海南岛早白垩世红层磁组构和古地磁新结果   总被引：1，自引：1，他引：1       下载免费PDF全文

张伙带  谈晓冬 《地球物理学报》2011,54(12):3246-3257

海南岛白垩纪红层是迄今产出古地磁结果最多的地层,但古地磁结果难以在海南岛周边古地磁结果和地质限制条件下作出合理解释.为了更好地认识海南岛白垩纪红层古地磁方向的可靠性,我们对采自前人工作地区的14个采点132个样品开展了古地磁和磁组构的综合研究.磁化率各向异性测试显示14个采点样品平均各向异性度为1.018,线理度为1....  相似文献   

厦门国家级珍稀海洋物种自然保护区文昌鱼(Branchiostoma belcheri)种群健康评价     

黄良敏  黎中宝  吝涛  李元跃  陈融斌  王家樵  陈强  李军 《海洋与湖沼》2013,44(1):103-110

利用2009-2010年四个季度月用底栖生物抓斗式采样器捕获的文昌鱼样品,从其资源分布、年龄结构、生物学和生态学特征等方面对厦门国家级珍稀海洋物种自然保护区文昌鱼的种群健康状况进行评价研究.结果表明:(1)文昌鱼种群资源分布衰减趋势明显,只在黄厝—前埔海区、小嶝岛—角屿海区和南线—十八线海区3个核心区还有分布,但资源密度低,分布范围狭小,而在鳄鱼屿实验区未能发现.(2)文昌鱼体重与体长之间关系:W=6.6895×10-4L3.1818;体长与体质量生长方程分别为:厶=65.63[1-e-0.68(t+032)],Wt=404.62[1-e-0.68(t+032)]3.1818;夏季、冬季航次的优势体长组分别为25-35mm和35-45mm,优势体重组分别为25-50mg和50-100mg;秋季低龄鱼较多,而冬季高龄鱼比例较高.(3)采用ELEFAN Ⅰ技术分析了厦门文昌鱼的Von Bertalanffy生长参数K、L∞、总死亡系数Z、自然死亡系数M和开发率E,发现其生长参数K值较大,自然死亡系数较高,开发率较大(0.69).综之,厦门自然保护区内的文昌鱼种群健康状况整体不佳,应注意资源保护,加强保护文昌鱼栖息地的底质和水质以及防止过度捕捞以实现其资源可持续利用.  相似文献   

Macrobenthic polychaete assemblages of the continental shelf and upper slope off the west coast of the South Island,New Zealand     

P. K. Probert  G. B. Read  S. L. Grove  A. A. Rowden 《新西兰海洋与淡水研究杂志》2013,47(5):971-984

Polychaete assemblages are described from replicate box‐core samples collected in summer 1983 at 18 stations on the continental shelf and upper slope (28–943 m) off the west coast of the South Island, New Zealand, south‐eastern Tasman Sea (c. 41–43°S, 169–172°E). Three main station groupings were identified by multivariate analysis: (1) inner shelf sandy stations characterised by Prionospio australiensis, Aricidea (Acesta) sp., Magelona cf. dakini, Paraprionospio aff. pinnata, Aglaophamus sp., Heteromastus filiformis, and Magelona sp.; (2) middle to outer shelf muddy stations characterised by Levinsenia cf. gracilis, Prionospio australiensis, Paraprionospio coora, Aglaophamus verrilli, and Auchenoplax mesos; and (3) upper slope sandy mud or mud stations characterised by Prionospio ehlersi. A combination of water depth and sediment clay content provided the best correlation with the biotic pattern. Spionidae was the most abundant family (49% of polychaete individuals), which may reflect the scope for opportunistic species in a shelf environment characterised by a high input of terrigenous sediment and episodic upwelling.  相似文献   

Heavy metal contamination in western Xiamen Bay sediments and its vicinity, China   总被引：5，自引：0，他引：5  

Zhang L  Ye X  Feng H  Jing Y  Ouyang T  Yu X  Liang R  Gao C  Chen W 《Marine pollution bulletin》2007,54(7):974-982

Concentrations of selected heavy metals (Cu, Pb, Zn, Cd, Cr, Ni and Fe) in surface sediments from nine sites in western Xiamen Bay and its vicinity were studied in order to understand current metal contamination due to urbanization and economic development in Xiamen, China. The sediment samples were collected in December 2004 and July 2005 respectively in order to examine temporal variations. In this study, we found that heavy metal concentrations in surface sediments sampled in the western Xiamen Bay and adjacent Maluan Bay and Yuandang Lagoon varied from 19 to 97mg kg(-1) for Cu, 45 to 60mg kg(-1) for Pb, 65 to 223mg kg(-1) for Zn, 0.11 to 1.01mg kg(-1) for Cd, 37 to 134mg kg(-1) for Cr, 25 to 65mg kg(-1) for Ni and 3.08 to 4.81% for Fe. Although all metal concentrations in sediments meets Chinese National Standard Criteria for Marine Sediment Quality, both metal enrichment factors (EF) and geoaccumulation index (I(geo)) show that Pb contamination exists in the entire study area and contamination of other metals are also present in some locations depending on the sources, of which sewage outlets and commercial ports are the main sources of contaminants to the area. This study shows that using the sediment quality standard criteria only to assess sediments cannot properly reflect sediment contamination. A multiple approaches should be applied for the sediment quality assessment.  相似文献   

Postglacial vegetation history of Mitkof Island, Alexander Archipelago, southeastern Alaska     

Thomas A. Ager  Paul E. Carrara  Victoria Anne  Joni Johnson 《Quaternary Research》2010,73(2):259-462

An AMS radiocarbon-dated pollen record from a peat deposit on Mitkof Island, southeastern Alaska provides a vegetation history spanning ∼12,900 cal yr BP to the present. Late Wisconsin glaciers covered the entire island; deglaciation occurred > 15,400 cal yr BP. The earliest known vegetation to develop on the island (∼12,900 cal yr BP) was pine woodland (Pinus contorta) with alder (Alnus), sedges (Cyperaceae) and ferns (Polypodiaceae type). By ∼12,240 cal yr BP, Sitka spruce (Picea sitchensis) began to colonize the island while pine woodland declined. By ∼11,200 cal yr BP, mountain hemlock (Tsuga mertensiana) began to spread across the island. Sitka spruce-mountain hemlock forests dominated the lowland landscapes of the island until ∼10,180 cal yr BP, when western hemlock (Tsuga heterophylla) began to colonize, and soon became the dominant tree species. Rising percentages of pine, sedge, and sphagnum after ∼7100 cal yr BP may reflect an expansion of peat bog habitats as regional climate began to shift to cooler, wetter conditions. A decline in alders at that time suggests that coastal forests had spread into the island's uplands, replacing large areas of alder thickets. Cedars (Chamaecyparis nootkatensis, Thuja plicata) appeared on Mitkof Island during the late Holocene.  相似文献   

海南岛三叠纪中基性岩的年代学、地球化学及其地质意义   总被引：1，自引：0，他引：1       下载免费PDF全文

唐立梅  陈汉林  董传万  沈忠悦  程晓敢  付璐露 《地质科学》2010,45(4):1139-1155

辉长岩大多为地幔岩石部分熔融的产物,辉绿岩脉及碱性正长岩的形成通常与伸展构造有关,本文对海南岛万宁辉长岩及辉绿岩脉和分界洲正长岩进行了系统的年代学和岩石地球化学研究,并以此来讨论其构造意义。LA-ICP-MS锆石U-Pb定年结果表明,万宁辉长岩及辉绿岩脉形成约在240 Ma,分界洲正长岩形成约在231 Ma,主量元素特征表明万宁辉长岩和辉绿岩分别属碱性系列和亚碱性系列,分界洲正长岩属于典型的碱性岩浆岩。万宁辉长岩及辉绿岩脉的稀土元素具有轻稀土富集的特点(LREE/HREE=7.22～8.50和8.11～11.10),微量元素具有岛弧型火山岩的特征,富集大离子亲石元素K、Rb、Ba、Th,贫高场强元素Nb、Ta和Zr、Hf;分界洲正长岩的微量元素特征显示出与A型花岗岩类似的特征。海南岛三叠纪中基性岩如分界洲正长岩和万宁辉长岩及辉绿岩脉形成的构造背景为陆内伸展环境,指示海南岛在240～230 Ma处于印支造山运动的应力松弛阶段。  相似文献   

新疆谢米斯台中段火山岩岩石地球化学特征、锆石U-Pb年龄及其地质意义   总被引：9，自引：6，他引：3  

孟磊  申萍  沈远超  刘铁兵  宋国学  代华五  李成凯  郎泽松 《岩石学报》2010,26(10):3047-3056

谢米斯台中段地区发育的火山岩主要为安山岩、英安岩和流纹岩。岩石地球化学研究表明,岩石的K2O、Na2O含量高(K2O=3.42%～9.85%;Na2O=0.48%～5.30%),大离子亲石元素(LILE)相对富集,高场强元素(HFSE)相对亏损,其中Nb、P、Ti强烈亏损,轻稀土元素(LREE)和重稀土元素(HREE)分馏较强;Pb同位素比值为206Pb/204Pb=18.435～19.409、207Pb/204Pb=15.535～15.602、208Pb/204Pb=38.36～39.213;火山岩具有高的初始εNd(t)值(+4.43～+6.65)和低的初始87Sr/86Sr值(0.700953～0.704435)。该地区流纹岩SIMS锆石U-Pb测年结果为422.5±1.9Ma。综合研究认为,谢米斯台中段地区火山岩是晚志留世准噶尔洋壳俯冲,在地幔楔形区,经过洋壳与富集地幔的局部熔融,经历了一定程度的分离结晶作用形成的中酸性岩浆喷发而成,在岩浆上升过程中有少量地壳物质的混染。  相似文献   

獐子岛海域和胶州湾表层微微型浮游植物丰度和生物量的季节变化比较     

李苏恒  董逸  赵苑  孙晓霞  张光涛  赵丽  张武昌  肖天 《海洋与湖沼》2022,53(6):1405-1414

为全面了解黄海典型海区微微型浮游植物的季节变化特征,于2009年7月至2010年6月在北黄海獐子岛海域和2010年1~12月在南黄海胶州湾进行逐月调查采样,利用流式细胞仪检测了表层海水中微微型浮游植物(picophytoplankton)的丰度,包括聚球藻(Synechococcus,SYN)和微微型真核浮游植物(picoeukaryotes,PEUK),并分析了其与环境因子的关系。獐子岛海域和胶州湾SYN和PEUK全年广泛分布,獐子岛海域SYN丰度范围在0.05×10³~120.00×10³cells/mL之间,丰度在秋季最高;胶州湾SYN丰度范围在0.02×10³~61.80×10³cells/mL之间,丰度在夏季最高。獐子岛海域PEUK丰度范围在0.01×10³~18.76×10³cells/mL之间,丰度在秋季最高;胶州湾PEUK丰度范围在0.25×10³~95.57×10³ cells/mL之间,丰度在春季最高。獐子岛海域微微型浮游植物丰度组成以SYN为主;而胶州湾以PEUK为主。PEUK是两海区微微型浮游植物生物量的主要贡献者。相关性分析结果表明,温度是影响两海区SYN丰度季节变化的最主要因素;影响PEUK季节分布的因素不完全一致,獐子岛海域PEUK丰度主要受温度调控;胶州湾PEUK丰度主要受温度和营养盐浓度影响。与已有研究比较,这两个海区的微微型浮游植物生物量对浮游植物生物量的贡献明显高于其他温带沿岸海域,预示微微型浮游植物在獐子岛海域和胶州湾生态系统中的重要作用,值得进一步深入研究。  相似文献   

芙蓉岛秋季鸟类生物多样性研究          下载免费PDF全文

陶卉卉  张亮  林森  黄蕊  王尽文  郑金金  郑诗峰  钟山 《海岸工程》2022,41(3):277-282

为了解芙蓉岛鸟类生态类群和多样性,本文以2019年9月芙蓉岛鸟类调查数据为基础,利用样点法对芙蓉岛鸟类的种类、生态类群、区系、居留型和鸟类多样性等进行了研究。结果表明：本次调查共记录鸟类5目15科31种,其中国家Ⅱ级保护鸟类7种,列入《濒危野生动植物种国际贸易公约及有效决议汇编》附录Ⅲ中的鸟类1种。从生态类群构成上：鸣禽19种,猛禽7种,涉禽4种,陆禽1种;从鸟类地理区系构成上：广布种23种,古北种7种,东洋界1种;从居留类型构成上：冬候鸟5种,留鸟3种,旅鸟17种,夏候鸟、冬候鸟和旅鸟混合类型6种。鸟类群落多样性指数（H''）为3.83,均匀度指数（J）为0.77。芙蓉岛鸟类优势种为红嘴鸥（Larus ridibundus）、家燕（Hirundo rustica）和树麻雀（Passer montanus）。本文对芙蓉岛鸟类生物多样性进行了报道,对芙蓉岛鸟类资源的本底调查以及该区域鸟类生物多样性保护具有重要意义。  相似文献   

海南新村潟湖潮汐、潮流特征及其对营养盐的影响          下载免费PDF全文

张奕璞  于硕  黄大吉  周泽斌 《海洋学研究》2022,40(2):69-82

基于海南新村潟湖2020年12月水文和水质多要素实测数据,研究了该海域的潮汐、潮流变化特征,并探讨了潮位变化对潟湖营养盐的影响。结果表明,新村潟湖的潮汐为不规则全日潮,潟湖口门处的潮流为往复流,涨潮历时15 h,落潮历时10 h。大、小潮期间3个观测站点溶解性无机氮(DIN)浓度变化范围为0.91~20.87 μmol/L,磷酸盐(PO3-4)浓度变化范围为0.11~5.92 μmol/L,硅酸盐(SiO2-3)浓度变化范围为2.36~134.75 μmol/L。大、小潮期间,潟湖内3个观测站点DIN、PO3-4、SiO2-3浓度随着涨、落潮过程发生变化。潟湖口门处流速对观测站点潮位变化有着重要的影响,潮通量基本决定了潮位的变化。潟湖口门处和渔排密集区域的营养盐浓度与潮位呈现显著的负相关关系,潮流流速对口门处和渔排密集区域的营养盐变化有着重要影响。该研究结果将为新村潟湖的污染治理及生态修复提供科学依据。  相似文献