Response of deep-sea ostracod assemblages to Late Cretaceous palaeoceanographical changes: ODP Site 689 in the Southern Ocean

Twenty-six deep-sea ostracod species are described from the late Campanian to late Maastrichtian of ODP Site 689 in the Southern Ocean. Three are described as new:Cytherelloidea megaspirocostata,Agulhasina sudoceanicaandPennyella foveolata. Correspondence analysis identified three faunal sample groups. The first is mainly characterised byA. sudoceanica,Kirthesp. andCytherellasp. This is replaced, first temporarily (betweenc. 71 and 69 Ma) by a group mainly characterised byArgilloeciaspp. andC. megaspirocostata, possibly a consequence of a short-lived global palaeoceanographic event marked by increased ventilation and cooling of intermediate waters at site 689. It then reappears before finally being replaced by a third group largely characterised byEucytherecf.circumcostata,P. foveolataandDutoitella mimicaDingle. This final change is coeval with a marked increase in the faunal density of ostracods, probably owing to an increase in food supply. However, the oxygen isotopic records of benthonic foraminifera suggests that the replacement of the first ostracod group by the third is a result of the long term Maastrichtian cooling of intermediate waters at high latitudes. This replacement is also coeval with a gradual change in benthonic foraminiferal assemblages at site 689. It is suggested, therefore, thatPennyellaandDutoitellahad a greater potential of adapting to successively colder palaeoceanographical conditions thanAgulhasina. The former genera have a cosmopolitan deep-sea distribution today.     

线性-动态规划改进模型及其应用

Becker和Yeh于1974年提出的线性(LP-DP)模型是一种功能很强的优化模型。然而该模型是针对梯级发电库群实时调度提出的,对并联系统并不适用。且该模型在理论上还不够严密,需进一步完善。本文所提出的LP-DP改进模型不但在理论上比较完整,而且扩展了应用范围,提高了优化效益。该模型现已成功地应用于江西省水火电力系统实时优化调度之中。     

Determining the cooling history of in situ lower oceanic crust—Atlantis Bank, SW Indian Ridge

The cooling history and therefore thermal structure of oceanic lithosphere in slow-spreading environments is, to date, poorly constrained. Application of thermochronometric techniques to rocks from the very slow spreading SW Indian Ridge provide for the first time a direct measure of the age and thermal history of in situ lower oceanic crust. Crystallization of felsic veins (∼850°C) drilled in Hole 735B is estimated at 11.93±0.14 Ma, based on U-Pb analyses of zircon by ion probe. This crystallization age is older than the ‘crustal age’ from remanence inferred from both sea surface and near-bottom magnetic anomaly data gathered over Hole 735B which indicate magnetization between major normal polarity chrons C5n.2n and C5An.1n (10.949-11.935 Ma). ⁴⁰Ar/³⁹Ar analyses of biotite give plateau ages between 11 and 12 Ma (mean 11.42±0.21 Ma), implying cooling rates of >800°C/m.y. over the first 500,00 years to temperatures below ∼330-400°C. Fission-track ages on zircon (mean 9.35±1.2 Ma) and apatite reveal less rapid cooling to <110°C by ∼7 Ma, some 4-5 m.y. off axis.Comprehensive thermochronometric data from the structurally intact block of gabbro between ∼700 and 1100 m below sea floor suggest that crust traversed by ODP Hole 735B mimics conductive cooling over the temperature range ∼900-330°C, characteristic of a 2-D plate-cooling model for oceanic lithosphere. In contrast, lower temperature chronometers (fission track on zircon, titanite, and apatite; T≤280°C) are not consistent with these predictions and record anomalously high temperatures for crust >700 m below sea floor at 8-10 Ma (i.e. 2-4 m.y. off axis). We offer two hypotheses for this thermal anomaly:

(i)

Off-axis (or asymmetric) magmatism that caused anomalous reheating of the crust preserved in Hole 735B. This postulated magmatic event might be a consequence of the transtension, which affected the Atlantis II transform from ∼19.5 to 7.5 Ma.

(ii)

Late detachment faulting, which led to significant crustal denudation (2.5-3 km removed), further from the ridge axis than conventionally thought.

     

大洋钻探与冲绳海槽地质

本文简要回顾大洋钻探计划实施十余年来所取得的成果，评述了西太平洋边缘海盆的研究概况，提出东海大陆边缘的重大地质问题是陆缘的构造演化历史和动力学过程，弧后扩张中心的热液成矿作用以及海洋沉积层序记录的古气候和古海洋环境变化，指出矿物－地球化学在大洋钻探研究中的重要性。     

Trade-offs and Synergies of Ecosystem Services in Karst Area of China Driven by Grain-for-Green Program

As an important means regulating the relationship between human and natural ecosystem,ecological restoration program plays a key role in restoring ecosystem functions.The Grain-for-Green Program(GFGP,One of the world’s most ambitious ecosystem conservation set-aside programs aims to transfer farmland on steep slopes to forestland or grassland to increase vegetation coverage)has been widely implemented from 1999 to 2015 and exerted significant influence on land use and ecosystem services(ESs).In this study,three ecological models(In VEST,RUSLE,and CASA)were used to accurately calculate the three key types of ESs,water yield(WY),soil conservation(SC),and net primary production(NPP)in Karst area of southwestern China from 1982 to 2015.The impact of GFGP on ESs and trade-offs was analyzed.It provides practical guidance in carrying out ecological regulation in Karst area of China under global climate change.Results showed that ESs and trade-offs had changed dramatically driven by GFGP.In detail,temporally,SC and NPP exhibited an increasing trend,while WY exhibited a decreasing trend.Spatially,SC basically decreased from west to east;NPP basically increased from north to south;WY basically increased from west to east;NPP and SC,SC and WY developed in the direction of trade-offs driven by the GFGP,while NPP and WY developed in the direction of synergy.Therefore,future ecosystem management and restoration policy-making should consider trade-offs of ESs so as to achieve sustainable provision of ESs.     

美国《洋陆边缘科学计划2004》述评

经过16年对科学问题的凝练,美国自然科学基金会公布了《洋陆边缘科学计划2004》。该文献确定了洋陆边缘的4个主要研究领域,即大陆岩石圈裂解、俯冲带物质转换、地震带实验、源-汇系统。该计划传递的一个重要信息是：现代海洋地质科学的重点已经从区域特征的刻画转向“过程”和“方法”的研究,即用系统科学的观点来理解过程、机制、动力学,发展和应用多学科交叉方法、过程模型方法、新型现场观测和采样技术。掌握这些最新动态对于我国边缘海基础研究的进一步深入是十分重要的。     

http://www.sciencedirect.com/science/article/pii/S1674987111001393

To study on the significance and basis of acidolysis index to China marine gas hydrate exploring,since 2006,111 samples derived from Leg 164 and 204 of the Ocean Drilling Program (ODP) were analyzed in...     

Piecemeal or combined? Assessing greenhouse gas mitigation spillovers in US forest and agriculture policy portfolios

ABSTRACT

Forest and agricultural sector response to comprehensive climate policy is well represented in the literature. Less analysis has been devoted to piecemeal solutions. We use the Forest and Agriculture Sector Optimization Model with Greenhouse Gases (FASOMGHG) to project the individual and combined effect of three existing U.S. Department of Agriculture programmes with potential to increase greenhouse gas (GHG) mitigation. We find that a combined policy scenario may achieve greater mitigation than individual constituent programmes, suggesting the possibility of complementary spillover effects in some periods. Mitigation varies over time, however, and some periods experience net emissions as markets and management practices respond to initial policy shocks. The regional distribution of GHG mitigation also varies between policy scenario. Differences in the magnitude and imputed cost of mitigation under each scenario, generating negative values for some programmes and time periods, reinforces the need to evaluate portfolio design to cost-effectively achieve near-term GHG mitigation.

Key policy insights

• Increased near-term GHG mitigation in the forest and agriculture sectors in the US may be possible by expanding or refocusing the emphasis of existing programmes.

• Implementing several such forest and agricultural programmes simultaneously may lead to greater GHG mitigation than when implemented separately, indicating the possibility of positive spillover effects.

• Programmes targeted to agricultural management may hold outsized potential to achieve near-term GHG mitigation; Policies aimed at influencing land use conversion appear to be more vulnerable to reversion and subject to larger inter-annual swings.

• The staged implementation of programmes could also be useful, helping to encourage increased mitigation (or the retention of already achieved mitigation) over time as markets re-equilibrate to initial shocks.

• Though the particular scenarios assessed here are unique to the US, our findings may be applicable to other locations outside the US where land management is influenced by individual market actors and there is competition between forest and agricultural land uses.

     

High-resolution upper Pliocene to Pleistocene calcareous nannofossil biostratigraphy in Ocean Drilling Program Hole 1146A in the South China Sea

We established a high-resolution calcareous nannofossil biostratigraphy for the late Pliocene–Pleistocene by analyzing a 242 m-thick, continuous sedimentary succession from Ocean Drilling Program Site 1146, Hole A, in the South China Sea (SCS). A total of 14 calcareous nannofossil datums were detected in the SCS succession. They are, in descending order: first occurrence (FO) of Emiliania huxleyi, last occurrence (LO) of Pseudoemiliania lacunosa, LO of Reticulofenestra asanoi, FO of Gephyrocapsa parallela, FO of R. asanoi, LO of large Gephyrocapsa spp., FO of large G. spp., FO of Gephyrocapsa oceanica, FO of Gephyrocapsa caribbeanica, LO of Calcidiscus macintyrei, LO of Discoaster brouweri, LO of Discoaster pentaradiatus, LO of Discoaster surculus, and LO of Discoaster tamalis. The FO of E. huxleyi was not precisely detected due to poor preservation and dissolution of nannofossils in the underlying strata. We refined the previous calcareous nannofossil biostratigraphy in the SCS by identifying Gephyrocapsa species and four evolutionary extinction events of the genus Discoaster. The proposed calcareous nannofossil biostratigraphy correlates with those reported in other terrestrial and marine areas/sites and global benthic foraminiferal δ¹⁸O records. The age–depth curves based on nannofossil biostratigraphy indicate a significant increase in the sedimentation rates at the LO of R. asanoi (0.91–0.85 Ma). The timing of this increase corresponds to reef expansion in the Ryukyu Islands linked to a stepwise increase in Kuroshio Current intensity. This timing is broadly coeval with a sea surface temperature increase of ∼2 °C in the northwestern Pacific due to expansion of the Western Pacific Warm Pool towards the north and south subtropical regions. This can be explained by increased weathering and erosion of terrestrial areas in glacial periods and increased rainfall causing higher sediment transport in interglacial periods, which were both linked to Middle Pleistocene Transition-related climatic changes.     

基于地理设计的三维道路设计系统研究与实现

道路规划设计是一项复杂的系统工程,现阶段道路设计采用传统的平台难以适应空间分析、三维展现、交互设计等新的需求,更不能充分利用GIS分析、参数化设计等新技术为设计服务。地理设计的诞生为将设计与分析的融合提供了指导思想,参数化设计则为基于规则的道路设计提供技术基础。本文以地理设计为指导、以参数化驱动设计为手段,构建一个基于三维地理环境的道路设计系统,阐述地理设计、参数化驱动设计在系统中的作用及系统的结构组成,最后展现系统建设成果。