Biogeographic characterization of Mediterranean and Black Seas faunal provinces using GIS procedures     

L. Garibaldi  J. F. Caddy 《Ocean & Coastal Management》1998,39(3):211-227

To identify Mediterranean and Black Seas areas where similar marine faunal provinces occur, geographical distribution maps of 536 species of actual or potential interest to fisheries have been digitized, using GIS software, and three different ecological areas have been delimited by depth, separated by the 200 and 1000 m isobaths. Information on the species ranges was taken mainly from the maps and the texts of the FAO Species Identification Sheets covering the region, and complemented by other sources when necessary. All the distribution maps have then been overlaid by a grid of points at regular intervals every half degree of latitude and longitude. This allowed creation of a matrix of presence or absence of the species at each point from which species richness maps have been generated. The species richness in the Mediterranean proper shows the same negative gradient eastwards that has been observed for nutrients, while the low number of species in the Black Sea could be linked to the fragility and recent fast degradation of this ecosystem. Through the calculation of 65 dissimilarity indices from 50 contiguous points along the coastline and the species richness maps, the region has been divided into nine faunal provinces. These faunal provinces have then been compared with the ten Mediterranean and Black Seas divisions used by the GFCM for statistical purposes, revealing few differences between the two classifications. The definition of faunal provinces in a region when deciding upon Natural Management Areas, and the appropriate GIS approach to be followed, are discussed.  相似文献   

Organic carbon isotopes of the Sinian and Early Cambrian black shales on Yangtze Platform, China   总被引：5，自引：0，他引：5  

Renwei Li  Jialan Lu  Shukun Zhang  Jiajin Lei 《中国科学D辑(英文版)》1999,42(6):595-603

Organic matter of the Sinian and early Cambrian black shales on the Yangtze Platform belongs to the light carhon group of isotopes with the δ¹³C values from - 27% to - 35 %, which are lower than those of the contempomneously deposited carbonates and phosphorites. A carbon isotope-stratified paleooceanographic model caused by upwelling is proposed, which can be used not only to interpret the characteristies of organic carbon isotopic compositions of the black shales, but also to interpret the paleogeographic difference in the organic carbon isotope compositions of various types of sedimentary rocks. Project supported by the National Natural Science Foundation of China (Grant No. 49472114) and the Open Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences.  相似文献   

盐源—宁蒗地区早泥盆世古地理特征及油气潜力分析          下载免费PDF全文

邓敏  程锦翔  王正和  余谦  张海全  张娣  陆俊泽 《沉积与特提斯地质》2020,40(4):25-35

为了探索康滇地轴以西地质条件复杂地区的油气资源潜力,通过面积性地质调查工作与钻孔资料、分析测试资料结合,对盐源—宁蒗地区下泥盆统黑色页岩开展综合研究。研究表明：盐源—宁蒗地区早泥盆世古地理主要受康滇古陆及古特提斯构造域的构造活动控制,靠近金-箐断裂地区发育滨岸-潮坪相,古隆起围限区出现局限海湾相,远离隆起的西北部地区发育台地、陆棚、盆地相;大瓜坪组（早泥盆世晚期）发育黑色页岩（局部地区发育硅质泥岩）,在羊排喜—岩口一带分布较为稳定、厚度大（20～100m）,普遍含钙质,有机碳含量较高,具较高的脆性矿物含量,热演化程度适中,是重要的烃源岩和页岩气富集有利层位;黑色页岩主要发育在局限海湾环境中,羊排喜—岩口—茅坪子一线是盐源—宁蒗地区黑色页岩富集区。  相似文献   

矿物组分对龙马溪组页岩动、静态弹性特征的影响          下载免费PDF全文

王斌  邓继新  刘喜武  潘建国  王佳庆  肖顺垚 《地球物理学报》2019,62(12):4833-4845

龙马溪组页岩是目前国内页岩气勘探的主要层位之一,其静态弹性性质是影响压裂效果的重要因素,而动态弹性性质则是页岩"甜点"地震预测的重要基础.但对龙马溪组页岩动、静态弹性特征相互关系及其影响因素缺少对比研究,致使运用动态弹性性质进行"甜点"预测时存在不确定性.在对龙马溪组页岩样品系统动、静态性质联合测量基础上,分析了页岩样品动、静态弹性性质的变化规律,并讨论了成岩作用与动、静态弹性性质变化规律的因果关系.研究结果表明,龙马溪组页岩上下两段成岩过程存在明显差异,致使上段页岩在结构上表现为以塑性黏土颗粒作为受力骨架,而下段页岩在结构上逐渐转变为脆性石英颗粒作为受力骨架.页岩岩石结构特征的变化控制了动、静态弹性特征的整体变化规律,表现为动、静态杨氏模量、峰值强度等随石英含量的增大表现出近似"V"型的变化形式,而与钙质含量变化呈现正相关关系,与黏土含量变化表现出负相关性.上段页岩宏观力学性质受微观石英+黏土颗粒集合体弹性性质控制,应力应变曲线表现出明显塑性段,动、静态杨氏模量比大于1.4,破裂易于发生在黏土与石英颗粒边界形成宏观单剪型破裂模式,样品脆性低,且脆性变化不受石英含量的影响.下段页岩宏观力学性质受微观石英颗粒集合体弹性性质控制,应力应变曲线表现为弹性变形,动、静态杨氏模量比小于1.4,破裂发生在石英颗粒内部形成宏观劈裂型破裂模式,样品脆性高,且脆性变化与石英含量呈明显正相关关系.研究结果可为龙马溪页气储层的测井解释和地震"甜点"预测提供依据.  相似文献   

The Adaptive Marine Policy (AMP) toolbox: Supporting policy-makers developing adaptive policies in the Mediterranean and Black Sea     

《Marine Policy》2017

Adaptive management is essential to the practical application of the Ecosystem-Based Approach (EBA). Despite there are frequent assertions that adaptive management is being used, evidence on its success is still limited. Indeed, it is difficult to bring the different elements of adaptive management together in a robust way and to choose the appropriate tools to do it. Therefore, it is necessary to provide a practical framework for adaptive policy action, consistent with the EBA. Accordingly, to operationalize the design and implementation of adaptive policies on the basis of the EBA, the Adaptive Marine Policy toolbox has been developed. The objective of the toolbox is to provide policy-makers a practical framework to design and implement adaptive policies. To show the functionality of the toolbox, the guidelines and resources provided within the toolbox have been applied to the marine litter issue in the Mediterranean and Black Sea as an example. The example application has shown that the toolbox is a useful and operational framework to build a science-policy interface according to the EBA. Despite some resources could be missing from the toolbox, they provide a practical and useful starting point to support the application of the different steps and key activities.  相似文献   

Black band disease as a possible factor of the coral decline at the northern reef-flat of Yongxing Island,South China Sea   总被引：1，自引：0，他引：1  

YANG HongQiang  SHEN JianWei  FU FeiXue  WANG Yue & ZHAO Na 《中国科学:地球科学(英文版)》2014,57(4):569-578

Black band disease(BBD),characterized by the Cyanobacterial dominated pathogenic consortium,is thought to play a key role in the global decline of the coral reef ecosystems.The present paper originally documents a case of BBD from Yongxing Island(Xisha Islands,South China Sea),and further probes the reasons of this abnormal phenomenon.Prior to 2007,corals at northern reef-flat of Yongxing Isand were in healthy growth.Catastrophic coral mortality occurred between 2007 and 2008.The 16S rRNA gene sequencing and PCR amplification,with universally conserved primers,were applied to detect the contagious bacterial community of the microbial mat.The results demonstrated that six bacterial divisions constituted the clone libraries derived from the BBD mat,and that Cyanobacteria are the most diversely represented group that inhabit BBD bacterial mats,despite the fact that species in five others divisions(α-Proteobacteria,γ-Proteobacteria,Bacteroidetes,Verrucomicrobia and Actinobacteria) are also consistently diverse within the BBD mats of diseased coral.Other factors such as coral bleaching,typhoons,ocean acidification and crown-of-thorns starfish outbreaks,are not primarily responsible for the coral mortality within such a short time interval.The disaster expansion of BBD associated with Cyanobacterial blooms is a more likely mechanism impacting these coral reefs.Excessive human activity enhances the eutrophication of the marine water of the reefal region and may result in occurrence of the BBD.  相似文献   

Organic Geochemistry of the Early Jurassic Oil Shale from the Shuanghu Area in Northern Tibet and the Early Toarcian Oceanic Anoxic Event   总被引：3，自引：0，他引：3  

CHEN Lan  YI Haisheng  HU Ruizhong  ZHONG Hong  ZOU Yanrong Open Laboratory of Ore Deposit Geochemistry  Institute of Geochemistry  Chinese Academy of Sciences  Guiyang  Guizhou  Graduate School of Chinese Academy of Sciences  Beijing Institute of Sedimentary Geology  Chengdu University of Technology  Chengdu  Sichuan State Key Laboratory of Organic Geochemistry  Guangzhou Institute of Geochemistry  Chinese Academy of Sciences  Guangzhou  Guangdong 《《地质学报》英文版》2005,79(3):392-397

This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearasfalciferrum Zone. Therefore,the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ^13C values of the kerogen (δ^13Ckerogen) fluctuating from -26.22 to -23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ^13Ckerogen values. The biological assemblage,characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.  相似文献   

Development of gullies and sediment production in the black soil region of northeastern China   总被引：11，自引：0，他引：11  

Yongqiu Wu  Qiuhong Zheng  Yongguang Zhang  Baoyuan Liu  Hong Cheng  Yanzai Wang 《Geomorphology》2008,101(4):683-691

Gully erosion is an important environmental hazard in the black soil region of northeastern China. It is a primary sediment source in the region which needs appropriate soil conservation practices. Gully incision in rolling hills typical of this region was monitored using real-time kinematic GPS to assess the rates of gully development and the resultant sediment production. From 2002 to 2005, gully heads in the study area retreated between 15.4 and 33.5 m, giving an average retreat rate of 8.4 m yr^− 1. Field measurements showed that total sediment production due to gully erosion during the three years ranged between 257 and 1854 m³ yr^− 1, which is equivalent to 326 to 2355 t yr^− 1, with gully-head retreat accounting for 0 to 21.7% (4.4% in average). The sediment delivery ratio was especially high during the summer rainy season (56% in average). Sediment production by ephemeral gullies and permanent gullies was 1.5 times greater than that from surface erosion. Gully heads retreated faster in the spring freeze–thaw period than in the summer. The stage of gully development could be identified based on short-term changes in the gully erosion rate.  相似文献   

Interaction between Microbes DNA and Atrazine in Black Soil Analyzed by Spectroscopy          下载免费PDF全文

Ying Zhang  Huosheng Guo  Dongfang Meng  Yang Wang  Po‐keung Wong 《洁净——土壤、空气、水》2015,43(6):867-871

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Actively forming Kuroko-type volcanic-hosted massive sulfide (VHMS) mineralization at Iheya North,Okinawa Trough,Japan     

《Ore Geology Reviews》2017

Modern seafloor hydrothermal systems provide important insights into the formation and discovery of ancient volcanic-hosted massive sulfide (VHMS) deposits. In 2010, Integrated Ocean Drilling Program (IODP) Expedition 331 drilled five sites in the Iheya North hydrothermal field in the middle Okinawa Trough back-arc basin, Japan. Hydrothermal alteration and sulfide mineralization is hosted in a geologically complex, mixed sequence of coarse pumiceous volcaniclastic and fine hemipelagic sediments, overlying a dacitic to rhyolitic volcanic substrate. At site C0016, located adjacent to the foot of the actively venting North Big Chimney massive sulfide mound, massive sphalerite-(pyrite-chalcopyrite ± galena)-rich sulfides were intersected (to 30.2% Zn, 12.3% Pb, 2.68% Cu, 33.1 ppm Ag and 0.07 ppm Au) that strongly resemble the black ore of the Miocene-age Kuroko deposits of Japan. Sulfide mineralization shows clear evidence of formation through a combination of surface detrital and subsurface chemical processes, with at least some sphalerite precipitating into void space in the rock. Volcanic rocks beneath massive sulfides exhibit quartz-muscovite/illite and quartz-Mg-chlorite alteration reminiscent of VHMS proximal footwall alteration associated with Kuroko-type deposits, characterized by increasing MgO, Fe/Zn and Cu/Zn with depth. Recovered felsic footwall rocks are of FII to FIII affinity with well-developed negative Eu anomalies, consistent with VHMS-hosting felsic rocks in Phanerozoic ensialic arc/back-arc settings worldwide.Site C0013, ∼100 m east of North Big Chimney, represents a likely location of recent high temperature discharge, preserved as surficial coarse-grained sulfidic sediments (43.2% Zn, 4.4% Pb, 5.4% Cu, 42 ppm Ag and 0.02 ppm Au) containing high concentrations of As, Cd, Mo, Sb, and W. Near surface hydrothermal alteration is dominated by kaolinite and muscovite with locally abundant native sulfur, indicative of acidic hydrothermal fluids. Alteration grades to Mg-chlorite dominated assemblages at depths of >5 mbsf (metres below sea floor). Late coarse-grained anhydrite veining overprints earlier alteration and is interpreted to have precipitated from down welling seawater as hydrothermal activity waned. At site C0014, ∼350 m farther east, hydrothermal assemblages are characterized by illite/montmorillonite, with Mg-chlorite present at depths below ∼30 mbsf. Recovered lithologies from distal, recharge site C0017 are unaltered, with low MgO, Fe₂O₃ and base metal concentrations.Mineralization and alteration assemblages are consistent with the Iheya North system representing a modern analogue for Kuroko-type VHMS mineralization. Fluid flow is focussed laterally along pumiceous volcaniclastic strata (compartmentalized between impermeable hemipelagic sediments), and vertically along faults. The abundance of Fe-poor sphalerite and Mg-rich chlorite (clinochlore/penninite) is consistent with the lower Fe budget, temperature and higher oxidation state of felsic volcanic-hosted hydrothermal systems worldwide compared to Mid Ocean Ridge black smoker systems.  相似文献