南海西北部陆架海域内孤立波特征及机理研究

关于南海北部内孤立波的研究，现在是一个国际性研究热点，以往对南海北部海域的内孤立波的研究大都集中于南海东北部，即东沙-吕宋海峡海域。对于南海西北部文昌海域的内波现场调查研究几乎是空白。2005年4-10月中科院海洋所对南海西北部陆架海域进行了现场内波观测，获得了到目前为止国内连续观测时间最长、高分辨率、高质量的温度及流场数据。本文使用此次观测所获得的海流和温度资料，主要针对观测海域内孤立波特征及机理进行分析研究，取得了若干有重要科学意义的成果,主要为: 该海域是内孤立波多发地区，其中从2005年4月中旬到6月孤立波频繁出现且振幅较大，而6月中旬到9月中旬，内孤立波的发生频率明显下降，振幅也相对较小; 内孤立波的极性也表现出明显的季节性变化特征。研究发现内孤立波的季节性变化特征是与跃层的深浅和强弱密切相关的。 在2005年9月期间观测到了一系列的大振幅内孤立波，其中在同一测站的不同天内分别发现上凸型和下凹型内孤立波。研究表明这些内孤立波极有可能是由陆架坡折处的内潮因非线性和频散效应而局地产生的。这是首次通过现场观测确认南海西北部存在上凸型并且其为局地生成的内孤立波。 进一步分析发现在2005年8月21-23日，观测到了第二模态的内孤立波，这些内孤立波是与第二模态的内潮同步发生的，在连续两天内几乎相同的时刻分别观测到第二模态的内孤立波说明这些孤立波是潮致的。 在2005年4月22-28日发现长时间的强海流现象，强海流现象发生在当地的天文潮小潮期间，沿岸方向的流速明显大于垂直于岸方向的流速，通过分析表明强海流是由当地的内潮流引起的。 根据观测的温、流数据分析了内波场对台风的响应过程及内波谱特征，发现台风对观测站位的温度场和流场结构均有显著的影响。 这些在南海西北部的新发现和新认识对推动内孤立波的产生机制和应用技术的研究具有重要的学术价值。

海洋微藻产生溶解有机物及东海溶解有机物三维荧光特征研究

本文通过胶州湾围隔实验、微藻培养实验研究了海洋微藻产生溶解有机物的三维荧光特性，并初步利用经验正交函数对三维荧光光谱图进行了主成分分析，通过东海取样研究了东海荧光溶解有机物的时空分布特征，并对荧光溶解有机物的来源进行了分析。得到了一些初步结论： 胶州湾围隔实验中不同营养盐培养结果表明浮游植物可产生类蛋白和类腐殖质荧光，类蛋白荧光峰由类酪氨酸(tyrosine-like)荧光峰和类色氨酸(tryptophan-like)荧光峰组成，主要位置为Exmax/Emmax=270nm/290~310nm，Exmax/Emmax= 270~290/320~350的荧光峰强度比较弱；在Exmax/Emmax=250~260/380~480nm(A峰)、Exmax/Emmax=310~320/380~420nm(C峰)和Exmax/Emmax=330~350/420~480nm(M峰)位置均出现零散的类腐殖质荧光峰，其中以A峰为主。类酪氨酸荧光强度明显高于类腐殖质荧光强度。浮游植物量降低时，类酪氨酸荧光强度与叶绿素a浓度呈明显的负相关。硅藻和甲藻产生的类酪氨酸和类色氨酸荧光强度之间具有较好的相关性，两者来源相似, 并且甲藻与硅藻相比能够产生更多的类蛋白荧光物质。不同环境下类腐殖质混合物的组分比例不同，甲藻生长环境下相对于硅藻具有较低的A:C比值。 在实验室培养中肋骨条藻（Skeletonema costatum）、塔玛亚历山大藻（Alexandrium tamarense）、微小亚历山大藻（Alexandrium mimutum）、锥状斯氏藻（Scrippsiella trochoidea）、东海原甲藻（Prorocentrum donghaiense）及海洋原甲藻（Prorocentrum micans）的实验结果表明，微藻在生长过程中产生出荧光溶解有机物，中肋骨条藻为代表的硅藻主要产生类腐殖质荧光物质，而甲藻在指数增长期主要产生类蛋白荧光物质。进入消亡期后类蛋白荧光和类腐殖质荧光强度迅速增大，原因可能是衰老、死亡藻细胞的破碎释放出大量的荧光有机物质所致，此外还有细菌对非荧光有机物进一步降解。塔玛亚历山大藻、微小亚历山大藻、东海原甲藻及海洋原甲藻的类蛋白荧光强度在消亡后期由于细菌降解或光降解等因素而降低。同属微藻产生的荧光物质相似，例如塔玛亚历山大藻与微小亚历山藻、东海原甲藻与海洋原甲藻，但具体荧光峰位置有所不同。利用经验正交函数能够对三维荧光光谱谱图进行主成份分析。 在利用三维荧光光谱法研究长江口海域台风前后不同站位荧光溶解有机物荧光特性及分布特征的结果表明，长江口海区主要的荧光溶解有机物荧光峰为T峰、S峰和A峰。风前和风后的类色氨酸分别来源于相似物质。风前，在表层浮游植物能够产生类蛋白荧光物质，而底层类蛋白荧光物质不受浮游植物的影响，长江冲淡水能够带来部分类蛋白荧光物质；表层的类腐殖质不受浮游植物的影响，而底层的浮游植物在降解过程中能够产生一部分类腐殖质，并且长江冲淡水对表层和底层的类腐殖质来源均有很大贡献。风后，表层的类色氨酸与叶绿素a浓度不呈相关性，而底层却呈正相关，另外表层和底层的类色氨酸均受到长江冲淡水的影响；表层和底层的类腐殖质与叶绿素a均没有相关性，但受陆源影响显著，长江冲淡水能带来类腐殖质。

东海陆架细颗粒沉积物组成分布特征及其物源指示

沉积物由源到汇的搬运过程是整个地球物质循环的一个重要环节；在这一过 程中，载有当时主要地质历史事件信息的沉积物汇入海洋；但因受到复杂的海洋 环境的改造以及人类活动的影响，这些信息的表现形式可能已经发生了改变。因 此，如何反演上述地质历史进程、预测其发展变化，成为海洋地质学研究的重要 内容。 本文通过对长江、黄河、钱塘江、瓯江和闽江等5 条中国东部入海河流沉积 物稀土元素（REE），以及东海陆架表层细颗粒沉积物中粘土矿物、元素组成等 的综合研究，借助数学统计，分析探讨了陆架区细颗粒沉积的物质来源、现代长 江入海沉积物在东海陆架区的影响范围，以及由源到汇输运过程中沉积物示踪标 记数值改变等问题。 长江口沉积物REE 在<2μm 和2-31μm 粒级中较富集，但全岩REE 总量 （ΣREE）在数值上受物质组成占优的2-31μm 粒级控制；因粉砂对水动力环境的 反映最为敏感，在输运过程中该粒级组成不稳定即可引起全岩REE 含量的变化。 全岩REE 含量在河口附近较高，在东海陆架区由岸向海有减小的趋势，轻重稀 土比值自28°N 向南有增大的趋势。在长江口和东海内陆架，水动力对沉积物的 作用可能对REE 含量空间分布模式的形成起着重要作用。 长江、黄河等五条河流沉积物的ΣREE、轻重稀土含量比值（L/HREE）等 参数在数值分布上有所不同。但陆架复杂的水动力环境可造成砂粒级沉积物中轻 重矿物分异、粉砂与粘土粒级间级配调整，并由此引起沉积物中REE 含量的数 值变化。此时，单由砂、粉砂等较大粒级区间内REE 含量的分布已经不能准确 判断沉积物物源的改变。在长期稳定的陆架沉积环境下，借助沉积物输运模型， 有可能解决因水动力因素造成的REE 分布变化的问题。 东海陆架区未能发现在数值上绝对不变的示踪标记物，而引起示踪指标变化 的决定性因素尚未明确。因此，本文采用前人研究中可以明显区分沉积物河流来 源的指标，借助统计学中聚类和判别分析方法定性地判断东海陆架区沉积物常、 微量元素和粘土矿物的可能物源。 根据四种主要粘土矿物相对含量与细颗粒沉积物微量元素的构成特征，推断 研究区表层类长江细颗粒物质主要为现代长江入海沉积物；它们主要分布在东海陆架中、西部区域，在中部可以跨越123°E 向东继续延伸，在北部可以达到外陆 架的东部边缘。研究区东侧、东海外陆架边缘表层细颗粒沉积物的微量元素构成 与现代长江沉积物存在较大差异，具有类黄河沉积物的性质，可能是在更新世冰 期干冷气候下形成的产物与现代河流入海细颗粒的混合物。

中国近海和西北太平洋温跃层时空变化分析、模拟及预报

温度跃层是反映海洋温度场的重要物理特性指标，对水下通讯、潜艇活动及渔业养殖、捕捞等有重要影响。本文利用中国科学院海洋研究所“中国海洋科学数据库”在中国近海及西北太平洋（110ºE-140ºE,10ºN-40ºN）的多年历史资料（1930-2002年，510143站次），基于一种改进的温跃层判定方法，分析了该海域温跃层特征量的时空分布状况。同时利用Princeton Ocean Model(POM)，对中国近海，特别是东南沿海的水文结构进行了模拟，研究了海洋水文环境对逆温跃层的影响。最后根据历史海温观测资料，利用EOF分解统计技术，提出了一种适于我国近海及毗邻海域，基于现场有限层实测海温数据，快速重构海洋水温垂直结构的统计预报方法，以达到对现场温跃层的快速估计。 历史资料分析结果表明，受太阳辐射和风应力的影响，20°N以北研究海域，温跃层季节变化明显，夏季温跃层最浅、最强，冬季相反，温跃层厚度的相位明显滞后于其他变量，其在春季最薄、秋季最厚。12月份到翌年3月份，渤、黄及东海西岸，呈无跃层结构，西北太平洋部分海域从1月到3月份，也基本无跃层结构。在黄海西和东岸以及台湾海峡附近的浅滩海域，由于风力搅拌和潮混合作用，温跃层出现概率常年较低。夏季，海水层化现象在近海陆架海域得到了加强，陆架海域温跃层强度季节性变化幅度(0.31°C/m)明显大于深水区(约0.05°C/m)，而前者温跃层深度和厚度的季节性变化幅度小于后者。20°N以南研究海域，温跃层季节变化不明显。逆温跃层主要出现在冬、春季节（10月-翌年5月）。受长江冲淡水和台湾暖流的影响，东南沿海区域逆温跃层持续时间最长，出现概率最大，而在山东半岛北及东沿岸、朝鲜半岛西及北岸，逆温跃层消长过程似乎和黄海暖流有关。多温跃层结构常年出现于北赤道流及对马暖流区。在黑潮入侵黄、东、南海的区域，多温跃层呈现明显不同的季节变化。在黄海中部，春季多温跃层发生概率高于夏季和秋季，在东海西部，多跃层主要出现在夏季，在南海北部，冬季和春季多温跃层发生概率大于夏季和秋季。这些变化可能主要受海表面温度变化和风力驱动的表层流的影响。 利用Princeton Ocean Model(POM)，对中国东南沿海逆温跃层结构进行了模拟，模拟结果显示，长江冲淡水的季节性变化以及夏季转向与实际结果符合较好，基本再现了渤、黄、东海海域主要的环流、温盐场以及逆温跃层的分布特征和季节变化。通过数值实验发现，若无长江、黄河淡水输入，则在整个研究海域基本无逆温跃层出现，因此陆源淡水可能是河口附近逆温跃层出现的基本因素之一。长江以及暖流（黑潮和台湾暖流）流量的增加，均可在不同程度上使逆温跃层出现概率及强度、深度和厚度增加，且暖流的影响更加明显。长江对东南沿海逆温跃层的出现，特别是秋季到冬季初期，有明显的影响，使长江口海域逆温跃层位置偏向东南。暖流对于中国东南沿海的逆温跃层结构，特别是初春时期，有较大影响，使长江口海域的逆温跃层位置向东北偏移。 通过对温跃层长期变化分析得出，黄海冷水团区域，夏季温跃层强度存在3.8年左右的年际变化及18.9年左右的年代际变化，此变化可能主要表现为对当年夏季和前冬东亚地区大气气温的热力响应。东海冷涡区域，夏季温跃层强度存在3.7年的年际变化，在El Nino年为正的强度异常，其可能主要受局地气旋式大气环流变异所影响。谱分析同时表明，该海域夏季温跃层强度还存在33.2年的年代际变化，上世纪70年代中期，温跃层强度由弱转强，而此变化可能与黑潮流量的年代际变化有关。 海洋水温垂直结构的统计预报结果显示，EOF分解的前四个主分量即能够解释原空间点温度距平总方差的95%以上，以海洋表层附近观测资料求解的特征系数推断温度垂直结构分布的结果最稳定。利用东海陆架区、南海深水区和台湾周边海域三个不同区域的实测CTD样本廓线资料，对重构模型的检验结果表明，重构与实测廓线的相关程度超过95%的置信水平。三个区重构与实测温度廓线值的平均误差分别为0.69℃，0.52℃，1.18℃，平均重构廓线误差小于平均气候偏差，统计模式可以很好的估算温度廓线垂直结构。东海陆架海区温度垂直重构廓线与CTD观测廓线获得的温跃层结果对比表明，重构温跃层上界、下界深度和强度的平均绝对误差分别为1.51m、1.36m和0.17℃/m，它们的平均相对误差分别为24.7%、8.9%和22.6%，虽然温跃层深度和强度的平均相对误差较大，但其绝对误差量值较小。而在南海海区，模型重构温跃层上界、下界和强度的平均绝对预报误差分别为4.1m、27.7m和0.007℃/m，它们的平均相对误差分别为16.1%、16.8%和9.5%，重构温跃层各特征值的平均相对误差都在20%以内。虽然南海区温跃层下界深度平均绝对预报误差较大，但相对于温跃层下界深度的空间尺度变化而言（平均温跃层下界深度为168m），平均相对误差仅为16.8%。因此说模型重构的温度廓线可以达到对我国陆架海域、深水区温跃层的较好估算。 基于对历史水文温度廓线观测资料的分析及自主温跃层统计预报模型，研制了实时可利用微机简单、快捷地进行温跃层估算及查询的可视化系统，这是迄今进行大范围海域温跃层统计与实时预报研究的较系统成果。

Estuarine nutrient loading affects phytoplankton growth and microzooplankton grazing at two contrasting sites in Hong Kong coastal waters

To investigate the effects of enhanced nutrient loading in estuarine waters on phytoplankton growth and microzooplankton grazing, we conducted monthly dilution experiments at 2 stations in Hong Kong coastal waters with contrasting trophic conditions. The western estuarine station (WE) near the Pearl River estuary is strongly influenced by freshwater discharge, while the eastern oceanic station (EO) is mostly affected by the South China Sea. Growth rates of phytoplankton were often limited by nutrients at EO, while nutrient limitation of phytoplankton growth seldom Occurred at WE due to the high level of nutrients delivered by the Pearl River, especially in the summer rainy season. Higher chlorophyll a, microzooplankton biomass, phytoplankton growth and microzooplankton grazing rates were found at WE than at EO. However, the increase in chlorophyll greatly exceeded the increase in phytoplankton growth rate, reflecting different response relationships to nutrient availability. Strong seasonality was observed at both stations, with temperature being an important factor affecting both phytoplankton growth and microzooplankton grazing rates. Picophytoplankton, especially Synechococcus, also exhibited great seasonality at EO, with summer abundances being 2 or 3 orders of magnitude higher than those during winter, Our results confirm that in eutrophic coastal environments, microzooplankton grazing is a dominant loss pathway for phytoplankton, accounting for the utilization of >50%, of primary production on average.

Nutrients in the Changjiang River

N, P and SiO3-Si in the Changjiang mainstream and its major tributaries and lakes were investigated in the dry season from November to December, 1997, and in the flood season in August and October, 1998. An even distribution of SiO3-Si was found along the Changjiang River. However, the concentrations of total nitrogen, total dissolved nitrogen, dissolved inorganic nitrogen, nitrate and total phosphorus, total particulate phosphorus increased notably in the upper reaches, which reflected an increasing impact from human activities. Those concentrations in the middle and lower reaches of the Changjiang River were relatively constant. Dissolved N was the major form of N and the particulate P was the major form of P in the Changjiang River. The molar ratio of dissolved N to dissolved P was extremely high (192.5-317.5), while that of the particulate form was low (5.6-37.7). High N/P ratio reflected a significant input of anthropogenic N such as N from precipitation and N lost from water and soil etc. Dissolved N and P was in a quasi-equilibrium state in the process from precipitate to the river. In the turbid river water, light limitation, rather than P limitation, seemed more likely to be a controlling factor for the growth of phytoplankton. A positive linear correlationship between the concentration of dissolved N and the river's runoff was found, mainly in the upper reaches, which was related to the non-point sources of N. Over the past decades, N concentration has greatly increased, but the change of P concentration was not as significant as N. The nutrient fluxes of the Changjiang mainstream and tributaries were estimated, and the result showed that the nutrient fluxes were mainly controlled by the runoff, of which more than a half came from the tributaries. These investigations carried out before water storage of the Three Gorges Dam will supply a scientific base for studying the influences of the Three Gorges Dam on the ecology and environment of the Changjiang River and its estuary.

Marine bacteria associated with marine macroorganisms: the potential antimicrobial resources

In order to explore marine microorganisms with medical potential, marine bacteria were isolated from seawater, sediment, marine invertebrates and seaweeds collected from different coastal areas of the China Sea. The antimicrobial activities of these bacteria were investigated. Ethyl acetate extracts of marine bacterial fermentation were screened for antimicrobial activities using the method of agar diffusion. The results showed that 42 strains of the isolates have antimicrobial activity. The proportion of active bacteria associated with marine invertebrates (20%) and seaweeds (11%) is higher than that isolated from seawater (7%) and sediment (5%). The active marine bacteria were assigned to the genera Alteromonas, Pseudomonas, Bacillus and Flavobacterium. The TLC autobiographic overlay assay implied that the antimicrobial metabolites produced by four strains with wide antimicrobial spectrum were different. Due to a competitive role for space and nutrient, the marine bacteria associated with marine macroorganisms (invertebrates and seaweeds) could produce more antibiotic substances. These marine bacteria were expected to be potential resources of natural antibiotic products.

Dynamics of dimethylsulfide and dimethylsulfoniopropionate produced by phytoplankton in the Chinese seas - Distribution patterns and affecting factors

Distribution of dimethylsulfide (DMS) and/or particulate dimethylsulfoniopropionate (DMSPp) concentrations in the Jiaozhou Bay, Zhifu Bay and East China Sea were investigated during the period of 1994 - 1998. Both DMS and DMSPp levels showed remarkable temporal and spatial variations. High values occurred in the coastal or shelf waters and low values in the offshore waters. The highest levels were observed in spring or summer and lowest in autumn. DMS or DMSPp distribution patterns were associated with water mass on a large geographical scale, while biological and chemical factors were more likely influential on smaller-scale variations. Diatoms could play an important role in total DMS or DMSPp abundance in coastal waters. Nitrate was found to have a two-phase relationship with DMSPp concentrations: positive when nitrate concentration was lower than 1 mumol/L, and negative when it was above. Anthropogenic factors such as sewage input and aquaculture also showed influences on DMS or DMSPp concentration.

Responses of a coastal phytoplankton community to increased nutrient input from the Changjiang (Yangtze) River

Nutrient input from the Changjiang River (Yangtze River) has been increasing dramatically since the 1960s. At the mouth of the Changjiang River, the nitrate concentration has increased about three-fold in 40 years, from 20.5 mu mol/L in the 1960s to 59.1 mu mol/L in the 1980s and to 80.6 mu mol/L in 1990-2004. Phosphate concentration increased by a factor of 30%, from 0.59 mu mol/L in the 1980s to 0.77 mu mol/L in 1990-2004. The increasing nitrate input has arisen mostly from the mid and lower reaches of the Changjiang River, where the river meets one of the most strongly developed agriculture areas in China. Responses of the coastal phytoplankton community to the increasing nutrient inputs are also seen in the available monitoring data. First, a trend of increasing phytoplankton standing stock from 1984 to 2002 appeared in the Changjiang River estuary and adjacent coastal waters, especially in late spring. Secondly, the proportion of diatoms in the whole phytoplankton community showed a decreasing trend from about 85% in 1984 to about 60% in 2000. Finally, red tides/harmful algal blooms increased dramatically in this area in terms of both number and scale. About 30-80 red tide events were recorded each year from 2000 to 2005 in the East China Sea. The scale of some blooms has been in excess of 10,000 km(2). (c) 2008 Elsevier Ltd. All rights reserved.

南海大陆边缘地壳结构与盆地形成机制--以珠江口－琼东南盆地为例

South China Sea is located in the convergence of Eurasian plate, the Pacific Ocean plate and Indian Ocean-Australia plate. The total area is about 3,500,000 km2, the geologic structure is complicated, and the structure line cut off reciprocal is the marginal sea taking form by that the seafloor spreads during the middle Oligocene. South China Sea continental margin have developed more than 10 large oil-gas bearing basins and a number of medium-small sized basins. These basins contain abundant mineral resources such as oil & gas. The marginal deepwater area in the north part of South China Sea has become our country’s strategic energy prospecting frontier. The deepwater area of Zhujiangkou and Qiongdongnan basins is the research target in this thesis. The thesis studied deep structure and the earth dynamics of the north part of South China Sea margin, and these researches provide scientific basis for oil-gas resources strategic investigation and valuation in deepwater sea area of north part slope of South China Sea. In order to develop the research of rebuilding velocities and density architecture of earth shell in region of interest, in marginal deepwater area in the north part of South China, we adopted 14 long-cable seismic reflection profile data of 3556.41 kilometers in total, the gravity measurement data along profiles (3851.44 kilometers in total), the magnetic observation along profiles (3838.4 kilometers in total) and depth measurement along profile, the logging data of 11 wells in project, the interpreted fault parameter and preexisting geologic and geophysical research achievement. This thesis has carried out concretely studying research as follows: 1. Overlay-velocity data sampling and analysis, interval velocity calculation, time-depth conversion, model building of earth shell velocity and layering character of earth shell are studied on 14 deep sections. Velocity structure in region of interest has revealed: Changchang is the sag with thinnest crust in Qiongdongnan basin; the sedimentary thickness lowers gradually from north to south, and the thickness change from west to east is milder. The sags’ sedimentary velocities in Qiongdongnan basin have obvious demarcation. The velocity of the 8000 meters sedimentary rocks is 4700 m/s in Shunde sag and Baiyun sag, and is the lowest; at that depth, the velocity very different in Liwan sag and Baiyun sag, which is about 800m/s. 2. Extracting gravity data and building of initial crust density model along the section; With Bouguer gravity anomaly data as constraint, revising density distributes of initial model, and building the crust density model. 3. With crust velocity and density as constraint, correcting the effect of thermobaric field and constructing constitution structure of rock in region of interest. By this research, we known that rocks in Zhujiangkou upper crustal layer are chiefly granite-gneiss, quartzite, granodiorite and basalt, however, rocks in Qiongdongnan basin upper earth shell are chiefly composed of granite-gneiss, quartzite, granodiorite, diorite and basalt. 4. Synthetically crust velocity and density structure, gaining expanding factor on crust and entire crust along section. The result is indicated: the expanding factor in every sag rises from northwest to southeast, which have reflected thinning characteristic of crust from continent to ocean. Intra-crustal deformation degree in Changchang and Ledong-Lingshui sag is bigger than that in Songnan-Baodao sag. Entire crust extension factor in Changchang and Songnan-Baodao sag is greater than that in Ledong-Lingshui sag, which can make an explanation of frequently event and longer heating process in middle-east of Qiongdongnan basin. 5. Synthesize multidisciplinary information to discuss the earth dynamics significance of discordogenic seismic profile in deepwater area of Zhujiangkou and Qiongdongnan basins.

多尺度分解与相位反褶积提高海上地震资料分辨率和信噪比

Offshore seismic exploration is full of high investment and risk. And there are many problems, such as multiple. The technology of high resolution and high S/N ratio on marine seismic data processing is becoming an important project. In this paper, the technology of multi-scale decomposition on both prestack and poststack seismic data based on wavelet and Hilbert-Huang transform and the theory of phase deconvolution is proposed by analysis of marine seismic exploration, investigation and study of literatures, and integration of current mainstream and emerging technology. Related algorithms are studied. The Pyramid algorithm of decomposition and reconstruction had been given by the Mallat algorithm of discrete wavelet transform In this paper, it is introduced into seismic data processing, the validity is shown by test with field data. The main idea of Hilbert-Huang transform is the empirical mode decomposition with which any complicated data set can be decomposed into a finite and often small number of intrinsic mode functions that admit well-behaved Hilbert transform. After the decomposition, a analytical signal is constructed by Hilbert transform, from which the instantaneous frequency and amplitude can be obtained. And then, Hilbert spectrum. This decomposition method is adaptive and highly efficient. Since the decomposition is based on the local characteristics of the time scale of data, it is applicable to nonlinear and non-stationary processes. The phenomenons of fitting overshoot and undershoot and end swings are analyzed in Hilbert-Huang transform. And these phenomenons are eliminated by effective method which is studied in the paper. The technology of multi-scale decomposition on both prestack and poststack seismic data can realize the amplitude preserved processing, enhance the seismic data resolution greatly, and overcome the problem that different frequency components can not restore amplitude properly uniformly in the conventional method. The method of phase deconvolution, which has overcome the minimum phase limitation in traditional deconvolution, approached the base fact well that the seismic wavelet is phase mixed in practical application. And a more reliable result will be given by this method. In the applied research, the high resolution relative amplitude preserved processing result has been obtained by careful analysis and research with the application of the methods mentioned above in seismic data processing in four different target areas of China Sea. Finally, a set of processing flow and method system was formed in the paper, which has been carried on in the application in the actual production process and has made the good progress and the huge economic benefit.

湖南、广西泥盆纪硅岩地球化学与沉积构造背景

During the Devonian, a complicated carbonate platform-basin configuration was created through transtensional rifting in the context of opening of Devonian South China Sea; extensive bedded chert, commonly interbedded with tuffaceous beds, occurred in the narrow, elongate interplatform basins (or troughs) in South China, where they occurred earlier (Early Devonian) in southern Guangxi and later (early Late Devonian) in northern Guangxi-south central Hunan. In order to unravel the origin and distribution of the bedded chert successions, and their relationships to basement faulting activities during the opening of the Devonian South China Sea, studies of element (major, minor and REE) geochemistry and Rb-Sr, Sm-Nd isotopic systematics are carried out upon the chert deposits. These chert deposits commonly have high SiO2 contents and (average 94.01%) and low TFe2O3 (average 0.55%), together with other geochemical parameters, suggestive of both biogenic and hydrothermal origins. However, Fe/Ti ratio are high along the elongate interplatform basins(troughs) to the northwest along Wuxiangling-Zhaisha-Chengbu, and to the southeast along Xiaodong-Mugui-Xinpu, suggesting relatively intense hydrothermal activities there. They generally contain very low total REE contents (∑REE average 31.21ug/g) with mediate negative Ce anomalies (mean Ce/Ce*=0.83) and low Lan/Cen values (average 1.64), indicating an overall continental margin basin where they precipitated. The northward increases in Ce/Ce* values, particularly along the elongate troughs bounded both to the east and west of the Guangxi-Huanan rift basin, suggest a northward enhancement of terrigenous influences, thereby reflecting a gradual northward propagation of open marine setting. Generally low positive Eu anomalies in the chert, except for the apparently high Eu anomalies in the chert from Chengbu (Eu/Eu* up to 4.6), suggest mild hydrothermal venting activities in general, except for those at Chengbu. The initial 87Sr/86Sr (0) ratios of chert generally vary from 0.712000 to 0.73000 , suggesting influences both from terrigenous influx and seawater. The Nd isotopic model ages (tDM or t2DM) and initial εNd (0) values of chert vary mostly from 1.5 to 2.1 Ga, and from –16 to –21, respectively, implying that the silica sources were derived from the provenances of the Palaeoproterozoic crust relics at depth. The high εNd (0) values of chert (-0.22 to 14.7) in some localities, mostly along the elongate troughs, suggest that silica sources may have been derived from deeper-seated mantle, being channeled through the interplate boundary fault zones extending downwards to the mantle. At Wuxiangling, Nanning, chert occurs extensively from the Emsian through the Frasnian strata, both U/Th ratios and tDM ages of chert reached up to a maximum in the early Frasnian corresponding to the extensive development of chert in South China, pointing to a maximum extensional stage of Devonian South China basin, which is supported by the Ce/Ce* values as is opposed to the previous datasets as the coeval minimum values.

南海北部陆缘深水区构造－热演化与烃源岩成熟度史研究

Abstract In order to provide basic data for evaluation of the petroleum potential in the deep water area of the northern margin of the South China Sea (SCS), present-day thermal regime and basin tectonothermal evolution are reconstructed and the maturation history of the Cenozoic major source rocks in the study area is derived. The present-day geothermal regime in the deep water area of the northern margin of SCS is defined according to the geothermal gradient, thermal properties and heat flow data. Tectonic subsidence history is reconstructed based on borehole and seismic data, and accordingly the stretching episodes are determined from the subsidence pattern. Heat flow history in the deep water area of the northern margin of SCS is estimated on a finite time, laterally non-uniform and multi-episode stretching model. Maturation history of the main source rocks in the study area is estimated through EASYRo% kinetic model and thermal history, and the potential of petroleum in the deep water area of the northern margin of SCS is evaluated based on the data above. The results show that the present-day geothermal regime in the deep water area of the northern margin of SCS is characterized by “hot basin” with high geothermal gradient (39.1±7.4℃/km) and high heat flow (77.5±14.8 mW/m2), and that the Qiongdongnan Basin (QDNB) underwent three stretching episodes and consequently suffered three heating episodes (Eocene, Oligocene and Pliocene time) with highest paleo-heat flow of 65～90 mW/m2 at the end of the Pliocene, that the Pearl River Mouth Basin (PRMB) two stretching and two heating episodes (Eocene, Oligocene time) with highest paleo-heat flow of 60～70 mW/m2 at the end of the Oligocene, and that the source rocks matured drastically responding to the heating episodes. There are four hydrocarbon generation kitchens in the deep water area of the northern margin of SCS which are favor of its bright petroleum perspective. Tectonothermal analysis indicates that the present-day geothermal regime which is characterized with “hot basin” in the deep water area of the PRMB resulted mainly from the Cenozoic stretching as well as faulting and magmatic activities during the Neotectonic period, and that the Pliocene heating episode of the QDNB is coupled with the transition from sinistral to dextral gliding of the Red Rive fault, and that the deep water basins in the northern margin of SCS are typical of multiple rifting which caused multi-episode heating process.

泥河湾盆地大长梁剖面岩石磁学和环境磁学研究

The fluvio-lacustrine sequence in the Nihewan Basin is an important archive of late Pliocene-Pleistocene climate and environment changes in temperate northern China, which provides excellent sources of early human settlements in high latitude East Asia. The recent years have witnessed a considerable progress in the paleomagnetic dating of its stratigraphy, which has notably increased our understanding of a series of important issues such as the early human occupation in the Old World, the infilling history of the Nihewan Basin, and the chronological sequence of the Nihewan faunas. Up to now, the long-term paleoenvironmental changes directly retrieved from this basin, which might influence the evolution and expansion of early humans in the Nihewan Basin, are still poorly constrained, although several paleoclimatic records have been retrieved from this area. In this study, a combined mineral-magnetic and geochemical investigation was carried out on the fluvio-lacustrine sequence from the Dachangliang section at the eastern margin of the basin in order to reveal its rock magnetic and environmental magnetic characteristics and its implications for early human evolution in East Asia. The major findings and conclusions are listed as the following: First, there is an increased cooling coupled with an intensified aridification recorded in the fluvio-lacustrine sequence of the Dachangliang section. The cooling is related to an up-section decrease in propensity to chemical weathering as inferred from an increase in low-field susceptibility after cycling to 700 °C. Close to 700 °C, reacting chlorite is providing the iron source for newly formed very fine-grained ferrimagnetic minerals which enhances the susceptibility signal. The reactivity of chlorite after annealing at temperatures above 600 °C is documented with X-ray diffraction. Second, degrees of chemical weathering in the Nihewan Basin are further estimated by clay mineralogy (i.e. chlorite and illite contents and chlorite/illite ratio) and a series of major element proxies (i.e. Na2O/Al2O3 versus K2O/Al2O3 diagram, Al2O3-(CaO + Na2O)-K2O ternary diagram (A-CN-K), chemical index of alteration (CIA), (CaO + Na2O + MgO)/TiO2, (CaO + Na2O + MgO + K2O)/(TiO2 + Al2O3), CaO/Al2O3 and CaO/TiO2). The up-section decrease in propensity to chemical weathering suggested by the aforementioned rock mangetic measurement is further confirmed by these geochemical analyses. Combining the chemical weathering records from the Nihewan Basin, Chinese Loess Plateau, South China Sea and eastern China, we find that the consecutive decreasing trend in chemical weathering intensity during the late Cenozoic is ubiquitous across China. This pattern may result from a long-term decreasing East Asian summer monsoon and increasing East Asian winter monsoon, and thus a consecutive increasing of aridification and cooling in Asia during the Quaternary. Furthermore, the chemical weathering intensity increased from South China to North China during the Quaternary, in line with the decreasing East Asian summer monsoon and increasing East Asian winter monsoon and thus the gradually intensified aridification and cooling from South China to North China. Third, a combined mineral-magnetic and geochemical investigation provides evidences that the large-amplitude alterations of concentration of magnetic minerals mainly result from preservation/dissolution cycles of detrital magnetic minerals in alternately oxic and anoxic depositional environments. The preservation/dissolution model implies that the high-magnetic and low-magnetic cycles of this sedimentary sequence represent glacial and interglacial climate cycles, respectively. This contribute significnatly to our understanding of the link between climate and magnetic properties. Finally, the paleoclimatic implications of these rock magnetic and geochemical characteristics significantly increase our understanding of the general setting of early humans in high northern latitude in East Asia. We propose that the cold and dry climate may have contributed significantly to the expansion and adaptation of early humans, rather than bringing hardship, as is often thought. The relationship between magnetic properties and climate possibly provides valuable information on the climatic context of the Paleolithic sites in the basin, especially whether the occupation occurred during an interglacial or glacial period.

南海张裂大陆边缘数值模拟研究

The South China Sea (SCS) is one of the largest marginal seas in the western Pacific, which is located at the junction of Eurasian plate, Pacific plate and Indian-Australian plate. It was formed by continent breakup and sea-floor spreading in Cenozoic. The complicated interaction among the three major plates made tectonic movement complex and geological phenomena very rich in this area. The SCS is an ideal place to study the formation and evolution of rifted continental margin and sea-floor spreading since it is old enough to have experienced the major stages of the basin evolution but still young enough to have preserved its original nature. As the demand for energy grows day by day in our country, the deep water region of the northern continental margin in the SCS has become a focus of oil and gas exploration because of its huge hydrocarbon potential. Therefore, to study the rifted continental margin of the SCS not only can improve our understanding of the formation and evolution processes of rifted continental margin, but also can provide theoretical support for hydrocarbon exploration in rifted continental margin. This dissertation mainly includes five topics as follows: (1) Various classic lithosphere stretching models are reviewed, and the continuous non-uniform stretching model is modified to make it suitable for the case where the extension of lithopheric mantle exceeds that of the crust. Then simple/pure shear flexural cantilever model is applied to model the basement geometries of SO49-18 profile in the northern continental margin of the SCS. By fitting the basements obtained by using 2DMove software with modeling results, it is found that the reasonable effective elastic thickness is less than 5km in this region. According to this result, it is assumed that there is weak lower crust in the northern continental margin in the SCS. (2) We research on the methods for stretching factor estimation based on various lithosphere stretching models, and apply the method based on multiple finite rifting model to estimate the stretching factors of several wells and profiles in the northern continental margin of the SCS. (3) We improve one-dimension strain rate inversion method with conjugate gradient method, and apply it to invert the strain rate of several wells in the northern continental margin of the SCS. Two-dimension strain rate forward modeling is carried out, and the modeling results show that effective elastic thickness is a key parameter to control basin’s geometry. (4) We simulate divergent upwelling mantle flow model using finite difference method, and apply this newly developed model to examine the formation mechanism of the northwest and central sub-basin in the SCS. (5) We inverse plate thickness and basal temperature of oceanic lithosphere using sea-floor ages and bathymetries of the North Pacific and the North Atlantic based on varied-parameters plate model, in which the heat conductivity, heat capacity and coefficient of thermal expansion depend on temperature or depth. A new empirical formula is put forward based the inversed parameters, which depicts the relation among sea-floor age, bathymetry and heat flow. Then various similar empirical formulae, including the newly developed one, are applied to examine the sea-floor spread issue in the SCS based on the heat flow and bathymetry data of the abyssal sub-basin.