古黄河三角洲若干问题的思考

孟村古黄河三角洲分流河道体系代表歧口三角洲超级叶瓣(700BC-11AD)的上三角洲平原沉积物，其下的三角洲沉积层序多属于更老的超级叶瓣。山东北部大口河至徒骇河口海岸700BC—1099AD多次受到黄河的影响，埕口—马山子东北部的海岸平原主要形成于893—1048年，那里岛链状贝壳堤开始形成的时间晚于1128年，与贝壳堤的^14C年龄相差700～1850a。苏北斗龙港口—弶港海岸平原地表之下约9m厚的沉积物主要是黄河入海泥沙在海流作用下向南搬运，并沉积下来。苏北黄河三角洲南界在谅港附近。自然地理和海洋地质工作者采纳“公元前602年或战国中期(公元前4世纪)发生第一次大改道”的观点是一个误会，实际上这是多数历史地理学家已经放弃的认识。     

Triassic platform-margin deltas in the western Barents Sea

The Early to Middle Triassic in the Barents Sea was dominated by prograding transgressive-regressive sequences. Internal clinoform geometries indicate that sediments were derived from the Baltic Shield in the south and the Uralian Mountains in the east and southeast. These systems were formed in a large, relatively shallow epicontinental basin, where modest variations in relative sea-level relocated the shoreline significantly. This study shows the development of strike elongated depositional wedges that thicken just basinward of the platform-edge. Seismic facies and time-thickness maps show the position and development of platform-margin delta complexes within each sequence. Seismic clinoforms and trajectory analysis show significant lateral variation from the axis of the delta complex to areas adjacent to the main delivery system. Frequent toplap geometries are observed in proximity to coarse-grained deposits, while aggradation of seismic clinoforms characterizes areas laterally to the platform-margin deltas. Complex shifts in depocenters are revealed by large-scale compensational stacking pattern and relict platform breaks. Locally, relict breaks are created due to pre-existing paleo-topography. Platform-margin deltas can be identified by careful mapping of clinoform geometries, clinoform angles and trajectories. However, seismic analysis of prograding clinoform units indicate that the shoreline and delta complexes commonly are positioned landward of the platform-edge. Deposition of platform-margin deltas is sometimes caused by locally increased sediment supply during slightly rising relative sea-level, and occasionally caused by a regional drop in relative sea-level with significant shelf bypass.Development, position, thickness and facies distribution of platform deltas and platform-margin deltas of very broad low-relief basins, like the Triassic of the epicontinental Barents Sea basin, are strongly sensitive to changes in relative sea-level due to rapid emergence and submergence of wide areas, and to changes in position of major rivers supplying sand to the delta systems. In this respect, the depositional model of the present study deviates from models of clinoform successions obtained from small and narrow basins or siliciclastic platforms with high coarse-clastic sediment supply.     

流域人类活动与降水变化对黄河三角洲造陆过程的影响

利用海图和遥感影像资料,确定了不同时期黄河三角洲的造陆速率,并将造陆速率的变化与流域降水和人类活动的变化相联系.研究发现,三角洲造陆速率与年降水量之间具有正相关关系,与各项水土保持面积和人类引水量之间具有负相关关系.运用多元回归分析方法,建立了黄河三角洲造陆速率与年降水量、梯田林草面积、淤地坝造地面积、人类年引水量等因子之间的多元回归方程.该方程表明,年降水量越大,三角洲造陆速率越大;梯田、林草面积和淤地坝造地面积越大,三角洲造陆速率越小;人类净引水量越大,三角洲造陆速率越小.     

Effects of trophic ecology and habitat use on maternal transfer of contaminants in four species of young of the year lamniform sharks

Organic contaminant and total mercury concentrations were compared in four species of lamniform sharks over several age classes to examine bioaccumulation patterns and gain insights into trophic ecology. Contaminants found in young of the year (YOY) sharks were assumed to be derived from maternal sources and used as a proxy to investigate factors that influence maternal offloading processes. YOY white (Carcharodon carcharias) and mako (Isurus oxyrinchus) sharks had comparable and significantly higher concentrations of PCBs, DDTs, pesticides, and mercury than YOY thresher (Alopias vulpinus) or salmon (Lamna ditropis) sharks. A significant positive relationship was found between YOY contaminant loads and maternal trophic position, suggesting that trophic ecology is one factor that plays an important role in maternal offloading. Differences in organic contaminant signatures and contaminant concentration magnitudes among species corroborated what is known about species habitat use and may be used to provide insights into the feeding ecology of these animals.     

Estimation of hydrocarbon biodegradation rates in marine environments: A critical review of the Q10 approach

Offshore oil & gas industry is moving exploration and production activities into Arctic and deep water regions. Governmental regulations require environmental impact assessments before operations to evaluate the possible effects of accidental oil releases. These are often performed by numerical fate models, like the Oil Spill Contingency and Response (OSCAR) model, which has become an industry standard in Norway. In this model, biodegradation rates are adjusted to local conditions by temperature compensation according to a Q₁₀ approach. Q₁₀ is the multiplier by which rates of enzymatic reactions increase at a 10 °C temperature rise. Herein, this Q₁₀ approach implemented in the OSCAR model is investigated based on published data and novel obtained results. Overall, biodegradation rate predictions calculated by temperature compensation are found to be questionable, and choosing one universal Q₁₀ value is considered not feasible. The high variation in Q₁₀ values is herein attributed to indirect effects of temperature.     

青岛近海潮流沉积体系

通过分析钻孔和浅地层剖面资料,研究了胶州湾及青岛前海潮流沉积体系。该体系包括大沽河-洋河潮控三角洲和与狭口海湾密切相关的涨、落潮流三角洲,潮流作用在各三角洲的形成过程中为主要的沉积动力。前者发育在湾西侧,形成了河口沙坝和分流间湾等沉积相;后者分布在湾口两侧,以潮道和潮流沙脊为主要特征。根据对各沉积相特征的分析,认为潮流沉积体系的演化已整体趋于稳定。     

Salt tectonics and tear faulting in the central part of the Zagros Fold-Thrust Belt,Iran

The central part of the Zagros Fold-Thrust Belt is characterized by a series of right-lateral and left-lateral transverse tear fault systems, some of them being ornamented by salt diapirs of the Late Precambrian–Early Cambrian Hormuz evaporitic series. Many deep-seated extensional faults, mainly along N–S and few along NW–SE and NE–SW, were formed or reactivated during the Late Precambrian–Early Cambrian and generated horsts and grabens. The extensional faults controlled deposition, distribution and thickness of the Hormuz series. Salt walls and diapirs initiated by the Early Paleozoic especially along the extensional faults. Long-term halokinesis gave rise to thin sedimentary cover above the salt diapirs and aggregated considerable volume of salt into the salt stocks. They created weak zones in the sedimentary cover, located approximately above the former and inactive deep-seated extensional faults. The N–S to NNE–SSW direction of tectonic shortening during the Neogene Zagros folding was sub-parallel with the strikes of the salt walls and rows of diapirs. Variations in thickness of the Hormuz series prepared differences in the basal friction on both sides of the Precambrian–Cambrian extensional faults, which facilitated the Zagros deformation front to advance faster wherever the salt layer was thicker. Consequently, a series of tear fault systems developed along the rows of salt diapirs approximately above the Precambrian–Cambrian extensional faults. Therefore, the present surface expressions of the tear fault systems developed within the sedimentary cover during the Zagros orogeny. Although the direction of the Zagros shortening could also potentially reactivate the basement faults as strike-slip structures, subsurface data and majority of the moderate-large earthquakes do not support basement involvement. This suggests that the tear fault systems are detached on top of the Hormuz series from the deep-seated Precambrian–Cambrian extensional faults in the basement.     

Quantitative evaluation of the reservoir potential and controlling factors of semi-deep lacustrine tempestites in the Eocene Lijin Sag of the Bohai Bay Basin,East China

Ancient lacustrine storm-deposits that act as petroleum reservoirs are seldom reported. The Lijin Sag, which is located in the southeastern corner of the Bohai Bay Basin in East China, is a NE–SW trending Cenozoic half-graben basin. Some of its Eocene deposits (Bindong deposits) were interpreted as lacustrine tempestites. The Bindong tempestites, which developed in the lower part of the upper fourth member of the Shahejie Formation (Es4¹), constitute a new kind of petroleum reservoir and are novel petroleum exploration targets in the Bindong Area. However, the characteristics of the Es4¹ Bindong tempestite reservoirs and their controlling factors are poorly understood. Point-count analyses of thin sections, scanning electron microscope image analyses, X-ray diffractometry data, and the petrophysical parameters of the Bindong tempestite reservoirs were utilized to estimate the reservoir quality. The reservoirs have undergone significant diagenetic alteration, which can be divided into negative and positive aspects. The negative alteration includes compaction, authigenic minerals, and cementation such as carbonates, clay minerals and overgrowths of quartz and feldspar. The uneven distribution of carbonate cement increased the reservoir’s heterogeneity, with carbonate cement commonly precipitating along the sandstone-mudstone contacts. The primary porosity was severely reduced because of compaction and extensive carbonate cementation. Positive alteration includes dissolution, carbonate cementation, undercompaction and fractures. Carbonate cementation exhibited both positive and negative effects on the reservoir quality. Overall, the objective reservoir quality is quite poor. A quantitative evaluation of the reservoirs’ potential was conducted. The cutoff values of several of the reservoir’s parameters were calculated. The lower limits of the porosity and permeability are 8.35–5.85% and 1.2587–0.2753 × 10^–3 μm², respectively, depending on the depth. The upper limits of the carbonate and mud content are approximately 18.5% and 9–10%, respectively. A fundamental understanding of these characteristics will provide necessary information for extracting hydrocarbons from analogous subsurface reservoirs.     

Late Quaternary Seismic Stratigraphy of the Eastern Bengal Shelf

An ultra-high-resolution seismic study of the eastern Bengal Shelf with the parametric narrow-beam echosounder Parasound allows the interpretation of late Quaternary depositional patterns in terms of seismic stratigraphy. Accommodation space was still present on the outer shelf during the last lowstand, where a prograding delta developed in the western survey area. Oolitic beach ridges were later formed on top of this lowstand delta. Farther east, large parts of the shelf were exposed to subaerial erosion and a river system extended seaward across the area. A subaqueous highstand delta prograded southwards following the maximum transgression about 7,000 years ago. Its foreset beds exhibit acoustic voids very likely generated by sediment liquefaction, possibly caused by episodic energetic events such as major cyclones and/or earthquakes. Bottomset sediments extend seaward close to the shelf break in the west, whereas no Holocene sediments cover the outer shelf in the east.     

曹妃甸老龙沟动力地貌体系及演化

老龙沟为典型沙坝-泻湖型潮汐汊道,潮汐汊道地貌结构完整.老龙沟口门处潮流动力最强,发育-20m的深槽.口门内涨潮流三角洲上发育完整的多级水道体系.口门外落潮三角洲止于-11 m水深处.以突起的末端坝为地形标志,落潮主水道偏于落潮三角洲东侧发育,落潮三角洲西侧发育宽缓冲流平台.落潮主水道以落潮流为优势,冲流平台上潮流动力...     

Stratigraphic models for microtidal tidal deltas; examples from the Florida Gulf coast

Extensive vibracoring of both flood- and ebb-tidal deltas along the central Gulf Coast of the Florida peninsula reveals a strong overall similarity with subtle distinctions between flood and ebb varieties. Although the coast in question is microtidal, the inlets range from tide-dominated to distinctly wave-dominated. Both types of tidal deltas overlie a muddy sand interpreted to have been deposited in a back-barrier environment. The sharp contact at the base of the tidal delta sequence is typically overlain by a thin shell gravel layer. The ebb-tidal delta sequence is characterized by fine quartz sand with shell gravel in various concentrations; coarse and massive at the margins of the main ebb channel, and finer and imbricated at the marginal flood channels. The flood-tidal deltas are characterized by the same facies but with a small amount of mud. Shelly facies on the channels on flood deltas are not as well developed as on the ebb deltas. The combination of the stratigraphic sequence and the lithofacies make tidal deltas readily identifiable in the ancient record. The differences between flood and ebb varieties are subtle but consistent.     

黄河三角洲浅海滩涂湿地鸟类多样性调查研究

1 996— 1 998年、1 997— 1 999年分别对黄河三角洲及其湿地鸟类多样性进行了全面调查 ,分析了浅海滩涂湿地鸟类种群组成、区系组成、季节居留型 ,研究了鸟类多样性及其特点 ,确定了鸟类多样性分布中心 ,提出了加强鸟类多样性保护的建议     

北部湾盆地涠西南凹陷W区流沙港组储层非均质性研究及应用

基于沉积微相研究和测井精细解释数据统计分析,开展了涠西南凹陷W区古近系始新统流沙港组储层非均质性研究。W区储层为流一段和流三段,沉积微相研究表明,流沙港组主要为正常三角洲相和扇三角洲相沉积。储层夹层岩性主要为泥岩、粉砂质泥岩,主要成因为分流水道间、水下分流河道与砂坝、砂坝与砂坝、辫流坝与辫状水道、辫状水道间的泥质沉积物。非均质性研究以沉积微相为基础进行,通过比较不同沉积微相的非均质性差别,分析储层的空间物性变化。非均质性研究表明,WA油田流一段夹层厚度>5 m的占51.4%,单层夹层层数>5个的占27.4%,变异系数平均值>1.2,整体上非均质性很强;WB油田流三段夹层分布均匀,东南部平面非均质性弱,西北部平面非均质强;WC和WD油田流三段整体上夹层多,但平面非均质性弱。依据非均质研究成果,对密井网的WA油田主力层进行了剩余油分布预测,并部署了2口调整井挖潜,实施后累增油4.2×104 t,采收率提高了2.3%。表明储层夹层分布和平面非均质性研究可以为油田剩余油挖潜提供依据,对油田高效开发具有重要意义。     

胶州湾口潮流沙脊特征

胶州湾内外的涨、落潮三角洲上发育有一定规模的潮流沙脊体系,通过多波束调查采集数据和浅剖、沉积物资料的分析,对沙脊特征进行了研究。湾内涨潮三角洲上分别分布有冒岛沙脊、中央沙脊和岛耳河沙脊;湾外落潮三角洲上分别发育了潮流沙脊大竹、南沙、北沙和位于主潮流通道末端的弧状沙脊。潮流沙脊体系的演变具有较为明显的继承性。沙脊以海侵时期发育的沙体为内核,沉积物组成以粒度较粗的砂质沉积物为主,物源基础为低海平面时期胶州湾盆地内堆积的河流三角洲相沉积物。据分析,沙脊现代物源较为匮乏,整体目前处于冲刷不淤的状态。在现代潮流水动力条件下,研究区潮流沙脊处于活动状态。     

长江三角洲地区晚更新世晚期(硬粘土层)的孢粉组合特征及环境分析

利用长江三角洲地区晚第四纪沉积10多口钻井的孢粉、藻类资料,在以往较少见到化石的晚更新世晚期的硬粘土沉积中找到了能明确指示古环境的孢粉、藻类化石,发现了两种不同的孢粉组合,一种是以环纹藻Concentricystes占优势的孢粉组合,另一种是以陆生植物Pinus-Cupressaceae-Picea-Abies-Quercus(deciduous)-Gramineae占优势的孢粉组合,证实了该层硬粘土形成期间曾经历滞水和水退的环境交替过程。     

长周期动力形态模型中地形演变方法探讨

PRD-LTMM是一个模拟和描述三角洲地形中、长期演变过程的动力形态模型.在长时间尺度的模拟过程中,必须从模型输入、模型物理系统本身到模型输出等各个角度考虑模拟约减处理.代表性输入条件是实现模型约减的基础,而地形时间的步长延长是提高长周期模型模拟效率的关键.延长技术通常有直接推延、时间中心推延、潮汐延展及泥沙输运率公式线性化等四种方法.通过系列敏感性试验,对PRD-LTMM模型选择潮汐延展技术来进行地形时间步长的延长处理,推延的时间长度为10 a,基于此条件下的PRD-LTMM在长周期模拟中不仅稳定性较好,而且结果也较精确.     

近年来黄河口以北水下岸坡的演变监测

1996年7月~2000年10月,在研究区进行4次水深地形调查监测,通过GoldenSoftware系统计算相连两次水深调查的数据得出局部冲蚀变化情况。研究分析表明:在1996年7~10月,由于洪水季节的影响,在短短的3个月内,有约4×108m3的沉积物发生淤积。其后几年,该区一直处于冲蚀状态。在1996年10月~1998年10月,有约8.9×107m3沉积物被冲蚀掉;在1998年10月~2000年10月,有约1.4×108m3沉积物被冲蚀掉。因此,在前4次调查期间,研究区有约1.7×108m3的沉积物发生淤积。2004年7月的补充调查表明:该区近岸部分还处于侵蚀状态,海滩剖面没有到达平衡。