浅谈陆相湖盆深水重力流沉积研究中的几点认识   总被引：1，自引：1，他引：0  

杨田  操应长  田景春 《沉积学报》2021,39(1):88-111

与海相盆地重力流沉积研究理论的快速发展相比,陆相湖盆重力流沉积的相关认识还存在着一定差距。综合国内、外重力流沉积相关研究成果,总结湖盆重力流沉积的相关认识,以明确湖盆重力流沉积研究中存在的不足。增强不同术语内涵及相互关系的理解、增加不同术语的解释说明,是减少术语混淆的有效途径;流体转化、流态转化和润滑作用是湖盆重力流搬运的主要动力学过程;受阻沉降、湍流抑制和牵引毯作用是湖盆重力流沉积物沉降的重要动力学过程。沉积物再搬运、洪水持续供给、漂浮羽流卸载是陆相湖盆重力流沉积主要的成因机制;重力流沉积相域类型、块状砂岩内部沉积特征和逆正粒序沉积特征精细解析可揭示重力流沉积成因。超临界浊流侵蚀作用形成重力流水道,盆地外部因素主控重力流物质成分和来源,盆地内部因素主控重力流分异效率,其综合表现形式即“源—汇”系统控制下的重力流砂体形成演化过程。洪水持续供给成因重力流沉积模式以重力流水道—堤岸沉积、水道—朵叶转换带和朵叶沉积依次过渡构成其典型沉积构型要素组合;沉积物再搬运成因沉积模式以三角洲前缘垮塌带、混杂沉积和朵叶沉积依次过渡构成其典型沉积构型要素组合。湖盆重力流沉积是非常规油气赋存的重要场所,流体转化成因的细粒沉积具有易于油气生成和富集,且易于压裂的先天优势,可能是页岩油气中的“甜点”区发育的优势沉积岩相组合类型。  相似文献   

Submarine groundwater discharge enhances primary productivity in the Yellow Sea,China:Insight from the separation of fresh and recirculated components     

Jianan Liu  Jinzhou Du  Xueqing Yu 《地学前缘(英文版)》2021,12(6):76-89

Submarine groundwater discharge(SGD)is being increasingly recognized as a significant source of nutri-ent into coastal waters,and generally comprises two components:submarine fresh groundwater dis-charge(SFGD)and recirculated saline groundwater discharge(RSGD).The separate evaluation of SFGD and RSGD is extremely limited as compared to the conventional estimation of total SGD and associated nutrient fluxes,especially in marginal-scale regions.In this study,new high-resolution radium isotopes data in seawater and coastal groundwater enabled an estimation of SGD flux in a typical marginal sea of the Yellow Sea.By establishing 226Ra and 228Ra mass balance models,we obtained the SGD-derived radium fluxes,and then estimated the SFGD and RSGD fluxes through a two end-member model.The results showed that the total SGD flux into the Yellow Sea was equivalent to approximately 6.6 times the total freshwater discharge of surrounding rivers,and the SFGD flux accounted for only 5.2％-8.8％of the total SGD.Considering the nutrient concentrations in coastal fresh and saline groundwater,we obtained the dissolved inorganic nutrient fluxes(mmol m-2 yr-1)to be 52-353 for nitrogen(DIN),0.21-1.4 for phosphorus(DIP),34-226 for silicon(DSi)via SFGD,and 69-262 for DIN,1.0-3.9 for DIP,70-368 for DSi via RSGD,with the sum of nutrient fluxes equaling to(1.8-9.3)-fold,(1.3-5.6)-fold and(2.0-9.5)-fold of the riverine inputs.Compared to the conventional estimation of the total SGD flux,the nutrient fluxes derived from the separation of SFGD and RSGD were(1.6-2.1),(1.6-1.8)and(4.0-4.9)times lower for DIN,DIP and DSi,respectively,indicating that the estimates by separating SFGD and RSGD could be conservative and representative results of the Yellow Sea.Furthermore,we suggested that SGD played an important role in nutrient sources among all the traditional nutrient inputs sources,providing 15％-48％,33％-68％and 14％-43％of the total DIN,DIP and DSi input fluxes into the Yellow Sea,and the high nutrient stoichiometric ratios(i.e.,DIN/DIP)in SGD probably contributed to the increasing ratios in the Yellow Sea.In addition delivering large amounts of nutrient into the Yellow Sea,SGD would create primary productivity of 10-49,1.6-6.8 and 8.8-42 g C m-2 yr-1 based on N,P and Si,which were equivalent to 5.2％-27％,0.9％-3.7％and 4.7％-23％of the total primary productivity,respectively.In par-ticular,the SFGD-derived DIN flux can be converted to primary productivity of 4.2-28 g C m-2 yr-1 thus demonstrating the disproportionately large role of SFGD in ecological environment of the Yellow Sea rel-ative to its flux.Therefore,we conclude that SGD,particularly SFGD,plays an important role as a nutrient source for the Yellow Sea,and not only affects nutrient budgets and structures but also enhances the pri-mary productivity.  相似文献   

珠江口海域气溶胶中重金属含量的时间变化特征及入海通量初步估算     

王欣睿  刘梦南  董燕红  倪志鑫  江志华 《台湾海峡》2014,(1):133-139

采用2009～2011年珠江口海域获取的代表春、夏、秋、冬4个季节的240个气溶胶样品,分析重金属（Cu、Pb、Zn、ca）质量浓度和大气干沉降通量的年、季变化特征．结果表明：气溶胶中zn的质量浓度最高,其次是Pb和Cu,Cd的质量浓度最低,年平均质量浓度依次为69,2、31．2、12．6和0．58ng／m3．Cu、Pb和Zn的年平均质量浓度和入海通量表现为2009年〉2011年〉2010年．Cd的年平均质量浓度和入海通量呈现逐年递减的变化趋势．各金属质量浓度及大气干沉降通量均为秋季最高,冬春季次之,夏季最低,这种季节性差异主要与季风和雨水冲刷作用有关．气溶胶中Cu、Ph、Cd和Zn平均质量浓度的较低值出现在2010年夏季．Pb在4个季节的平均质量浓度低值均出现在2010年,平均质量浓度依次为18．9、3．8、56．7、20．2ng／m3,表明加强人为污染物排放的控制,可有效地降低气溶胶中重金属的含量,提高环境空气质量．通过评估金属元素分别从大气和河流进入珠江口海域的输入量,该海域金属物质输送入海仍以河流输入为主,但大气中Pb对该海域的输入具有重要作用．  相似文献   

春、夏季长江口及邻近海域溶解甲烷的分布与释放通量     

孙明爽  张桂玲  王岚  叶旺旺  任景玲 《中国海洋大学学报(自然科学版)》2014,44(12):61-68

分别于2012年3和7月对长江口及其邻近海域进行了大面调查,测定了表、底层海水中溶解甲烷浓度,并对其海-气交换通量进行了估算。结果表明,春、夏季表层甲烷的平均浓度分别为(28.33±38.33)和(19.92±19.18)nmol·L-1,甲烷浓度从内河口向外海逐渐降低。长江口溶解甲烷浓度和饱和度有明显季节变化,其中春季内河口甲烷浓度和饱和度高于夏季,但外河口及邻近海域则相反,这主要是温度和长江冲淡水中甲烷浓度的季节差异造成的。该海域溶解甲烷的分布受陆源输入影响显著,夏季长江冲淡水影响范围较春季更广,但由于稀释效应夏季甲烷浓度低于春季。夏季沉积物的释放对河口区甲烷的贡献较春季更为明显。调查期间该海域溶解甲烷都处于过饱和状态,是大气甲烷的净源;根据W92公式初步估算出长江口及其邻近海区年释放CH4量约为8.81×108 mol·a-1,占全球海洋年释放量的0.08%,远高于其面积比0.01%,因此该海区是甲烷产生和释放的活跃海域。  相似文献   

遥感SST产品误差在海-气CO2通量计算中的传递及贡献分析     

窦文洁 《海洋与湖沼》2014,45(1):148-156

海-气界面CO2通量的估算对于碳的生物地球化学循环和全球气候变化等研究具有重要的意义,利用遥感手段是进行全球尺度海表面碳通量估算的唯一手段,但是由于不确定性的存在限制了海-气界面CO2通量遥感估算产品在决策应用上的可靠性。本文通过建立海-气界面CO2通量直接控制参量(气体交换速率k、海表面CO2溶解度S和海表面CO2分压pCO2sw)误差结构图,以通量估算的主要影响因子—海表温度（SST）为例,建立了SST在通量计算中的误差传递流程图,并采用Monte Carlo方法模拟了SST误差在通量计算中的传递规律和对最终误差的贡献。结果表明在遥感SST误差为0.5℃并为正态分布的假设下,误差在k、S计算中的传递为指数分布和近似指数分布,而在pCO2sw模型计算中为正态分布,最终在通量FCO2中的传递为指数分布;在大气CO2分压为固定值370μatm的情况下,SST对最终的通量结果带来的误差为1.2mmol?m-2?day-1左右。本文以SST为例,提供了一种通量计算中遥感参数误差传递和贡献的计算方法,可以为其他遥感获取的参量提供分析依据和参考。  相似文献   

戈壁地区夏季碳和水热循环及其湍流特征          下载免费PDF全文

赵子龙  张宏升  康凌 《地球物理学报》2013,56(8):2574-2582

本文利用2006年夏季大气边界层观测资料,采用涡动相关法分析了我国西北地区戈壁下垫面碳收支及水热循环的规律和特征,并分析了大气湍流特征.结果表明:夏季白天的CO₂湍流通量呈逆输送特征,即CO₂白天向下输送,夜间向上输送,平均数值为-0.199 mg·m^-2·s^-1,整体上表现为碳汇;戈壁地区湿度小,其数值受水平来流的影响较大,日变化特征不明显;温度的归一化标准差与稳定度参数的关系满足Monin-Obukhov Similarity (MOS)理论;温度和CO₂的能谱相似;互谱uc与uθ,wc与wθ相似;水汽和CO₂的输送主要受水平方向湍流的影响.  相似文献   

Assessing the factors controlling high sedimentation rates from the latest Barremian–earliest Aptian in the hemipelagic setting of the restricted Organyà Basin,NE Spain     

《Cretaceous Research》2014

The Organyà Basin, south–central Spanish Pyrenees, developed as a marginal depocenter during a rapid extensional phase of anticlockwise rotation of the Iberian plate. As a result of increased subsidence, an important change in sedimentation occurred from the late Barremian to the Aptian leading to unusually high sediment accumulation rates. Approximately 1000 m of hemipelagic marls and limestones accumulated during this time interval.Here we studied the basal 85 m of the hemipelagic facies of the El Pui section, Organyà Basin, that are characterized by alternating 15 cm – ∼3 m thick beds of limestone and marls. Geochemical analyses indicate high total inorganic carbon (TIC) values (average 70%) suggesting enhanced CaCO₃ production and deposition. SEM analyses of the samples indicate high abundance of calcareous nannofossils, which together with the absence of shallow water taxa characteristic of the Urgonian Carbonate platform of Organyà, and the lack of sedimentary facies attributable to carbonate platform components point to nannofossils as the main source for the elevated TIC. Organic-rich levels (total organic carbon (TOC) up to 1.74%) concurrent with positive excursions up to 2‰ in δ¹³C_org, imply enhanced preservation of organic matter (OM) in the basin. In addition, pronounced peaks of δ¹³C_org higher than the global average suggest superimposed local factors related to intensified ¹²C removal due to primary productivity. Biomarker analyses and the δ¹³C_org profile suggest an autochthonous origin of the OM from phytoplankton and possible additional contributions from microbial communities.X-ray diffraction (XRD) results attest for sustained terrestrial fluxes as the source of nutrients to the basin because of a 30% average non-carbonate bulk mineral content in the sediment. The non-carbonate fraction is dominated by quartz (average, 14%) whereas the clay mineral assemblages are characterized by high illite content (>73 relative%) with minor concentrations of kaolinite (<5%), illite /smectite mixed layers (<17%) and chlorite (<15%), consistent with a provenance from the Paleozoic metamorphic terranes adjacent to the Organyà Basin.The integrated results suggest a high sediment accumulation rate (5 cm/ky–7.5 cm/ky) and enhanced carbon burial during the latest Barremian–earliest Aptian in the hemipelagic setting of the El Pui section.  相似文献   

Settling of Kaolinite in Different Aqueous Environment     

Abidin Kaya  Ali Hakan Ören  Yeliz Yükselen 《Marine Georesources & Geotechnology》2013,31(3):203-218

Settling characteristics of soils carry great importance for geotechnical engineers since sediments properties are formed during the settling of soil particles in an aqueous environment. In this study, settling characteristics of kaolinite are investigated. Different ionic strengths of NaCl, CaCl₂ and AlCl₃ were considered as a function of pH in aqueous environment of varying solid concentrations. Factors affecting the settling characteristics and fabric of kaolinitic sediments have been identified. The results of the study reveal that kaolinite settles in either flocculated or dispersed forms depending on pH and ion concentration. Flocculated settling occurs in acidic pH due to formation of flocs in edge-to-face structure with increasing positive charges at the particle edges. Dispersed settling occurs in alkaline pHs when ionic strength is low. When ionic strength is increased in alkaline pHs, kaolinite particles settle in flocculated form. Furthermore, the results show that pH has a significant role on the final sediment thickness or void ratio of kaolinite. Densely packed structures in alkaline and loosely packed structures in acidic aqueous environments are formed depending on pH level. Results also show that as the solid concentration increases, the settling rate decreases due to buoyancy effect. Finally, the zeta potential of kaolinite is correlated with the final sediment thickness or void ratio of kaolinite as a function of pH. This correlation proves that there is a good agreement between zeta potential and the final sediment thickness or void ratio, especially when the soil is settled in a dispersed form.  相似文献   

不同边界层稳定性下海气湍流热通量日变化的前沿问题探讨     

徐常三  宋翔洲  齐义泉 《热带海洋学报》2021,40(3):57-68

海气湍流热通量(潜热和感热)是研究海气相互作用和大洋环流的关键要素, 认识其变化机理对理解“海洋动力过程及气候效应”有重要意义。然而, 受观测手段和计算能力两方面的限制, 过去对海气湍流热通量日变化研究存在“特征认识较粗、机制理解较疏”的现象。本文探讨了在不同边界层稳定性下海气湍流热通量日变化研究中的问题与难点, 并讨论了“不同边界层稳定性下海气湍流热通量日变化过程和机理”这一关键科学问题。本文提出, 可基于海洋浮标、平台和波浪滑翔机等综合观测数据和高时空分辨率再分析资料, 利用块体算法和脉动分离方法, 揭示全球海气湍流热通量的精细化日变化特征和决定因素, 以及海气湍流热通量日变化强度(日内小时级变化的标准差)与极端天气过程和气候事件的动力关联。同时, 为更精准认识日变化过程, 在技术上可通过耦合高频海表流速和校正边界层物理参数观测高度等方式提升海气湍流热通量估算的精确度。本文提出可将多时空尺度海气湍流热通量变化维度转换到边界层稳定性上, 以便集中认识其日变化特征和机理, 支撑全球海气能量平衡的科学认识。  相似文献   

A motion correction on direct estimations of air-sea fluxes from a buoy   总被引：1，自引：1，他引：0  

HUANG Yansong  SONG Jinbao  FAN Conghui 《海洋学报(英文版)》2013,32(3):63-70

A flux system deployed on a moored buoy has been described, which is capable of directly estimating the airsea fluxes after removing the contamination in the signal due to buoy motion. A triple loop fitting method has been demonstrated for determining the three angular offsets between measurement axes of the sonic anemometer and motion pack. The data collected in an experiment in the Northern Huanghai Sea is used to correct the three sonic anemometer measurements of turbulent wind for buoy motion. The effective removal of wave-scale motion from the spectra and cospectra are demonstrated. Estimates of along-wind momentum flux, sensible heat flux and latent heat flux calculated by the eddy correlation method based on data obtained by sonic anemometer 81000V are shown to be in the same trend and scale with those determined by the bulk aerodynamic method after motion correction. The motion correction not only greatly improve the estimation of the momentum flux but also has a great impact on the calculated sensible heat flux.  相似文献