http://www.sciencedirect.com/science/article/pii/S1674987112000084

Seismic anisotropy and its main features along the convergent boundary between Africa and Iberia are detected through the analysis of teleseismic shear-wave splitting.Waveform data generated by 95 teleseismic events recorded at 17 broadband stations deployed in the western Mediterranean region are used in the present study.Although the station coverage is not uniform in the Iberian Peninsula and northwest Africa,significant variations in the fast polarization directions and delay times are observed at stations located at different tectonic domains.Fast polarization directions are oriented predominantly NW-SE at most stations which are close to the plate boundary and in central Iberia;being consistent with the absolute plate motion in the region.In the northern part of the Iberian Peninsula,fast velocity directions are oriented nearly E—W;coincident with previous results.Few stations located slightly north of the plate boundary and to the southeast of Iberia show E—W to NE-SW fast velocity directions,which may be related to the Alpine Orogeny and the extension direction in Iberia.Delay times vary significantly between 0.2 and 1.9 s for individual measurements,reflecting a highly anisotropic structure beneath the recording stations.The relative motion between Africa and Iberia represents the main reason for the observed NW-SE orientations of the fast velocity directions.However,different causes of anisotropy have also to be considered to explain the wide range of the splitting pattern observed in the western Mediterranean region.Many geophysical observations such as the low Pn velocity,lower lithospheric Q values,higher heat flow and the presence of high conductive features support the mantle How in the western Mediterranean,which may contribute and even modify the splitting pattern beneath the studied region.     

西伯利亚西部白垩纪孢粉的参照序列:演化阶段,相和对比

研究西伯利亚西部白垩纪沉积层的孢粉可以建立孢粉组合的参照序列。本文运用采自海相剖面的材料与菊石化石带进行对比,建立了下白垩统和上白垩统一些层位中的孢粉化石带。这些新确立的孢粉组合层序反映了白垩纪孢粉植物群的演化阶段。由于生物相和古地理特征的变化,孢粉组合在横向上变化较大,很难依据孢粉资料进行地区间的精确对比。然而,有些孢粉组合演化发展的总体趋势能用于对比、定义部分地层层位。     

鄂东南矿集区程潮大型矽卡岩铁矿的花岗质岩与成矿关系探讨

程潮铁矿床位于鄂东南矿集区鄂城岩体南缘,矿体主要产于花岗质岩与大理岩或花岗质岩与闪长质岩的接触带附近。矿区矽卡岩和花岗质岩与矿体的接触关系密切。稀土元素分析结果表明:石榴子石、绿帘石和磁铁矿矿石的稀土元素配分模式具有右倾、轻稀土富集、Eu正异常和Ce无明显异常的特点,显示它们具有相同的来源,并且是在一种高温、高氧逸度、Eu较富集的流体环境中形成的;花岗质岩与矽卡岩、矿体在稀土元素组成特征方面具有相似性,暗示它们具有成因联系。结合地质特征和稀土元素化学特征可知,程潮铁矿的花岗质岩与矽卡岩和矿体在时间、空间和成因上都有着密切的联系。     

多种形貌羟基磷灰石的控制合成及其生物矿化意义

羟基磷灰石是生物硬组织的重要无机组元,主要存在于骨、牙齿和腕足类动物外壳等矿化结构中。研究发现,生物体不同的组织或者器官中,羟基磷灰石矿物矿化的程度、晶体尺寸、形貌以     

辽西九佛堂组建组剖面的地层划分及相关问题

提要：针对辽西九佛堂组目前的多种划分方案及相关问题,通过对位于小孤山—旧烧锅的九佛堂组建组剖面的重新测量,在兼顾岩相组合和喀左盆地九佛堂组其他剖面沉积特征的基础上,以凝灰质岩石组合作为标志层组,将九佛堂组建组剖面划分为一、二、三、四段。比较详细地阐述了该剖面九佛堂组以粉砂岩、泥质岩为主,其间夹众多极薄层状灰岩或泥灰岩;自下而上具有滨浅湖相、深湖相夹浅湖相、浅湖相的沉积演化特征。小孤山—旧烧锅剖面与九佛堂组其他剖面的差异性表现在碎屑岩的粒度总体较细,未见湖泊三角洲相和扇三角洲相;在二段下部发育3层中、薄层状硅化凝灰岩;九佛堂组建组剖面未出露九佛堂组四段上部和五段。为全面认识九佛堂组,建议在建组剖面的基础上引入辅助剖面,并推荐回民沟—平房东沟剖面、付杖子—烧锅街剖面或张麻子沟—桃花池剖面分别作为九佛堂组一段、四至五段的辅助剖面。     

Climate Reconstruction based on Pollen Analysis in Inner Mongolia, North China from 51.9 to 30.6 kaBP

The palynomorph assemblage of lake sediments younger than 51.9 kaBP from Wulagai Gobi in Inner Mongolia was analyzed to reconstruct the vegetation and climate.From 51.9 to 30.6kaBP,the vegetation was arid to semi-arid grassland with only slight changes.According to the palynomorphs,trees and shrubs were very rare.The large number and diversity of algae indicate the presence of a lake.Quantitative climatic conditions were reconstructed using the Best Analogues Method.The results indicate that the annual mean temperature was higher than that at present.The combination of temperature and annual precipitation suggests a change in the climate from cool dry to warm dry and then cool humid.Our results show that the annual precipitation values were mostly higher than that at present but were lower than 400 mm.It infers that the study area was already within the arid to semi-arid regions but with a stronger influence of the summer monsoon during 51.9to 30.6 kaBP than at present.With slight differences mainly in time scale,the changing trend of the annual temperature curve is consistent with the other climatic records from Antarctica,Greenland,Hulu Cave(East China),and the Tibetan Plateau during the last glacial period.From 30.6 kaBP to present,very few palynomorphs were detected in the samples.Hence,no information about the vegetation and climate could be extracted.Combined with other studies during Late Pleistocene,we presume that the reason for the lack of pollen during this period was caused by an abrupt temperature fall after 30.6 kaBP or that the lacustrine conditions were unsuitable for pollen deposition.It was probably incurred by the oxidation on land prior to deposition.But for those samples only with algae,it might be caused by the fact that algae could finish their life history in a very short time in a seasonal lake.     

加拉帕戈斯三联点北部岩石层的开裂

加拉帕戈斯三联点是由科科斯板块、纳斯卡板块和太平洋板块在加拉帕戈斯微板块处汇聚形成的脊-脊-脊型三向连接构造。在科科斯—纳斯卡裂谷的大部分内斜坡以北区域,长约250km、宽约50km的西北—东南向的火山岩裂谷横插在东太平洋海隆的南北向海山上。在过去的4百万年中,东北—西南向的东太平洋海隆为一系列的较小裂谷提供了条件,使得那些小裂谷通常与东太平洋海隆共同形成三联点,而且与正在扩张的科科斯—纳斯卡裂谷有50～100km的距离。本文假设该裂谷的位置是由压力控制的,并且压力与占主导作用的科科斯—纳斯卡裂谷相关,随着与东太平洋海隆的距离增大而增大。我们推测,在科科斯—纳斯卡裂谷的南侧也曾有类似的短暂性的裂谷发生,并且曾有助于旋转的加拉帕戈斯微板块的初期形成(大约是1.5百万年)。     

球形模板压入仪在冻土长期强度测试中的应用

球形模板压入仪（球模仪）在前苏联和俄罗斯等冻土区土力学性质测试中得到广泛应用。在60多年的工程实践中,试验理论、方法等方面都得到了完善。因其试验简单易行且测试结果能较好地反映冻结土的力学性质,特别是在冻结土黏聚力的长期强度评价及预测方面广泛应用。简要介绍该试验理论、试验方法、试验仪器。以莫斯科郊外冰碛粉质黏土作为研究对象。在恒定-7～20 ℃温度条件下,在封闭状态下分别进行3、6、20、40次冻融循环试验。对各试验阶段土样进行物理性质测试,之后用球模仪对冻结土样进行强度测试。冻融循环后土样的各物理指标均有不同程度的减小,随着冻融次数的增加,其强度降低。冻融过程中,土样中水体积的变化使其密度减小、孔隙率增大是造成这一结果的原因。     

考虑初始损伤和蠕变损伤的岩石蠕变全过程本构模型

考虑到天然岩石存在不同程度初始损伤以及蠕变过程中岩石受载后裂隙扩展而导致的新损伤,对具有初始损伤的岩石蠕变特性进行全面描述。根据不闭合结构面应力与法向变形之间的关系,提出裂隙岩石塑性变形体元件,描述岩石蠕变过程中的瞬时塑性变形。引入初始损伤影响因子,建立具有初始损伤的岩石损伤变量演化方程,构建模拟岩石加速蠕变的蠕变损伤体元件。将裂隙岩石塑性变形体和蠕变损伤体与描述瞬时弹性变形和黏弹性变形的广义开尔文模型进行串联组合,形成能够反映具有初始损伤的岩石瞬时弹-塑性变形、稳定蠕变和加速蠕变的蠕变全过程本构模型,提出了进行少量蠕变试验既能解析模型参数的方法,在不同应力水平下模型理论曲线与蠕变试验曲线吻合。     

化学方法改良吹填土固结沉降性质研究

大连市大窑湾港区的吹填土为高分散性低液限粉质黏土,其特点是亲水性高,含水量大,排水率低,这造成了吹填土承载力低,在荷载作用下变形量大,在很长一段时间内无法作为正常建筑地基使用.通过在盐水环境下添加不同剂量的浓度为0.1%的絮凝剂Praestol-2515或Praestol-650溶液,可以观察到土颗粒迅速聚合,土粒粒径明显增大,粒间胶结更加均匀和紧密,形成絮状物,从而促进了土颗粒与自由水分的分离,导致过饱和吹填土（悬浊液）沉降速度大大提高,极大地缩短了吹填土的排水固结时间,在短期内达到建筑地基所需要的变形量和承载能力.研究结果对于沿海地区过饱和吹填土的造陆工程,以及类似的高含水率黏性土的地基处理具有重要的启示意义.