Development of northwest Pacific guyots: General results from Ocean Drilling Program legs 143 and 144   总被引：1，自引：0，他引：1  

Peter Flood 《Island Arc》1999,8(1):92-98

Results of the Ocean Drilling Program legs 143 and 144, which investigated the nature and origin of seven guyots in the northwest Pacific Ocean, document a history of prolonged volcanism (128–84 Ma), followed by subsidence, accumulation of shallow-water carbonates, emersion following a sea-level fall, then continued subsidence, and drowning. Generally, the life span of a guyot is of the order of 5–20 million years. The stratigraphic sequence in each guyot consists of 3–10 m-thick, shoaling-upward cycles, which display a 100-Ka periodicity perhaps related to sea-level fluctuations. The drilling results indicate that the demise of the shallow-water carbonate platforms is related to either a temporal (110–100 Ma) event or paleolatitude location (0–10°S) involving nutrient-rich water not conducive to production of calcium carbonate by shallow-water organisms. Following emergence and erosion, re-submergence occurred during a rise of sea-level. However, the rate of sediment accumulation was unable to keep pace with the rate of sea-level rise and the guyots drowned. Subsidence continued as the lithospheric plate cooled. The majority of guyots are now at ~ 1500 m below sea-level. Plate movements over the past 100 million years have carried the guyots from ~ 14°S to their current location in the northwest Pacific. Guyots are flat-topped submerged volcanic islands capped by thick sequences of shallow-water carbonates. The flat-top morphology is constructional, not related to wave planation as originally thought and reported in most textbooks.  相似文献   

西太平洋富钴结壳元素组合特征及其地质意义   总被引：10，自引：0，他引：10  

何高文  薛婷  孙晓明  张学华  朱克超  王生伟 《矿物岩石地球化学通报》2005,24(2):125-129

海山富钴结壳是一种重要的海底固体矿产。对西太平洋海山的56个结壳样品进行了23种化学组分分析,并利用R型聚类分析和R型因子分析,分别提取四组元素组合和四个主因子。综合特征表明．富钴结壳在形成过程中,经历了一次强度较大的锰矿物相成矿作用,Co、Ni等元素的富集与此有关;铁矿物相的成矿作用强度较小,但表现出多期次的特点;锰、铁矿物是不同成矿作用的产物;结壳形成过程中,可能遭受了二次磷酸盐化作用,结壳中磷酸盐矿物的形成对铁矿物相的形成可能有抑制作用。  相似文献   

不同表面活性剂修饰TiO2柱撑粘土的制备及其光催化活性研究   总被引：1，自引：0，他引：1  

陈嘉鑫  安太成  丁雪军  袁建梅  盛国英  傅家谟 《矿物岩石地球化学通报》2005,24(4):286-292

本文分别采用阴离子、非离子、阳离子三种不同类型的表面活性剂对河北蒙脱石进行改性修饰,并以酞酸丁酯和盐酸分别为前驱物和酸催化剂,采用溶胶-凝胶法（Sol-gel）制备了不同表面活性剂修饰TiO2柱撑粘土催化剂.用X射线粉末衍射（XRD）和场发射扫描电子显微镜（SEM）等手段表征了催化剂的微观结构,以2,4,6-三氯苯酚（2,4,6-trichlorophenol, TCP）和甲基橙染料的吸附、降解为模型反应,考察了改变溶胶和表面活性剂的不同添加顺序对阳离子表面活性剂所修饰的催化剂性质的影响,以及不同类型的表面活性剂修饰所得的催化剂的光催化活性.实验结果表明,通过添加不同的表面活性剂能够不同程度地改变柱撑粘土的BET比表面积,并使其对不同目标污染物具有不同的吸附能力和光催化活性.阴离子表面活性剂十二烷基苯磺酸钠（DBS）修饰的TiO2柱撑粘土具有较好的光催化活性,其次是非离子表面活性剂聚乙烯醇（PVA）修饰的TiO2柱撑粘土,而阳离子表面活性剂十六烷基三甲基溴化铵（CTMAB）修饰的柱撑粘土光催化活性较差.  相似文献   

Preliminary study on community structures of meiofauna in the middle and eastern Chukchi Sea     

Dingyong Huang  Jianjia Wang  Qianhui Zeng  Jiaguang Xiao  Peng Tian  Sujing Fu  Feng Guo  Wentao Niu 《海洋学报(英文版)》2021,40(6):83-91

Sediment core samples were collected from 17 stations in the middle and eastern Chukchi Sea during the sixth Chinese National Arctic Research Expedition(CHINARE-Arctic) in summer 2014.The samples were analyzed for composition,abundance,biomass,vertical distribution,size spectra,and ecological indexes of meiofauna.A total of 14 meiofauna taxa were detected,and the free-living marine nematodes comprised the most dominant taxon,accounting for 97.21% of the average abundance.The abundance and biomass of meiofauna were within ranges of(218.12±85.83)-(7 239.38±1 557.15) ind./(10 cm~2) and(130.28±52.17)-(3 309.56±1 751.80) μg/(10 cm~2),with average values of(2 391.90±1 966.19) ind./(10 cm~2) and(1 549.73±2 042.85) μg/(10 cm~2)(according to dry weight)respectively.Furthermore,91.26% of the individuals were distributed in the top layer of 0-5 cm of surface sediment,and 90.84% had sizes of 32-250 μm.Group diversity index of meiofauna in the survey area was low,and the variation of abundance was the main difference in meiofauna communities among all stations.Abundance and biomass of meiofauna were not significantly correlated with environmental factors except concentration of nutrient Si in bottom seawater.Abundance of meiofauna in shallow water of marginal seas in the Pacific sector of the Arctic Ocean is likely at a same level and higher than that in most of China sea areas,suggesting that the shallow water of the summer Chukchi Sea is a continental shelf area with rich resources of meiofauna.The Chukchi Sea is important for studying the ecosystem of the Arctic Ocean and environmental responses.However,studies on meiofauna in the Chukchi Sea are still not enough,and in the future,natural and human disturbances may increase due to global warming,the Arctic channel opening,and other factors.Thus,more studies on meiofauna should be required,in order to know more about how the Arctic benthic community would alter.  相似文献   

Absolute sea level variability of Arctic Ocean in 1993–2018 from satellite altimetry and tide gauge observations     

Yanguang Fu  Yikai Feng  Dongxu Zhou  Xinghua Zhou 《海洋学报(英文版)》2021,40(10):76-83

Arctic absolute sea level variations were analyzed based on multi-mission satellite altimetry data and tide gauge observations for the period of 1993–2018. The range of linear absolute sea level trends were found ?2.00 mm/a to 6.88 mm/a excluding the central Arctic, positive trend rates were predominantly located in shallow water and coastal areas, and negative rates were located in high-latitude areas and Baffin Bay. Satellite-derived results show that the average secular absolute sea level trend was (2.53±0.42) mm/a in the Arctic region. Large differences were presented between satellite-derived and tide gauge results, which are mainly due to low satellite data coverage, uncertainties in tidal height processing and vertical land movement (VLM). The VLM rates at 11 global navigation satellite system stations around the Arctic Ocean were analyzed, among which 6 stations were tide gauge co-located, the results indicate that the absolute sea level trends after VLM corrected were of the same magnitude as satellite altimetry results. Accurately calculating VLM is the primary uncertainty in interpreting tide gauge measurements such that differences between tide gauge and satellite altimetry data are attributable generally to VLM.  相似文献   

印度洋上层经向翻转环流的冬夏季节对比     

刘雨  徐康  王卫强  谢强  王玉国 《海洋与湖沼》2021,52(5):1104-1114

上层经向翻转环流(shallow meridional overturning circulation, SMOC)主导热带-副热带上层海洋水体交换,对海洋物质输运和热量交换具有重要意义。基于7套海洋再分析数据产品,本文主要探讨了印度洋SMOC的冬夏季节变化及其差异的原因。结果显示,印度洋SMOC主要由南半球副热带环流圈(southern subtropical cell, SSTC)和跨赤道环流(cross-equatorial cell, CEC)组成,并且具有显著的季节差异。夏季风期间, SSTC和CEC均为表层南向输运,表层以下北向输运的逆时针环流结构。冬季风盛行时, SSTC仍维持逆时针结构,但环流中心南移且深度加深,强度弱于夏季;然而, CEC却转向为表层北向输运,表层以下向南输运的顺时针环流结构,其环流中心位置与夏季接近,环流强度与夏季相当。这种印度洋SMOC冬夏结构差异究其原因主要由风生环流主导, CEC冬夏季节环流方向反转是北印度洋冬夏季风转向的结果,而南印度洋信风的季节性位移和强度变化是SSTC强度和位置季节差异的主要原因。  相似文献   

Living coccolithophores in the western Pacific Ocean with mesoscale eddies     

Danyue Huang  Haijiao Liu  Jun Sun  Yuqiu Wei  Liuyang Li  Guicheng Zhang  Laxman Pujari 《海洋学报(英文版)》2021,40(6):111-128

Living coccolithophores(LCs) are regarded as a group of calcifiers and play important roles in global carbon cycle.This study used microscopic observations of LCs in the western Pacific Ocean to investigate their community structure and biodiversity,especially to test whether local physical traits(mesoscale eddies) could explain their biogeographic distributions during autumn of 2017.The coccolithophore calcite inventory based on carbon-volume transformation was estimated in this study.A total of 28 taxa of coccospheres and 19 types of coccoliths were identified from 161 samples.Gephyrocapsa oceanica was the most predominant species in all the coccolithophore community,followed by Florisphaera profunda,Emiliania huxleyi,Umbilicosphaera sibogae,Gladiolithusflabellatus and Umbellosphaera tenuis.The abundance of coccospheres and coccoliths ranged from 0 to 26.8×10~3 cells/L and from 0 to 138.5×10~3 coccoliths/L,averaged at 4.2×10~3 cells/L and 10.9×10~3 coccoliths/L,respectively.This study indicated that coccolithophore community in the survey area can be clustered into four groups.Three ecological niches of coccolithophores were characterized by their vertical profiles and multivariate statistical analysis.Coccolithophore abundance and species composition were remarkably different among warm-eddy region,G.oceanica dominated warm-eddy region,while F.profunda dominated warm-eddy and none-eddy region.The average values of estimated particulate inorganic carbon,particulate organic carbon were0.197 μg/L and 0.140 μg/L,respectively.The current field study widened the dataset of coccolithophores in western Pacific Ocean.  相似文献   

Inversion of the three-dimensional temperature structure of mesoscale eddies in the Northwest Pacific based on deep learning     

Fangjie Yu  Zeyuan Wang  Shuai Liu  Ge Chen 《海洋学报(英文版)》2021,40(10):176-186

Mesoscale eddies, which are mainly caused by baroclinic effects in the ocean, are common oceanic phenomena in the Northwest Pacific Ocean and play very important roles in ocean circulation, ocean dynamics and material energy transport. The temperature structure of mesoscale eddies will lead to variations in oceanic baroclinity, which can be reflected in the sea level anomaly (SLA). Deep learning can automatically extract different features of data at multiple levels without human intervention, and find the hidden relations of data. Therefore, combining satellite SLA data with deep learning is a good way to invert the temperature structure inside eddies. This paper proposes a deep learning algorithm, eddy convolution neural network (ECN), which can train the relationship between mesoscale eddy temperature anomalies and sea level anomalies (SLAs), relying on the powerful feature extraction and learning abilities of convolutional neural networks. After obtaining the temperature structure model through ECN, according to climatic temperature data, the temperature structure of mesoscale eddies in the Northwest Pacific is retrieved with a spatial resolution of 0.25° at depths of 0–1 000 m. The overall accuracy of the ECN temperature structure is verified using Argo profiles at the locations of cyclonic and anticyclonic eddies during 2015–2016. Taking 10% error as the acceptable threshold of accuracy, 89.64% and 87.25% of the cyclonic and anticyclonic eddy temperature structures obtained by ECN met the threshold, respectively.  相似文献   

青藏高原和热带印度洋5月热力异常与新疆夏季降水的关系     

王天竺  赵勇 《高原气象》2021,40(1):1-14

基于1979-2017年美国国家海洋和大气管理局(NOAA)提供的海表温度资料和美国国家环境预测中心(NCEP)/美国国家大气研究中心(NCAR)提供的大气环流再分析资料以及青藏高原地区149个站点观测资料计算的地表感热通量和新疆气象信息中心提供的全疆81站逐月降水资料等,研究了5月青藏高原和热带印度洋加热对新疆夏季降...  相似文献   

北太平洋冬季环境背景场分析及优选航线     

黄彬  张增海  孙明华 《气象科技》2008,36(5):622-626

根据船舶气象导航的原理以及影响航线设计的各种因素,通过对北太平洋冬季大气和海洋环境背景的特征分析,指出船舶在设计航线时,应根据气候状况、海洋环境、天气形势分析结合中短期预报充分利用有利的风、浪、流等天气和海洋条件优选航线,不仅可以规避恶劣天气、确保航行安全,而且大大节约海运时间、降低航运成本.  相似文献