Diffusion-creep modelling of fibrous pressure-shadows

Grain-scale deformation of a bimineralic composite by normal-stress-driven grain-boundary diffusive mass-transfer has been modelled using diffusion-creep software that, for the first time, allows different diffusion coefficients for interphase boundaries and grain-boundaries as well as for different components. By selecting suitable coefficients we have obtained a fully coupled mechanical and mass-transfer numerical solution for the formation of fibrous pressure-shadows or strain fringes at the interface between a rigid object and a deforming rock matrix of different compositions. The model is two-dimensional and run in pure-shear velocity mode to a stretch ratio of 1.4. The first results are reported, which show dissolution and face-controlled antitaxial growth of a soluble, polycrystalline, calcite matrix at the interface with a circular and relatively insoluble pyrite object.The ratio of CaCO₃ diffusion along calcite–pyrite versus calcite–calcite boundaries strongly influences the extent of pressure-shadow growth and the pattern of strains in the matrix. A low ratio produces little growth, significant perturbation, and deflection of total-strain axes around the pyrite. An intermediate ratio produces appreciable growth, little perturbation, and near-parallel total-strain axes. A high ratio produces larger pressure-shadows, and total-strain axes that bend in towards the pyrite as if it were a weak object. Sliding and rotation of matrix grains are also affected.These results differ fundamentally from purely physical models of ductile flow around a rigid object and demonstrate the influence of interface diffusional properties on the resulting behaviour. In particular, assumptions such as perturbation of the flow by the object, deflection of external foliation around pre-deformational porphyroblasts and relationships of pressure-shadow strain to bulk strain may need to be re-examined in the light of this finding.     

Climatic evolution in the Yangtze Delta region in the late Holocene epoch

Neolithic site sections, natural sections and other proxy indicators like paleotrees and peat are collected for further understanding the environmental changes during the past 10,000 years in the Yangtze Delta region. The results indicate that cultural interruption in the Yangtze Delta was the result of water expansion induced by climatic changes like more precipitation. For fragile human mitigation to the natural hazards in the Neolithic cultural period, environmental changes usually exerted tremendous influences on human activities, havocking the human civilization, which is meaningful for human mitigation to natural hazards under the present global warming. At the same time, some uncertainties in reconstruction of paleo-environmental changes were discussed in the text.     

南方山区县域森林可持续经营标准与指标——以福建省永安市为例

以福建省永安市为例，探讨南方山区以集体林为主的县域森林可持续经营标准与指标，旨在为相类似区域森林可持续经营标准与指标研究提供借鉴。在借鉴国内外森林可持续经营标准与指标的基础上，根据南方山区县域和森林经营单位水平森林可持续经营的要求，从森林可持续经营的保障条件、森林资源状态、森林生态系统健康、森林生产、生物多样性、土壤和水及经济、社会和文化方面等七个方面，构建福建省永安市森林可持续经营标准与指标。     

Time variations in the geophysical fields above a gas field on Sakhalin Island

Results of repeated geophysical observations above the Yuzhno-Lugovskoye gas field (southern Sakhalin) carried out from 2003 to 2006 are considered. It is shown that the gas field is a natural indicator of geodynamic processes occurring in the gas field and beyond it. A complex of methods and observations is offered to estimate the degree of productivity of the objects involved in prospecting drilling. They provide further development of the short-term forecast of seismic events by geophysical methods, because seismic pulses propagating from an external source cause sharp changes of the geophysical fields above the gas-containing structure.     

Cyclic terpenoids of contemporary resinous plant detritus and of fossil woods, ambers and coals

Cyclic terpenoids present in the solvent extractable material of fossil woods, ambers and brown coals have been analyzed. The sample series chosen consisted of wood remains preserved in Holocene to Jurassic sediments and a set of of ambers from the Philippines (copalite), Israel, Canada and Dominican Republic. The brown coals selected were from the Fortuna Garsdorf Mine and Miocene formations on Fiji.The fossil wood extracts contained dominant diterpenoid or sesquiterpenoid skeletons, and aromatized species were present at high concentrations, with a major amount of two-ring aromatic compounds. Tricyclic diterpenoids were the predominant compounds in the ambers. Aromatized derivatives were the major components, consisting of one or two aromatic ring species with the abietane and occasionally pimarane skeletons. The saturated structures were comprised primarily of the abietane and pimarane skeletons having from three to five carbon (C₁, C₂, etc.) substituents. Kaurane and phyllocladane isomers were present in only minor amounts. Bicyclic sesquiterpenoids as saturated and partial or fully aromatized forms were also common in these samples, but only traces of sesterterpenoids and triterpenoid derivatives were found.The brown coal extracts were composed of major amounts of one- and two-ring aromatized terpenoids, with a greater proportion of triterpenoid derivatives than in the case of the woods and ambers. This was especially noticeable for the German coal, where the triterpenoids were predominant. Open C-ring aromatized structures were also present in this coal. Steroid compounds were not detectable, but some hopanes were found as minor components in the German brown coal.An overview of the skeletal structure classes identified in each sample, as well as the general mass spectrometric characteristics of the unknown compounds are included in the present paper. It can be concluded from these structural distributions that aromatization is the main process for the transformation of terrestrial cyclic terpenoids during diagenesis, constituting a general pathway for all terpenoids.     

水利水电工程征地移民项目实物指标调查测绘

本文探讨水利水电工程征地移民项目中的实物指标调查测绘方案。基于GIS地籍数据,配合河南省高分卫星高分辨率对地观测系统省级数据与应用中心自2016年至2020年数据,使用2次750m通场的厘米级航空摄影数据和1次基于无人机平台的可见光光学倾斜摄影和激光点云成像数据,最终形成13张细化标注农作物和树木种类的亚米级彩色平面地图,4张亚米级建筑物及其他附属设施三维地图,2张厘米级建筑物及其他附属设施三维地图,形成全面控制近5年征迁地区实物评价的最终指标数据。本文个案在该数据的支持下,征迁过程迅速高效完成,虽然也经历了部分诉讼调解过程,但最终对本文个案测量数据的支持率和认同率均为100%。本文调查测绘方案对水利水电工程征地移民项目有积极意义。     

芬兰科密铬铁矿床研究新进展

芬兰科密铬铁矿床是欧洲规模最大的铬铁矿床。对该矿床的地质背景、矿床特征、矿床成因及找矿标志进行了总结。结果表明,该矿床与古元古代层状超镁铁质杂岩体具有密切的时空分布关系,杂岩体内的铬铁矿床具典型的层状堆积特征,矿层延伸稳定。由于Cr/Fe值较低,该矿床矿石品位在世界同类矿床中属偏低水平。同位素年代学证据表明,其形成于古元古代早期(2.44 Ga),是由卡累利阿造山作用诱发多期次岩浆侵入活动并与新太古代基底岩层发生混染作用形成的。科密铬铁矿床属于层状铬铁矿床,其地质特征与中国目前已发现的豆荚状或似层状铬铁矿床存在一定区别。     

Measuring the adaptation goal in the global stocktake of the Paris Agreement

The Paris Agreement establishes a global goal on adaptation which will be assessed through the global stocktake, the first attempt by the international climate change regime to measure collective progress on adaptation. This policy analysis identifies four main challenges to designing a meaningful assessment. These are: designing a system that can aggregate results; managing the dual mandate of reviewing collective progress and informing the enhancement of national level actions; methodological challenges in adaptation; and political challenges around measurement. We propose a mixed-methods approach to addressing these challenges, combining short-term needs for reporting with longer-term aims of enhancing national adaptation actions.

Key policy insights

• Broad domains of adaptation activity could be identified within each of the objectives of the adaptation goal and progress could be measured and aggregated through simple scorecards.

• The goal should have both process and outcome indicators as well as some narrative linking activities to outcomes over time.

• Reporting could be a compilation of national data using qualitative and quantitative sources, aligning with the global stocktake’s aim of enhancing national actions over time and reducing immediate reporting burdens.

• There would be a complementary role at least in the short term for an expert assessment of priority areas.

     

华南北热带11.5―2.5 ka B.P. 温度集成重建与特征分析

基于“综合-比例法”（Composite Plus Scale,CPS）,利用近年来已发表的数据集成重建我国华南北热带地区11.5―2.5 ka B.P.温度变化序列。结果表明,该地区冷暖变化可以分为三大阶段：11 500―9 500 a B.P.为全新世早期阶段;9 500―4 000 a B.P.为全新世大暖期阶段;4 000―2 500 a B.P.开始出现降温过程。功率谱和小波分析表明：华南北热带气候变化具有多时段、多尺度冷暖周期变化特征,在千年尺度上,1.3 ka和3.3~3.9 ka是其冷暖变化的主要周期。序列中可以识别出一系列气候波动事件,如8.2 ka、7.9 ka、7.1 ka、4.1 ka气候事件。交叉小波谱分析表明：ENSO对华南北热带地区温度变化有着显著影响,特别是7 ka B.P.以来其影响进一步加强。通过与其他序列的对比发现：华南北热带地区的气候变化是对全球变化的响应,但也同样存在区域差异。     

典型海岸线指标识别与特征研究——以江苏中部海岸为例

从海岸线空间资源监测和综合管理出发,对高潮线、湿地线、海堤线、堤坝线、植被线、水边线等典型海岸线指标类型和特征进行了探讨,并以江苏中部海岸为例,利用遥感技术提取2014年海岸线指标,并采用基线法和统计方法对海岸线指标空间分布及海岸演变特征进行了分析。结果显示：① 江苏中部射阳河口与梁垛河口之间岸段海岸线指标总体呈西北东南走向,自陆向海依次为湿地线、海堤线、堤坝线、高潮线、植被线和水边线,湿地线与水边线之间的湿地总面积达1 178.94 km²;② 海滨湿地总体呈宽通道分布态势,总体纵深北高南低,其中湿地线-海堤线间平均纵深3 704 m,海堤线-堤坝线间平均纵深3 418 m,堤坝线-平均大潮高潮线间平均纵深447 m,高潮线-植被线间平均纵深984 m,植被线-水边线间平均纵深1 836 m;③ 海岸潮滩围垦长期活跃,尚未开发的潮上带区域仅分布在2个保护区岸段,潮间带盐沼在各个岸段均有分布,潮间带光滩保持了海岸总体冲淤态势,自北向南纵深逐步增大。