海南岛红树林泥炭的海侵成因研究及其意义

本文在海南岛全新世红树林泥炭及其含沉积特特征，形成环境详细研究的基础上，对比会南晚更新世以来的海平面变化，综合分析得出：红树林泥炭形成于泥炭坪相；晚更新世晚期－全新世的快速海侵为含炭沉积的形成提供了古地理背景；红树林泥炭发育于４０００ａ以来的海平面波动上升时期；泥炭坪的发育主要取决于海平面的上升速度和植物有机质的堆积速度。海南岛全新世海侵成碳的研究为华北晚古生代含煤建筑的解释提供了比较沉积学的论据     

Peat formation and accumulation mechanism in northern marginal basin of South China Sea

In the present study, the coal-rock organic facies of Oligocene Yacheng Formation of the marginal basin in the South China Sea were classified and divided. In addition, through the correlations of the large-scale coal-bearing basins between the epicontinental sea and the South China Sea, it was concluded that the coal forming activities in the South China Sea presented particularity and complexity. Furthermore, the coal forming mechanisms also presented distinctiveness. The marginal basins in th...     

Influence of refractory organic matter on source rock hydrocarbon potential: A case study from the Second White Specks and Belle Fourche formations,Alberta, Canada

Dilution by inert, refractory organic carbon can have a significant impact on the hydrocarbon potential of source rocks. In this study, a correction of total organic carbon, based on petrographic observations, is proposed to give a better indication of hydrocarbon generation potential. This correction shows that although the Second White Specks Formation is an excellent hydrocarbon source rock, hydrogen index and total organic carbon are influenced by dilution from refractory organic carbon of various sources. The results show that a higher degree of dilution occurs within the Belle Fourche Formation than the Second White Specks Formation. This dilution can have a significant impact on the hydrocarbon potential of the rock.Volumetric calculation of the inert carbon fraction using organic petrographic methods provides a semi quantitative method to correct total organic carbon values for the refractory organic carbon dilution effect. Incorporation of the dilution corrected organic carbon value in hydrogen index calculations allows a greater understanding of source rock hydrocarbon potential. This method provides better differentiation of the small scale variation between micro-facies and formation, as observed in the Second White Specks and Belle Fourche formations, than traditional bulk geochemical methodologies and previously proposed correction methodologies. Degree of dilution, either through transport of recycled allochthonous or autochthonous reworking of organic matter in-situ is highly variable and represents a significant challenge in the characterization of heterogeneous source rocks.This study investigates the organic petrology and geochemistry of a sediment core from the thermally immature area of the Upper Cretaceous Second White Specks Formation and Belle Fourche Formation. Reflectance and relative abundance of three maceral groups (bituminite, alginite, and refractory organic carbon macerals) showed significant organic matter compositional differences between micro-facies in the Second White Specks Formation. A change is also observed in organic matter composition from the upper part of the Belle Fourche Formation to the Second White Specks Formation. These compositional changes represent shifts in sediment source, sea floor oxygen levels, and depositional energy levels. These changes can be episodic, as observed between micro-facies, or longer time scale trends, as observed between the studied formations.     

Can Rock Composition Affect Sublittoral Epibenthic Communities?

Abstract. Biomineralogy, as the complex of interactions at different levels (cell, organism, species, and community) between organisms and minerals, may play a significant role in the spatial distribution and structure of marine communities. For instance, a negative influence of quartz has been underlined on the Mediterranean benthic communities, which show a species-poorer structure in quartz-rich environments. Excluding the role of quartz, the aim of this work is to verify whether the composition of various mineralogical substrata can affect a hard-bottom benthic community. In the Ligurian Sea, the Levanto area shows an astonishing complex of substrata with different petrographic characters: in a few kilometres, sandstones, serpentinites, gabbros, and basalts occur in geometric association. Consequently, this area represents a suitable frame for this type of study. Herein, algal photophilic assemblages growing on the four mineralogical substrata show significant differences in number of species and percentage cover or abundance. This suggests a significant influence of rock mineral composition on the hard bottom community. Therefore, rock composition must be taken into account for a better understanding of the processes at the basis of hard-bottom community development and diversity.     

南沙群岛南科1井白云岩发育特征及铁白云石成因机制的初步研究

南海自新生代以来发育了大量的碳酸盐岩台地和生物礁,并普遍发生白云岩化作用,具有广阔的油气勘探前景。文章通过开展岩相学观察、矿物学分析、常微量元素和碳氧同位素分析,同时结合Fe组分及Fe同位素地球化学分析,对南沙群岛南科1井白云岩的发育特征和成岩环境进行了系统研究。结果表明:南科1井上中新统—下更新统白云岩主要形成于近地表环境中,溶蚀孔隙发育,残余结构明显。白云岩层中发育有多个与暴露成因有关的界面,未发现石膏层的存在。同时,白云岩普遍具有低Fe、Mn和Sr的特征以及与现代海水相似的REE分布模式, δ¹³C和δ¹⁸O多为正值,但不存在相关性。整体来看,白云岩可能形成于轻微蒸发海水的渗透回流作用,还受到了与古气候变冷有关的海平面下降的控制。此外,南科1井岩芯中多个层位发育铁白云石,并且集中分布在暴露面附近。Fe组分和Fe同位素组成结果显示,白云岩中Fe主要来源于海水中碳酸盐的沉淀,成岩过程中基本不存在额外的陆源或热液来源的Fe混入。铁白云石主要形成于低温和浅埋藏环境中,大气淡水对生物骨架、生物碎屑以及自生碳酸盐矿物的淋滤-溶解作用为其提供了重要的...     

Cenozoic giant coal-bearing basin belt discovered in China’s sea area

Sea area is an important area of oil and gas exploration in China. It has been found that China’s sea area mainly consists of coal type oil and gas, and the exploration of coal-bearing series source rocks has become an important part of oil and gas exploration there. Through years of comprehensive geological research in China’s sea area, it has been revealed that it has undergone multiple occurrences of tectonic opening and closing movements in varying degrees in the Paleogene, forming 26 Cenozoic sedimentary basins of various types, such as active continental margin, passive continental margin, transitional continental margin and drift rift basins. In the present study, it is observed for the first time that coal type source rocks are mainly developed in 14 continental margin basins in China’s sea area, revealing that a very large C-shaped coal-bearing basin group developed there in the Cenozoic. Next, based on the coupling analysis of paleoclimate, paleobotany, paleogeography and paleostructure, it is observed that there are five coal-forming periods in China’s sea area, namely the Paleocene, Eocene, early Oligocene, late Oligocene and Miocene-Pliocene, and the coal-forming age is gradually new from north to south. It is also found that the coal seams in the sea area are mainly developed in three coal-forming environments in Cenozoic, namely delta, fan delta and tidal flat-lagoon. The coal seams developed in different environments are characterized by thin thickness, many layers and poor stability. However, the coal-bearing series source rocks in China’s sea area have a wide distribution range, very high thickness and large amount, thus forming a material basis for the formation of rich coal type oil and gas.     

南海现代沉积地质学的若干问题

本文根据大量实际调查资料,从地质学和海洋沉积学角度,论述南海现代沉积地质学7方面的规律问题,获得初步认识是:(1) 沉积物有8种沉积成因类型,5种沉积环境和相,及具有3次海退、海进旋回的沉积演化模式;(2) 沉积成因类型以陆源碎屑和生物源为主;(3) 生物沉积是判别沉积环境和相的重要标志。沉积物粒度特征,是反映主要水动力作用的可靠标志;(4) 海洋有用砂矿物和锰结核的沉积,受沉积成因类型和沉积环境所控制。     

西太平洋某海域锰结核的矿物学及矿物化学研究

锰结核中的矿物是对结核生长环境反映。对结核进行X射线衍射分析表明:结核中锰矿物主要为水羟锰矿,并含有石英、钙十字沸石、斜长石、以及绿脱石、辉石、方解石和少量的蒙脱石、伊利石、角闪石、绿泥石、白云石、锐钛矿等。锰矿物表明该区为氧化环境,且受到火山、热液活动的影响。定量分析结果表明结核各矿物的含量变化很大,说明结核的生长过程中环境发生了变化。电子探针分析结果表明:结核锰矿物的组分含量变化较大,表明结核的元素来源的不稳定性。     

Stock assessment for Atlantic yellowfin tuna based on extended surplus production model considering life history

The modern fishery stock assessment could be conducted by various models, such as Stock Synthesis model with high data requirement and complicated model structure, and the basic surplus production model, which fails to incorporate individual growth, maturity, and fishery selectivity, etc. In this study, the Just Another Bayesian Biomass Assessment (JABBA) Select which is relatively balanced between complex and simple models, was used to conduct stock assessment for yellowfin tuna (Thunnus albacares) in the Atlantic Ocean. Its population dynamics was evaluated, considering the influence of selectivity patterns and different catch per unit effort (CPUE) indices on the stock assessment results. The model with three joint longline standardized CPUE indices and logistic selectivity pattern performed well, without significant retrospective pattern. The results indicated that the stock is not overfished and not subject to overfishing in 2018. Sensitivity analyses indicated that stock assessment results are robust to natural mortality but sensitive to steepness of the stock-recruitment relationship and fishing selectivity. High steepness was revealed to be more appropriate for this stock, while the fishing selectivity has greater influence to the assessment results than life history parameters. Overall, JABBA-Select is suitable for the stock assessment of Atlantic yellowfin tuna with different selectivity patterns, and the assumptions of natural mortality and selectivity pattern should be improved to reduce uncertainties.     

Impact of the central Pacific zonal wind divergence and convergence on the central Pacific El Nio event

The central Pacific(CP) zonal wind divergence and convergence indices are defined, and the forming mechanism of CP El Nio(La Nia) events is discussed preliminarily. The results show that the divergence and convergence of the zonal wind anomaly(ZWA) are the key process in the forming of CP El Nio(La Nia) events. A correlation analysis between the central Pacific zonal wind divergence and convergence indices and central Pacific El Nio indices indicates that there is a remarkable lag correlation between them. The central Pacific zonal wind divergence and convergence indices can be used to predict the CP events. Based on these results, a linear regression equation is obtained to predict the CP El Nio(La Nia) events 5 months ahead.     

Reprint of: Diagenetic controls on evolution of porosity and permeability in lower Tertiary Wilcox sandstones from shallow to ultradeep (200–6700 m) burial,Gulf of Mexico Basin,U.S.A.

Reservoir quality is a critical risk factor in deep to ultradeep reservoirs at depths >4.5 km. Analysis of Paleogene Wilcox sandstones on the upper Texas Gulf Coast provides insight into the evolution of reservoir quality during shallow to ultradeep burial diagenesis. Reduction of porosity and permeability with burial in Wilcox sandstones was evaluated using subsurface samples from 200 to 6700 m, at temperatures of 25–230 °C. Diagenesis and petrophysical properties were interpreted from petrographic data and core analyses. Wilcox sandstones are mostly lithic arkoses and feldspathic litharenites having an average composition of Q₅₉F₂₂R₁₉. Provenance did not change significantly during Wilcox deposition in this area, nor does average sandstone composition vary among lower, middle, and upper Wilcox sandstones. However, composition does vary with sequence-stratigraphic position; lowstand slope-fan deposits contain more rock fragments than do deposits from highstand or transgressive systems tracts. Given observations from this onshore dataset, Wilcox sandstones deposited in deepwater environments in the Gulf of Mexico are likely to contain more rock fragments than their linked highstand equivalents.     

Diagenetic controls on evolution of porosity and permeability in lower Tertiary Wilcox sandstones from shallow to ultradeep (200–6700 m) burial,Gulf of Mexico Basin,U.S.A.

Reservoir quality is a critical risk factor in deep to ultradeep reservoirs at depths >4.5 km. Analysis of Paleogene Wilcox sandstones on the upper Texas Gulf Coast provides insight into the evolution of reservoir quality during shallow to ultradeep burial diagenesis. Reduction of porosity and permeability with burial in Wilcox sandstones was evaluated using subsurface samples from 200 to 6700 m, at temperatures of 25–230 °C. Diagenesis and petrophysical properties were interpreted from petrographic data and core analyses. Wilcox sandstones are mostly lithic arkoses and feldspathic litharenites having an average composition of Q₅₉F₂₂R₁₉. Provenance did not change significantly during Wilcox deposition in this area, nor does average sandstone composition vary among lower, middle, and upper Wilcox sandstones. However, composition does vary with sequence-stratigraphic position; lowstand slope-fan deposits contain more rock fragments than do deposits from highstand or transgressive systems tracts. Given observations from this onshore dataset, Wilcox sandstones deposited in deepwater environments in the Gulf of Mexico are likely to contain more rock fragments than their linked highstand equivalents.     

南沙群岛海域第四纪颗石藻类初步研究

通过对南沙海域表层沉积及活塞钻孔中颗石藻化石相对丰度和属种分异度的分析,得出颗石藻的组合面貌,并讨论了影响颗石藻组合的环境因素及晚更新世以来的气候变化。     

崂山花岗岩地区含锶、偏硅酸矿泉水的形成机理

报道了崂山花岗岩地区矿泉水的特征。指出其矿泉类型为含锶、偏硅酸型，并讨论了其形成机理。     

High-resolution Reconstruction of a Holocene Coastal Sequence (NW Germany) Using Inorganic Geochemical Data and Diatom Inventories

Holocene deposits of the NW German coastal plain consist of many different lithological facies, for example tidal flats, brackish water sediments and peat beds. The effects of the Holocene sea-level rise on palaeoenvironmental conditions of this coastal sequence were studied by inorganic geochemical methods in conjunction with diatom analyses. Three hundred samples from two parallel sediment cores which cover the entire NW German Holocene were taken at high resolution and were examined for major and minor elements and bulk parameters. Selected samples were analysed for redox-sensitive trace elements and REE distribution, reactive iron and bulk sediment³⁴S/³²S-ratios. Chemical parameters, for example Si/Al and Ca/Sr-ratios and total organic carbon (TOC) contents correlate with depositional factors such as wave-energy and lithofacies changes, which allow a detailed reconstruction of the palaeoenvironment. Diatom analyses reveal information about changes between marine, brackish and limnic conditions and serve to reconstruct palaeosalinity. Early diagenetic effects are evident in the TOC-rich intervals. Most peat layers are affected by sulphate reduction and resulting pyrite formation as well as by enrichments in redox-sensitive trace elements. The highest enrichments are seen for As, Mo, Re and U, indicating a distinct seawater influence. S-isotope ratios of peat samples are compatible with pyrite formation under both open- and closed-system conditions, depending on exposition to seawater. The inorganic geochemical and diatom data suggest limnic conditions at the base of the sequence and repeated changes towards marine conditions within the overlying clastic units. On the other hand, data obtained from the clastic units yield evidence of a recurrent succession from open to restricted marine, brackish-lagoonal, and finally fen environments. Clastic sediments overlying peat layers, correlate with the increase of marine-derived geochemical signatures and pelagic diatoms attest transgressive overlaps. The analyses suggest that major controls on the palaeoenvironments were (i) climate-related oscillations of the coast line and (ii) the morphology of the coastal region allowing marine incursions even into distal semi-terrestrial lowlands.     

硼同位素地球化学应用研究进展

硼的2个稳定同位素(10B和11B)间较大的同位素相对质量差导致自然界明显的硼同位素分馏,加上硼易溶于水和活泼的化学性质,使其在不同的地质环境下具有不同的同位素组成。现已查明自然界硼同位素组成(δ11B)的变化范围为-70‰~+75‰。较负的δ11B值见于非海相蒸发硼酸盐矿物和某些电气石,而较正的δ11B值见于盐湖卤水和蒸发海水。20世纪80年代以来,随着硼同位素测量方法的建立和改进,硼同位素地球化学研究领域不断拓宽。目前,硼同位素已成功地应用于判别沉积环境、示踪地下水污染、研究矿床成因、示踪海水入侵、重建古海洋与古气候条件和研究大陆化学风化等方面。综合概述了硼同位素的分馏机理、硼同位素在自然界的分布及其硼同位素在地球化学领域研究中取得的成果、最新进展以及研究中存在的问题,以促进硼同位素地球化学研究在我国的进一步发展。     

东太平洋多金属结核的一般特征与影响因素

本文主要阐述了东太平洋海盆国家海洋局调查区内多金属结核的物性特点、形态分区、粒级分布、矿物成分以及结核丰度、品位与生成环境因素的关系，并指出了勘探与选冶的较佳区块。     

海底热液矿床地质和地球化学特点研究

海底热液矿床具有重要的经济价值和科学意义。其产出构造背景包括洋中脊、弧后扩张中心及板内热点处。处于不同构造环境的热液矿床具有不同的地质和地球化学特点。系统总结了海底热液矿床产出的地质和地球化学特点,主要包括热液矿床产出的构造背景、围岩类型、矿区的矿物及矿物组合特点以及不同热液区矿床的元素组成、稀土和硫同位素特点等,对各构造环境中热液矿床的特点进行了对比,指出不同热液区热液矿床地质和地球化学特点差异的根本原因在于所处构造环境的不同和扩张速率的差异。文章最后提出了今后应着重研究的几个问题。     

胃含物分析样本数量对生态系统指标估计的影响

本研究应用在胶州湾构建的Ecopath生态系统模型,评估了在模型构建过程中,3种鱼类胃含物分析不同样本数量获得的食性数据对模型输出结果的影响。该模型的生态系统指标被分为3种类别：（1）直接指标,如物种营养级等被胃含物分析样本量直接影响的指标;（2）间接指标,如无脊椎生物生态效率（Ecology efficiency, EE）等受营养关系影响的指标;（3）系统指标,如系统总流量（TST）等用来描述整个生态系统的指标。本研究评估了不同的胃含物分析数量对这些指标的影响。结果表明生态系统模型的系统指标最为稳健,受胃含物分析样本数量的影响最低,而与物种直接相关的指标则在胃含物分析样本量较低时准确度较低。当更多的鱼类胃含物分析数量降低时,生态系统指标的不确定性会增加。本研究有助于理解食性信息的质量如何影响生态系统模型输出,同时可以指导为生态模型构建而进行的胃含物分析实验设计。     

Kraken海洋声学模型及其声传播与衰减的数值试验

针对射线、简正波、PE、FFP等传播模型的算法原理及其适用的海洋环境,建立了以Kraken声学模型计算软件为基础的海洋声场数值预报系统.应用该预报系统对4组典型的海洋声场进行了数值试验,结果表明:在相同的海面和海底边界条件下,声场分布是由声速剖面和声源位置决定的.在负梯度声场中,所有声线都折向海底,在极限声线外产生阴影区.声源位于声道轴附近的温跃层中会产生波导传播.用射线理论解释了上述现象的成因,指出了其实际应用价值.