南塔斯曼海隆2Ma以来碳酸钙沉积记录及其对环流系统和轨道周期的响应

南大洋CaCO3沉积在记录生物泵调节大气CO2的同时,也记录了南大洋表层锋面系统和深部环流格局的重要转变.通过南塔斯曼海ODP 1170站位2 Ma以来CaCO3％和MAR-CaCO3的研究发现,CaCO3％以冰期低和间冰期高的“大西洋”型溶解作用旋回为主,并以MIS 34/35期(约1.15 Ma BP)和MIS 14/15期(约0.55 Ma BP)为界线,表现出3种沉积模式.而MAR-CaCO3以MIS 57/58,21/22,13/14和11/12为界表现出“两高三低”5个阶段.CaCO3％与轨道参数ETP和底栖有孔虫δ18O的交叉频谱和小波分析显示,其主导周期明显具有从40 ka向100 ka转变的中更新世气候转型(MPT)特征,转型起始与终止时间为1.15～0.55 MaBP.CaCO3沉积模式的转变与南大洋太平洋区西风带和环南极表层锋面系统的迁移密切相关,在时间上与MPT同步.MPT时期,西风带和环南极表层锋面系统的快速南北迁移,导致CaCO3沉积受到硅质和陆源物质稀释作用的影响.而MAR-CaCO3的阶段性变化主要与南大洋深层环流的变化格局和水团化学性质的变化有关.在1.5～0.85 MaBP期间,南大洋太平洋区深层水通风增强,利于CaCO3的保存和埋藏,MAR-CaCO3增加;在0.85 ～0.55 Ma BP期间,CO32-处于不饱和状态的CDW增强,导致南大洋深部CaCO3溶解作用增强,溶跃面上升,MAR-CaCO3降低.     

中国加入国际大洋钻探计划的5年总结（1998-2002）

    国际大洋钻探计划（ODP,1985-2003）及其前身深海钻探计划（DSDP,1968-1983）,是20世纪地球科学规模最大、历时最久的国际合作研究计划,30多年来一直在推动学科发展的前沿,导致了学科的一场革命。我国经国务院批准于1998年春正式加入大洋钻探计划,年付50万美元,成为第一个"参与成员"（as sociated member）。加入大洋钻探计划近 5年来,已经取得重大进展。
    （1）成功地在南海实施了ODP184航次。这次在我国科学家建议、设计和主持下的航次在南海 2 000～3 000 m深水区的 6个站位取芯超过 5 000 m,实现了中国海大洋钻探零的突破,使我国一举进入国际深海研究的前沿。在航次后的研究中,我国取得的成果也遥遥领先,不仅在不同时间尺度上取得了西太平洋区迄今为止最佳的深海沉积记录,而且在气候演变的周期性、亚洲季风变迁和南海盆地演化等方面获得了大量创新成果,其中包括学术上的突破性进展,目前正在逐步向国际学术界展示。
    （2）促进了我国深海基础研究及其基地建设。加入ODP近 5年来,我国深海基础研究迅速发展,继国家自然科学基金重大项目（东亚古季风的海洋记录）后,又于2000年底启动了国家重点基础研究发展规划项目"地球圈层相互作用中的深海过程和深海记录",并实现了深海国家重点基础研究发展规划（973）项目和"大洋专项"的相互结合,已有教育部、中国科学院、海洋局、国土资源部等部门的10多个实验室或研究所在不同程度上加入深海基础研究,其中包括至少 6所重点大学在内,已经初步建成了以深海研究为重要目标的重点实验室,初步涌现出一批有成就的青年科学家。
    （3）增强了我国在有关国际学术界的地位。尽管我国支付的成员费只占ODP整个预算的百分之一强,4年来所起的作用已远不以此为限。特别在筹备新的"综合大洋钻探"计划中,我国代表在有关专业组中的席位已应邀由 2个增至 5个,仅2001-2002年春一年内就有 3次大洋钻探的国际会议在我国举行,近 5年来ODP和筹备中的IODP方面至少有 6批共数十人次访华,是90年代新加入ODP各个成员中最为活跃的一个。
    大洋钻探是一项长周期、高层次的国际科研计划,近 5年来我国以南海航次为中心的研究成果刚开始产出,预计近两年内将达到高潮;而随之建立起来的队伍和基地也可望在未来几年在更大领域范围内进入国际前沿,取得新的重大进展。     

洋底高原：了解地球内部的窗口

洋底高原是洋壳的重要组成部分,它是分布在洋底的一种面积广大、且具有异常洋壳厚度的区域。洋底高原通常规模巨大,绝大多数喷发于大洋环境,岩石组成主要为镁铁质到超镁铁质,岩石类型主要为拉斑玄武岩。大多数洋底高原的岩石组成较为相似,而且均形成于一期或两期时间较短却大规模集中喷发的岩浆活动,目前认为是大规模的热地幔物质从地幔深部上升到岩石圈底部,由于巨大地幔柱头部（地幔羽）引起的熔融作用形成的。正是由于洋底高原与地幔柱之间具有这种十分密切的关系,因此对洋底高原的研究将成为我们了解地球内部的窗口。以ODP对翁通-爪哇和凯尔盖朗（Kerguelen）海台的研究为例,简单介绍了洋底高原的基本特征、地幔柱在其形成过程中的作用以及目前在这一领域还未解决的一些问题。     

A 23 Myr magnetostratigraphic time framework for Site 1148, ODP Leg 184 in South China Sea and its geological implications

The Ocean Drilling Program (ODP) Leg 184 recovered a continuous sedimentary sequence since Miocene at Site 1148 in the northern South China Sea (SCS), which provided a unique record for better understanding the tectonic, environmental and climatic evolution of the SCS. In this study, we report a detailed paleomagnetic study on 881 discrete samples from the upper 460 m cores of Hole 1148A through stepwise alternating field demagnetization (AF) or thermal demagnetization (TD). Rock magnetic results from isothermal remanent magnetization (IRM) acquisition, temperature dependence magnetic susceptibility (κ-T) and hysteresis loop parameters of representative samples indicate that the main magnetic mineral is low coercivity pseudo-single domain magnetite. The characteristic remanent magnetization (ChRM) with moderate downward or upward inclinations was identified after removing a low-stability drilling-induced remanence with steep downward inclinations. A new 23 Myr magnetostratigraphic time framework was established by correlating the magnetic polarity sequence to the Geomagnetic Polarity Time Scale 2012 (GPTS 2012; Ogg, 2012) in combination with biostratigraphic data. The mean sediment accumulation rates for lithostratigraphic Units V and IV, Unit III and lower Unit II, upper Unit II, Unit IB and Unit IA are calculated as ∼20.8 m/Myr, ∼15–17 m/Myr, 24.18 m/Myr, 17.07 m/Myr and 49.01 m/Myr, respectively.     

Quaternary palaeoceanographic changes in the northern South China Sea (ODP Site 1146): radiolarian evidence

The abundance and accumulation rates of siliceous microfossils in the northern South China Sea, including radiolarians, diatoms and sponge spicules, increased during most glacial intervals within the past 1100 kyr. Similar trends are observed in the index of thermocline surface radiolarians (TSR), diatom accumulation rates (DAR), charcoal accumulation rates (CAR) and the abundance of radiolarian species Cycladophora davisiana davisiana. Decreasing sea‐surface temperature accompanied by increased seasonality since 900 ka is indicated by a decline in the tropical radiolarian assemblage, including Tetrapyle octacantha and Octopyle stenozona, and by an increase in the subtropical assemblage, including Pterocorys zancleus, Peromelissa phalacra and Ommatartuts tetrathalamus tetrathalamus. Rapid increases at about 800 to 700 ka of siliceous microfossils, charcoal, subsurface and intermediate radiolarians, as well as the TSR index and the DAR, imply a fundamental shift in climate and a shoaling thermocline. Although these fundamental changes in the silicious fauna and flora of the South China Sea take place within the context of a developing 100‐kyr cycle, they do not change in step with changing sea‐level as indicated by marine δ¹⁸O. This is most clearly illustrated by the step‐like increase in silica accumulation (radiolaria, diatoms and sponge spicules) at 680 ka. Rather, these fundamental changes probably reflect intensified surface productivity associated with enhanced East Asian winter‐monsoon circulation. Copyright © 2003 John Wiley & Sons, Ltd.     

Simulation experiments on gas production from hydrate-bearing sediments

Experiments were made on 58 sediment samples from four sites(1244,1245,1250 and 1251) of ODP204 at five temperature points(25,35,45,55 and 65℃) to simulate methane production from hydrate-bearing sediments.Simulation results from site 1244 show that the gas components consist mainly of methane and carbon dioxide,and heavy hydrocarbons more than C2+ cannot be detected.This site also gives results,similar to those from the other three,that the methane production is controlled by experimental temperatures,gene...     

Geochemical variations in the Cocos Plate subducting beneath Central America: implications for the composition of arc volcanism and the extent of the Galápagos Hotspot influence on the Cocos oceanic crust

New geochemical data from the Cocos Plate constrain the composition of the input into the Central American subduction zone and demonstrate the extent of influence of the Galápagos Hotspot on the Cocos Plate. Samples include sediments and basalts from Ocean Drilling Program (ODP) Site 1256 outboard of Nicaragua, gabbroic sills from ODP Sites 1039 and 1040, tholeiitic glasses from the Fisher Ridge off northwest Costa Rica, and basalts from the Galápagos Hotspot Track outboard of Central Costa Rica. Site 1256 basalts range from normal to enriched MORB in incompatible elements and have Pb and Nd isotopic compositions within the East Pacific Rise MORB field. The sediments have similar ²⁰⁶Pb/²⁰⁴Pb and only slightly more radiogenic ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb isotope ratios than the basalts. Altered samples from the subducting Galápagos Hotspot Track have similar Nd and Pb isotopic compositions to fresh Galápagos samples but have significantly higher Sr isotopic composition, indicating that the subduction input will have a distinct geochemical signature from Galápagos-type mantle material that may be present in the wedge beneath Costa Rica. Gabbroic sills from Sites 1039 and 1040 in East Pacific Rise (EPR) crust show evidence for influence of the Galápagos Hotspot ∼100 km beyond the morphological hotspot track.     

A new biostratigraphic correlation for Late Cretaceous–Paleocene strata of the Gulf of Guinea: Evidence from dinoflagellate cysts

A new biostratigraphic correlation for Late Cretaceous and Palaeocene strata of the Côte d’Ivoire–Ghana continental margin has been developed from the identification of significant dinoflagellate cyst events in ODP Hole 959D. The Late Cretaceous stage boundaries are mostly consistent with previous studies. However, the Maastrichtian/Danian boundary is placed much lower than previously recognized on the basis of the first occurrences of Carpatella cornuta and Damassadinium californicum. The base of the Selandian is recognized from the last occurrence of Cerodinium diebelii and the first occurrence of Adnatosphaeridium multispinosum. The base of the Thanetian is recognized from the first occurrence of Areoligera gippingensis. The rarity of the age-marker taxa is the main reason for different age determinations among studies of the same section.     

中国房间空调器行业淘汰HCFC-22的环境效益分析

中国是当前最大的HCFCs(含氢氟氯烃类物质)年生产和消费国家,而其中HCFC-22的生产量约占全部HCFCs的80%。2007年国际社会决定加速淘汰HCFCs,这将带来巨大的环境效益。为此,选择房间空调器行业对我国加速淘汰HCFC-22的环境效益进行了分析。通过淘汰情景和基线情景对比得出,采用HC-290(丙烷)替代制冷剂既可以直接实现温室气体减排,又可以节电从而间接减少温室气体排放。比较HFC-410A和HC-290两种替代淘汰情景,后者的环境效益显著高于前者。     

Responses of foraminiferal isotopic variations at ODP Site 1143 in the southern South China Sea to orbital forcing

The foraminiferal δ ¹⁸O and δ ¹³C records for the past 5 Ma at ODP Site 1143 reveal the linear responses of the Plio-Pleistocene climatic changes in the southern South China Sea to orbital forcing at the obliquity and precession bands. The phase of the δ ¹⁸O variations with the orbital forcing is opposite to that of the δ ¹³C, which may be caused by the frequent El Niño events from the equatorial Pacific. The amplification of the Northern Hemisphere Ice Sheet at ñ3.3 Ma probably affected the development of the 100-ka climatic cycles. Its further spreading may spur the 100-ka climatic cycle to become the dominant cycle in the late Pleistocene. The “Mid- Pleistocene Transition” event has localized influence on the isotopic variations in the southern South China Sea. The foraminiferal δ ¹³C records for the past 5 Ma at Site 1143 are highly coherent with the orbital forcing at the long eccentricity band, and lead the δ ¹⁸O records at the shorter eccentricity band, highlighting the importance of the carbon cycle in the global climate change.