Crystal structures of synthetic 7 angstrom and 10 angstrom manganates substituted by mono- and divalent cations

The crystal structures of synthetic 7 angstrom and 10 angstrom manganates, synthetic birnessite and buserite, substituted by mono- and divalent cations were investigated by X-ray and electron diffractions. The monoclinic unit cell parameters of the subcell of lithium 7 angstrom manganate, which is one of the best ordered manganates, were obtained by computing the X-ray powder diffraction data: a = 5.152 angstroms, b = 2.845 angstroms, c = 7.196 angstroms, beta = 103.08 degrees. On the basis of the indices obtained by computing the X-ray diffraction data of Li 7 angstrom manganate, monovalent Na, K and Cs and divalent Be, Sr and Ba 7 angstrom manganates were interpreted as the same monoclinic structure with beta = 100-103 degrees as that of Li 7 angstrom manganate, from their X-ray diffraction data. In addition, divalent Mg, Ca and Ni 10 angstrom manganates were also interpreted as the same monoclinic crystal system with beta=90-94 degrees. The unit cell parameters, especially a, c and beta change possibly with the type of substituent cation probably because of the different ionic radius, hydration energy and molar ratio of substituent cation to manganese. However, these diffraction data, except for those of Sr and Ba 7 angstrom and Ca and Ni 10 angstrom manganates, reveal only some parts of the host manganese structure with the edge-shared [MnO6] octahedral layer. On the other hand, one of the superlattice reflections observed in the electron diffractions was found in the X-ray diffraction lines for heavier divalent cations Sr and Ba 7 angstrom and Ca and Ni 10 angtrom manganates. The reflection presumably results from the substituent cation position in the interlayer which is associated with the vacancies in the edge-shared [MnO6] layer and indicates that the essential vacancies are linearly arranged parallel to the b-axis. Furthermore, the characteristic superlattice reflection patterns for several cations, Li, Mg, Ca, Sr, Ba and Ni, manganates were interpreted that the substituent cations are regularly distributed in the interlayer according to the exchange percentage of substituent cation to Na+. In contrast, the streaking in the a-direction observed strongly in the electron diffractions for heavier monovalent cations, K and Cs, manganates probably results from the disordering of their cations in the a-direction in the interlayer.     

2016年5月6日重庆万盛短时强降水雨滴谱特征分析

利用激光雨滴谱仪对2015年5月6日四川盆地东南部与云贵高原交界处的重庆万盛地区一次由地形强迫抬升形成的短时强降水过程进行观测,分析了雨滴谱相关特征值变化情况。结果表明：雨滴谱能够较好的反映本次过程雨量的细节,谱型能够较好地反映对流的生消过程;雨滴的数浓度并不是影响雨强的决定性因素,粒子大小对雨强的贡献同样很重要;大粒子虽然很少,但对雨强的贡献远大于小粒子（如大于3mm的粒子在雷达反射率因子中起主要贡献,达到97%）;强烈的对流使大粒子在下落过程中破碎形成小粒子;三参数Gamma分布能够较好的拟合本次降水过程雨滴谱分布;小粒子的速度谱大于实验典型值,与大粒子在下落过程中破碎形成小粒子有关。     

深部砂岩热储沉降监测分层标建设与结构合理性初探——以鲁北平原深部砂岩热储沉降监测分层标组为例

目前,山东省尚无分层标建设的专业规范,针对不同深度分层标,尤其是深度较大分层标,用以明确其标杆结构、标组组成等。施工流程、标体结构的不合理导致使管材浪费,一定程度上增加了分层标的监测误差及建设成本。本文以鲁北平原深部砂岩热储沉降监测分层标组为例,对分层标选址、分层标结构、标桩个数、深度确定等进行阐述,探究分层标结构的合理性,对类似地层结构的分层标建设具有指导作用,对地质灾害监测具有重要意义。     

祁连山俄博岭地区热融洼地与冻胀草丘活动层融化深度差异性对比研究

全球气候变暖背景下,活动层厚度的加深是多年冻土退化最主要表现特征之一,但其变化存在强烈的空间异质性,尤其是在复杂山地环境显得更为突出。以祁连山黑河流域俄博岭为研究区,采用钎探的方法,在样方尺度上探究冻胀草丘和热融洼地两种微地貌下伏活动层融化深度的差异性。结果表明：6—10月,冻胀草丘和热融洼地活动层融化深度的变化范围分别为（44.48±4.97）~（118.38±20.94） cm和（29.22±7.42）~（93.40±15.45） cm,且冻胀草丘活动层融化深度加深的速度快于热融洼地。样方尺度上,两种微地貌下伏活动层最大融化深度差异比较明显,冻胀草丘处的活动层融化深度是热融洼地的2倍之多,这主要由不同微地貌之间土壤含水量的差异而导致的。另外,借助一维热传导模型模拟了两种微地貌下的活动层热状态,结果表明土壤水分差异性致使热融洼地的融化深度较冻胀草丘浅。山地环境条件下,不同微地貌之间活动层融化深度差异性研究有助于为未来开展高精度活动层融化深度制图提供可靠的技术支撑。     

Ophiolitic Chromitites Originated from Ancient SCLM

<正>Ophiolitic chromitites are traditionally considered as the products of melt-mantle interaction in the supra-subduction zone after partial melting of mantle peridotites during upwelling of asthenosphere at oceanic spreading centers.The occurrence of natural diamonds in situ in chromitites and peridotites in southern Tibet(Yang et al.,2013;Griffin     

全球主动和被动大陆边缘大型海底峡谷的特征及分布

1 引言 海底峡谷纵切入陆架与陆坡,是沉积物由陆地向深海传输的通道.头部止于陆坡的峡谷称为盲谷或无头谷,而大型的海底峡谷通常能切入陆架,甚或如陆架下切谷那样与现代河流直接衔接.海底峡谷有多种成因,一些峡谷的发育受构造作用的控制,在基岩发生断裂和破碎的区域侵蚀作用发育;构造作用也可影响峡谷的路径选择,一些峡谷的中泓水道偏向于沿断层和构造要素发育;但总体上,在海底峡谷的形成中最重要的是块体搬运体系(滑动与海底滑坡)和浊流对陆坡的侵蚀作用.     

中国新沂马陵山白垩纪恐龙足迹——从虎到肉食龙及由传说至古生物学（英文）

江苏省新沂市马陵山地区的4个神秘的印记,传统上被解释为“李存孝打虎处”的“虎爪印”和“人足迹”,重新将其解释为大盛群田家楼组恐龙足迹。这些足迹中只有一个最深的“虎爪印”保存了可识别的趾印,表明它是一个有着后内侧拇趾印的兽脚类恐龙左足迹,是一道单步约50cm的直线行迹的一部分;另一种解释是该足迹为小型蜥脚类恐龙的右后足迹,形成行迹的右侧部分,其左侧部分没有保存。马陵山足迹点提供了恐龙足迹如何影响中国民间传说的另一个案例。     

Nanoscale resetting of the Th/Pb system in an isotopically-closed monazite grain: A combined atom probe and transmission electron microscopy study

Understanding the mechanisms of parent-daughter isotopic mobility at the nanoscale is key to rigorous interpretation of Ue The Pb data and associated dating. Until now, all nanoscale geochronological studies on geological samples have relied on either Transmission Electron Microscope(TEM) or Atom Probe Microscopy(APM) characterizations alone, thus suffering from the respective weaknesses of each technique. Here we focus on monazite crystals from a ~1 Ga, ultrahigh temperature granulite from Rogaland(Norway). This sample has recorded concordant UeP b dates(measured by LA-ICP-MS) that range over 100 My, with the three domains yielding distinct isotopic Ue Pb ages of 1034 ± 6 Ma(D1; Srich core), 1005 ± 7 Ma(D2), and 935 ± 7 Ma(D3), respectively. Combined APM and TEM characterization of these monazite crystals reveal phase separation that led to the isolation of two different radiogenic Pb(Pb*) reservoirs at the nanoscale. The S-rich core of these monazite crystals contains Cae Srich clusters, 5 -10 nm in size, homogenously distributed within the monazite matrix with a mean interparticle distance of 40 -60 nm. The clusters acted as a sink for radiogenic Pb(Pb*) produced in the monazite matrix, which was reset at the nanoscale via Pb diffusion while the grain remained closed at the micro-scale. Compared to the concordant ages given by conventional micro-scale dating of the grain,the apparent nano-scale age of the monazite matrix in between clusters is about 100 Myr younger, which compares remarkably well to the duration of the metamorphic event. This study highlights the capabilities of combined APM-TEM nano-structural and nano-isotopic characterizations in dating and timing of geological events, allowing the detection of processes untraceable with conventional dating methods.