北京寒武系第二统昌平组凝块石特征及成因

北京西郊下苇甸地区下寒武统昌平组底部含燧石角砾白云岩之上发育的一套豹斑灰岩,实为发育在高能环境下的凝块石灰岩,宏观形态上可包括斑状凝块石、带状凝块石和网状凝块石3种,其成因多与厚微生物席相关,且分别具有不同的微观结构。露头实测和镜下观察结果表明凝块石的初始沉积组分受控于沉积大/微环境,且三者的互动决定了凝块石的最终沉积特征。该套沉积成因的凝块石,其白云质凝块不局限于潜穴,且潜穴内部见大量保存完好微生物结构和疑似球状原生白云石,因此这种白云质凝块很可能与微生物白云石化密切相关,并以此区别于局限于生物遗迹位置,且内部充填物为粉细晶白云石的成岩成因的豹斑灰岩。     

北秦岭构造带与华北板块关系探讨:来自宽坪杂岩变碎屑岩锆石U-Pb年代学与变质作用证据

宽坪杂岩是连接北秦岭构造带和华北板块的重要岩石-构造单元之一,其物质组成和变质变形特征可为探讨北秦岭构造带与华北板块构造关系及演化提供重要证据。本文在已有研究基础上,对宝鸡-眉县-洛南一带宽坪变碎屑岩进行了系统的岩石学、矿物学和碎屑锆石U-Pb年代学研究。结果表明,宽坪碎屑岩最年轻碎屑锆石年龄峰值为～550Ma,最主要碎屑锆石年龄集中区为～2.5Ga和1.0～0.9Ga,次要年龄集中区为1.3～1.0Ga和850～750Ma。通过与周缘可能物源区的年代学特征对比揭示,宽坪碎屑岩物源主要来自北秦岭新元古代花岗岩与秦岭岩群副片麻岩,部分来自南秦岭和扬子板块北缘新元古代花岗岩以及太古宙基底岩系,缺乏华北板块物质;宽坪碎屑岩的碎屑锆石年龄谱特征与南侧的二郎坪碎屑岩近乎一致,暗示两者可能形成于同一沉积盆地。相平衡模拟结果显示,洛南红土岭宽坪杂岩含石榴子石石英片岩记录了顺时针P-T演化轨迹,峰期变质条件为P=7.17～7.92kbar,T=557～563℃,形成于大陆碰撞过程。结合前人报道宽坪杂岩～440Ma的变质年龄,我们认为在早志留世时期宽坪和二郎坪沉积盆地闭合,北秦岭构造带与华北板块碰撞形成现今的构造格局,在此之前北秦岭构造带与华北板块不具有亲缘性。     

中国南极昆仑站深冰芯科学钻探工程进展

我国于2012年1月在南极Dome A区域正式开展实施了南极昆仑站深冰芯科学钻探工程,截至2021年,钻孔深度已达803.54 m。该工程是我国第一个深冰芯钻探工程,也是国际上第一个在Dome A地区开展的深冰芯钻探项目。本文介绍了昆仑站深冰芯科学钻探工程实施的整体情况,对过去近10年的钻探活动以及取得的成果和经验进行了总结,以期为后续的深冰芯钻探工作提供理论和经验指导。     

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基于赫尔默特方差分量估计的水准网平差方法研究

复杂地区水准网平差时传统定权方法存在不合理性。根据高差观测误差与地形起伏的关系,建立高差分类新标准,推导出各类高差观测值权的计算公式,并引入赫尔默特方差估计法来合理匹配各类高差观测值的权比关系,最后通过算例验证本文方法的优越性。     

南海北部白云深水区东北部小型峡谷内的块体搬运

The process of mass movements and their consequent turbidity currents in large submarine canyons has been widely reported, however, little attention was paid to that in small canyons. In this paper, we document mass movements in small submarine canyons in the northeast of Baiyun deepwater area, north of the South China Sea(SCS), and their strong effects on the evolution of the canyons based on geophysical data. Submarine canyons in the study area arrange closely below the shelf break zone which was at the depth of –500 m. Within submarine canyons, seabed surface was covered with amounts of failure scars resulted from past small-sized landslides. A complex process of mass transportation in the canyons is indicated by three directions of mass movements.Recent mass movement deposits in the canyons exhibit translucent reflections or parallel reflections which represent the brittle deformation and the plastic deformation, respectively. The area of most landslides in the canyons is less than 3 km2. The trigger mechanisms for mass movements in the study area are gravitational overloading, slope angle and weak properties of soil. Geophysical data indicate that the genesis of submarine canyons is the erosion of mass movements and consequent turbidity currents. The significant effects of mass movements on canyon are incision and sediment transportation at the erosion phases and fillings supply at the fill phases. This research will be helpful for the geological risk assessments and understanding the sediment transportation in the northern margin of the SCS.     

热带风压场平衡特征及其对GRAPES系统中同化预报的影响研究Ⅱ:动力与统计混合平衡约束方案的应用

研究I的结果表明:线性平衡方程(LBE)在热带地区不适用,而进一步改进方向是削弱LBE在该区域的约束程度。本文以此为基础,在GRAPES(global/regional assimilation and prediction system)全球变分同化系统中引入动力与统计混合平衡约束方案。新方案在逐层求解LBE的基础上增加垂直方向的线性回归,回归系数随纬度和高度变化。针对背景误差协方差的分析表明,新方案可以更好的保证独立分析变量间预报误差不相关的基本要求,并大幅度减小热带地区平衡气压预报误差方差的量值和占总方差的比例。单点试验结果表明,与LBE方案相比,新方案对中、高纬影响很小,但在热带地区成功实现了风、压场分析的解耦,两者分析更为独立。并且,虽未考虑具体波动模态,但新方案给出的风、压场协相关结构与研究I的理论分析结果相近。一个月的同化循环与预报结果表明,引入新方案后,赤道外地区的同化预报效果为中性偏正,而热带地区风场的同化预报效果显著提高,LBE方案中平流层低层的风场同化预报异常被基本消除。     

NUMERICAL EXPERIMENTS ON MULTI-LEVEL STATISTICAL ESTIMATION OF DYNAMIC BALANCE CONSTRAINTS IN GRAPES-3DVAR

This paper further explores the estimating and expressing of dynamic balance constraints using statistical methods in GRAPES-3DVAR (Version GM). Unlike the single-level scheme which only considers the coupling between mass and wind at one level, the multi-level scheme considers the coupling between their vertical profiles and calculates the balanced mass field at each layer using the rotational wind at all model levels. A reformed ridge regression method is used in the new scheme to avoid the multicollinearity problem and reduce the noises caused by unbalanced mesoscale disturbances. The results of numerical experiments show that the new scheme can get more reasonable vertical mass field, reduce the magnitude of the adjustment by the initialization, and improve the potential temperature analysis performance. Furthermore, the results of forecast verification in January (winter) and July (summer) both confirm that the new scheme can significantly improve the temperature forecast accuracy and bring slight positive effects to the pressure and wind forecast.     

秀丽隐杆线虫在环境内分泌干扰物研究中的应用

模式生物秀丽隐杆线虫(Caenorhabditis elegans)具有繁殖速度快、世代周期短,通体透明、体细胞数目恒定,基因组小并被完全测序等优点,已经广泛地应用于生态毒理学研究。C.elegans的胚胎发育、蜕皮、繁殖等重要生理过程是通过激素调控的,外源激素的代谢产物可以作为核受体(NRs)的配体,C.elegans的寿命与胰岛素/胰岛素样生长因子信号(IIS)通路和固醇/类固醇信号通路密切相关。近年来已经建立了在分子、细胞、个体和种群水平上,利用vit-2、hsp、消化道与性腺、产卵数、胚胎发育时间、内禀增长率、性别比例等系统地筛选EDCs的指标体系。以C.elegans为模式生物,从线虫的蜕皮、IIS通路等角度探讨了EDCs对线虫寿命的影响及作用机制,并展望了C.elegans在EDCs导致的细胞增殖与细胞分化失调而诱发的癌症、糖尿病等研究中的应用前景。     

深海采矿锰结核泵的试验研究

锰结核泵是深海采矿扬矿系统中的关键设备,为了研究泵结核矿浆工作性能,在实验室构建了一套高30 m、内径204 mm,可提供最大管网阻力2.5 MPa的泵矿浆性能试验系统,采用不同模拟结核粒径进行了泵矿浆工作特性试验。试验结果表明,锰结核泵基本上达到了预期设计指标,分析了模拟结核粒径d≤50 mm矿浆回流试验泵流道堵塞的原因,初步讨论了锰结核泵的环形格栅通道和泵流道问题,可作为我国中试多级锰结核泵的设计依据。