Stratigraphic signatures of punctuated rise in relative sea-level in an estuary-dominated heterolithic succession: Incised valley fills of the Toarcian Ostreaelv Formation,Neill Klinter Group (Jameson Land,East Greenland)     

《Marine and Petroleum Geology》2014

The Ostreaelv Formation (latest Pliensbachian–Toarcian) of the Neill Klinter Group is exposed along a >105 km wide, ENE-trending section in Jameson Land, East Greenland. Deposition took place in a large embayment (Jameson Land Basin) that was connected to the proto-Norwegian-Greenland Sea. Lithofacies in the Ostreaelv Formation range from clean sandstone to muddy heterolithic facies typified by strong grain-size contrasts.The Ostreaelv Formation is divided into four distinct and overall retrograding allostratigraphic units each composed of a characteristic set of tide-influenced, tide-dominated and wave-influenced facies associations. The allostratigraphic units are bounded by subaerial unconformities, interpreted as sequence boundaries, and are up to 75 m thick and 16 to >20 km in width. The allostratigraphic units include a sandy heterolithic estuary bay-head delta succession overlain by two sandy tide-dominated estuary fill successions, interbedded with a muddy heterolithic offshore marine succession. Each of the three estuarine allostratigraphic units was accumulated in an incised valley formed during fall in relative sea level and filled during successive transgressions with sediment supplied from marine and reworked fluvial deposits.In the three incised valleys fluvial sediments were deposited on top of an initial subaerial unconformity surface (SU) and were later reworked by succeeding transgressive ravinement along a transgressive surface (TS), thus creating combined SU/TS sequence boundaries. The data from the Ostreaelv Formation also provides knowledge and conceptual understanding of valley infill processes (tidal current, wave and fluvial energy), and both lateral and vertical variations in lithofacies architecture within incised valleys.Moreover, the study provides quantitative input data, such as incised valley dimensions, sand-containing capacity, and geometry to subsurface reservoir characterisation and modelling efforts of estuary fill successions.  相似文献   

基于AMBI和M-AMBI指数的黄河口及邻近海域底栖生境质量评价   总被引：4，自引：3，他引：1  

罗先香  张娟  杨建强  宋文鹏  崔文林 《海洋学报(英文版)》2014,33(9):117-124

The protection of the biological diversity and the maintenance of the regional ecological integrity for the Huanghe （Yellow River） Estuary and its adjacent areas are practically significant and valuable. However, frequent human activities and natural climate changes have caused vigorous disturbances on the ecosystem in these sea areas. An objective assessment on the benthic habitat quality （BHQ） of the Huanghe Estuary and its adjacent areas is conducted, using AZTI＇s Marine Biotic Index （AMBI） and multivariate AMBI （M-AMBI） based on the data of macrobenthos in May and August 2011. The results show that both the indices do not correlate significantly, and their assessment results are greatly different. All of the samples assessed using the AMBI were ＂high＂ or ＂good＂, because the ecological group I （EGI） and the ecological group II （EGII） were dominant macrobenthic ecological groups in the research area. Owing to a low species＇ richness and a high individual abundance in some samples, the BHQ levels using the M-AMBI were worse than those of the AMBI. Significant correlations are observed between the M-AMBI, water depth, bottom water salinity and dissolved inorganic nitrogen, thus the M-AMBI could sensitively respond to environmental changes and distinguish influences from uninfluenced stations, but the AMBI could not. The consistent results between the AMBI and the M-AMBI mainly appeared in the uninfluenced （undisturbed or slightly disturbed） sta- tions. Therefore, the M-AMBI is more effective than the AMBI in assessing the benthic habitat quality in the Huanghe Estuary and its adjacent areas. Using the M-AMBI to assess the BHQ of the Huanghe Estuary and its adjacent areas, the results show that 3% of the stations are undisturbed and the BHQs are ＂high＂, and 61% of the stations are slightly disturbed and those of the BHQ are ＂good＂, and the rest are meanly disturbed and those of the BHQ are ＂moderate＂.  相似文献   

Distributions of picophytoplankton and phytoplankton pigments along a salinity gradient in the Changjiang River Estuary,China     

Baoli Wang  Congqiang Liu  Fushun Wang  Siliang Li  Sivaji Patra 《中国海洋大学学报(英文版)》2014,13(4):621-627

We investigated the abundance of different picophytoplankton groups and the phytoplankton pigment ratio in relation to environmental factors such as nutrients and suspended solids along a salinity gradient in the Changjiang River Estuary. The average numbers of Synechococcus spp.(Syn) and picoeukaryotes(Euk) were(2.7 ±5.1) ×103 and(1.1±1.4) ×103 cells m L-1, respectively. Prochlorococcus spp.(Pro) was only found in the high-salinity brackish water with the concentration of 3.0×103 cells m L-1. Syn and Euk numbers both tended to increase offshore and Syn showed a larger variation in cell abundance than Euk. The contribution of picophytoplankton to total phytoplankton biomass increased with increasing salinity and decreasing nutrient concentrations from the estuary to the open ocean. The response of different picophytoplankton groups to environmental variables was different. Water temperature was more important in its control over Euk than over Syn, while nutrients were more important in their influence over Syn than over Euk. Phytoplankton pigment ratios were different in the three different ecological zones along the salinity gradient(i.e., freshwater zone with 0-5 range, fresh and saline water mixing zone with 5-20 range, and high-salinity brackish water zone with 20-32 range), where three different phytoplankton communities were discovered, suggesting that phytoplankton pigment ratios can be considered as a complementary indicator of phytoplankton community structure in the Changjiang River Estuary.  相似文献   

长江口南港底沙输移及其对南、北槽分汊口的影响   总被引：7，自引：1，他引：7  

巩彩兰恽才兴  虞志英 《海洋工程》2003,21(3):62-67

以1958年以来浏河口至横沙水文站之间南港系列水下地形图数字化分析资料为基础，以成形活动沙洲和隐形活动沙包作为底沙推移的判别标志，研究底沙输移规律，底沙输移对南港河槽分化和南、北槽分汊演变趋势的影响。研究结果表明长江口底沙活动范围向口门地区推移，底沙绝大部分进入南槽。  相似文献   

珠江口悬浮泥沙迁移数值模拟   总被引：13，自引：1，他引：13       下载免费PDF全文

陈晓宏  陈永勤  赖国友 《海洋学报》2003,25(2):120-127

建立了珠江口海域三维悬浮泥沙的非饱和输沙数学模型,并与珠江口三维水动力斜压模型耦合,对悬沙迁移分布进行了模拟。模型由4个点的逐时实测含沙量过程进行了验证。各点模拟含沙量与实测含沙量吻合较好,表层分布与同期珠江口悬沙分布遥感图像基本一致.模拟结果表明,珠江口海域悬沙分布分层明显,河口附近水域大多为底层含沙量大于表层,但在盐淡水交汇处出现中层含沙量最小的情况总体上,自各个口门输出的泥沙受沿岸流作用向西南万向输送明显。大多数河口落潮时相对涨潮时含沙量等值线外移,反映珠江口水域悬浮泥沙主要来自河流。  相似文献   

长江口潮沼植物对动力沉积过程的影响   总被引：36，自引：5，他引：36  

杨世伦  时钟  赵庆英 《海洋学报》2001,23(4):75-80

为探讨潮沼植物对动力沉积过程的影响,在长江口南汇东滩沼泽和邻近的光滩上进行了近底层流速、波浪、悬沙浓度、沉积物粒径和滩面淤积速率等对比实验,并在九段沙潮沼中做了两种先锋植物黏附悬沙的实验.结果表明,沼泽和同高程的邻近光滩近底层平均流速的比值为0.16～0.84;两种环境平均波周期、平均波高和平均悬沙浓度的比值分别为1.4,0.43,和0.71.波浪传入沼泽后,一方面波高大大降低,另一方面变得规则有序.海三棱草和草两种先锋植物群落黏附的悬沙分别达到298和40g/m2.由于水动力降低和植物的捕沙功能,细颗粒泥沙易于在沼泽中沉积下来,导致沼泽环境沉积物明显较相邻光滩细;沼泽中沉积速率加快,侵蚀受到抑制.  相似文献   

粒径趋势分析对长江南支口外沉积物输运的指示意义          下载免费PDF全文

王国庆  石学法  刘焱光  王昆山 《海洋学报》2007,29(6):161-166

沉积物粒径趋势分析是自20世纪80年代逐步发展起来的一种粒度分析方法,其核心是从沉积物粒度参数的空间分布变化规律中提取沉积物净输运方向的信息[1].这一方法已经成功地被应用于河流体系、湖泊、海岸带、港口、河口乃至陆架、海底峡谷等多种沉积环境中进行沉积物输运趋势的分析[2~11].目前将该方法直接应用于大河三角洲沉积体系来探讨沉积物在三角洲体系内部的输运趋势的研究还较少见.  相似文献   

Maltivariate Analysis of the Occurring Process of Skeletonema costatum Red Tide in the Changjiang Estuary     

黄秀清  蒋晓山  陶然  洪君超 《海洋通报(英文版)》2001,3(1)

Using the SAS software, the data of environmental factors vs. red tide biomass were analysed during the process of Skeletonema costatum red tide which broke out in the Changjiang Estuary on June 9～15, 1990. The results of the multivariate statistical analysis show that the environmental factors are similar in their developing and maintenance periods and that the values of environmental factors begin to be restored to normal levels during the disappearing period.The results obtained from using the methods of correlation, variable cluster and main component analyses are basically identical. The important factors contributing to the occurrence of this red tide are atmospherical pressure, water temperature, salinity, pH, No3-, -N, Po43--P and Fe, among which,salinity, Fe and PO43--P are the leading factors which have triggered the occurrence of the red tide as determined by the step-by-step regression analysis. Meanwhile, the linear discrimination functions have been established for the red tide. The environmental factor data of another occurring process of Skeletonema costatum red tide in the Changjiang Estuary have been chosen for red tide discrimination with satisfactory results.  相似文献   

珠江口哲水蚤桡足类肠含物荧光分析     

黄创俭  陈清潮  黄良民 《海洋科学》1991,15(3):60-64

本项研究以哲水蚤桡足类为实验材料,通过用荧光法测定其肠内植物色素(叶绿素a+褐色素)的办法,来估算哲水蚤的现场摄食活动。在鉴定的16个种中,有13种含有肠荧光。观察肠荧光与周围食物之间不存在显著相关。还观察到有3个种的肠荧光有强烈昼夜变化,其高值出现在夜间。  相似文献   

黄河口铀的化学行为   总被引：3，自引：0，他引：3  

周仲怀  徐丽君  刘兴俊 《海洋科学》1989,13(2):38-42

本文根据1984年4月—1984年11月和1987年10月对黄河口铀的调查结果,讨论了铀的某些化学行为,提出,黄河口(特别是河门站)水中铀可能是处于热力学不平衡状态,较详细地探讨了影响黄河口水中铀存在形态的各种因素。黄河口水中铀除以可溶态存在外,悬浮态铀的存在比较明显。还初步认为黄河口水申铀的地球化学异常现象具有一定的非保守性质。  相似文献