Surface sediment diatoms from the western Pacific marginal seas and their correlation to environmental variables

Diatom data of 192 surface sediment samples from the marginal seas in the western Pacific together with modern summer and winter sea surface temperature and salinity data were analyzed.The results of canonical correspondence analysis show that summer sea-surface salinity(SSS) is highly positively correlated with winter SSS and so is summer sea-surface temperature(SST) with winter SST.The correlations between SSSs and SSTs are less positively correlated,which may be due to interactions of regional current pa...     

近190ka B.P.以来西太平洋暖池北缘上层海水结构和古生产力演化特征及其控制因素——来自钙质超微化石、有孔虫和同位素的证据

对取自西菲律宾海暖池北缘的Ph05—5岩芯进行了钙质超微化石和有孔虫研究。在利用氧同位素曲线对比和AMS^14C数据进行地层划分的基础上,依据超微化石和有孔虫及其同位素组成等指标,分析了近190 ka B．P以来区域生产力和上层海水结构的演变特征,探讨了其控制因素和所指示的古海洋学意义。钙质超微化石下透光带属种Florisphaera profunda百分含量和基于浮游有孔虫转换函数的温跃层深度变化表明,Ph05—5岩芯所在的热带西太平洋暖池北缘约190kaB．P．以来,营养跃层和温跃层冰期（MIS 6期和5d-2期）浅,间冰期（MIS5e）和全新世深,而MIS5e期是最近两个冰期旋回中营养跃层和温跃层深度最深时期。通过Fprofunda百分含量初级生产力转换方程计算结果和与钙质超微化石绝对丰度的变化显示,冰期初级生产力高,间冰期和全新世初级生产力低,MIS5e期初级生产力为末两次冰期旋回之最低。此外,Ph05—5岩芯△δ^13Cc.wullerstorfi-coccolith和△6δ^12Cc.wullerstorfi-N.dutertrei.差值变化显示,190ka B．P以来表层输出生产力冰期高,间冰期低,其中最为突出的特征也是MIS5e期为生产力输出的最低值期。上层海水结构和生产力的上述变化特征与现代La Nina事件暴发时的海洋环境相当类似,该海区MIS5e期可能是LaNina事件频繁爆发的一段时期,可以与现代LaNina现象类比。同时,根据Wyrtki提出的信风张弛理论推测MIS5e期,由于LaNina事件的频繁暴发黑潮主流应该是增强的。     

末次冰期低纬度西太平洋硅藻席沉积与生态特征

硅藻在全球碳循环中发挥着重要的作用。"树荫种"硅藻在次表层水体中的勃发成席,并迅速埋藏成为硅藻席沉积,使人们逐渐意识到次表层生产在整个生产力及输出生产中起着重要作用。介绍了首次在低纬度西太平洋区域发现的硅藻席沉积的分布特征,硅藻席发现站位呈带状分布,大致呈北西-南东向展布,大部分散布在17.5°～20°N之间。采集到硅藻席沉积物的站位其水深在碳酸钙补偿深度(CCD)以下4837～6150m的深水区,多分布在较平坦的海底,且受风力和陆源物质输入影响相对较强的区域。该区域硅藻席的形成可能是由于末次冰期时该海区有大洋锋面的形成所致。该区域的成席硅藻Ethmodiscus rex(Wallich)Hendey为典型的"树荫种"硅藻,可以通过自身调节浮力的作用,在水体相对稳定的贫氧大洋中生存并勃发成席。末次冰期低纬度西太平洋硅藻席沉积的发生,可能使该区成为CO2的汇。     

7500a BP以来冲绳海槽北部孢粉组合及古环境意义

通过分析冲绳海槽北部DOC024柱状样的孢粉记录,重建了该地区7500a BP以来的植被和气候变化历史.该孔自下而上分为4个孢粉组合带：P1带（7500-6600a BP）气候较寒冷湿润;P2（a）带（6600-4900a BP）亚热带植物花粉含量升高,气候变温暖,P2（b）带（4900-3100a BP）温度变化不明显,湿度降低;P3带（3100-1500a BP）温带植物花粉含量升高,热带-亚热带植物花粉含量降低,气温下降;P4带（1500-200a BP）随着蕨类植物的大量繁盛,气温又回升,但从300a BP起,气候又出现下降趋势.文中还对浮游有孔虫δ18O曲线进行了分析,发现它的变化趋势与孢粉组合之间存在着对应性.     

日本海西南陆坡全新世对马暖流演化的沉积学和地球化学记录

对日本海西南陆坡对马暖流主流轴下方高沉积速率沉积物柱状样,进行了沉积学和地球化学系统研究,以探讨全新世以来对马暖流在研究区的形成与演化,并得出了与附近地区古海洋学方法非常相近的结果,从而为今后研究区的对马暖流演化研究提供了沉积学和地球化学指标。据此,该柱状样中所记录的对马暖流演化可划分为5个主要阶段。全新世初期(9.6kaBP),对马暖流开始进入日本海,其强度较弱,同时,伴随着富营养东海沿岸水的影响,海底环境由还原性向氧化性转变;6.5kaBP时,对马暖流控制下的日本海南部现代对流模式最终建立起来,东海沿岸水的影响基本消失,随后,对马暖流明显减弱;3.0kaBP时,对马暖流再次增强并基本达到现在水平,且在随后的3ka里保持总体稳定,期间在2.0～0.7kaBP存在一次较弱的减弱过程。     

内蒙古沙巴尔吐地区中二叠世蛇绿构造混杂岩及同期花岗质杂岩的发现及地质意义

中亚造山带东段内蒙古兴安盟扎赉特旗地区作为二连-贺根山断裂的东延部分,蕴含了古亚洲洋俯冲消亡过程及洋-陆转换的关键信息,然而对于该区蛇绿构造混杂岩的研究相对薄弱,成为制约古亚洲洋构造演化研究的瓶颈.本文在扎赉特旗沙巴尔吐地区发现了蛇绿构造混杂岩、与岛弧环境相关的英云闪长岩-奥长花岗岩和碱长花岗岩组合.对蛇绿构造混杂岩中...     

西太平洋深海沉积物古菌多样性垂直分布

以提取并纯化的西太平洋深海沉积物DNA为模板,利用古菌PCR特异性引物扩增出样品中古菌的16S rDNA片段,构建其克隆文库,建立阳性克隆子RFLP(Restriction Fragment Length Polymor-phism)酶切图谱。据酶切图谱对所获得的120个克隆进行测序,并与数据库中的序列进行比对,从而进行古菌的多样性和系统发育分析。结果表明,沉积物中扩增的16S rDNA古菌序列分别来自泉古生菌(Crenarchaeota)和广古生菌(Euryarchaeota),以Marine Benthic Group B(11.8%)、Marine Benthic Group D(13.6%)、Marine Crenarchaeotic Group(68.69%)为主。少量序列为South African Gold Mine Euryarchaeotic Group(1.07%)、Deep-Sea Hydrothermal Vent Euryarchaeotic Group(1.61%)、UIIB(1.25%)、VALIII(1.79%)、Marine Benthic Group E(0.18%)。以上结果表明西太平洋深海沉积物中有丰富多样的古菌群落。     

Sea surface temperature and salinity reconstruction based on stable isotopes and Mg/Ca of planktonic foraminifera in the western Pacific Warm Pool during the last 155 ka

Changes in sea surface temperature(SST), seawater oxygen isotope(δ 18 O sw), and local salinity proxy(δ 18 O sw-ss) in the past 155 ka were studied using a sediment core(MD06-3052) from the northern edge of the western Pacifi c Warm Pool(WPWP), within the fl ow path of the bifurcation of the North Equatorial Current. Our records reveal a lead-lag relationship between paired Mg/Ca-SST and δ 18 O during Termination II and the last interglacial period. Similarity in SST between our site and the Antarctic temperature proxy and in CO 2 profi le showed a close connection between the WPWP and the Antarctic. Values of δ 18 O sw exhibited very similar variations to those of mean ocean δ 18 O sw, owing to the past sea-level changes on glacial-interglacial timescale. Calculated values of δ 18 O sw-ss refl ect a more saline condition during high local summer insolation(SI) periods. Such correspondence between δ 18 O sw-ss and local SI in the WPWP may refl ect complex interaction between ENSO and monsoon, which was stimulated by changes in solar irradiance and their infl uence on the local hydrologic cycle. This then caused a striking reorganization of atmospheric circulation over the WPWP.     

Tests of new in-situ seabed acoustic measurement system in Qingdao

A new in-situ seabed acoustic measurement system is developed for direct in-situ measurement of sediment geoacoustic properties （compressional wave velocity and attenuation）. The new in-situ system consists of two parts： the deck control unit and the underwater measurement unit. The underwater measurement unit emits sonic waves that propagate through the seafloor sediment, receives the returning signals, and transmits them to the deck control unit for waveform display and analysis. The entire operation is controlled and monitored in real time by the deck control unit on the research vessel and can provide recording of full waveforms to determine the sound velocity and attenuation. This paper outlines the design of the system, the measurement process, and demonstrates its application in tests carded out on seabed sediment off the Qingdao coast, China. The test results show that the system performed well and rapidly provided accurate in-situ acoustic velocity and attenuation estimates of the seafloor sediment.     

有孔虫初房特征变化在珠江三角洲晚全新世东亚夏季风降雨研究中的应用

研究中国降雨格局变化对理解东亚夏季风演化意义重大。本文分析了珠江三角洲柱状样ZJK03-Z中浅水底栖有孔虫常见种Rotalidium annectens的平均初房大小、微球型/显球型比值和壳体δ18O值,以及底栖有孔虫组合中瓷质壳的百分含量,探讨它们对由夏季风降雨引起的河口水体盐度变化的响应,得到了珠江三角洲3114—1260a BP季风降雨的强度变化,识别出了这期间14次季风降雨减少的偏干期。与南美洲Cariaco海盆的钛含量记录对比,二者一致的结果表明,珠江三角洲晚全新世的东亚夏季风降雨与热带辐合带(ITCZ)的南北移动密切相关:夏季风降雨减少,对应于ITCZ纬度位置的南移。