provide insights into the phylogeny of Brachyura.     

Comparative mitochondrial genome analysis of Varunidae and its phylogenetic implications

Complete mitochondrial genomes(mitogenomes) can indicate phylogenetic relationships, as well as useful information for gene rearrangement mechanisms and molecular evolution. Currently, the phylogenetic location of the genus Varuna(Brachyura: Varunidae) has not been well resolved mainly because of limited representatives(only two extant species). Here, we determined a new mitogenome of this genus(Varuna litterata) and added the published mitogenomes to reconstruct the phylogeny of Varunidae. The ...     

Calcareous nannoplankton in the surface sediments of the East China Sea and its environmental implications

Calcareous nannoplankton flora in the surface sediments of the East China Sea has been investigated many times based on isolated sample collections since 1980. In the present study, 73 surface sediment samples recovered from the East China Sea, extending from the estuaries to the Okinawa Trough (about 10 -2000 m in depth of water), were chosen to investigate the floral distributional pattern and to discuss in greater detail the controlling factors. Thirty-nine species were identified under polarized microscope and SEM. In general, nannoplankton abundance and diversity increase progressively with the increase of depth. In estuaries and the inner shelf nannoplankton are extremely rare. The 50 m isobath is a sharp boundary for the development of calcareous nannoplankton. Another low floral concentration is encountered at the edge of the outer shelf where Pleistocene relict sediments outcrop. The nannoflora displays a scattered distributional pattern in the Okinawa Trough. Nannoplankton of larger sizes is m     

Physical and biological response of the Arabian Sea to tropical cyclone Phyan and its implications

The response to the tropical cyclone Phyan, which developed in the eastern Arabian Sea during 9-11 November 2009, was rapid cooling of sea surface temperature (SST), enhancement of chlorophyll a and two-fold increase in net primary productivity (NPP). Cooling of SST was immediate in response to the strong wind-mixing, and the subsequent upward Ekman pumping sustained the cooling even after the dissipation of Phyan. The biological response mediated by the upward Ekman pumping driven vertical transport of subsurface nutrient showed a time lag of 3-4 days. The CO? flux to the atmosphere associated with Phyan was 0.123 Tg C, which accounted for ~85% of the total out-gassing from the eastern Arabian Sea during November. Thus, an increased occurrence of cyclones in a warming environment will lead to an enhanced biomass production and also increase in CO? out-gassing.     

中全新世以来冲绳海槽氧化还原环境重建及其气候效应

通过对位于冲绳海槽黑潮主轴流经区的GHN056-09柱状沉积物进行粒度、常微量元素、AMS 14C分析,获得了中全新世以来粒度和常微量元素随时间变化的高分辨率曲线。结果表明,6235aBP以来研究区沉积环境稳定,沉积物中MnO/Al2O3、U/Th和V/Cr等3个地球化学指标在近6235aBP以来均发生了数次不同程度的波动,大致可以划分为3个阶段：阶段1(1830aBP至今)的生产力和氧化还原程度强烈波动期、阶段2(4000~1830aBP)的低生产力和弱还原期、阶段3(6235~4000aBP)的高生产力和相对较强还原期。中全新世以来地球化学指标可共同识别出的6次极值揭示了同期的相对高生产力和较强还原状态,分别发生在R1(260aBP)、R2(1200aBP)、R3(2125aBP)、R4(2700aBP)、R5(4250aBP)和R6(5700aBP),且与海水温度和黑潮强度关系密切,揭示了中全新世以来冲绳海槽区海气相互作用的区域性响应特征。     

Seismic anisotropy surrounding South China Sea and its geodynamic implications

Several mechanisms have been proposed for the opening of the South China Sea. Here, we use SKS splitting analysis to investigate the mantle flow surrounding the South China Sea. We use a total of 23 seismic stations and 87 events. We applied spectral analysis and cluster analysis to find a stable splitting solution for each event. The main conclusions are: (1) In northern Vietnam, the NW–SE fast direction is parallel to the absolute plate motion as well as GPS observations with splitting times larger than 1 s, indicating a coupled lithosphere and mantle. In contrast, in southern Vietnam, the NE–SW fast direction suggests that the lithosphere and asthenosphere are decoupled. (2) The fast directions beneath the South China Block and central Taiwan are NE–SW and NS respectively, both parallel to surface deformations with splitting times greater than 1 s, indicating that mantle flow and surface deformation are related. (3) The observed NW–SE fast directions beneath Hainan Island reflect the India–Eurasia collision, and show no signatures of an upwelling mantle plume directly underneath Hainan Island. This implies that Hainan Island is tectonically closely related to the Red River Fault, not the South China Block. (4) In Borneo, the observed NE-SW direction is parallel to the Palawan Trench, consistent with flow associated with the inactive proto-South China Sea subduction system. The SKS splitting observations surrounding South China Sea cannot be explained by a single geologic process, with either the collision-driven extrusion model or the slab pull model fitting the data presented here.     

Evolution of Posidonia oceanica seagrass meadows and its implications for management

Results of the monitoring network of the Posidonia oceanica meadows in the Valencia region in Spain are analysed. For spatial comparison the whole data set has been analysed, however, for temporal trends we only selected stations that have been monitored at least 6 years in the period of 2002–2011 (26 stations in 13 localities).At the south of the studied area, meadows are larger, and they have higher density and covering than that in the Valencia Gulf, excluding Oropesa meadow. Monitoring of P. oceanica meadows in the Valencia region in Spain indicates that most of them are stationary or they are increasing their density and covering while no decline was observed in the studied meadows. These results indicate that there is not a general decline of P. oceanica meadows and that the decline of P. oceanica, when it has been observed in other studies, is produced by local causes that may be managed at the local level. This study also reflects the importance of long series of direct data to analyse trends in the population dynamics for slow-growing species.     

Geology and Exploration of the Manteo Prospect off North Carolina

The Manteo Prospect is located about 45 mi northeast of Cape Hatteras, North Carolina. It is a high-risk prospect with world-class potential. The 21-lease unit was approved by the Minerals Management Service (MMS) in May 1990. A suspension of operations (SOO) was issued in October 1992 by the MMS. Chevron was approved for an exploration permit for Block 510 while Mobil's plan for Block 467 was under appeal. The Baltimore Canyon Trough and the Carolina Trough are the two large and deep sedimentary basins of the Atlantic Continental Margin. The Manteo unit is at the juncture of these two sedimentary basins. The Manteo Prospect is interpreted as a reef with its overlying structural high on the seaward edge of a carbonate platform. The structure is approximately30 mi long and 3-5 mi wide. The initial exploration well will be located at the highest point on the structure. Potential source rocks for the prospect are euxinic basinal shales and black micrite as well as interior lagoonal shales associated with the reef. The geothermal gradient projected from wells in the Baltimore Canyon Trough indicates that thermally mature sediments would be encountered below 12,000 ft in the vicinity of the Manteo Prospect. Mobil estimated that the Manteo Prospect may contain as much as 5 trillion ft3 of dry natural gas. A meeting was held between the State of North Carolina, MMS, and Chevron in February 1997 to discuss the proposal for the Manteo Prospect. An additional meeting held in September concentrated on drilling technology. A well could be drilled on Block 467 or Block 510 during the year 2000. Chevron has not decided which type of drilling vessel will be employed. The potential shorebase for operations is Morehead City, North Carolina.     

尼罗河三角洲盆地油气地质特征及勘探潜力

尼罗河三角洲盆地经历了古特提斯汇聚到新特提斯裂开的被动陆缘、挤压应力为主的前陆盆地及以断裂活化作用为主的走滑盆地3个构造演化阶段。盆地发育北三角洲和南三角洲2个次盆单元,总体上贫油富气,且大多气藏位于深水区。研究区发育两套有利烃源岩：渐新统和中新统海相页岩和泥灰岩以及上白垩统黑色页岩, 有机质碳含量丰富,主要以Ⅲ型干酪根为主,主力储集层为中新统三角洲砂岩及上新统深水斜坡水道砂岩,圈闭以构造圈闭为主,油气主要沿着断层和不整合面向上部储层运移。尼罗河三角洲盆地生储盖匹配良好,是未来勘探开发的有利区块。     

Geology and Exploration of the Manteo Prospect off North Carolina

The Manteo Prospect is located about 45 mi northeast of Cape Hatteras, North Carolina. It is a high-risk prospect with world-class potential. The 21-lease unit was approved by the Minerals Management Service (MMS) in May 1990. A suspension of operations (SOO) was issued in October 1992 by the MMS. Chevron was approved for an exploration permit for Block 510 while Mobil's plan for Block 467 was under appeal. The Baltimore Canyon Trough and the Carolina Trough are the two large and deep sedimentary basins of the Atlantic Continental Margin. The Manteo unit is at the juncture of these two sedimentary basins. The Manteo Prospect is interpreted as a reef with its overlying structural high on the seaward edge of a carbonate platform. The structure is approximately30 mi long and 3-5 mi wide. The initial exploration well will be located at the highest point on the structure. Potential source rocks for the prospect are euxinic basinal shales and black micrite as well as interior lagoonal shales associated with the reef. The geothermal gradient projected from wells in the Baltimore Canyon Trough indicates that thermally mature sediments would be encountered below 12,000 ft in the vicinity of the Manteo Prospect. Mobil estimated that the Manteo Prospect may contain as much as 5 trillion ft3 of dry natural gas. A meeting was held between the State of North Carolina, MMS, and Chevron in February 1997 to discuss the proposal for the Manteo Prospect. An additional meeting held in September concentrated on drilling technology. A well could be drilled on Block 467 or Block 510 during the year 2000. Chevron has not decided which type of drilling vessel will be employed. The potential shorebase for operations is Morehead City, North Carolina.     

Trend analysis and its tectonic implications using digital bathymetric data

Abstract

Quantitative and objective trend analysis of bottom topography in order to detect the tectonic structures has become available by use of the processed Seabeam data. The following two procedures of trend analysis are introduced.

(1) Edge detection procedures in digital image processing are applicable to the analysis of topography for extraction of the lineament of tectonic structures and prediction of the existence of faults based on the digital bathymetric data.

(2) Automatic calculation of water flow using the topographic grid data is used for estimation of not only water flow pattern and volume but also the construction of the ridge or trough axis by calculating the accumulated water volume. This method was also applied to the Seabeam bathymetric data. This is quite useful for detection of offset structures and hidden faults.

These two methods are applied to the topographic data obtained in the North Fiji Basin, which is characterized by active spreading ridges. The regional tectonic structure of the North Fiji Basin was found to be expressed by the topographic trend of the central axis.